JPH05313760A - Voltage generator - Google Patents

Abstract

PURPOSE:To provide the voltage generator which has a high output precision and allows addition of subsidiary functions and easily obtains many kinds of output waveforms. CONSTITUTION:A CPU 1 has digital data corresponding to one period of a desired voltage waveform and successively outputs this digital data at a preliminarily determined certain timing. This digital data is converted by a D-A converter and is supplied to an error amplifier 4 as the target value of the output voltage in the next period. The output of a saw tooth-wave oscillator 2 and the output of the error amplifier 4 are compared with each other by a comparing circuit 5 to generate a PWM signal. Since the output of a high voltage output circuit 6 is analogously controlled toward the target value in the next period by this PWM signal, the quick processing is possible and the output precision is improved, and the operation time of the CPU is shortened, and subsidiary functions can be added.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage generator such as an AC high voltage generator used in electrophotographic copying machines and printers.

[0002]

2. Description of the Related Art Conventionally, a developing bias circuit of a jumping developing system, which is a one-component developing system, and a primary charging voltage circuit of a contact charging system for charging an electrode by contacting an electrode with a photosensitive drum, include an AC boosting transformer and a DC-DC Composed of an inverter, 500 Vp at a frequency of 200 Hz to 2 KHz
0 to 600 for alternating current with amplitude of -p to 2KVp-p
A bias in which a DC voltage of V is superimposed is used.

[0003]

In the above-mentioned conventional example, there is a problem that the transformer becomes large in size to obtain an alternating current output of low frequency, which hinders downsizing and weight saving of the entire apparatus.

On the other hand, recently, a method of controlling a small high-frequency transformer and a high-voltage transistor for discharging by a microcomputer (hereinafter referred to as a microcomputer) to obtain an alternating high-voltage waveform by repeating boosting and discharging is a special feature. It is proposed as Japanese Patent Application No. 3-157918.

However, in this method, the output waveform cannot be controlled in real time because the calculation of the PWM pulse for driving the high frequency transformer and the calculation of the discharge time during the discharge control take a lot of time, and the accuracy with respect to the desired output cannot be obtained. There is a problem that will fall. There is also a problem that the microcomputer is occupied by the arithmetic control of the high-voltage output, and it is not possible to easily add the accessory function.

On the other hand, in the conventional control method using an analog circuit, when trying to obtain many kinds of AC waveforms (for example,
When two-color copying is performed with different types of toner, the optimum developing bias waveform differs depending on the type of toner. ), It is necessary to construct a circuit for each type of output waveform, and there are problems such as high cost due to an increase in circuit scale, securing a circuit installation space, and an increase in development labor.

The present invention has been made under such circumstances, and has a high output accuracy, an additional function can be added, and a variety of output waveforms can be easily obtained. It is intended to provide.

[0008]

In order to achieve the above-mentioned object, in the present invention, a voltage generator is constructed as in the following (1) to (5).

(1) Control means which has digital data for one cycle of a desired voltage waveform and sequentially outputs this digital data at a predetermined fixed timing, and digital data output from this control means. Digital-analog conversion means for converting into an analog signal, output voltage detection means for detecting an output voltage of the device and outputting a signal proportional to the output voltage, a signal output from the output voltage detection means and the digital- Deviation detecting means for detecting a deviation from the analog signal converted by the analog converting means, PWM signal generating means for generating a PWM signal based on the output of the deviation detecting means, and PWM signal generated by the PWM signal generating means And a output voltage generating means for generating an output voltage of the device according to the above.

(2) Control means which has digital data for one cycle of a desired voltage waveform and sequentially outputs this digital data at a predetermined constant timing, and digital data output from this control means. Digital-analog conversion means for converting into an analog signal, and PWM
A voltage generating means for generating a voltage according to the signal; a generated voltage detecting means for detecting the generated voltage of the voltage generating means and outputting a signal proportional to the generated voltage; and a signal output from the generated voltage detecting means. Deviation detecting means for detecting a deviation from the analog signal converted by the digital-analog converting means, PWM signal generating means for generating a PWM signal according to an input signal and supplying the PWM signal to the voltage generating means, and the voltage generating means. A coupling capacitor for coupling a load to a load, discharging means for discharging the electric charge charged in the coupling capacitor in accordance with an input signal, and determining means for determining whether the voltage generated by the voltage generating means is rising or falling. , The output of the deviation detecting means is supplied to the PWM generating means when the voltage generated by the voltage generating means rises and the output of the deviation detecting means decreases when the generated voltage rises. Voltage generator and a switching means for switching so as to supply to said discharge means.

(3) The PWM signal generating means compares the input signal with the triangular wave generated by the triangular wave generating means and the triangular wave generating means which outputs a plurality of triangular waves at each timing of outputting the digital data from the control means. The voltage generator according to (1) or (2) above, further comprising:

(4) The voltage generator according to (2), wherein a low-pass filter is inserted between the generated voltage detecting means and the deviation detecting means or between the deviation detecting means and the switch means.

(5) The output current detecting means for detecting the output current of the apparatus is provided, and the control means compares the output of the output current detecting means with the target output current data which is stored in advance, and outputs the desired output so that they coincide with each other. The voltage generator according to (1) or (2) above, wherein the voltage waveform digital data is changed and output.

[0014]

With the configurations (1) to (5), the output of the voltage generating means is analogically controlled toward the next target value by the PWM signal. In the configuration (2), the voltage generated by the voltage generating means is further increased. The electric charge of the coupling capacitor is discharged by the discharging means at the time of falling, and the PWM signal is generated by the triangular wave generating means in the configuration of (3). In the configuration of (4), the feedback signal to the voltage generating means is a low-pass filter. In the configuration of (5), the digital data of the desired output voltage waveform is changed so that the output current becomes the target value.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples. (First Embodiment) FIG. 1 is a block diagram of a "voltage generator" according to the first embodiment. In the figure, 1 is a CPU such as a microcomputer for controlling the apparatus, 2 is an oscillator for receiving a synchronization signal from the CPU and outputting a sawtooth wave (may be an appropriate triangular wave), 3 is a C
A DA converter for converting the digital signal from PU1 into an analog voltage signal, 4 is an error amplifier for amplifying the difference between the output of the DA converter 3 and the output of the voltage detection circuit 8, and 5 is the output of the oscillator 2. A comparator circuit having a pulse width limiting circuit for comparing the outputs of the error amplifier 4 and outputting binary voltage signals of "H" and "L", 6 drives a high frequency transformer according to the signal from the comparator circuit 5, A high-voltage output circuit that generates a high-voltage output, 7 is a voltage detection circuit that divides the high-voltage output and outputs a low-voltage signal proportional to the high-voltage output, and 8 is a load such as a developing device or a charger to which high voltage is applied. The oscillator 2 and the comparison circuit 5 are referred to as "PWM signal generating means" in the claims.
Equivalent to.

Next, the operation of generating a sine wave voltage will be described with reference to FIGS. FIG. 2 shows the relationship between the time and the output voltage when one cycle of the desired sine wave output is equally divided by the time Δt, and FIG. 3 is a timing chart of the desired output voltage and each signal up to the time 2. Here, Δt is longer than the D-A conversion time of the D-A converter 3 and is sufficiently longer than one cycle (Ts) of the oscillation frequency of the oscillator 2 (in the present embodiment, Δt = 4). XTs). First, the CPU 1 outputs the output voltage V at time 1.
A digital signal is output to the D-A converter 3 so that it becomes ₁ . The DA converter 3 converts the received digital signal into an analog signal and outputs it to the error amplifier 4.
The error amplifier 4 amplifies the difference between the analog signal and the output voltage at that time and outputs it to the comparison circuit 5. In this case, since the current output voltage is 0, the error amplifier 4 outputs a relatively low voltage, and the comparison circuit 5 outputs the pulse signal having the maximum width as a result of comparison with the output of the oscillator 2. Since this pulse signal is input to the high-voltage output circuit 6 and becomes the driving timing of the internal high-frequency transformer, the comparison circuit 5 includes a limiting circuit so that the duty of the output pulse does not exceed 50%. From the above, the output of the comparison circuit 5 is PW.
The M signal is generated, and the high voltage output circuit 6 is driven to generate a high voltage output. The generated high voltage output is divided by the voltage detection circuit 7 and input to the error amplifier 4 as a feedback signal. The output of the error amplifier 4 is changed by this feedback signal, and as a result, the PWM of the comparison circuit 5 is changed.
The output is also changed.

In the case of the present embodiment, since Δt = 4 × Ts, four PWM signals are output until the time 1 is reached, and each PWM signal has its pulse width changed and the output voltage V ₁ is changed. Controlled to aim. That is, the output voltage of the high-voltage output circuit 6 increases and the voltage of the error amplifier 4 increases as time 0 approaches time 1, and the output inversion timing of the comparison circuit 5 is delayed, so that the duty of the PWM signal decreases as shown in the figure. Then, the output voltage gradually approaches V ₁ .

When the output of the four PWM signals is completed, C
The PU 1 outputs a digital signal corresponding to the desired voltage V ₂ to the DA converter 3 at time 2. D-
The A converter 3 immediately performs D-A conversion, but if a PWM signal is output during the conversion, there is a problem that a signal different from the required PWM signal is output. Therefore, the oscillation cycle Ts is set to be twice or more the DA conversion time Tc,
The CPU 1 synchronously controls the oscillator 2 and the DA converter 3 so that the PWM signal is output at the timing shown in FIG. For this timing control, the oscillator 2 has a CP
It operates with the synchronization signal from U1.

As described above, the internal RO of the CPU 1
The desired output voltages V ₁ , V ₂ , V ₃ , ... Are stored in M, etc., and the sine wave as shown in FIG. 2 is repeated by repeating times 1, 2, 3, ..., 8, 9, 0, 1. Can be obtained.

Next, FIG. 4 shows an example of the control flow of this embodiment. The figure shows an example in which a timer interrupt is used for time management and a synchronization signal (or oscillation itself) of the oscillator 2 is generated by a counter or the like using the same clock. S4
01 to initialize the microcomputer built-in RAM and D
-Set the data so that the A converter 3 outputs 0 level. In S402, the value of the timer counter for the timer interrupt is set, and at the same time, the counter value for outputting the synchronization signal is set. In step S403, the timer interrupt is enabled and the timer is started. At the same time, the counter for the synchronizing signal is started and the synchronizing signal is output.

On the other hand, if a timer interrupt occurs, S404
Interrupts once and the data corresponding to the next desired output voltage is selected in S405. Subsequently, the data selected in S405 is set in the DA converter 3 in S406 to start the DA conversion, and then the interrupt is permitted again in S407.

In the above description, the count value of the timer corresponds to Δt, and the counter value of the synchronization signal is set to a value for outputting the clock of the cycle Ts, for example.

In the embodiment, the sine wave output changing from 0 level to V ₅ level as shown in FIG. 2 has been described as an example. However, by appropriately setting the voltage data to be stored in the ROM, DC It is possible to freely change the components and output complex waveforms other than sine waves.

(Embodiment 2) In Embodiment 1, the case where the factor of the load is ignored and the output of 0 level or more is obtained has been described. An example will be described here in the case where the load has a capacitive characteristic and it takes time for the waveform to fall, or in the case where it is desired to output an AC waveform centered on the 0 level.

FIG. 5 shows a block diagram of this embodiment. In the figure, 9 is a coupling capacitor for coupling the output from the high voltage output circuit 6 applied to the load 8, 10 is a discharge circuit for controlling the discharge of the electric charge charged in the coupling capacitor 9, and 11 is the high voltage output circuit 6. A switching circuit for switching between the charging operation by the CPU 1 and the discharging operation by the discharging circuit 10 in response to an instruction from the CPU 1, and 12 is a DC application circuit for applying a DC voltage to the load 8.

Next, the operation will be described with reference to FIG. In this embodiment, the voltage that has been boosted once is the coupling capacitor 9
However, since this path is an integrating circuit with a large time constant, it takes a long time to discharge, and a desired AC output cannot be obtained. Therefore, a desired AC output is generated. As shown in FIG. 6, the switch circuit 11 is divided into a charging period having a positive slope and a discharging period having a negative slope, and controlling the high voltage output circuit 6 during the charging period and the discharging circuit 10 during the discharging period.
Is configured to switch. In the charging period from time 1 to 5, the switch circuit 11 selects the comparison circuit 5 and performs the same control as that shown in the first embodiment. on the other hand,
In the discharge period from time 6 to time 10, the switch circuit 11 selects the discharge circuit 10 and performs the operation described below.

When the output waveform has entered the discharge period, the CPU
It can be known by itself from the waveform information written in the first program. That is, the discharge control may be performed from the time point beyond time 5, and the switch to the discharge control can be performed only by switching the switch circuit 11 to the discharge circuit 10. By this switching, the CPU 1 outputs a desired voltage value as a digital signal to the D-A converter 3 at the next time as in the control during the charging period, and the D-A converter 3 converts the received digital signal into an analog signal. And output to the error amplifier 4. The error amplifier 4 amplifies the difference between the current voltage value information output from the voltage detection circuit 7 and the output voltage from the DA converter 3 and outputs the amplified difference to the discharge circuit 10. The discharge circuit 10 discharges in response to this signal, and the output voltage decreases accordingly. Since the voltage detection circuit 7 detects this voltage and feeds it back to the error amplifier 4, the output voltage is stabilized at a voltage according to the instruction from the CPU 1. The CPU 1 can instruct a new voltage value at time points 6, 7, 8 and 9 to obtain an output waveform in a desired discharge period. That is, when the difference between the current voltage value information and the output voltage from the DA converter 3 is small, the discharge circuit 10 discharges a small current, and when the difference is large, it discharges a large current, and a desired falling output. Is obtained.
Further, at the time of time 10, the switch circuit 11 is switched to the comparison circuit 5 side again to switch to the control of the charging period.

A desired AC voltage waveform can be obtained by repeating the above. In this embodiment, however, since the DC component is cut by the coupling capacitor 9, the DC component is not applied to the load 8. It is necessary to separately perform this by the DC application circuit 12 connected to the side.

(Third Embodiment) In the first and second embodiments, the high voltage output circuit is controlled to obtain a desired AC output voltage, and the high voltage output circuit and the discharge circuit are controlled to obtain the desired AC output voltage. The case of trying to obtain the AC output voltage of Here, an embodiment will be described in the case of obtaining a smoother output waveform in performing the above high voltage output control.

FIG. 7 shows a block diagram of this embodiment. In the figure, 13 is an integrating circuit (first-order lag element) composed of a resistor and a capacitor for integrating the output from the error amplifier 4. As a result, the output of the error amplifier 4 is integrated, so that the change at the time of voltage switching becomes smooth, and the output ripple at the time of charging or discharging can be suppressed.

FIG. 8 shows timing charts of signals with and without an integrating circuit. When the integrating circuit is not provided as shown in (a), when the output of the DA converter 3 changes rapidly, the output of the error amplifier 4 also changes rapidly, and the pulse width of the output from the comparator 5 changes rapidly. Increase.
As a result, the output of the high voltage output circuit 6 changes rapidly,
Ripple voltage that exceeds the target output voltage is output. On the other hand, when the integrating circuit is provided, the output of the error amplifier 4 changes smoothly as shown in (b).
The pulse width of the output of the comparator 5 also increases smoothly, and the output of the high voltage output circuit 6 also increases smoothly.

The above effects can be similarly obtained in the case of discharge control. In the above description, the error amplifier 4
Although the case where the integrating circuit is provided on the output side of is described, the invention is not limited to this, and may be provided on the input side of the error amplifier 4, for example. The circuit 13 is not limited to the integrator circuit and may be any circuit as long as it smoothes the change of the signal, and such a circuit is expressed by the term low pass filter in the claims.

(Embodiment 4) In each of the above embodiments, the case of controlling the voltage waveform has been described. Here, an example in which a constant current control is performed by providing a current detecting means in a similar method will be described.

In the electrophotographic copying process, the contact charging method is one of the primary high-voltage charging methods for uniformly charging the surface of the photosensitive drum. This is a system in which an electrode such as a roller or a blade is brought into contact with the surface of the photosensitive drum and a high voltage is applied to the electrode to charge the electrode. In this charging method using contact charging, a DC voltage of a constant voltage is applied in order to charge the surface of the photoconductor with a uniform charge regardless of environmental changes such as temperature and humidity.
A power supply in which a constant current AC high voltage is superimposed on a high voltage is used.

FIG. 9 shows a block diagram of this embodiment. In the figure, 14 is a current detection circuit provided in the current path of the high-voltage output circuit 6 and the discharge circuit 10, and 15 is an AD converter for converting the detected current value into a digital value. The current detection circuit 14 converts the AC current into a voltage, detects the voltage, integrates the voltage, and outputs it as an effective value of the current to the AD converter 15. The A / D converter 15 converts the voltage of the received signal from the CPU 1 into a digital value,
Output to 1. The CPU 1 calculates a desired voltage for each time required from the received current value and changes the data to be output to the DA converter 3. There are various possible methods for calculating the desired voltage. For example, the ratio between the current value and the current value to be controlled can be calculated, and the desired voltage can be calculated from the ratio and the current voltage data.

As described above, the amplitude of the output AC voltage is changed, and as a result, a constant-current AC high voltage output can be obtained.

FIG. 10 shows an outline of the control flowchart of this embodiment. The figure shows the flow of a timer interrupt. The main flow is the same as that shown in FIG. 4 and can be realized. Figure 10
To explain, the interrupt is prohibited in S1001 so that a new interrupt is not applied. In S1002, a memory area for data to be DA converted is selected. The memory area for D-A data is provided with two areas for writing the operation result for performing a constant current and for reading the DA conversion data, and one side is used for reading. In this case, the other one is switch-controlled so that it is used for writing the operation result. In S1003 and S1004, the DA conversion data in each data area is selected.
S1005 is a routine for inputting the selected DA conversion data to the DA converter 3, and outputs a conversion start signal when the DA converter 3 requires a conversion signal. S1006 is a routine for reading the current value, calculating the DA conversion data, and setting the calculation result in the memory.
The operation is divided into several interruptions according to the operation time. S1007 is a routine for confirming that all the operations divided into several times are completed. If the operations are completed, S107 is executed.
At 08, the end flag is set. This operation end flag is used when selecting a data area, and thereby determines which area is selected. S1009 is S100
In the routine that returns the interrupt that was prohibited in 1 to the enabled state again,
Upon completion of the above, the next interrupt is awaited.

In this embodiment, the current is detected by inserting a resistor in the current path, but the present invention is not limited to this, and the load side of the coupling capacitor 9 may be a current detecting transformer such as a pulse transformer. Can also be performed using.

Further, in the above description, the case where a sine wave output is obtained has been described as an example, but the present invention is not limited to this, and the number of divisions in one cycle is not limited to the example of the embodiment.

(Embodiment 5) In each of the above embodiments, one type of output waveform is obtained. However, an example in which a plurality of types of output waveforms are switched and output will be described.

As an example, a case will be described in which two types of alternating current outputs ((a) has an A waveform and (b) has a B waveform) are switched and output as shown in FIG. A block diagram of this embodiment is shown in FIG. As shown in FIG. 12, the CPU
A switching signal indicating whether to output the A waveform or the B waveform and an ON signal for instructing ON / OFF of the AC output are input to 1. These signals are output from, for example, the copying machine main body, and are separated according to various settings, conditions, and timings. Further, in the program ROM in the CPU 1, the voltage data (V _A0 , V _A1 ,
V _A2 , ... V _A8 , V _A9 , V _B0 , V _B1 , V _B2 , ... V _B7 ,
V _B8), and the division number data (N _A, N _B) are stored (see FIG. 13).

With the above configuration, two kinds of outputs are switched and output. An example of a control flow chart in this case is shown in FIG. Explaining this, S141
The output is turned off with and the A waveform and B are output in S142.
Which of the waveforms is output is determined by monitoring the switching signal. S according to the determination result of S142
143, A waveform data, S144 B waveform data R
Set on AM. In S145, it is determined whether or not the output is turned ON by monitoring the ON signal, and when the ON signal is received, the control of the AC output is immediately started in S146 (the division number data and the voltage data are Data is referred to). Succeedingly, in S147, as soon as the OFF signal is received by the monitoring of the ON signal, the S signal is received.
Returning to 141, this stops the output operation.

Although each of the above embodiments produces a high voltage output, the present invention is not limited to this, and can be applied to an apparatus that produces an output of an appropriate value such as low voltage. The high-voltage output circuit of each embodiment uses a high-frequency transformer, but the present invention is not limited to this, and can be implemented with a circuit configuration that does not use a transformer.

[0044]

As described above, according to the present invention,
Since the output of the voltage generating means is controlled in an analog manner toward the next target value by the PWM signal, high-speed processing is possible, the accuracy of the output is improved, and the CP required for output control is increased.
The calculation time for U can be greatly reduced and additional functions can be added. Further, by switching digital data of a desired voltage waveform, it is possible to easily obtain various kinds of output waveforms.

In addition to the above effects, the inventions of claims 2, 4 and 5 have the following effects. That is, according to the second aspect of the present invention, by providing the discharging means and the coupling capacitor, it is possible to easily obtain an AC output centered at 0 [V]. According to the invention of claim 4, by inserting the low-pass filter in the circuit of the PWM signal, it is possible to reduce overshoot and undershoot at the time of data switching.
According to the invention of claim 5, a constant current output is obtained by providing an output current detecting means and changing digital data of a desired voltage waveform according to the detected value.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is a diagram showing an example of output of the first embodiment.

FIG. 3 is a timing chart of the output and each signal of the first embodiment.

FIG. 4 is a control flowchart of the first embodiment.

FIG. 5 is a block diagram of a second embodiment.

FIG. 6 is a diagram showing an example of output of the second embodiment.

FIG. 7 is a block diagram of a third embodiment.

FIG. 8 is a timing chart for explaining the third embodiment.

FIG. 9 is a block diagram of a fourth embodiment.

FIG. 10 is a control flowchart of the fourth embodiment.

FIG. 11 is a diagram showing an example of output of the fifth embodiment.

FIG. 12 is a block diagram of the fifth embodiment.

FIG. 13 is an explanatory diagram of a ROM according to the fifth embodiment.

FIG. 14 is a flowchart showing the operation of the fifth embodiment.

[Explanation of symbols]

 1 CPU 2 Oscillator 3 DA Converter 4 Error Amplifier 5 Comparison Circuit 6 High Voltage Output Circuit 7 Voltage Detection Circuit

Claims (5)

[Claims] 1. A control means which has digital data for one cycle of a desired voltage waveform, and which sequentially outputs this digital data at a predetermined constant timing, and an analog digital data output from this control means. Digital-analog conversion means for converting into a signal, output voltage detection means for detecting an output voltage of the device and outputting a signal proportional to the output voltage, a signal output from the output voltage detection means and the digital-analog The deviation detection means for detecting a deviation from the analog signal converted by the conversion means, the PWM signal generation means for generating a PWM signal based on the output of the deviation detection means, and the PWM signal generated by the PWM signal generation means An output voltage generating means for generating an output voltage of the device in response thereto. 2. Control means having digital data for one cycle of a desired voltage waveform, which sequentially outputs the digital data at a predetermined constant timing, and digital data output from the control means are analog. Digital-analog converting means for converting into a signal, voltage generating means for generating a voltage according to the PWM signal, and generated voltage detecting means for detecting a generated voltage of the voltage generating means and outputting a signal proportional to the generated voltage. Deviation detecting means for detecting a deviation between the signal output from the generated voltage detecting means and the analog signal converted by the digital-analog converting means, and a PWM signal corresponding to the input signal to generate a PWM signal in the voltage generating means. PWM signal generating means to be supplied, a coupling capacitor for coupling the voltage generating means to a load, and a coupling capacitor Discharging means for discharging the electric charge charged in the capacitor according to an input signal, judging means for judging whether the voltage generated by the voltage generating means is rising or falling, and the deviation detecting means according to the output of the judging means. And a switch means for switching the output of the above to the PWM generating means when the generated voltage of the voltage generating means rises and to the discharge means when the generated voltage falls. 3. The PWM signal generating means compares the triangular wave generating means for outputting a triangular wave of a plurality of waves at each timing of outputting the digital data from the control means with the input signal and the triangular wave generated by the triangular wave generating means. 3. The voltage generator according to claim 1 or 2, further comprising a comparison means. 4. The voltage generator according to claim 2, wherein a low-pass filter is inserted between the generated voltage detecting means and the deviation detecting means or between the deviation detecting means and the switch means. 5. An output current detecting means for detecting an output current of the device is provided, and a control means compares an output of the output current detecting means with a target output current data which is previously stored, and a desired output voltage is obtained so that they coincide with each other. 2. The waveform digital data is changed and output.
Alternatively, the voltage generator according to claim 2.