JPS5844452A - Controlling method for image formation - Google Patents

Abstract

PURPOSE:To obtain a small-sized device of simplified constitution while realizing accurate control free of the influence of a noise, etc., by digitizing a signal obtained by detecting copying conditions, and performing arithmetic through a microcomputer and then finding a control value. CONSTITUTION:A reference lamp 22 flashes to form light and dark parts on a photosensitive drum surface, and their potentials are measured by a probe 21 to obtain a value (a), which is digitized by an A-D converter and stored in an RAM through a CPU. According to a prescribed program, the CPU decides on voltages to be applied to corona chargers 2 and 4 so that the drum surface potential has a reference value. On the basis of the voltage control signals, output equipment determines the voltage value of a charger power source transformer to control an AC high-voltage transformer and a DC transformer on the basis of an analog value obtained by a D-A converter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method K1 for controlling image formation in electrophotography.
Take 1l.

Conventionally, in an image forming apparatus using an electrophotographic method such as a copying machine, the surface potential on the photoreceptor is measured by a potential needle or the like in a rounded shape to stabilize the surface potential, and this surface potential is measured by a gun, compared to an analog value t, and calculated. A method is used in which a charger and the like are controlled by processing.

In this type of system, because of analog processing, the rounding circuit for processing comparisons, calculations, etc. is a horizontal line, and many parts are used, and malfunctions are likely to occur due to noise and the like.

In recent years, due to advances in semiconductor technology, calculation parts, register parts,
A nine-chip microprocessor is provided that includes an accumulator, a program counter, a stack pointer, etc., and it is conceivable that such a microprocessor could be applied to control and diagnosis of image forming apparatuses such as copying machines.

In view of the above points, it is an object of the present invention to provide a jlig I formation control device that is round and can be digitally controlled by a processor. For this purpose, the present invention detects the copying conditions, converts the detection signal into a digital value, reads it into the processor as a count value, calculates the control value by the processor, and controls the copying process based on the result. It is characterized by this.

Further, the present invention detects a copying condition, reads the detection signal into the processor t6c, calculates the control value by the processor, converts the result into an analog value, and controls the copying process based on the analog value. It is characterized by this.

The present invention will be explained below using drawings.

T! Figure 1 shows an example of electrophotographic technology. First, a photoreceptor 1 (Mylar 101,
The surface of C (18102, conductive substrate 103) is exposed to a light image through the lens system S, and at the same time, a static electricity layer is formed along with the discharge of the static eliminator 4, and if necessary, the entire surface is exposed with a lamp to contrast the layer. , a developing device 6 forms a visible image, and a paper feed roller 7 transfers the visible image onto a transfer paper 9 fed from a cassette 8 using a transfer charger 10 .
The transfer paper 9 is separated from the photoconductor 1 by the separation roller 11, and then fed to the fixing device 12 consisting of the fixing roller 2, where it is fixed and discharged to the tray 13. In copying machines, the potential on the surface of the photoreceptor, which has the greatest effect on visible images, is affected by variations in the installation of the charger, variations in the voltage of the charging transformer, changes in ambient temperature and humidity, and variations and deterioration in the characteristics of the photoconductor. It is difficult to maintain a predetermined potential.

The surface potentials of the photoreceptor obtained in the bright and dark areas of each copying process position as described above are shown in FIG. The surface potentials ■ and O at the zero point change as shown in Figure 5 ■ and ■ when the humidity around the photoreceptor increases, and change as shown in Figure 4 ■ and ■ as the photosensitive drum ages. However, the contrast between bright and dark areas cannot be obtained. Furthermore, even if the distance from the drum surface of the charger is different from that of 4, it goes without saying that the desired value of the potential of 2 and 0 cannot be obtained.

Therefore, the copying conditions are controlled so that the potential at the zero point is constant at 4 under any conditions, as shown by ω' and ■' in FIG. 5.4.

Further explanation will be given with reference to the embodiment shown in FIG. In the figure, 21 is a probe for detecting the surface potential of the photoreceptor, 22 is a reference light source, which is provided to emit light through a static eliminator, and 25 is an exposure lamp 2.
Exposure diaphragm that automatically adjusts the amount of light from 4> Reversible motor, 25
26 is a sample document.

That is, the potential at the zero point when the reference light source is on and off is detected by the surface potential detection probe 21, the charging transformer is controlled based on the signal, and the potential of the charging transformer is adjusted to obtain the optimum surface potential. Once the voltage is fixed, the original exposure lamp is turned on without using the reference light source, and the sample paper placed in one corner of the original table is irradiated. The exposure diaphragm is varied by rotating the lens drive unit forward or backward until the potential of O' becomes equal to the potential of O'.

Nine control circuits will be explained using a microcomputer that embodies the above method.

In the figure, the MDC converter converts the input signal a into digital data and outputs it to the next stage.The CPU reads and decodes the input and instruction data from the MCU converter, memory ROM, and RAM, performs addition/subtraction, and performs logical operations. , a central control unit with processing functions such as comparison, ROM is a special memory for storing the procedure (program) for operating the control circuit for the above purpose, and RAM is a memory for storing the program processing. The output device 1 is a writable memory that temporarily stores the data of the . Outputs a signal to set the voltage of the transformer (DC) and the voltage of the DC lance.

The output device 4.5 outputs signals for on/off control of the high-voltage transformer M, the high-voltage transformer DCC, the main drive motor, the full-surface exposure lamp, the reference light source, the document exposure lamp, and the reversible motor for controlling the exposure aperture. This signal is also connected to the real load via an interface circuit. The outputs of the MuC high voltage transformer 1 and 2 are connected via diodes with opposite directions, but this means that the MuC high voltage transformer 1 outputs only the Φ component, and the MuC high voltage transformer 2 outputs the O component. This is to output only the θ component and the Φ component. In other words, the static electricity is eliminated by the difference between these two components.Therefore, in Figure 3.4, the input voltage of the high voltage transformer 2 is adjusted so as to increase the voltage of the rounded K(E) component, which changes from ■ to O' in Figure 3.4. In order to increase the voltage and make the change from ■ to ■', the input voltage of the DC lance is increased.

The input device inputs a clock signal for executing a copying sequence, a drum position (home) signal, a registration signal for transfer timing, a developer concentration, a signal for detecting a jam, etc. (not shown).

Dmu 1-5 are D-mu converters which convert the digital signals from each output device 1-5 into an analog quantity and output voltage to the so-called MuC high-voltage transformer and DC high-voltage transformer. The output timing is determined by the signal. The ROM stores a program for controlling the potential according to the flowchart shown in FIG. Above RA
M has the optimum 0 potential, θ potential and DC optimum potential of M C, and the MUS converter is controlled by the control signal line and the address bus, and outputs a 4-bit digital conversion signal to the data bus.

The operation will be explained based on the flowchart in FIG. Prior to the copy cycle, the CPU specifies the address of the output device (1) via the address bus, and sends a binary signal to the output device (1) via the data bus to set a predetermined potential of the high voltage transformer 1. Output to.

This is converted into an analog quantity by the D-M converter and provides a potential to the M-C high voltage transformer 1. However, at this point, the control signal line (2) of the D-mconverter p- is not set, so data is simply transferred to the output device (1). Next, in the same way, the output device (2), (
A predetermined binary signal is transferred to 3). Furthermore, cptr specifies the address tube of the output device (5) to output a binary code of 1000 to turn on the main drive motor. This is a code when the output device (5) can output 4 bits in parallel, and is output via the data bus M (hereinafter referred to as data bus), and means that one terminal of the main motor is 1 and the other terminal is O ( op-1).

Next, the timer is operated until the rotation of the drum becomes constant (8P-2), and the next execution is waited. When the time is up, cpa outputs the binary code 1111 to the output device (4), and the primary high voltage transformer Turn on the high voltage transformer 1.2 full exposure lamp and reference light source (8P/-S).

BP-4 to 8F-14 are routines that turn on the reference light source and change the high-voltage transformer 2 to find an appropriate value for the bright area potential of the photosensitive drum. , is a routine for finding an appropriate value for the dark potential of the photosensitive drum by changing the DC high voltage transformer.

The so-called KFlmg determines whether to branch or not in program execution, and depending on the set,
The reset advances execution to the lno side.

If the DC high voltage transformer is changed from 8F-15 to BP-24, 4 changes will be given to the bright area potential, so 8P-1 will be changed again.
A loop α is provided for rounding to return to the routine of 5 to 8P-24 and check again. Flag 1 is the sand-throwing sea flag 2. The potential of both the bright and dark areas is at the appropriate value and the number 9 can be confirmed at 8P-27. Flag 5 does not generate spark discharge, so 8P-4~5p-148P-15~
This is provided to memorize the number 9 when the voltage limit is reached in BP-24. Therefore, when Flag2 is set #18
Fla does not execute routines P-4 to sp-14.
When g3 is set, 8F-15 to BP-24 are not executed and the program is forced to proceed to the later program.

BP-28 to 8P-45 turn on the document exposure lamp and rotate the exposure aperture control motor forward or reverse to obtain the appropriate amount of light so that the potential IL is equal to the potential IL set in 8P-4 to 5p-14. There are 4 routines to set.

When this is completed, the entire load is set to 011F in BP-56 and the process starts (copy cycle). In the above example, the optimum potential of the standard color tone was obtained, and nine reference light sources and sample paper were provided corresponding to the color 1i111. However, since the color tones of originals vary, after setting the appropriate aperture, the operational connection between the lens drive unit and the motor is released, and the operative connection is made with the GK adjustment dial, so that the color tone of the original can be matched. You can obtain images using

From the flowchart shown in FIG. 6 above, it is easy for those skilled in the art to create a programmer step using a dedicated instruction code using a general-purpose microcomputer (μmCOM (MTIL8080, etc.)), so the instruction step is omitted.

Note that the timer can be implemented by storing the timer time in advance as a code in RAM, and providing a routine that sequentially subtracts the above code one by one and determines whether it is OK.
It is also possible to provide an external timer means, start the timer at Out of the control circuit, and detect time-up at In.

Furthermore, by providing a photosensitive drum circumference NK, a chetar zone to which reference light and sample light are irradiated, control can be performed even during copy production.

In this way, the detection signal is converted into digital, read as a count value, and the judgment function of the microcomputer is used to obtain the appropriate electrostatic voltage, which is converted into analog and applied to the high-voltage transformer, and the appropriate amount of light is obtained and exposed. It has tailored features.

Furthermore, a reference light source is provided, and in the first step, prior to the copying cycle, the potential of the surface of the photoreceptor when the reference light source is turned on and the potential when the light is turned off are detected by a surface potential detection probe, and a detection signal is detected. It is characterized by controlling the output of the transformer.

In addition, in the second step, the sample paper (corresponding to the bright area) provided on the paper stacking table for exposing the original was irradiated, and the potential of the photoreceptor surface during scanning was measured in the same way as above. The present invention is characterized in that the light is adjusted in such a way that the paper surface potential becomes equal to the potential of the bright area (when lit) obtained in the first step, based on this detection signal.

The reason why it is divided into the first stage and the second stage is that when the photosensitive drum deteriorates due to aging, the
The potential of the primary charging transformer and the static eliminating transformer must be raised to reduce the voltage, but since the upper limit of this potential must be below the spark discharge starting voltage, this voltage can guarantee against deterioration of the photosensitive drum. Since the potentials of (1) and (0) must be set to optimum values, the first step is to set and maintain the potential of the transformer. If the light from the original exposure lamp is used without using a reference light source, the surface potential of monochromatic images with different irradiation light amounts may be affected by the instability of the light intensity of the original exposure lamp or the setting value of the exposure aperture adjustment dial. Since this cannot be confirmed, in the first step, a reference light source that does not pass through the lens system is provided to set the appropriate surface potential, and in the second step, the aperture is varied). I decided to find the appropriate value again.

As described above, the present invention converts the detection signal into digital, reads it as a count value, determines the control value (by the judgment function of the processor), and controls the copying process. Since the copying and copying process is controlled by converting the data into analog, the effects of noise and the like can be removed, allowing for more accurate control. Furthermore, since the configuration is simple, the device can be downsized.

Furthermore, even when predetermined input/output is repeatedly performed, real-time processing is possible without any time delay.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the electrophotographic device, Figure 2 is a graph 4 showing the surface potential related to Figure 1, Figure 3 is a diagram showing changes in surface potential with respect to humidity, and Figure 4 is a graph of surface potential. 5 is a circuit diagram of the stabilizing device of the present invention, and FIG. 6 is a flowchart showing the procedure for stabilizing the surface potential according to FIG. 5. In FIG. Potential detection probe, 22 is a reference light source, 2
5 is an aperture screen, 24 is an exposure lamp, and 26 is a sample original. Applicant Canon Co., Ltd.

Claims (2)

[Claims] (1) A computer that detects the copying conditions, converts the detection signal into a digital value, reads it as a count value into the processor tK, calculates the control value using the processor, and controls the copying process based on the result. An image formation control method characterized by: (2) Detect the ml copying conditions, read the detection signal into a processor, calculate the control value by the processor, convert the result into an analog value, and control the copying process based on the analog value. An image formation control method characterized by: