Title: Image projector, projected image pattern, laser driver, imaging device
Abstract: Image projection apparatus wherein, a focusing lens is controlled when a shutter is operated so that a contrast signal, obtained when a luminance signal from a camera signal processing circuit is supplied to an auto focusing detection circuit, may become maximum. A laser diode is driven to generate laser beams that are condensed into parallel laser beams by a condenser. These parallel laser beams are applied to a hologram plate and thereby diffracted. The diffracted laser beams interfere with each other, to produce a hologram image with sufficient contrast. Therefore, satisfactory focusing can be made in an auto focus mode of the contrast detection system or in a manual focus mode.
Patent Number: 6,892,027 Issued on 05/10/2005 to Nakamura
| Inventors:
|
Nakamura; Makibi (Tokyo, JP)
|
| Assignee:
|
Sony Corporation (Tokyo, JP)
|
| Appl. No.:
|
203117 |
| Filed:
|
December 5, 2001 |
| PCT Filed:
|
December 5, 2001
|
| PCT NO:
|
PCTJP01/10620
|
| 371 Date:
|
January 21, 2003
|
| 102(e) Date:
|
January 21, 2003
|
| PCT PUB.NO.:
|
WO0246820 |
| PCT PUB. Date:
|
June 13, 2002 |
Foreign Application Priority Data
| Dec 07, 2000[JP] | 2000-373075 |
| Sep 05, 2001[JP] | 2001-269177 |
| Sep 05, 2001[JP] | 2001-269178 |
| Current U.S. Class: |
396/106; 348/370; 396/431 |
| Intern'l Class: |
G03B 013/18 |
| Field of Search: |
396/106-113,431
|
References Cited [Referenced By]
U.S. Patent Documents
| 5485235 | Jan., 1996 | Meyers.
| |
| 5569904 | Oct., 1996 | Meyers.
| |
| 5701015 | Dec., 1997 | Lungershausen et al.
| |
| Foreign Patent Documents |
| 0 693 700 | Jan., 1996 | EP.
| |
| 61-48883 | Mar., 1986 | JP.
| |
| 8-54559 | Feb., 1996 | JP.
| |
| 10-254337 | Sep., 1998 | JP.
| |
| 11-353422 | Dec., 1999 | JP.
| |
Primary Examiner: Perkey; W. B.
Attorney, Agent or Firm: Frommer Lawrence & Haug LLP, Frommer; William S.
Claims
1. An image projection apparatus that is used with a camera apparatus and has
a function to project onto an object a hologram reproduced image that is obtained
by applying light of laser beams to a hologram plate, said image projection apparatus comprising:
a laser light source for generating light of diffused laser beams;
a lens for converting said light of diffused laser beams to light of parallel
laser beams; and
said hologram plate irradiated with said light of parallel laser beams, wherein
said lens is integrated with said hologram plate into one body unit.
2. A projection image pattern that is projected by an image projection apparatus
that is used with a camera apparatus, possesses a function to project onto an object
a hologram reproduced image that is obtained by applying light of laser beams to
a hologram plate, and is comprised of a laser light source for generating said
light of laser beams and said hologram plate, said projection image pattern being
composed of at least part of first to fifth segments, that are comprised of one
or a plurality of segments, each segment including a predetermined number of light
spots arrayed in a straight line, wherein
said first segment is provided in the center of a projected image at an angle
of approximately 45 degrees with horizontal and vertical axes of an image pickup
plane;
four said second segments are provided, at right angles with said first segment,
at each vertex of a square that circumscribes a circle centered at the center of
said first segment and has a predetermined length of diameter;
eight said third segments are provided, in parallel with said first segment,
at each vertex and at each vertex and at a midpoint in each side of a square that
circumscribes a circle centered at the center of said first segment and has a diameter
twice the predetermined length;
twelve said fourth segments are provided, at right angles with said first segment,
at each vertex and at points trisecting each side of a square that circumscribes
a circle centered at the center of said first segment and has a diameter three
times the predetermined length;
four said fifth segments are provided, in parallel with said first segment, at
a midpoint of each side of a square that circumscribes a circle centered at the
center of said first segment and has a diameter four times the predetermined length.
3. A projection image pattern according to claim 2, wherein the central light
spot is removed from said predetermined number of light spots forming said first segment.
4. A camera apparatus comprising an image projection apparatus including:
a laser light source for generating light of diffused laser beams;
a lens for converting said light of diffused laser beams to light of parallel
laser beams; and
a hologram plate irradiated with said light of parallel laser beams and integrated
with said lens into one body unit, wherein
said image projection apparatus projects onto an object a hologram reproduced
image that is obtained by applying said light of parallel laser beams to said hologram
plate, and
said camera apparatus performs an auto focusing operation by using a projected
image of said hologram reproduced image projected onto said object.
5. A camera apparatus comprising an image projection apparatus including:
a laser light source for generating light of diffused laser beams;
a lens for converting said light of diffused laser beams to light of parallel
laser beams; and
a hologram plate irradiated with said light of parallel laser beams and integrated
with said lens into one body unit, wherein
said image projection apparatus projects onto an object a hologram reproduced
image that is obtained by applying said light of laser beams to said hologram plate;
and
operation means for projecting said hologram reproduced image in a manual focus
mode is provided.
Description
TECHNICAL FIELD
The present invention relates to an image projection apparatus, a projection
image pattern, a laser drive apparatus and a camera apparatus fit for use in an
electronic still camera, for example. Particularly, the present invention relates
to an image projection apparatus, a projection image pattern, a laser drive apparatus
and a camera apparatus each of which helps focusing adjustment when a user takes
a picture, for example, in the dark.
BACKGROUND ART
When a user takes a picture by a still camera, for example, in the dark because
it is difficult for a user to visually confirm an object, the object cannot be
brought into focus by an auto focus camera, for example, of a contrast detection
type. It is also difficult to bring the object into focus in a manual focus mode.
To solve this problem, there has been employed so far a method which enables an
auto focusing operation by irradiating the object with an auxiliary floodlight
such as an LED. According to this method, however, when an object has low contrast,
it used to be difficult to bring the object into focus.
On the other hand, for example, a floodlight for producing a large output required
for obtaining the brightness enough to focus on the object consumes large electric
power and thus produces such a great deal of heat that the floodlight cannot be
used near the object. Alternatively, there is known, for example, a method in which
light is condensed by a lens to floodlight an object. However, when light is condensed
into a narrow area in order to increase the brightness of an object, if a user
takes a picture using a wide-angle lens, then a floodlighted area will be too narrow
to make focusing easily. Conversely, if the floodlighted area is made so wide as
corresponds to that in the wide-angle photographing, a sufficient brightness of
the object cannot be obtained disadvantageously.
Further, while there is employed an auxiliary floodlight in which a lens
and a slit are placed in front of an LED or an electric bulb, etc. to project an
image of the slit onto the object, a projected image has low contrast, so that
satisfactory focusing is made difficult. Moreover, according to this method, light
loss is unavoidably produced in the floodlight due to the slit, and hence electric
power consumption for obtaining a necessary quantity of light is extremely large.
As a result, it is difficult for the above-mentioned auxiliary floodlight to be
incorporated into, for example, a small electronic still camera and driven by a
power supply such as a built-in battery.
Aside from these prior arts, there has been proposed an image projection apparatus
in which an arbitrary hologram reproduced image is projected by using, for example,
a laser light source and a hologram plate. Such hologram reproduced image can enhance
contrast of a projected image. Accordingly, it is conceived that this hologram
reproduced image is projected onto an object to be made use of focusing. That is
to say, the detection in the manual focus mode or in the auto focus mode is performed
using the hologram reproduced image that is projected onto the object.
However, the image projection apparatus is such that a hologram plate is
added to the existing so-called "laser pointer", the structure of which is shown
in FIGS. 14A and 14B, for example. Specifically, as shown in FIG. 14A, a laser
light source 71 for generating light of diffused laser beams and a condenser
72 for converting the light of diffused laser beams to light of parallel
laser beams are provided within a lens barrel 70. The light of parallel
laser beams converted by this condenser 72 is used as a laser pointer for
indicating an arbitrary point and so on.
A hologram plate 73 is provided within a lens barrel 74 which is
fitted onto the lens barrel 70. Then, when the light of parallel laser beams
is applied to this hologram plate 73, a hologram reproduced image is formed
and projected onto the object. However, in this image projection apparatus, the
laser light source 71 and the condenser 72 are integrated with each
other as a single unit by the lens barrel 70, and the hologram plate 73
of the lens barrel 74 is added to this unit thus formed. When the lens barrel
74, for example, is broken, there is a risk that only the hologram plate
73 may be detached from the unit.
Accordingly, when the hologram reproduced image is projected onto the
object to be used for focusing as described above, if only the hologram plate 73
is detached from the unit and the light of parallel laser beams from the condenser
72 is directly applied to the object as shown in FIG. 14B, then the object,
for example, a man will feel discomfort due to a dazzling light of parallel laser
beams if he sees it. When the hologram plate 73 is present, the hologram
reproduced image is formed and hence light of laser beams is diffused, so that
the discomfort given to a man will be alleviated.
The present invention is made in view of the aforesaid points and the problems
to be solved is as follows: When a user takes a picture by a still camera in the
dark, for example, it is difficult for the user to focus in the auto focus mode
of the contrast detection system or in the manual focus mode. On the other hand,
the camera apparatus using the conventional auxiliary floodlight does not allow
a satisfactory focusing to be performed. Moreover, because the conventional auxiliary
floodlight consumes large power, it cannot be incorporated into a small electronic
still camera for use.
Furthermore, the image projection apparatus using, for example, the
laser light source and the hologram plate has a risk that, when the hologram plate
is detached and so forth, a man as an object will feel uncomfortable very much
due to a dazzling light of parallel laser beams if he sees it.
DISCLOSURE OF INVENTION
The present invention seeks to facilitate the focalization when a user takes
a picture, for example, in the dark. For this purpose, the present invention is
arranged to project onto the object the hologram reproduced image which is obtained
by using the laser light source and the hologram plate. In this connection, there
will be disclosed below an image projection apparatus, a projection image pattern,
a laser drive apparatus and a camera apparatus according to the present invention.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram showing an embodiment of an image projection apparatus
and a camera apparatus according to the present invention.
FIG. 2 is a flow chart for explaining an operation of the embodiment.
FIG. 3 is a flow chart for explaining another operation of the embodiment.
FIG. 4 is a diagram showing an embodiment of a projection image pattern according
to the present invention.
FIG. 5 is a graph for explaining the pattern.
FIG. 6 is a flow chart showing an operation of a laser drive apparatus according
to an embodiment of the present invention.
FIG. 7 is a flow chart showing an operation of a laser drive apparatus for adjusting
an output of a laser light source according to another embodiment of the present invention.
FIG. 8 is a diagram showing environment for the laser drive apparatus to adjust
the output of the laser light source.
FIG. 9 is a block diagram showing a specific circuit of the laser drive apparatus
according to an embodiment of the present invention.
FIG. 10 is a flow chart showing an operation of a laser drive apparatus according
to still another embodiment of the present invention.
FIGS. 11A and 11B are waveform diagrams of a pulse signal for explaining a
laser drive apparatus according to yet another embodiment of the present invention.
FIGS. 12A and 12B are specific structure diagrams of an image projection apparatus
and a camera apparatus according to the present invention.
FIG. 13 is a diagram for explaining the above embodiments of the present invention.
FIGS. 14A and 14B are structure diagrams of conventional image projection apparatus.
BEST MODE FOR CARRYING OUT THE INVENTION
An image projection apparatus, a projection image pattern, a laser drive apparatus
and a camera apparatus according to the present invention will be described below
with reference to the drawings, FIG. 1 of which is a block diagram showing structures
of an image projection apparatus and a camera apparatus according to an embodiment
of the present invention.
Referring to FIG. 1, image light from an object (not shown), for example,
is condensed through a main lens
1, a zoom lens
2 and a focusing
lens
3 and an object image is brought into focus on a charge coupled device
(hereinafter abbreviated to "CCD")
4 serving as an image pickup means. This
object image is photoelectrically converted by the CCD
4 and further converted
into a digital signal by a sample/hold and gain control (hereinafter abbreviated
to "S/H & AGC) circuit
5.
This digital signal is further converted into a chrominance signal and a luminance
signal by a camera signal processing circuit
6 and then outputted to a signal
recording system, not shown. The luminance signal from this camera signal processing
circuit
6 is supplied to an auto focusing (hereinafter abbreviated to "AF")
detection circuit
7, in which a contrast signal necessary for AF is generated
using this luminance signal. Then, the contrast signal thus generated is supplied
to a microcomputer (hereinafter abbreviated to "micon")
8 for use in control operations.
Thus, if the micon
8 detects that a shutter release
9, for example,
is half depressed, then the micon controls the focusing lens
3 so as to
make the above-mentioned contrast signal maximum in level for AF operation. The
focusing lens
3 may be controlled by sending an amount signal to a motor
driver circuit
10 for driving a focus motor
11. Similarly, the zoom
lens
2 may be controlled by sending an amount controlling signal to the
motor driver circuit
10 for driving a zoom motor
12.
A control signal is supplied from the micon
8 to a laser driver
13,
whereby a laser diode
14 is driven to generate light of laser beams only
while this control signal is supplied from the micon to the laser driver. The light
of laser beams thus generated is condensed by a condenser
15 into light
of parallel laser beams and the light of parallel laser beams is applied to a hologram
plate
16, in which the light of parallel laser beams is diffracted by a
hologram provided in the hologram plate
16. Then, the laser beams thus diffracted
are caused to interfere with each other, thereby making a hologram reproduced image
17 reproduced.
As a result, this hologram reproduced image
17 can be projected onto the
object which lies , for example, in the optical axis direction of the main lens
1. In this case, if the hologram reproduced image
17 is composed
of segments, then an area where the image is projected can be decreased as compared
with a projection range. Thus, an image with high contrast can be projected to
increase illuminance of the object. In other words, by projecting the image with
high contrast onto the object, satisfactory focusing can be done with ease.
Additionally, the means (apparatus) itself for projecting the above-mentioned
hologram reproduced image
17 is readily available as an auxiliary device
for use with the existing laser pointer, for example, which apparatus can easily
be formed by applying such device thereto. Because the laser diode
14 for
use with such laser pointer can be driven with extremely small power consumption,
such laser diode can be incorporated, for example, into a small electronic still
camera, and can easily be driven by a built-in battery and the like.
There is further provided a manual switch
18 for controlling a manner
in which the hologram reproduced image
17 is projected onto the object.
When this manual switch
18 is operated, a high potential signal is supplied
to the micon
8. Further, a control signal from the micon
8 is supplied
to a flash device
19 so that the light emission of the flash device
19
may be controlled by this control signal as needed. Moreover, data corresponding
to measured values and controlled values generated within the micon
8 are
stored in a nonvolatile memory (e.g., EEPROM)
20.
FIG. 2 shows a flow chart of exemplary processings executed when the auto focusing
operation is performed by the above-mentioned apparatus. Specifically, in FIG.
2, following the start of operation, it is first determined at a step [
1]
whether or not the shutter release
9 is half depressed. If it is not depressed
(No), then this step [
1] is repeated. If it is determined at the step [
1]
that the shutter release
9 is depressed (Yes), then the laser diode
14
is driven at a step [
2] to start the projection of laser beams.
At a step [
3], the AF operation is performed and it is determined at a
step [
4] whether or not the AF operation is over. If the AF operation is
not over (No), then the steps [
2], [
3] are repeated. If it is determined
at the step [
4] that the AF operation is over (Yes), then the laser diode
14 is deactivated to halt the projection of light of laser beams. At a step
[
6], for example, the flash device is activated to capture an image (photograph)
and the processing is stopped.
The processings are executed in this manner when the above-mentioned apparatus
is applied to the auto focusing operation. In this case, while the AF operation
is performed at the step [
3], the hologram reproduced image
17 which
is reproduced at the step [
2] is projected onto the object, and hence an
extremely satisfactory AF operation can be performed using this hologram reproduced
image
17. Because the projection of this hologram reproduced image
17
is halted at the step [
5] when the image is captured (photographed), this
hologram reproduced image will never hinder the user from taking a picture.
FIG. 3 is a flow chart showing exemplary processings executed when the above-mentioned
apparatus is used in the manual focus mode. In this case, for example, when the
manual switch
18 of the above-mentioned apparatus is operated, the processing
is started. Following the start of operation, at a step [
11], the laser
diode
14 is driven first to start the projection of light of laser beams.
It is determined at the next step [
12] whether or not the shutter release
9 is half depressed.
If it is determined at the step [
12] that the shutter release
9
is not depressed (No), then the manual focus mode is not over, and hence the steps
[
11], [
12] are repeated. On the other hand, if the manual focus mode
is over and it is determined at the step [
12] that the shutter release
9
is depressed (Yes), then the laser diode
14 is deactivated to halt the projection
of light of laser beams at a step [
13]. Then, an image is captured (photographed)
at a step [
14] and the processing is stopped.
The processings are executed in this manner, when the above-mentioned apparatus
is used in the manual focus mode. In this case, because the hologram reproduced
image
17 which is reproduced at the step [
11] is projected onto the
object, a user can make an extremely satisfactory manual focusing by visually confirming
this hologram reproduced image
17. Because this hologram reproduced image
17 is turned off at the step [
13] when the image is captured (photographed),
this hologram reproduced image will never hinder the user from taking a picture.
Accordingly, in this embodiment, because the hologram reproduced image
obtained by using the laser light source and the hologram plate is projected onto
the object, the hologram reproduced image having sufficient contrast can be projected
onto the object by small power consumption. Thus, satisfactory focusing can be
done in the auto focus mode of the contrast detection system or in the manual focus
mode. At the same time, this apparatus can easily be incorporated into, for example,
a small electronic still camera.
As described above, when a user takes a picture by a still camera, for example,
in the dark, it is difficult for the user to focus in the auto focus mode of the
contrast detection system or in the manual focus mode. On the other hand, the user
not can make sufficient focusing with the camera apparatus using the conventional
auxiliary floodlight. Furthermore, the conventional auxiliary floodlight consuming
a large amount of electric power cannot be incorporated into a small electric still
camera or the like. According to the present invention, these problems can be overcome
with ease.
In the above-mentioned apparatus, as the projection image pattern of the hologram
reproduced image for use in projection, such one shown in FIG. 4 is used, for example.
FIG. 4 shows a projection image pattern according to an embodiment of the present
invention. As shown in FIG. 4, the projection image pattern is comprised of at
least one or a plurality of first to fifth segments A to E on each of which a predetermined
number of light spots are arrayed in a straight line. The first segment A is provided
at the center of the projection image at an angle of approximately 45 degrees with
horizontal and vertical axes of the image pickup plane.
There are provided four second segments B
1 to B
4, at
right angles with the first segment A, at each vertex of a square X
1 which
circumscribes a circle that is centered at the center of the first segment A and
has a predetermined length of diameter a (X
1 is shown by broken lines:
the square shown by broken lines is not a projection image pattern and hereinafter
the same applies.). There are further provided eight third segments C
1 to
C
8, in parallel with the first segment A, at each vertex and at a midpoint
in each side of a square X
2 (shown by broken lines) which circumscribes
a circle that is centered at the center of the first segment A and has a diameter
2a twice the predetermined length a.
There are also provided twelve fourth segments D
1 to D
12,
at right angles with the first segment A, at each vertex and at points trisecting
each side of a square X
3 (shown by broken lines) which circumscribes
a circle that is centered at the centre of the first segment A and has a diameter
3a three times the predetermined length a. There are further provided
four fifth segments E
1 to E
4, in parallel with the first
segment A, at a midpoint of each side of a square X
4 (shown by broken
lines) which circumscribes a circle that is centered at the center of the first
segment A and has a diameter
4a four times the predetermined length
a. In this way, the projection image pattern composed of twenty-nine segments in
total is formed.
In this projection image pattern, each of the segments A to E is comprised of,
for example, a fifteen light spots, arrayed in a straight line. The length of these
segments A to E are set at 0.8 degree by a projection angle, for example. The central
spot of the arrayed light spots is removed from the segment A. Specifically, a
hologram for making the segments A to E shown in FIG. 4 into a reproduced image
is found by calculation, and the hologram based upon this calculation is provided
on the hologram plate
16.
The circle having a diameter of the predetermined length a, which is inscribed
in the square X
1, is set at, e.g. three degrees by a projection angle.
As a result, a projection angle of the circle which is inscribed in the square
X
2 will be six degrees; a projection angle of the circle which is inscribed
in the square X
3 will be nine degrees; and a projection angle of the
circle which is inscribed in the square X
4 will be twelve degrees. In
this case, a pattern within the circle which is inscribed, e.g. in the square X
2
is comprised of seven segments substantially. Thus, an output of the laser
diode
14 is set so that the quantity of heat produced when light corresponding
to the seven segments strikes man's retina may be less than the value of safety standards.
Therefore, according to this embodiment of the projection image pattern,
even if positions of view points are moved under the respective projection angles,
the heat generated will never exceed the value of safety standards. FIG. 5 is a
graph showing the relation between the maximum powers and receptive angles with
respect to heat generated, which was found by simulation. As this figure shows,
even continuous generation of laser beams conforms to the safety standards of 1000
second AEL of the class 1 of the JIS.
Moreover, according to the embodiment of the above-mentioned projection
image pattern, because the angles of adjacent segments are alternately changed
from each other, the substantial space between the segments can be reduced by the
distance of half the length of the segment. Therefore, when the detection range
of the auto focus is, e.g. about 3 degrees in terms of the projection angle, even
if the optical axis of a camera lens is not coincident with the center of the projection
image pattern, it is possible to remove such a risk that no segment will fall within
the detection range.
Furthermore, in the above embodiment of the projection image pattern,
the central light spot is removed from the light spots forming the first segment
A located at the center. As a consequence, although in the hologram reproduced
image zero-order light may sometimes be generated at the center of the image in
addition to an original image pattern, a brightness of the light spot at the center
of the first segment A can be prevented from being raised due to such zero-order
light, thus allowing a satisfactory detection to be done. Even if the light spot
at the center of the first segment has no brightness, there is no risk that the
detection, e.g. in the auto focus mode may be interfered with.
In the above-mentioned apparatus, the laser diode
14 is driven as shown
in FIG.
6. That is, FIG. 6 is a flow chart showing exemplary operations
of the laser drive apparatus according to an embodiment of the present invention.
Referring to FIG. 6, upon the start of operation, it is first determined
at a step [
21] whether or not the shutter release
9 is half depressed.
If it is depressed (Yes), it is determined at a step [
22] whether or not
a value of "on-counter" of an arbitrary register is less than 100 seconds. If the
on-counter value is less than 100 seconds (Yes), a predetermined value is added
to the on-counter value at a step [
23]. A value of an "off-counter" of an
arbitrary register is reset to zero at a step [
24], and the application
of light of laser beams is maintained at a step [
25].
It is further determined at a step [
26] whether or not a command for making
the power supply off is issued. If such command for making the power supply off
is issued (Yes), then the operation comes to an end (End). If it is determined
that no command for making the power supply off is issued (No), then the operation
is returned to the step [
21]. If it is determined at the step [
21]
that the shutter release
9 is not depressed (No) and if it is determined
at the step [
22] that the on-counter value is not less than 100 seconds
(No), then it is determined at a step [
27] whether or not the off-counter
value is less than five seconds.
If it is determined at the step [
27] that the off-counter value is less
than five seconds (Yes), then a predetermined value is added to the off-counter
value at a step [
28]. If it is determined at the step [
27] that the
off-counter value is not less than five seconds (No), then the on-counter value
is reset to zero at a step [
29]. After the steps [
28] and [
29]
have been finished, the application of light of laser beams is stopped at a step
[
30], and it is determined at the step [
26] whether or not the command
for making the power supply off should be issued.
Accordingly, in this flow chart, when the on-counter value goes greater
than 100 seconds, the application of light of laser beams is stopped. Besides,
while the off-counter value remains less than five seconds, the on-counter value
is not reset. Therefore, the apparatus is operated so that duration in which the
application of light of laser beams is stopped may always be five seconds or longer.
Thus, when the light of laser beams, for example, is applied continuously, an output
of the apparatus can be prevented from falling due to heat and the like. As a consequence,
it is possible to eliminate a radiator plate or the like that has so far been used
as a conventional countermeasure against the heat generation.
Moreover, in the above-mentioned apparatus, an output of the laser diode
14 is adjusted as shown in FIGS. 7 and 8. Specifically, FIG. 7 is a flow
chart showing operations of the laser drive apparatus to adjust the output of the
laser diode
14 according to another embodiment of the present invention.
FIG. 8 shows an environment under which the output of the laser diode is adjusted
by the laser diode drive apparatus.
Referring to FIG. 8, a screen
200 is attached to one of wall surfaces
of a box
100 the inside of which is painted in black. The above-mentioned
camera apparatus is disposed through an opening
300 provided on the wall
surface opposite to the screen
200. Then, the above-mentioned hologram reproduced
image
17 is projected onto the screen
200 and the projected image
on this screen
200 is picked up by the CCD
4. Further, the image
picked-up output from this CCD
4 is detected to adjust the output from the
laser diode
14.
Referring to FIG. 7, upon the start of adjustment operation, a control
value (DA) supplied from the micon
8 to the laser driver
13 is set
as an initial value at a step [
31], and the lens position is set for a distance
between the camera apparatus disposed through the opening
300 and the screen
200 at a step [
32]. Then, at a step [
33], the above-mentioned
control value (DA) is supplied through a DA output from the micon
8 to the
laser driver
13. At a step [
34], the laser diode
14 starts
to be driven.
In this way, the laser diode
14 is driven in accordance with the predetermined
initial value, the hologram reproduced image
17 based upon the laser output
according to this initial value being projected onto the screen
200, and
this projected image being picked up by the CCD
4. Then, at a step [
35],
an automatic exposure (AE) detected value (AE DATA) is detected from the image
picked-up output and compared with an AE target value (AE TARGET) at a step [
36].
If the two values are not equal to each other (No), then, a control value (DA)
is calculated at a step [
37].
Specifically, at the step [
37], a new control value (DA) is
calculated from an expression, e.g. DA=DA×(AE TARGET)÷(AE DATA) and the
resultant value is returned to the step [
33]. This operation will be repeated
until (AE DATA)=(AE TARGET) is satisfied at the step [
36]. Then, when the
two values become equal to each other (Yes), the control value (DA) is stored in
the nonvolatile memory
20 at a step [
38] and the operation comes
to an end.
In this manner, the value which is used to adjust the dispersion of the output
from the laser diode
14 is stored in the nonvolatile memory
20. In
actual practical use, the control value (DA) for driving the laser diode
14
is calculated based upon the value stored in this memory
20 and taking other
conditions and the like into consideration. In other words, when a user takes a
picture, the stored value is read out from this memory
20 to be used as
a basic value for adjustment. At the same time, information on stop, zoom position
and the like is considered to control the output of the laser diode
14.
The dispersion of the output of the laser diode
14 can be adjusted by
using not only the above-mentioned automatic exposure detected value but also a
contrast detected value and the like. For example, the control value (DA) in which
the contrast detected value forms the target value is stored in the memory. Moreover,
if not only the above-mentioned control value but also the detected value itself
and other measured values are stored in the memory
20, then such stored
values can be used, for example, to check products in manufacturing, and also to
check their performances when services or repairs are made after the products have
been shipped.
Accordingly, in this embodiment, the output of the laser diode
14
as well as the sensitivity of the CCD
4 is adjusted. Specifically, while
the output of the laser diode
14 according to the control value has dispersion
between individual products, the sensitivity of the CCD
4 also fluctuates
similarly about 20 percent. Accordingly, by adjusting the output of the assembled
camera apparatus using the image picked-up output of the CCD
4, the adjustment
which absorbs both the dispersion and fluctuation can be carried out.
In the above-mentioned apparatus, the laser driver
13 has a specific structure
as shown in FIG.
9. FIG. 9 is a block diagram showing a specific circuit
of a laser drive apparatus according to an embodiment of the present invention.
Referring to FIG. 9, the laser diode
14 is driven by a power supply
of, e.g. 5V, and other circuits including the micon
8 are driven by a power
supply of 3.2V. An output signal from the micon
8 is supplied through a
switching transistor
51 to a switching transistor
52 provided at
the power supply line of 5V, whereby the power supply of 5V is turned on and off.
A voltage from the power supply of 5V which is turned on and off is supplied through
a transistor
53 to the laser diode
14.
A photodiode
54 is provided in the vicinity of this laser diode
14.
An output from this photodiode
54 is supplied to a non-inverting input terminal
of an operational amplifier
55, whereas a control value from the micon
8
is supplied to an inverting input terminal of the operational amplifier
55
through a digital-to-analog converter (DAC)
56. An output from this operational
amplifier
55 is supplied to the base of the transistor
53. This causes
the output of the laser diode
14 to be adjusted so that the output of the
photodiode
54 may be kept at a desired value.
An output from the switching transistor
52 is supplied to a falling edge
trigger input terminal of a monostable multivibrator (hereinafter abbreviated to
"mono-multi")
57. A Q output of this mono-multi
57 is supplied through
the transistor
58 to the base of a transistor
59. A signal obtained
at the collector of this transistor
59 is supplied to the base of a transistor
60 connected between the 5V power supply line after the switching transistor
52 and the base of the transistor
53.
Thus, in this circuit, when the laser diode
14 is continuously driven,
for example, by the output continuously generated from the switching transistor
52, if the time period driving this laser diode exceeds an inverting time
of the mono-multi
57, then the transistor
58 is turned on, the transistor
59 being turned off and the transistor
60 being turned on. As a result,
the base potential of the transistor
53 rises to make and the transistor
53 turned off, whereby such continuous driving of the laser diode
14
is stopped.
Further, in the above-mentioned circuit, the output of the photodiode
54
is supplied to an A/D converting input terminal of the micon
8 which monitors
the output of the photodiode
54 to operate, for example, as shown in FIG.
10.
FIG. 10 is a flow chart showing operations of a laser drive apparatus according
to a still another embodiment of the present invention. Referring to FIG. 10, it
is first determined at a step [
41] whether or not the shutter release
9
is half depressed. If the shutter release is depressed (Yes), it is determined
at a step [
42] whether or not a monitor voltage obtained from the photodiode
54 is equal to an arbitrary reference voltage. Then, if the monitor voltage
is equal to the reference voltage (Yes), the application of light of laser beams
is maintained at the following step [
43].
On the contrary, if it is determined at the step [
41] that the shutter
release
9 is not depressed (No) or if it is determined at the step [
42]
that the monitor voltage is not equal to the reference voltage (No), then the application
of light of laser beams is stopped at a step [
44]. Further, it is determined
at a step [
45] whether or not a command for making the power supply off
is issued. If such command for making the power supply off is issued (Yes), then
operations come to an end. If no command for making it off is issued (No), then
the operation is returned to the step [
41].
Accordingly, in this embodiment, when the monitor voltage obtained from
the photodiode
54 becomes equal to the arbitrary reference voltage, the
application of light of laser beams is stopped. In other words, the generation
of light of laser beams is stopped, provided that the output of the monitor means
exceeds an arbitrary tolerance limit. This makes it possible to remove such a risk
that the laser diode
14 may be broken or degraded in durability by an abnormal
driving of the laser diode
14.
Moreover, in the specific circuit of the laser drive apparatus shown in
FIG. 9, a pulse signal, for example, as shown in FIGS. 11A and 11B, is outputted
from the micon
8, and the laser diode
14 is driven according to this
pulse signal. FIGS. 11A and 11B are waveform diagrams of pulse signals for explaining
a laser drive apparatus according to yet another embodiment of the present invention.
In this connection, the micon
8 can form a pulse signal with accuracy,
of for example, 0.8 μsec by using a counter, and can control the pulse width,
for example, by the 0.16 msec. Moreover, a peak output of the pulse signal can
be adjusted, for example, in a range of 0 to 3 mW by the 0.1 mW. Accordingly, for
example, based upon the value that is stored in the memory
20 in the above-mentioned
operations shown in FIG. 7, the peak output of the pulse signal may be determined
and the pulse width may be controlled in consideration of other conditions.
As shown in FIG. 11A, based upon the value stored in the memory
20, the
amplitude of the pulse signal is determined to be ,for example, 2.5 mW. Moreover,
the pulse width of each pulse may be controlled depending on whether the built-in
flash device
19 or an external flash device is used or not. Specifically,
for example, when the built-in flash device
19 is in use, the pulse width
of the pulse signal is controlled to be 5 msec, and when the external flash device
is in use, because long distance to an object is assumed, then the pulse width
is controlled to be 10 msec.
Furthermore, when the photography system is based upon the NTSC system,
the micon forms the pulse signal at a cycle of 33 msec synchronized with the frame.
Because the auto focusing operation can be controlled within 50 frames, it is designed
that 50 pulses are generated during one operation at maximum. In this manner, the
output of the laser diode
14 is adjusted. Such operations are executed by
software of the micon
8.
FIG. 11B shows a waveform of a pulse signal generated when the half depression
of the shutter release
9 is repeated. Specifically, when a user takes a
picture in a normal mode, because it takes approximately four seconds to store
image data in a memory device, an interval of 4 seconds is inevitably formed. Even
if the shutter release
9 is half depressed very quickly, it is arranged
that an interval of one second is formed. Such operations are also executed by
software of the micon
8 and intervals of 0 to 4 seconds are set by the 0.25
second, for example, based upon the values stored in the memory
20.
Moreover, when the laser diode is driven according to the pulse signal
as described above, if the inverting time of the above-mentioned mono-multi
57
shown in FIG. 9 is set to be, for example, 33 msec, then the generation of light
of laser beams can be stopped when the falling edge of the pulse signal does not
occur. Thus, when the means for adjusting a quantity of light of laser beams malfunctions,
the laser diode
14 can be stopped from being driven. This makes it possible
to remove the risk that the laser diode
14 may be damaged or less durable.
Therefore, in this embodiment, the quantity of light of laser beams can
be adjusted satisfactorily by driving the laser light source according on the pulse
signal having an arbitrary pulse width. Moreover, the quantity of light of laser
beams can also be adjusted by controlling the pulse width depending on the presence
or absence of the built-in flash device
19 or the external flash device.
Furthermore, when the means for adjusting the quantity of light of laser beams
malfunctions, the driving of the laser diode
14 can be stopped to remove
the risk that the laser diode
14 may be broken or less durable.
By applying the above-mentioned image projection apparatus, the projection image
pattern or the laser drive apparatus to the camera apparatus according to the present
invention, the hologram reproduced image having a sufficient contrast can be projected
onto the object with small power consumption, so that satisfactory focusing can
be attained. At the same time, these apparatus can easily be incorporated into
a small electronic still camera and the like.
As described above, the image projection apparatus of the present invention comprises
the laser light source for generating light of laser beams and the hologram plate.
By projecting onto the object the hologram reproduced image which is obtained by
applying light of laser beams to the hologram plate, the hologram reproduced image
having good contrast can be projected onto the object with small power consumption,
thus allowing satisfactory focusing to be performed. Also, this apparatus can easily
be incorporated into a small electronic still camera and the like.
Further, according to the projection image pattern of the present invention,
by employing the above-mentioned pattern of FIG. 4, heat produced can be prevented
from exceeding the safety standards limit, even if the position of the view point
is moved under the respective projection angles. At the same time, because the
substantial space between the segments can be reduced by a distance which is half
a length of the segment, even if the optical axis of the camera lens is not coincident
with the center of the projection image pattern, there can be removed such a risk
that a state in which no segment is captured within the detection range may occur.
Moreover, according to the laser drive apparatus of the present invention,
because this laser drive apparatus includes the laser light source for generating
light of laser beams and the laser light source is stopped from generating the
light of laser beams for a fixed time period or longer, on condition that the duration
of emitting the light of laser beams exceeds the predetermined time period, for
example, when the light of laser beams is applied continuously, the output can
be prevented from falling due to heating or the like. Thus, a radiator plate that
has so far been used as a conventional countermeasure against heat generation can
be dispensed with.
Furthermore, the laser drive apparatus of the present invention includes
the laser light source for generating light of laser beams, the means for adjusting
the quantity of light of laser beams and the camera means, and further comprises
the memory means for storing therein the adjustment value found according to an
output of the camera means which has taken the image under previously projected
light of laser beams. Thus, the output of the laser light source as well as the
sensitivity of the camera means can be adjusted by adjusting the quantity of light
of laser beams based upon the stored adjustment value. In other words, the adjustment
absorbing dispersions of the output and the sensitivity can be carried out.
Furthermore, the laser drive apparatus of the present invention includes
the laser light source for generating light of laser beams and the monitor means
for detecting light of laser beams, and is arranged so that the laser light source
may be stopped from generating light of laser beams on condition that an output
of the monitor means exceeds the arbitrary tolerance limit. Thus, it is possible
to remove the risk that the laser light source may be damaged or less durable by
an abnormal driving of laser light source.
Moreover, the laser drive apparatus of the present invention includes the
laser light source for generating light of laser beams and the means for adjusting
the quantity of light of laser beams, and is arranged so that the quantity of light
of laser beams may be adjusted by driving the laser light source using the pulse
signal having the arbitrary pulse width. Thus, the quantity of light of laser beams
can be adjusted satisfactorily, and also the quantity of light of laser beams can
be adjusted depending on the presence or absence of the built-in flash device,
so that it is possible to remove the risk that the laser light source may be broken
or degraded in durability.
Furthermore, the camera apparatus of the present invention includes
the projection means having the laser light source and the hologram plate, for
projecting onto the object a hologram reproduced image which is obtained by applying
light of laser beams from the laser light source to the hologram plate. Thus, the
hologram reproduced image having good contrast can be projected onto the object
with small power consumption, thereby allowing satisfactory focusing to be attained.
At the same time, this apparatus can easily be incorporated into a small electronic
still camera or the like.
In short, the above-mentioned camera apparatus has the advantageous effects as follows:
{circle around (1)} The focusing is enabled in the AF mode even on condition
that the illuminance of an object is low.
{circle around (2)} Even an object with low contrast can be brought into
focus in the AF mode.
{circle around (3)} Because light of laser beams with high contrast is projected
on an object, the focusing is enabled in the auto focus mode with higher accuracy
than before.
{circle around (4)} The long-distance projection, which has heretofore been
difficult to be made with a conventional auxiliary floodlight having low output,
becomes possible.
{circle around (5)} Because of a projecting efficiency several times as high
as that of the conventional auxiliary floodlight, a low-output projection apparatus
can be used for obtaining a sufficient illuminance, so that energy consumption
thereof is reduced to a reciprocal of several of conventional energy consumption.
{circle around (6)} Because an effective projected area is small, it is less
possible that those who are photographed will feel dazzled.
{circle around (7)} An object with low illuminance and low contrast, which
has been hard to be brought into focus in the conventional manual focus mode, can
be brought into focus with ease.
{circle around (8)} The projection compatible to both of wide-angle lens
mode and telephoto lens mode, which has so far been difficult to be made with the
conventional auxiliary floodlight, becomes possible.
FIGS. 12A and 12B show specific structures of the image projection apparatus
and the camera apparatus according to the present invention. Referring to FIG.
12A, only a laser diode
14 for generating light of diffused laser beams
is provided within a laser-support frame
21. A condenser
15 which
converts light of diffused laser beams to light of parallel laser beams is provided
within a lens-support frame
22 which is fitted on the laser-support frame
21. At the same time, a hologram plate
16 is attached to the lens-support
frame, e.g. by a retaining ring
23. Thus, these elements are integrally
formed as a single unit.
After a clearance between the laser-support frame
21 and the lens-support
frame
22 is adjusted, these laser- and lens-support frames
21 and
22 are fixed by an adhesive and the like. Then, these laser- and lens-support
frames
21 and
22 are attached to a predetermined position of a camera
housing
25 through a transparent acrylic cover
24. In other words,
a window covered by the transparent acrylic cover
24 is provided at the
predetermined position of the camera housing
25 and the laser-and lens-support
frames
21 and
22 are attached to this transparent acrylic cover
24.
As a result, when the laser diode
14 is driven in this state, light of
the diffused laser beams thus generated is converted into light of parallel laser
beams by the condenser
15 and the light of parallel laser beams is applied
to the hologram plate
16, thereby causing a hologram reproduced image (not
shown) to be produced. Then, this hologram reproduced image is projected onto the
object through the transparent acrylic cover
24 provided at the predetermined
position of the camera housing
25.
Accordingly, in this embodiment, the condenser
15 and the hologram
plate
16 are integrated into one body unit. Thus, for example, when the
lens-support frame
22 is broken as shown in FIG. 12B, both of the condenser
15 and the hologram plate
16 are detached from the laser diode
14.
In other words, when the lens-support frame
22 is broken and the hologram
plate
16 is detached from the laser diode, the condenser
15 is also
detached from the laser diode
14 at the same time.
In this case, because only the light of diffused laser beams is generated by
the
laser diode
14 from which the condenser lens
15 is detached, even
if the light of diffused laser beams is directly applied to an object, when the
object is, for example, a man, there will be no risk that a man will feel discomfort
due to the dazzling light of parallel laser beams. Therefore, according to this
embodiment, even if the hologram plate is detached from the laser diode, there
can be removed such a risk that a man may feel discomfort due to the dazzling light
of laser beams.
As described above, when a user takes a picture by a still camera in the dark,
or the like, it is very difficult to focus in the auto focus mode of the contrast
detection system or in the manual focus mode. On the other hand, the image projection
apparatus employing the laser light source and the hologram plate involves a risk
that a man as an object will feel uncomfortable very much if he sees the dazzling
light of parallel laser beams when the hologram plate is detached from the laser
diode. According to the present invention, these problems can be overcome with ease.
In the above-mentioned apparatus, as shown in FIG. 13, for example, when a small
hologram image for taking a picture in the telephoto lens mode and a large hologram
image for taking a picture in the wide-angle lens mode are both projected onto
the object at the same time, it will be possible to make adapt for both of the
wide range projection and the telephotograph projection. Additionally, in FIG.
13, there are projected such hologram images that a projection angle of an inner
circle is set at about 5 degrees and a projection angle of an inner circle is set
at about 20 degrees. In addition, when the hologram images are composed of fine
lines, even the apparatus whose output is small can project with sufficient brightness.
As described above, the image projection apparatus according to the present invention
comprises the laser light source for generating the light of diffused laser beams,
the condenser for converting the light of diffused laser beams to the light of
parallel laser beams and the hologram plate which is irradiated with the light
of parallel laser beams. Because the condenser is integrated with the hologram
plate
