JPS62225163A - Electronic power unit - Google Patents

Abstract

PURPOSE:To control instantaneous voltage of power in program, by a method wherein current control having period and ON-time corresponding to load variation is performed based on data from ROM. CONSTITUTION:A pulse signal generator 13 outputs pulse signal l3a having ON-time and period of value inputted in form of data from a ROM 10. A DC chopper circuit 14 performs power control based on the pulse signal l3a, and even if there is load variation current control (instantaneous voltage control) having period and ON-time corresponding to the load variation is performed, and the control is performed so that the output voltage becomes constant. DC output voltage is supplied to an error voltage detector 16, and the error voltage is supplied through an A/D converter 15 to a control circuit 11.

Description

[Detailed Description of the Invention] [Field of Application in Industry A] The present invention relates to a power supply device used, for example, in a charger of a copying machine, and particularly to a power supply device that performs digital power control using, for example, a microcomputer. .

[Prior Art] Conventional pulse generation circuits controlled by logic control circuits such as microcomputers often have a fixed frequency and change only the pulse width. Moreover, the role of the microcomputer in such pulse generation and generation circuits is often only for the purpose of D/A conversion for setting reference values (time constants) in external analog circuits. However, as microcomputers become more sophisticated and faster, it becomes necessary to reduce the number of components and set values by controlling the analog circuits themselves.As a result, not only the duty ratio but also the Pulses of variable period may also be required.

That is, for example, in the case of a power supply device using a chopper circuit, etc., it is necessary to supply power to an inductive load such as a transformer, and as a result, not only the pulse width (duty ratio) but also the frequency do not change. It will no longer be possible. This is so-called instantaneous value control. Furthermore, the a! Along with this issue, the following issues have also arisen: For example, high-voltage generators used in copying machine chargers, etc. are constructed of analog circuits as independent units that operate independently, but in the past, only the power-on and power-off operations of this high-voltage generator were performed. A microcomputer controlled the sequence. However, due to the demands for improved functionality of copying machines and the so-called "lighter, thinner, and smaller size" seen in desk-top copying machines, etc., control functions that had been difficult to separate in the past have been brought together in a central location, making it possible to flexibly change the control values of control objects and Delete the parts that are
Since it is desired to improve the packaging density, it has been desired to use a microcomputer to control the power of the power supply device of such a copying machine.

[Problems to be Solved by the Invention] In response to the above-mentioned demands, the present invention provides a power supply device that performs programmatic instantaneous value control of power control.

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the power supply device of the embodiment shown in FIG. A pulse signal generation circuit 13 generates a pulse number 13a for control, and an error voltage detection circuit 16 for detecting load fluctuations. The A/D converter 15, the ROM10 which stores in advance data corresponding to the pulse signal 13a set in accordance with this load fluctuation, and the pulse pulse of the data read from the ROM10 in accordance with the detected load fluctuation. It has a control circuit 11 that inputs to the signal generation circuit 13.

[Function] In the above configuration, the pulse signal generation circuit 13 has a configuration as shown in FIG. Output. The DC chopper circuit 14 performs power control based on this pulse signal 13a, and even if there is a load fluctuation, current control (instantaneous value control) is performed with a period and ON time according to the load fluctuation, so that the output voltage is constant. to control. In this way, unlike pulse width modulation (PWM) with a constant period and variable ON time, and pulse period modulation (PFM) with a constant ON time and variable 1 period, instantaneous value control according to load fluctuations is possible, especially for inductive loads. effective against fluctuations in

[Examples] Examples according to the present invention will be described in more detail below with reference to the accompanying drawings. Figure 2 shows the basic configuration of the pulse generation circuit, Figure 3 (a) and (b) show the specific circuit diagram of the pulse generation circuit, and Figure 4 (a) and (b) show the timing chart. 51 and subsequent figures show a power supply device using the pulse generator as a part.

Pulse signal generation circuit FIG. 2 is a basic conceptual diagram of the pulse generator.

21 is a so-called microcomputer (MPU), and the period of the pulse generated by the pulse signal generation circuit 24;
Data that determines the duty ratio, ON time, OFF time (hereinafter collectively referred to as time data), etc. are read out from the ROM 20 in which they are stored and latched into the latch 22.2.
3 is latched. The purpose of the latches 22.23 is that since the timer used in the pulse signal generation circuit 24 uses a parallel load type binary counter, the latches 22.23 are used when the counter is retriggered.
3 so that time data can be brought from MPU2
1 eliminates the need to read time data from the ROM 20 one by one.

FIG. 3(a) shows an example of a pulse signal generating circuit 24 in which the cycle and ON time are set as time data stored in the latches 22 and 23. A timing chart of the pulse signal generation circuit of FIG. 3(a) is shown in FIG. 4(a). 3
0.31 is a parallel load type 8-bit (=258) pinarikunta, 30 is for setting the cycle, and 31 is for setting the ON time. CLKo is 4M
Hz, CLK is an 8 MHz clock. CLKo
The reason why the ROM2 is set to 4MH2 is that the period is always longer than the ON time, so by setting the frequency to a low one, the ROM2
This is to allow a wide range of cycles even if the amount of data stored in 0 is small. The preset data input section is connected to latches 22 and 23, and each time a load signal (LOAD/) is input to each counter, the latch 2
The value of 2.23 is reset in the counters 30, 31 so that each counter is of the retrigger type. E
P is an energizing terminal of the counter, and it becomes possible to count only when "1" is input.

Therefore, the counter 30 can count at all times, and the counter 31 can count only when the JK flip-flop 32 is set.

Also, RCO is a ripple carry output and the counter is (
If you count 256 hourly data) clocks,
In other words, when the RCO becomes "1", the counter times out.

The circuit operation from the time the counter 30 times out will now be explained. This RCO activates the load signal and sets time data in the counters 30 and 31. RCo also sets flip-flop 32 and flip-flop 320 is set to counter 3.
1 is energized. That is, after the counter 30 times out, the counter 30 immediately resumes counting, and the counter 30
1 comes out of the deactivated state and starts counting. The counter 31 has (256-ON time) CLK
When r is counted, RCO is output. This RCO resets the flip-flop 32. That is, counter 3
(256-ON time data) xcLK+ set to 1
is the ON time of the pulse. When the remaining time set in the counter 30 has elapsed, the counter 30 times out, resets the flip-flop 32, and repeats the operation described above. (256-period data)xCL K o determines the period of the pulse. FIG. 4(a) shows a timing chart of the above operation.

FIG. 3(b) is an example of a pulse signal generation circuit that sets OFF time and ON time. Although the circuit is basically the same as that of FIG. 3(a), the counter 35 is activated only when the flip-flop 37 is in the reset state, and the counter 36 is activated only when the flip-flop 37 is in the set state. FIG. 4(b) shows the operation timing chart.

In this way, pulses according to the time data (period, ON time, OFF time) set in the latches 22 and 23 are output from the pulse signal generation circuit 24, and this fact is reflected in the MPU 2.
1 means that if the time data stored in the ROM is read out in accordance with a predetermined purpose, a pulse signal having a desired period and ON time can be obtained. Therefore, an example of a power supply device in which the pulses generated from the pulse signal generation circuit described above are applied to a chopper will be described below.

<Power Supply Device> FIG. 5 is a circuit configuration diagram of such a power supply device, which is, for example, a power supply device for generating a DC high voltage for transfer of a copying machine, and a DC high voltage for a cylinder. 50 is a microcomputer that performs power control, and 51 is a pulse signal generation circuit that generates pulses that control a DC chopper circuit 52 that energizes a high voltage transformer. This pulse signal generation circuit 51 is basically the same as the pulse signal generation circuit shown in FIG.
By changing the N time, power conversion is performed using so-called instantaneous value control, which is a step beyond PWM control. 53 is an A/D
The converter 54 is a timer, ie, an interwoven timer, that determines the service interval for the MPU 50 to perform power control in the embodiment. 55 is a high voltage flyback transformer,
PV is an output for charging, and TV is an output for transfer. Although not shown, there is a charging and transfer section of the copying machine beyond the PV and TV, each of which has a rated load of more than ten MΩ. The DC chopper circuit 52 that drives the primary side of the high-voltage transformer 55 responds to this load fluctuation by changing the period and ON state as shown in FIG.
Feedback is applied to keep the current flowing through the load constant using a pulse signal that changes both over time. Since the transformer 55 is an inductive load, instantaneous value control is suitable.

The polarity of the applied voltage for charging and transfer in a copying machine differs depending on the characteristics of the photoreceptor and toner, but in this embodiment, a negative polarity is applied that draws the current from the load side, and the charging current is passed through the resistor 56. The transfer current flows through the resistor 57 to the housing ground FG. The charging current value at that time is obtained by digitizing the voltage across the resistor 56 by the A/D converter 53 and taking it into the MPU 50. The A/D converter 53 starts conversion in response to a conversion start signal (A/DSTART) issued from the MPU 50 at regular intervals, and completes the conversion (A/D COMPLETE).
Then, an interrupt is sent to the MPU 50. This interrupt is MP
Input to EX I NT of U50, A/D conversion value is MP
It is input to the data bus (Do~D?) of U50, and the RAM
59.

To explain other functions of the MPU 50, among the time data supplied to the pulse signal generation circuit 51, the period is supplied from boat A (PAo to PA,), and the ON time data is supplied from boat B (Pa, to PB7). Output. In addition, MPU 50. Since each output port has a latch function, there is no need for a latch as shown in FIG. The above-mentioned A/DSTART is from the PC, and is connected to the interwoven timer 5.
The set time of 4 is output from PCI-PC7. Interrupts from the interwoven timer 54 are input to To I NT.

The ROM 58 corresponds to 80M2o in FIG. 2, and stores cycle and ON time data for power control shown in FIG. 6 together with a control program to be described later. R
The AM 59 is for storing intermediate data necessary for executing the control program, and its details are shown in FIG.

Figure 6 is an example of time data stored in the ROM 58. The period and ON time values after correction according to load fluctuations (impedance changes) are stored in bare combinations in the ROM 58, and are made into a ROM table. . Furthermore, since it is a function that changes linearly as shown in the figure, it is also possible to formulate it into a calculation formula. According to the configuration of the ROM 58 shown in FIG. 8, the start address of the ROM table is DPT.
R (stored in area 67 in RAM 59),
The amount of offset from DPTR is represented by P (stored in area 64 in RAM 59), period data is stored in DPTR+P, and ON time data is stored in DPTR+P+1. In this embodiment, load fluctuations are treated as current changes and a predetermined current flows through the load, but load fluctuations are treated as output voltage changes and the output impedance of the power supply device is changed to maintain a constant output voltage. There's also the kind of control you get. However, it can be said that the instantaneous value control of this embodiment is suitable for output current control.

FIGS. 9(a) to 9(d) show flowcharts for high voltage control. FIG. 9(a) shows the program configuration in the ROM 58. In FIG. 9(a), an INT analyzer 70 analyzes the type of each interrupt that occurs, and includes a vector table to a processing routine according to the type. In this embodiment, there are two interrupts, To I NT and EX I NT, as described above, and their INT processing is shown in FIG. 9 (C) and (
Shown in d). In addition, each interrupt process executes a process specific to that INT, and if necessary, a table indicating the next TASK to be executed (for example, calculation flag 60 in RAM 59) is executed.
) and returns to the interrupt source address. The TASK that executes the schedule routine is the power control TASK 72, the details of which are shown in FIG. 9(b).

Now, regarding the control procedure, T. We will explain from the point of occurrence of OINT. To
When an I NT occurs, the INT analysis processing routine 70
Then control is transferred to To I NTfi 73, and the process shown in FIG. 9 (
Execute the flowchart in C). In step S40, a new timer value 66 is set in the interwoven timer 54. In step S42, the A/DSTART signal is sent to port C.
The interrupt signal is output to the A/D converter 53 through the interrupt source address, and returns to the interrupt source address. Eventually, the A/D conversion end interrupt (EXI
NT) occurs. Then, in step S44, the calculation flag 60 is set. In step S46, the A/D measurement value is input from the input port to the data bus, and
9 is stored in area 61.

Now, normal program control is TASK schedule 7.
TAS that is controlled by 1 and that this routine should execute next
Searching for K. Since the calculation flag 60 was set in step S44 described above, the TASK schedule routine 71 executes the power control TASK72. First, in step S2, confirm that the calculation flag is set, calculate the difference Δ(63) between the measured value (61) measured by A/D conversion and the reference value (62), and calculate the difference according to the difference. Increase or decrease the period and ON time of the pulse signal currently energizing the transformer. As mentioned above, the period of the pulse signal and the value of ON time have the relationship as shown in FIG. 6, and are stored in the ROM 58. The outline of current control is as follows. Control is performed differently depending on the value of Δ(6·3), and when the absolute value of Δ(63) is less than 3, there is no large load fluctuation in this embodiment. Even if you want to, do not change the period or ON time. However, Δ(63) is 3
When it is above, control is further divided depending on whether it is less than 8 or not. If 3≦1Δ1×8, a relatively small correction is made to the current cycle and ON time (pointed to by DPTR+P) (steps S12 and S30).

On the other hand, if 1Δ1≧8, it is considered that there is a significant deviation from the standard of the steady state, and therefore the correction to be made to the period and ON time will also be large (step S22, 532).

The reason why the sign of Δ(63) is changed by subtracting or adding to P(64) is that the load one-hour data characteristic shown in FIG. 6 has a positive slope. Similarly, the cycle set timing (step S20,
536) and ON time set timing (step S1
6,540) is reversed in the characteristics shown in Fig. 6. For example, if the sign of Δ(63) is positive and you change the period, the timer 30.3 is reversed immediately after setting the period.
This is because if the load signal (LOAD/) is input to the output signal 1, the duty of the output signal will be opposite to the direction in which it is desired to change.

The timer interrupt routine shown in FIG. 9(C) will be described in detail. This routine provides the timing of the conversion start signal to the A/D converter tJls4W53. An internal timer is set so that the timer interrupt is always executed within a certain period of time (for example, 1m5ecVk). If the load fluctuations are severe, shortening this set time will improve the ability to follow the load fluctuations.

As described above, since the transfer and charging current values can be controlled using software, it is possible to easily respond to changes in environmental conditions and copying process conditions by simply changing the current setting values.

In the embodiment described above, the pulse signal generation circuit and the A/D converter 53 are arranged outside the MPU 50, but it is also possible to integrate the respective functions into one chip and use the MPU 90 shown in FIG. 10, which is directly connected to the internal bus. good. The MPU90 is shown in Figure 3 (
a) and (b) include a similar pulse signal generation circuit, a built-in A/D converter 84, etc. In that case, the aforementioned boats A, B,
C, but register REG80. By setting the period and ON time for REG82, Fig. 9(b) to (
The same control as shown in d) becomes possible. FIG. 11 is a high voltage generation circuit diagram using the MPU shown in FIG. 10, and the number of components other than the driver and transformer section is much smaller than in FIG. 5.

<Effects of the Embodiment> As explained above, according to the pulse generator of the present embodiment, the period and the ON time, or the ON time and the OFF time, can be changed freely. Moreover, the circuit is given versatility.

Since the time can be freely set digitally, it is possible to use a microcomputer, and it is also possible to perform unified central control using the microcomputer.

Furthermore, if the power supply device including the pulse generator described above is applied to a copying machine, the charging or transfer current value can be controlled using software, so the current setting value can be changed depending on the environmental conditions or copying process conditions. This can be easily addressed by simply changing the . It also enables centralized control, including the power supply, using a microcomputer, contributing to fewer parts and improved mounting efficiency.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a power supply device that performs instantaneous value control of power control in a programmatic manner.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of an embodiment according to the present invention, FIG. 2 is a basic configuration diagram of a pulse generator according to an embodiment, and FIGS. 3(a) and (b) are specific examples of a pulse generator. Figures 4 (a) and (b) are timing charts of the circuits in Figures 3 (a) and (b), Figure 5 is the circuit diagram of the power supply, and Figure 6 is the circuit diagram in ROM. A diagram showing the relationship between stored time data and load, Figure 7 is a diagram of the data configuration in ZRAM, Figure 8 is a diagram of the data configuration of ROM 58, and Figure 9 (a) is a diagram of the configuration of the program area in ROM 58. , FIGS. 9(b) to 9(d) are flowcharts showing the procedure of current control of the power supply device, and FIGS. 10 and 11 are diagrams of other modified examples. In the figure, 10.20.58・ROM, 11...control circuit, 1
2...DC power supply, 81.83...Timer, 21,5
0.90...MPU, 22.23...Latch, 13
゜24.51...Pulse signal generation circuit, 30,31゜35.36...Counter, 32,37.85...Flip-flop, 14.52...DC chopper circuit,
15.53.84... A/D converter, 54... Interwoven timer, 55... Transformer, 80.82...
-Register, 86...Multiplexer. :, Figure 23 (G) Figure 4 (a) Figure 4 (b) Figure 9 (0) Grade 9 Figure (C) Cram Figure 9 (d)

Claims (5)

[Claims] (1) A power supply device that converts input DC voltage to supply power to a load, which includes a chopper circuit, a pulse signal generation circuit that generates a pulse signal to control the chopper circuit, and a detection circuit that detects load fluctuations. , a storage circuit that stores in advance data corresponding to a pulse signal to be set according to the load fluctuation; and a storage circuit that stores data corresponding to the pulse signal to be set according to the load fluctuation; and a storage circuit that stores data corresponding to the pulse signal to be set according to the load fluctuation; A power supply device having a control circuit that inputs input to a generation circuit. (2) The data stored in the storage circuit consists of data regarding the period and ON time of the pulse signal, and the pulse signal generation circuit has a retriggerable first timer and a second timer, and the output of the first timer and the second timer. It has a flip-flop that uses the output of the timer as a set input and a reset input, respectively, and a timer energizing circuit that always energizes a first timer and energizes a second timer only when the flip-flop is in the set state, The control circuit uses the periodic data read from the storage circuit and O
2. The power supply device according to claim 1, wherein the N time data are input as the set time of the first timer and the set time of the second timer, respectively. (3) The data stored in the memory circuit is the OF of the pulse signal.
Consisting of data regarding F time and ON time, the pulse signal generation circuit uses a retriggerable first timer and a second timer, and uses the output of the first timer and the output of the second timer as set input and reset input, respectively. flip-flop and
a timer energizing circuit that energizes a first timer only when the flip-flop is in a reset state and a timer energizing circuit that energizes a second timer only when the flip-flop is in a set state; OFF time data and O
2. The power supply device according to claim 1, wherein the N time data are input as the set time of the first timer and the set time of the second timer, respectively. (4) The power supply device according to claim 2 or 3, wherein the first timer and the second timer are presettable binary counters. (5) The power supply device according to any one of claims 2 to 4, wherein the memory circuit, control circuit, and pulse generation circuit are formed on a monolithic silicon substrate.