Title: Power control apparatus for a bicycle
Abstract: A power control apparatus for a bicycle that uses a first power supply and a second power supply to provide electrical power includes a voltage sensor for sensing a voltage from the first power supply. A control unit is coupled to the voltage sensor and is coupled for receiving power from the first power supply and the second power supply. The control unit outputs power from the second power supply when the voltage sensed by the voltage sensor is below a selected value, and the control unit outputs power from the first power supply when the voltage sensed by the voltage sensor is above the selected value.
Patent Number: 7,015,598 Issued on 03/21/2006 to Oohara
| Inventors:
|
Oohara; Kouji (Sakai, JP)
|
| Assignee:
|
Shimano, Inc. (Osaka, JP)
|
| Appl. No.:
|
226496 |
| Filed:
|
August 23, 2002 |
| Current U.S. Class: |
307/47; 307/68; 474/70 |
| Current Intern'l Class: |
H02J 1/16 (20060101) |
| Field of Search: |
474/70
307/47,65,66,68
|
References Cited [Referenced By]
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| 5455774 | Oct., 1995 | Khawand et al.
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| 5612580 | Mar., 1997 | Janonis et al.
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| 5847641 | Dec., 1998 | Jinbo.
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| 6122181 | Sep., 2000 | Oughton, Jr.
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| 6163445 | Dec., 2000 | Zoellick.
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| 6192300 | Feb., 2001 | Watarai et al.
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| 6216078 | Apr., 2001 | Jinbo et al.
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| 6222343 | Apr., 2001 | Crisp et al.
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| 6569045 | May., 2003 | Campagnolo.
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| 6646400 | Nov., 2003 | Uno.
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| 2001/0027495 | Oct., 2001 | Campagnolo.
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| Foreign Patent Documents |
| 200 16 669 | Feb., 2001 | DE.
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| 199 48 798 | May., 2001 | DE.
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| 21266 | Jan., 1981 | EP.
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| 1216916 | Jun., 2002 | EP.
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| 2061033 | May., 1981 | GB.
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| 2126438 | Mar., 1984 | GB.
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| 2161040 | Jan., 1986 | GB.
| |
| 10-109681 | Apr., 1998 | JP.
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| 10-291491 | Nov., 1998 | JP.
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| 2001/-311737 | Nov., 2001 | JP.
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| 2001/-318005 | Nov., 2001 | JP.
| |
| WO 81/0127/4 | May., 1981 | WO.
| |
Primary Examiner: Sircus; Brian
Assistant Examiner: Squires; Brett
Attorney, Agent or Firm: Deland; James A.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of copending application Ser. No.
10/131,151, filed Apr. 23, 2002.
Claims
What is claimed is:
1. A power control apparatus for a bicycle that uses a first power supply and
a second power supply to provide electrical power comprising:
a voltage sensor for sensing a voltage from the first power supply;
a control unit coupled to the voltage sensor and coupled for receiving power
from the first power supply and the second power supply;
wherein the control unit comprises:
a first power supply switch coupled for outputting power from the first power
supply; and
a separate second power supply switch coupled for outputting power from the second
power supply;
wherein the control unit outputs power from the first power supply when the voltage
sensed by the voltage sensor is above a first selected value, wherein the control
unit outputs power from the second power supply when the voltage sensed by the
voltage sensor is below a second selected value, and wherein the voltage sensor
actually switches the first power supply switch and the second power supply switch
a second power supply voltage sensor for sensing a voltage from the second power
supply, wherein the control unit is coupled to the second power supply voltage
sensor, wherein the control unit outputs power from the first power supply when
the voltage sensed by the second power supply voltage sensor is below a third selected
value, and wherein the control unit outputs power from the second power supply
when the voltage sensed by the second power supply voltage sensor is above a fourth
selected value.
2. The apparatus according to claim 1 wherein the control unit outputs power
only from the second power supply when the voltage sensed by the voltage sensor
is below the second selected value.
3. The apparatus according to claim 1 wherein the control unit outputs power
only from the first power supply when the voltage sensed by the voltage sensor
is above the first selected value.
4. The apparatus according to claim 1 wherein the first power supply switch comprises
a switching voltage regulator.
5. The apparatus according to claim 1 wherein the second power supply switch
comprises a transistor.
6. The apparatus according to claim 1 wherein the control unit includes a processor
coupled to the first power supply switch and to the second power supply switch,
wherein the first power supply switch and the second power supply switch are controlled
at least in part by the processor.
7. The apparatus according to claim 6 further comprising a second power supply
voltage sensor for sensing a voltage from the second power supply, wherein the
processor is coupled to the second power supply voltage sensor, and wherein the
processor controls the first power supply switch and the second power supply switch
in response to the voltage sensed by the second power supply voltage sensor.
8. The apparatus according to claim 7 wherein the processor controls the first
power supply switch to output power from the first power supply when the voltage
sensed by the second power supply voltage sensor is below a third selected value,
and wherein the processor controls the second power supply switch to output power
from the second power supply when the voltage sensed by the second power supply
voltage sensor is above a fourth selected value.
9. The apparatus according to claim 8 wherein the first selected value equals
the second selected value.
10. The apparatus according to claim 8 wherein the third selected value equals
the fourth selected value.
11. The apparatus according to claim 8 wherein the first selected value equals
the second selected value, and wherein the third selected value equals the fourth
selected value.
12. The apparatus according to claim 8 wherein the first power supply switch
comprises a switching voltage regulator, and wherein the second power supply switch
comprises a transistor.
13. The apparatus according to claim 1 further comprising a housing, wherein
the voltage sensor and the control unit are both disposed within the housing.
14. The apparatus according to claim 1 wherein the first selected value equals
the second selected value.
15. The apparatus according to claim 1 wherein the control unit switches power
from the first power supply to the second power supply when the voltage sensed
by the voltage sensor is below the second selected value.
16. The apparatus according to claim 1 wherein the control unit switches power
from the second power supply to the first power supply when the voltage sensed
by the voltage sensor is above the first selected value.
17. The apparatus according to claim 1 wherein the control unit switches power
from the first power supply to the second power supply when the voltage sensed
by the voltage sensor is below the second selected value, and wherein the control
unit switches power from the second power supply back to the first power supply
when the voltage sensed by the voltage sensor is above the first selected value.
18. The apparatus according to claim 17 wherein the first selected value equals
the second selected value.
19. The apparatus according to claim 1 wherein the first selected value equals
the second selected value.
20. The apparatus according to claim 1 wherein the third selected value equals
the fourth selected value.
21. The apparatus according to claim 1 wherein the first selected value equals
the second selected value, and wherein the third selected value equals the fourth
selected value.
22. A power control apparatus for a bicycle that uses a first power supply and
a second power supply to provide electrical power comprising:
a voltage sensor for sensing a voltage from the first power supply;
a control unit coupled to the voltage sensor and coupled for receiving power
from the first power supply and the second power supply;
wherein the control unit outputs power from the first power supply when the voltage
sensed by the voltage sensor is above a first selected value, and wherein the control
unit outputs power from the second power supply when the voltage sensed by the
voltage sensor is below a second selected value;
a second power supply voltage sensor for sensing a voltage from the second power
supply, wherein the control unit is coupled to the second power supply voltage sensor;
wherein the control unit outputs power from the first power supply when the voltage
sensed by the second power supply voltage sensor is below a third selected value,
and wherein the control unit outputs power from the second power supply when the
voltage sensed by the second power supply voltage sensor is above a fourth selected
value; and
wherein the control unit outputs power only from the second power supply when
the voltage sensed by the second power supply voltage sensor is above the fourth
selected value even when the voltage sensed by the voltage sensor is above the
first selected value.
23. A power control apparatus for a bicycle that uses a first power supply and
a second power supply to provide electrical power comprising:
a voltage sensor for sensing a voltage from the first power supply;
a control unit coupled to the voltage sensor and coupled for receiving power
from the first power supply and the second power supply;
wherein the control unit comprises:
a first power supply switch coupled for outputting power from the first power supply;
a second power supply switch coupled for outputting power from the second power
supply; and
a processor coupled to the first power supply switch and to the second power
supply switch, wherein the first power supply switch and the second power supply
switch are controlled at least in part by the processor;
wherein the control unit outputs power from the first power supply when the voltage
sensed by the voltage sensor is above a first selected value, and wherein the control
unit outputs power from the second power supply when the voltage sensed by the
voltage sensor is below a second selected value;
a second power supply voltage sensor for sensing a voltage from the second power
supply, wherein the processor is coupled to the second power supply voltage sensor,
and wherein the processor controls the first power supply switch and the second
power supply switch in response to the voltage sensed by the second power supply
voltage sensor;
wherein the processor controls the first power supply switch to output power
from the first power supply when the voltage sensed by the second power supply
voltage sensor is below a third selected value, and wherein the processor controls
the second power supply switch to output power from the second power supply when
the voltage sensed by the second power supply voltage sensor is above a fourth
selected value; and
wherein the processor controls the first power supply switch and the second power
supply switch to output power only from the second power supply when the voltage
sensed by the second power supply voltage sensor is above the fourth selected value
even when the voltage sensed by the voltage sensor is above the first selected value.
Description
BACKGROUND OF THE INVENTION
The present invention is directed to bicycles and, more particularly, to inventive
features of a power control apparatus for a bicycle.
Many bicycle signal processing systems have been developed. A typical system
often gathers and displays information related to bicycle speed, cadence, distance
traveled and the like. Such systems usually include a magnet mounted to a wheel
spoke, a magnet mounted to one of the pedal cranks, and magnet sensors mounted
to the bicycle frame for sensing the passage of the magnets as the wheel and crank
revolve. An electrical pulse is generated every time a magnet passes its associated
sensor (e.g., once per wheel or crank revolution). The speed of the bicycle can
be calculated based on the number of pulses received from the wheel sensor per
unit of time and the circumference of the wheel. Similarly, the distance traveled
can be calculated based on the number of pulses received over a length of time
and the circumference of the wheel. The cadence can be calculated based on the
number of pulses received from the crank sensor per unit of time. One or more switches
ordinarily are provided for entering operating parameters (e.g., the wheel circumference),
for selecting what information is displayed to the rider, and for starting and
stopping various timers used for calculating the desired information.
More sophisticated systems have the ability to display information related to
the state of the bicycle transmission. For example, some bicycles have a plurality
of front sprockets that rotate with the pedal cranks, a plurality of rear sprockets
that rotate with the rear wheel, and a chain that engages one of the front sprockets
and one of the rear sprockets. A front derailleur is mounted to the bicycle frame
for shifting the chain among the plurality of front sprockets, and a rear derailleur
is mounted to the bicycle frame for shifting the chain among the plurality of rear
sprockets. Manually operated switches or levers may control the front and rear
derailleurs. Position sensors (e.g., potentiometers or contact sensors) are mounted
to the switches or levers so that the front and rear sprockets currently engaged
by the chain may be determined by the positions of the corresponding switches or
levers. Such information may be displayed to the rider so that the rider may operate
the transmission accordingly. Even more sophisticated systems use small electric
motors to control the bicycle transmission. The motors may be controlled manually
by the foregoing switches or levers, or automatically based on bicycle speed and/or cadence.
The switches, sensors and other electrical components of the signal processing
system require electrical power to operate. Such power may be supplied from simple
batteries or from a dynamo that generates power from the rotation of one of the
bicycle wheels. Batteries have the disadvantage that they are drained by the operation
of the signal processing system and must be recharged or replaced. Larger batteries
can be used to accommodate greater power requirements, but such batteries can add
excessive weight to the bicycle. Dynamos have the disadvantage that they stop generating
power when the bicycle is stopped, and the signal processing system may malfunction accordingly.
SUMMARY OF THE INVENTION
The present invention is directed to features of a power control apparatus for
a bicycle that can be used with multiple power sources to achieve benefits not
available from or in addition to those available by using a single power source.
In one embodiment of the present invention, a power control apparatus is provided
for a bicycle that uses a first power supply and a second power supply. The power
control apparatus includes a voltage sensor for sensing a voltage from the first
power supply. A control unit is coupled to the voltage sensor and is coupled for
receiving power from the first power supply and the second power supply. The control
unit outputs power from the second power supply when the voltage sensed by the
voltage sensor is below a selected value, and the control unit outputs power from
the first power supply when the voltage sensed by the voltage sensor is above the
selected value.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a bicycle that includes a particular embodiment of
a signal processing device;
FIG. 2 is an oblique view of the handlebar mounted components of the signal
processing device;
FIGS. 3A and 3B are detailed block diagrams of a particular embodiment of the
signal processing device;
FIG. 4 is conceptual schematic diagram of a prior art signal processing device;
FIG. 5 is a conceptual schematic diagram showing a particular embodiment of
an impedance converting circuit;
FIG. 6 is a schematic diagram of a particular embodiment of a signal processing
element and impedance converting circuit;
FIGS. 7(A) and 7(B) together comprise a schematic diagram of a circuit for
communicating power and data from a first signal processing element to a second
signal processing element;
FIGS. 8(A)-8(F) are diagrams showing the waveforms of signals at various points
in the circuit shown in FIGS. 7(A) and 7(B);
FIG. 9 is a block diagram of an alternative embodiment of a device for communicating
power and data from a first signal processing element to a second signal processing
element; and
FIG. 10 is a schematic diagram of a particular embodiment of a power control apparatus.
DETAILED DESCRIPTION OF THE EMBODIMENTS
FIG. 1 is a side view of a bicycle
10 that includes a particular embodiment
of a signal processing device
12 (FIG. 3). Bicycle
10 has a frame
14, a front fork
18 rotatably supported in a head tube
22
of frame
14, a front wheel
26 rotatably supported by fork
18,
a handlebar
30 for rotating fork
18 (and hence front wheel
26)
in the desired direction, and a rear wheel
34 rotatably supported at the
rear of frame
14. A pair of crank arms
38, each supporting a pedal
42, are mounted to an axle
46 that is rotatably supported in a lower
portion of frame
14. A plurality of front sprockets
50 are mounted
to the right side crank arm
38 for rotating with the right side crank arm
38, and a plurality of rear sprockets
54 are mounted to the rear
wheel
34 for rotating with rear wheel
34. A chain
58 engages
one of the front sprockets
50 and one of the rear sprockets
54. A
front derailleur
62 is mounted to frame
14 in close proximity to
the plurality of front sprockets
50 for moving chain
58 among the
plurality of front sprockets
50, and a rear derailleur
66 is mounted
to frame
14 in close proximity to the plurality of rear sprockets
54
for moving chain
58 among the plurality of rear sprockets
54. A front
braking unit
70 is mounted to fork
18 for braking front wheel
26,
and a rear braking unit
74 is mounted to the rear of frame
14 for
braking rear wheel
34. Front braking unit
70 is connected to a Bowden-type
control cable
78 that is connected to a brake lever assembly
82 mounted
on the right side of handlebar
30 as shown in FIG. 2. Similarly, rear braking
unit
74 is connected to a Bowden-type control cable
88 that is connected
to a brake lever assembly
92 mounted on the left side of handlebar
30.
As shown in FIGS. 1-3, a display housing
100 having an LCD display
104
is coupled to a mounting bracket
108 attached to handlebar
30. As
shown in FIG. 3, display housing
100 houses a backlight
112 for display
104, a processor
116 for controlling the operation of display
104,
a real time clock (RTC) circuit
120 for providing timing information, a
battery
124 for providing optional power for the data stored in processor
116, a receiver circuit
128 for receiving data in a manner described
below, a power circuit
132 for receiving power in a manner described below,
a resistance (e.g., resistor) R
8 coupled to processor
116, and a
switch
138 having a terminal
142 coupled to a node
144 between
resistance R
8 and processor
116 for selecting the information displayed
on display
104. The other terminal
146 of switch
138 is connected
to a ground potential.
Mounting bracket
108 houses serially connected resistances (e.g.,
resistors) R
1 and R
2, a buffer amplifier
150 having an input
terminal
154 connected to a node
156 between resistances R
1
and R
2, a voltage regulator
158 for supplying a regulated voltage
to buffer amplifier
150, a voltage regulator
162 for supplying a
regulated voltage to resistance R
1, and a connector
166. Connector
166 includes an external output terminal
170 connected to an output
terminal
174 of buffer amplifier
150, a power/data input terminal
178 for communicating power to voltage regulators
158 and
162
in mounting bracket
108 and to power circuit
132 in display housing
100 and for communicating data to receiver circuit
128 in display
housing
100, and a ground terminal
182 for providing a ground potential
to the components in mounting bracket
108 and display housing
100.
External output terminal
170, power/data input terminal
178 and ground
terminal
182 have exposed contact surfaces
170a,
178a
and
182a, respectively.
In this embodiment, the relevant signal processing elements within display housing
100 are directly connected to the relevant signal processing elements within
mounting bracket
108. In other embodiments, display housing
100 may
be detachably mounted to mounting bracket
108 in a known manner, wherein
exposed electrical contacts (in electrical communication with the relevant components
in display housing
100) on display housing
100 contact exposed electrical
contacts (in electrical communication with the relevant components in mounting
bracket
108) on mounting bracket
108.
A right switch housing
190 containing a mode switch
194, a rear
derailleur
upshift switch
198, a rear derailleur downshift switch
202 and serially
connected resistances (e.g., resistors) R
3 and R
4 is mounted to the
right side of handlebar
30. The relevant signal processing elements within
right switch housing
190 are coupled to an intermediate communication path
206 which, in this embodiment, comprises a ground potential communication
path
210, a resistance communication path
214 and a resistance communication
path
218. More specifically, ground potential communication path
210
is connected to a terminal
222 of mode switch
194, to a terminal
226 of rear derailleur upshift switch
198 and to a terminal
230
of rear derailleur downshift switch
202. Another terminal
234 of
mode switch
194 is connected to a node
236 on resistance communication
path
214 near resistance R
3, another terminal
238 of rear
derailleur upshift switch
198 is connected to a node
240 between
resistances R
3 and R
4, and another terminal
242 of rear derailleur
downshift switch
202 is connected to a node
244 on resistance communication
path
218 near resistance R
4.
A left switch housing
250 containing a mode switch
254, a front
derailleur
upshift switch
258, a front derailleur downshift switch
262 and serially
connected resistances (e.g., resistors) R
5, R
6 and R
7 is mounted
to the left side of handlebar
30. The relevant signal processing elements
within left switch housing
250 are coupled to an intermediate communication
path
266 which, in this embodiment, comprises a ground potential communication
path
270, a resistance communication path
274 and a resistance communication
path
278. More specifically, ground potential communication path
270
is connected to a terminal
282 of mode switch
254, to a terminal
286 of front derailleur upshift switch
258 and to a terminal
290
of front derailleur downshift switch
262. Another terminal
294 of
mode switch
254 is connected to a node
296 between resistances R
5
and R
6, another terminal
298 of front derailleur upshift switch
258
is connected to a node
300 between resistances R
6 and R
7,
and another terminal
302 of front derailleur downshift switch
262
is connected to a node
304 on resistance communication path
278 near
resistance R
7. Resistance communication path
274 is connected to
resistance R
5.
As shown in FIG. 1, a front derailleur control housing
310 is mounted
to
frame
14, and it is coupled to mounting bracket
108 through an intermediate
communication path
314. A rear derailleur control housing
315 is
mounted to rear derailleur
66, and it is electrically coupled to front derailleur
control housing
310 through an intermediate communication path
316.
As shown in FIG. 3, front derailleur control housing
310 contains a processor
318, a rectifier and charge control circuit
322 for receiving current
from a hub dynamo
326 mounted to rear wheel
34 (not shown) through
a communication path
330 and for supplying power to processor
318
through a communication path
330, a capacitance (e.g., capacitor)
334
coupled to rectifier and charge control circuit
322 through a communication
path
338 for storing power for use by rectifier and charge control circuit
322, and a programmable memory
342 for storing the programming for
processor
318. A crank sensor
343 coupled to processor
318
through a communication path
344 is provided for sensing signals from a
magnet (not shown) coupled to the left side crank arm
38. An optional motor
driver
346 is coupled to processor
318 through a communication path
350 for controlling the operation of a motor
354 through a communication
path
362 for adjusting an optional front suspension
358, and an optional
motor driver
364 is coupled to processor
318 through a communication
path
368 for controlling the operation of a motor
372 through a communication
path
380 for adjusting an optional rear suspension
376. A contact
sensor shown as contacts
384a,
384b and
384c
is coupled to processor
318 through a communication path
388
for providing signals indicating the position of a front derailleur motor
400
used to position front derailleur
62. A motor driver
392 is coupled
to processor
318 through a communication path
396 for controlling
the operation of front derailleur motor
400 through a communication path
404. Motor driver
392 also provides signals over a communication
path
408, which is part of intermediate communication path
316, for
controlling the operation of a rear derailleur motor
412 contained in rear
derailleur control housing
315. A potentiometer
416 contained in
rear derailleur control housing
315 is coupled to processor
318 through
a communication path
420, which is part of intermediate communication path
316, for providing signals indicating the position of motor
412,
and hence rear derailleur
66.
A power/data transmitter
430 is coupled to processor
318 through
a communication path
434 for providing power and data signals through a
communication path
442 to an external power/data output terminal
438
having a contact surface
438a. An external switch signal input terminal
446 having a contact surface
446a is coupled to processor
318 through a communication path
450, and a ground terminal
454
having a contact surface
454a is used to communicate a ground potential
among the components in front derailleur control housing
310. Terminals
438,
446 and
454 form part of a connector
456.
As noted above, front derailleur control housing
310 is electrically connected
to mounting bracket
108 through an intermediate communication path
314.
Intermediate communication path
314 includes a connector
460 that
couples to connector
166 on mounting bracket
108, a connector
464
that couples to connector
456 on front derailleur control housing
310,
an intermediate ground potential communication path
468, an intermediate
power/data communication path
472, and an intermediate switch signal communication
path
476. In this embodiment, each communication path
468,
472
and
476 comprises a wire, but of course one or more of these communication
paths may be an optical communication element or be replaced by a wireless communication
method. In this embodiment, connector
460 includes connector terminals
480,
484 and
488 with contact surfaces
480a,
484a
and
488a for contacting the respective contact surfaces
170a,
178a and
182a of external output terminal
170,
power/data input terminal
178 and ground terminal
182. Similarly,
connector
464 includes terminals
492,
496 and
498 with
contact surfaces
492a,
496a and
498a for
contacting the respective contact surfaces
446a,
438a and
454a of switch signal input terminal
446, power/data output
terminal
438 and ground terminal
454.
Before continuing with the description of signal processing device
12,
it may be helpful to consider a prior art signal processing device
500 shown
conceptually in FIG. 4. As shown in FIG. 4, signal processing device
500
includes a housing
504 containing a signal processing element
508
(a switch, sensor, etc.) connected to a processor
512 through a communication
path
516, a housing
520 containing a processor
524, and an
intermediate communication path
526. Processor
512 is connected to
external terminals
528,
532 and
536 having respective contact
surfaces
528a,
532a and
536a. Similarly,
processor
524 is connected to external terminals
540,
544
and
548 having respective contact surfaces
540a,
544a
and
548a. Terminals
528,
532 and
536 form
part of a connector
538, and terminals
540,
544 and
548
form part of a connector
550. Intermediate communication path
526
includes a connector
580 for coupling to connector
538 on housing
504, a connector
584 for coupling to connector
550 on housing
520, an intermediate ground potential communication path
588, an
intermediate power communication path
592, and an intermediate data signal
communication path
596. Intermediate ground potential communication path
588 is shown coupled to a ground potential because the ground potential
need not originate in processor
512 or processor
524. Such a ground
potential may exist at the terminal of a power supply, at the metallic or other
conductive elements forming housings
504 and/or
520, or even the
bicycle frame or other conductive components attached to the bicycle. Each communication
path
588,
592 and
596 typically comprises a wire. The signals
on communication paths
592 and
596 typically are high impedance signals,
and very little current flows through them. Connector
580 includes connector
terminals
600,
604 and
608 with contact surfaces
600a,
604a and
608a for contacting the respective contact
surfaces
528a,
532a and
536a of terminals
528,
532 and
536. Similarly, connector
584 includes
terminals
612,
616 and
620 with contact surfaces
612a,
616a and
620a for contacting the respective contact
surfaces
540a,
544a and
548a of external
terminals
540,
544 and
548.
If water were to enter between connector
580 and connector
538,
for example, there is a possibility that the water, being somewhat conductive,
will form a conductive path between communication paths
592 and/or
596
and the ground potential. The effect may be similar to current siphoned off through
a resistance of, for example, 1K ohms to a ground potential. Since the signals
on intermediate communication paths
592 and
596 are high impedance
signals, and since the current flowing through the intermediate communication paths
592 and
596 is very small, the voltage appearing at processor
524
will vary greatly even if the current lost through the conductive path is small.
Indeed, it is possible that a complete short circuit may result. In any event,
such a voltage variation may cause processor
524 to malfunction. To prevent
such malfunctioning, it is necessary that connectors
580 and
584
be constructed to provide a waterproof seal. This not only increases the initial
cost of the device, but over time the connectors may lose their waterproof quality,
thus requiring replacement of the connectors, if not the entire device.
FIG. 5 is a conceptual schematic diagram showing how the circuit of FIG. 4 is
modified in accordance with the present embodiment. In this case, signal processing
element
508 is not connected through processor
512 (processor
512
has been omitted from the diagram, but processor
512 still may be connected
for communicating with intermediate communication paths
588 and
592
as shown in FIG. 4). Instead, signal processing element
508 is connected
to intermediate data signal communication path
596 through an impedance
converting circuit
630 that converts the high impedance switch signal appearing
on communication path
516′ into a low impedance switch signal that
is communicated on intermediate data signal communication path
596. In this
example, impedance converting circuit
630 may be an operational amplifier
632 having an input terminal
634 connected to communication path
516′, an output terminal
638 connected to external terminal
528, and an input terminal
642 connected to a feedback path
643
that is connected to a node
644 between output terminal
638 and external
output terminal
528.
FIG. 6 is a detailed schematic diagram showing how the principles of the present
embodiment are applied to the device shown in FIG. 3. Buffer
150 functions
as an impedance converting circuit, and in this embodiment it comprises an operational
amplifier
650 having the input terminal
154 connected to the node
156 between resistances R
1 and R
2, the output terminal
174
connected to external output terminal
170, and an input terminal
652
connected to a feedback path
654 that is connected to a node
656
between output terminal
174 and external output terminal
170. One
of ordinary skill in the art will readily recognize that, in this embodiment, operational
amplifier
650 is configured as a noninverting, unity gain amplifier. Buffer
150 converts the high impedance signal at input terminal
154 into
a low impedance signal at output terminal
174. The signal at output terminal
174 has an impedance of substantially zero.
Resistances R
1-R
8 are connected together in series, with
switches
194,
198,
202,
254,
258 and
262
each having one terminal connected to a node
236,
240,
244,
296,
300 and
304, respectively, between adjacent pairs of
the resistances. The other terminals of switches
194,
198,
202,
254,
258 and
262 are connected to the ground potential appearing
on ground potential communication paths
210 and
270. Resistances
R
1-R
8 thus function as a voltage divider such that the analog voltage
appearing at input terminal
154 of operational amplifier
650 (and
hence output terminal
174 of operational amplifier) will vary depending
upon which switch
194,
198,
202,
254,
258 and
262 is closed. In this embodiment, resistances R
1-R
8 have
values of 10 k, 2.2 k, 2.2 k, 2.2 k, 3.3 k, 5.6 k, 8.2 k and 18 k ohms, respectively.
Because the varying voltage signal set by the switches
194,
198,
202,
254,
258 and
262 and appearing at output terminal
174 of operational amplifier
650 is a low impedance signal, it will
be substantially unaffected by any water that enters between connectors
166
and
460 and/or connectors
456 and
464. Also, the switch signals
may be communicated directly to the processor
318 in front derailleur control
housing
310. Thus, it is not necessary to incur the expense of using a separate
processor to process the switch signals as in the prior art. Operational amplifier
650 also stabilizes the voltages for use by processor
318 (e.g.,
10 millivolts either way).
As noted above when discussing the prior art device shown in FIG. 4, conventional
devices have separate power and data communication paths for communicating power
and data from one signal processing element to another. The present device shown
in FIG. 3 is constructed to eliminate such separate communication paths and to
communicate power and data over a single communication path. More specifically,
the device shown in FIG. 3 includes power/data transmitter
430 in front
derailleur control housing
310 for communicating power and data over communication
path
442, then to intermediate power/data communication path
472,
and ultimately to receiver circuit
128 and power circuit
132 in display
housing
100.
FIGS. 7(A) and 7(B) together comprise a detailed schematic diagram of the relevant
components of transmitter
430, receiver circuit
128 and power circuit
132. Transmitter
430 comprises a switching circuit
700, a
gate drive circuit
704, and a signal shaping circuit
708. Switching
circuit
700 comprises a field-effect transistor
712 having a gate
terminal
716, a source terminal
720 coupled for receiving a voltage
Vcc from capacitance
334 (FIG. 4), and a drain terminal
724 coupled
to communication path
442.
Gate drive circuit
704 controls the operation of switching circuit
700,
and it includes NPN bipolar transistors Q
3, Q
6, Q
7 and Q
8,
resistances (e.g., resistors) R
9, R
10 and R
11, and diode D
1.
Transistor Q
3 has a collector terminal
728 coupled for receiving
voltage Vcc, a base terminal
732 connected to a node
734 between
a terminal
736 of resistance R
9 and a collector terminal
740
of transistor Q
6, and an emitter terminal
744 connected to an anode
terminal
748 of diode D
1. The other terminal
750 of resistance
R
9 is coupled for receiving voltage Vcc. Transistor Q
6 further has
a base terminal
752 connected to a node
754 on communication path
434a from processor
318, and an emitter terminal
760
connected to a node
765 between a base terminal
764 of transistor
Q
7 and a terminal
768 of resistance R
10. The other terminal
770 of resistance R
10 is coupled to a ground potential. Transistor
Q
7 further has a collector terminal
772 connected to a node
774
between gate terminal
716 and a cathode terminal
776 of diode D
1,
and an emitter terminal
780 coupled to a ground potential. Transistor Q
8
further has a base terminal
784 connected to a terminal
788 of resistance
R
11, and an emitter terminal
792 coupled to a ground potential. The
other terminal
796 of resistance R
11 is connected to a node
798
between communication path
434b from processor
318 and a terminal
799 of resistance R
12.
Signal shaping circuit
708 shapes the signal appearing at drain terminal
724 of transistor
712 of switching circuit
700, and it includes
NPN bipolar transistors Q
4 and Q
5. Transistor Q
4 includes
a collector terminal
800 connected to a node
802 between drain terminal
724 of transistor
712 and a collector terminal
804 of transistor
Q
5, a base terminal
808 connected to the other terminal
812
of resistance R
12, and an emitter terminal
816 connected to a base
terminal
820 of transistor Q
5. The emitter terminal
824 of
transistor Q
5 is coupled to a ground potential.
The operation of transmitter
430 may be understood by the signals shown
in FIGS. 8(A)-8(D). Lower voltage switching signals shown in FIG. 8(A) (approximately
3.0 volts) are produced by processor
318 on communication path
434(A)
(point (A) in FIG.
7(A)), and such signals cause gate drive circuit
704
to produce the higher voltage gate drive signals shown in FIG. 8(B) (approximately
4.5 volts) at gate terminal
716 of transistor
712 (point (B)) to
operate switching circuit
700. In response, switching circuit
700
produces the signals shown in FIGS. 8(C) and 8(D) at drain terminal
724
(point (C)). Processor
318 produces the signals on communication path
434b
to operate signal shaping circuit
708. The signals on communication
path
434b are similar to the signals produced on communication path
434a (FIG. 8(A)) and are substantially the complements (opposites)
of the signals produced on communication path
434a (taking into account
propagation delay and necessary timing). These signals, through the operation of
transistor Q
8, ensure that gate drive circuit
704 rapidly shuts off
transistor
712. The signals on communication path
434b also
cause signal shaping circuit
708 to rapidly sink current from drain terminal
724 of transistor
712 to produce a signal on communication path
442
(point (D)) that more nearly resembles a square wave as shown in FIG. 8(E). The
signals shown are for example only. In reality, the signals will have varying pulse
widths. Also, in this embodiment the pulses should have a frequency greater than
20 Hz to avoid flicker in the display and other artifacts, but in other embodiments
that may not be necessary.
As shown in FIG. 7(B), receiver circuit
128 comprises transistors Q
1
and Q
2 and resistances (e.g., resistors) R
13, R
14, R
15
and R
16. Transistor Q
1 has a collector terminal
850 connected
to a node
854 between a power line
858 and a terminal
862
of resistance R
14, a base terminal
866 connected to a terminal
870
of resistance R
13, and an emitter terminal
874 connected to a node
878 between a terminal
882 of resistance R
15 and a terminal
886 of resistance R
16. The other terminal
886 of resistance
R
13 is coupled through mounting bracket
108 to power/data input terminal
178, and the other terminal
890 of resistance R
16 is coupled
to a ground potential. Transistor Q
2 has a collector terminal
894
connected to a node
898 between the other terminal
902 of resistance
R
14 and a communication path
906 to processor
116, a base
terminal
910 coupled to the other terminal
912 of resistance R
15,
and an emitter terminal
916 coupled to a ground potential.
Power circuit
132 comprises a commercially available voltage regulator
920, capacitances (e.g., capacitors) C
1-C
3, and a diode D
2.
Diode D
2 has an anode terminal
924 coupled through mounting bracket
108 to power/data input terminal
178 and a cathode terminal
928
connected to a node
932 between terminals
936 and
940 of capacitances
C
1 and C
3 and an input terminal
944 of voltage regulator
920.
The other terminals
948 and
952 of capacitances C
1 and C
3
are coupled to a ground potential. Voltage regulator
920 has an output terminal
956 coupled to power line
858 for supplying operating voltage to
processor
116 and receiver circuit
128, and a ground terminal
960
coupled to a ground potential. Capacitance C
2 has a terminal
964
connected to a node
966 between output terminal
956 and power line
858, and a terminal
968 coupled to a ground potential.
The operation of receiver circuit
128 and power circuit
132 may
be understood by the signals shown in FIGS. 8(C)-8(F). The pulse signals output
from switching circuit
700 (FIG. 8(C)) and shaped by signal shaping circuit
708 (FIG. 8(D)) are communicated over the single intermediate power/data
communication path
472 and through mounting bracket
108 to receiver
circuit
128 and power circuit
132. Diode D
2 rectifies the
incoming signal and charges capacitances C
1 and C
3 to produce the
input signal shown in FIG. 8(E) on input terminal
944 (point (E)). Voltage
regulator
920 and capacitance C
2 thereafter produce a stable signal
(approximately 3 volts) on output terminal
956. The power signal is communicated
to processor
116 and receiver circuit
128 through power line
858.
Receiver circuit
128 demodulates the incoming signal and produces the data
signal shown in FIG. 8(F) (approximately 3 volts) on communication path
906
(point (F)).
FIG. 9 is a block diagram of an alternative embodiment of a transmitter
970
for communicating power and data from a first signal processing element to a second
signal processing element, wherein frequency modulation is employed. In this embodiment,
a processor
972 controls a sine wave (or other waveform) generator
974
through a communication path
976. The generated waveform is communicated
to a mixing circuit
978 through a communication path
980. Mixer
978
receives power from a power source
980 through a communication path
982,
combines the power and waveform signals, and communicates the combined signals
on a communication path
984. In such an embodiment, the frequency of the
waveform should be less than 500 KHz to avoid radio interference or other artifacts,
but that may not be necessary in other embodiments.
FIG. 10 is a schematic diagram of an alternative embodiment of power circuit
132, labeled
990. This embodiment comprises a first power supply
switch such as a commercially available switching voltage regulator
1000,
capacitances C
1-C
3, and a diode D
2 interconnected substantially
as in the embodiment shown in FIG. (
7B). That is, diode D
2 has an
anode terminal
924 coupled for receiving power from capacitance
334
(charged by dynamo
326) in front derailleur control housing
310,
and a cathode terminal
928 connected to a node
932 at a junction
of terminals
936 and
940 of capacitances C
1 and C
3
and an input terminal
944 of voltage regulator
1000. The other terminals
948 and
952 of capacitances C
1 and C
3, together with
a ground terminal
960 of voltage regulator
1000 and a terminal
968
of capacitance C
2, are coupled to a ground potential. Voltage regulator
1000 has an output terminal
956 connected to power line
858
for supplying operating voltage to processor
116, receiver circuit
128,
and any other desired components. A terminal
964 of capacitance C
2
is connected to a node
966 on power line
858.
Power circuit
990 also comprises a voltage sensor
1004, a second
power supply switch such as a switching circuit
1008, NPN bipolar transistors
Q
9-Q
10 and resistances (e.g., resistors) R
17-R
20. Voltage
sensor
1004 has an input terminal
1012 connected to node
932,
an output terminal
1016 connected to a node
1020 between terminals
1024 and
1028 of resistances R
18 and R
19, respectively,
and a ground terminal
1032 coupled to a ground potential. Another terminal
1036 of resistance R
18 is connected to a node
1038 between
a control terminal
1040 of switching circuit
1008 and a collector
terminal
1042 of transistor Q
10, and another terminal
1043
of resistance R
19 is connected to a node
1044 between a chip enable
terminal
1048 of voltage regulator
1000 and a collector terminal
1049 of transistor Q
9. Emitter terminals
1050 and
1051
of transistors Q
9 and Q
10, respectively, are coupled to a ground potential.
In this embodiment, switching circuit
1008 comprises a field-effect transistor
1052 and a diode D
3. Control terminal
1040 is the gate terminal
of transistor
1052. Transistor
1052 also has a source terminal
1056
connected to a node
1057 between a cathode terminal
1065 of diode
D
3 and power line
858, and a drain terminal
1060 connected
to a node
1062 between a terminal
1064 of resistance R
17 and
an anode terminal
1066 of diode D
3.
Another terminal
1068 of resistance R
17 is coupled to a node
1072 between a terminal
1076 of battery
124 and a terminal
1080 of a resistance R
20. Another terminal
1077 of resistance
R
20 is connected to a node
1081 between a terminal
1084 of
a capacitance C
4 and a battery monitor terminal
1088 of a second
power supply voltage sensor such as a battery voltage sensor
1090 which,
in this embodiment, is a program module within CPU
116. The other terminal
1092 of capacitance C
4 is coupled to a ground potential. Switching
circuit
1008 thus receives power from battery
124, and resistance
R
20 and capacitance C
4 allow CPU
116 to monitor the voltage
of battery
124. CPU
116 includes a first power supply switch override
terminal
1096 connected to a terminal
1100 of a resistance R
21.
Another terminal
1101 of resistance R
21 is connected to a base terminal
1102 of transistor Q
9. CPU
116 also includes a second power
supply switch override terminal
1104 connected to a base terminal
1108
of transistor Q
10.
In operation, voltage sensor
1004 senses the voltage at node
932
(which originates from capacitance
334 in front derailleur control housing
310) and controls switching voltage regulator
1000 and switching
circuit
1008 (which together function as a control unit) to supply power
to power line
858. More specifically, whenever the sensed voltage is above
a prescribed value (e.g., 3.5 volts) voltage sensor
1004 provides a signal
for turning on switching voltage regulator
1000 and turning off switching
circuit
1008 for providing power from capacitance
334 to power line
858. This is desirable when capacitance
334 is sufficiently charged
by dynamo
326. Conversely, whenever the sensed voltage is below the prescribed
value, voltage sensor
1004 provides a signal for turning off switching voltage
regulator
1000 and turning on switching circuit
1008 for providing
power from battery
124 to power line
858. This typically occurs when
the bicycle is moving slowly or has stopped and dynamo
326 is not able to
sufficiently charge capacitance
334.
In this embodiment, CPU
116 may override the normal operation of voltage
sensor
1004, voltage regulator
1000 and switching circuit
1008.
For example, suppose CPU
318 in front derailleur control housing
310
issues a command to CPU
116 in display housing
100 to operate in
a particular mode, wherein CPU
116 normally uses power from battery
124
when operating in that mode. If battery voltage sensor
1090 in CPU
116
determines that the voltage of battery
124 is above a prescribed value (e.g.,
3.5 volts), then CPU
116 may provide signals on first power supply switch
override terminal
1096 and second power supply switch override terminal
1104 to turn off switching voltage regulator
1000 and turn on switching
unit
1008, even when the voltage at node
932 normally would result
in power being supplied from capacitance
334. As a re
