Miscellaneous active electrical nonlinear devices – circuits – and – Specific signal discriminating without subsequent control – By amplitude
Reexamination Certificate
2002-03-26
2003-10-21
Lam, Tuan T. (Department: 2819)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific signal discriminating without subsequent control
By amplitude
C327S080000, C327S077000
Reexamination Certificate
active
06636081
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a voltage-comparing device applied in a cursor-control input device, and more particularly, to a voltage-comparing device with an analog-signal converter.
BACKGROUND OF THE INVENTION
Following the development of the personal computer, peripheral devices of the personal computer also develops vigorously. Now, the software is well used in Window's interface system and the cursor-control input device becomes an essential peripheral device of the personal computer, wherein a mouse is applied popularly.
FIG. 1
depicts a circuit of a prior mouse for detecting the movement of the position and transferring it into a digital control signal, wherein a light-emitting diode
11
provides a light emitted to a photo-transistor
13
and a raster-wheel
12
disposed between light-emitting diode
11
and the photo-transistor
13
rotates in response to the rotation of a ball included in the mouse. The photo-transistor
13
receives a bright/dark photo-signal and outputs a sine-wave-like current signal in response to the light-and shade photo-signal while the emitting light is influenced by the rotation of the raster-wheel
12
. FIG.
2
(
a
) illustrates an analog-input-voltage signal Vin transformed by a resistor
14
and FIG.
2
(
b
) illustrates a digital-output-voltage signal Vout obtained in an ideal situation after a comparator
15
formed by an operational amplifier compares the analog input voltage signal Vin with a regulated reference voltage Vref. Accordingly, a follow-up circuit can calculate relative moving distances in X axle and Y axle of the mouse in response to the number of square waves of the digital-output-voltage signal Vout.
However, the prior art always causes a lot of uncontrollable errors during producing photoproducts. Parameter-errors and process-errors of devices also cause the yields of products to be reduced. Referring to
FIG. 3
, it illustrates signals of the photoproducts in the normal work. After comparing an input signal
30
with a regulated reference voltage
31
, the part larger than the reference voltage
31
is defined as a digital signal
1
, the part lower than the reference voltage
31
is defined as a digital signal
0
and then a digital signal
32
is obtained. Referring to
FIG. 4
, it illustrates an error of photoproducts. The photoproduct produces an under-potential-input signal
40
and an over-potential of the input signal
42
due to parameter-errors and process-errors and outputs error output signals
41
and
43
respectively. We can determine that the reduction in the yield is almost caused by above error signals, but not any broken device or error designs, which can be prevented through a good detection. Even though some people try to solve the problem by using more precision devices and machines, those methods increasing a lot of cost still can't solve the problem and improve the yield.
On the other hand, the effect of the noise during inputting signal is another problem. Referring to FIG.
11
(
a
), it is an amplified drawing illustrating an input-voltage signal Vin similar to the regulated reference voltage Vref. As shown in FIG.
11
(
b
), the digital input-voltage signal Vin and the regulated reference voltage Vref will cause crossover phenomenon several times because of the shift of power level and noises produced by transistor devices and background light. The digital output signals Vout will have abnormal numbers of square waves and that error will cause the follow-up circuit to calculate wrong and make the control cursor of the mouse move incorrectly.
Hence, the main purpose of the present invention is to overcome prior problems and provides a practical and novel voltage-comparing device.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a voltage-comparing device applied in a cursor-control input device.
It is another object of the present invention to provide a voltage-comparing device with an analog-signal converter for reducing the complexity of the circuit, the noise of all devices, and the cost of the voltage-comparing device.
According to the present invention, an analog-signal converter comprises a reference-voltage detecting circuit for outputting a reference-voltage signal in response to an input signal, and a first comparing device for comparing the input signal and the reference-voltage signal to obtain an output digital signal, wherein the reference-voltage detecting circuit comprises a second comparing device for comparing the input signal and a potential-calibrating signal to obtain an index signal,a voltage-follower control device electrically connected with the second comparing device for outputting a potential-control signal and a counting signal in response to the index signal and a pulse signal, a voltage-follower device electrically connected between the second comparing device and the voltage-follower control device for outputting the potential-calibrating signal in response to the potential-control signal, a detecting device electrically connected with the voltage-follower device and the voltage-follower control device for detecting the counting signal, the potential-calibrating signal and the pulse signal to obtain an extreme signal, an operational device electrically connected with the detecting device for operating the extreme signal to output an average signal, a signal converter electrically connected with the operational device for executing a signal-converting procedure by inputting the average signal to output a dynamic reference-voltage signal, and a pulse generator electrically connected with the voltage-follower device and the detecting device for producing the pulse signal to obtain the dynamic reference-voltage signal.
Certainly, the input signal can be an analog signal.
Certainly, the input signal can be a waveform signal obtained from a photoelectric convertion.
Certainly, the first comparing device can be a comparator.
Preferably, the comparator compares the input signal with the reference-voltage signal and obtains a first-state digital signal while the potential of the input signal is larger than that of the reference-voltage signal and a second-state digital signal while the potential of the input signal is smaller than that of the reference-voltage signal.
Preferably, the second comparing device further comprises an upper comparator and a lower comparator.
Preferably, the index signal further comprises an upper index signal outputted from the upper comparator and a lower index signal outputted from the lower comparator.
Preferably, the potential-calibrating signal further comprises a potential-calibrating upper signal and a potential-calibrating lower signal.
Preferably, the upper comparator outputs the upper index signal in response to the input signal and the potential-calibrating upper signal in the second comparing procedure.
Preferably, the lower comparator outputs the lower index signal in response to the input signal and the potential-calibrating lower signal in the second comparing procedure.
Certainly, the upper index signal and the lower index signal can be digital signals.
Preferably, the second comparator compares the input signal with the potential-calibrating signal for obtaining a first-state digital signal while the potential of the input signal is larger than that of the potential-calibrating and a second-state digital signal while the potential of the input signal is smaller than that of the potential-calibrating signal.
Preferably, the voltage-follower control device further comprises an input-voltage-tracing circuit and an up/down counter electrically connected with the input-voltage-tracing circuit.
Preferably, the input-voltage-tracing circuit outputs the counting signal in response to the index signal.
Preferably, the up/down counter outputs the potential-control signal in response to the counting signal in the operational procedure.
Preferably, the operational procedure further comprises an upper count procedure and a lower count procedure.
Preferably, the voltage-fol
E-CMDS Corporation
Lam Tuan T.
Nguyen Hiep
Volpe and Koenig P.C.
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