JPS6252572A - Electrostatic transfer type color recording device - Google Patents

Abstract

PURPOSE:To improve the quality of a recording image by repeating a process in which an electrostatic latent image is formed on a charge carrier and visualized by a developing means and the visual image is transferred to a recording sheet on a transfer drum while colors of developers are changed successively. CONSTITUTION:Recording mode changeover switch means KMA-KMC are provided to select plural operation modes. In the 1st mode, the image forming and transfer process is performed once for each color and in the 2nd mode, the image forming and transfer process is carried out plural times (normally twice) for each color. Consequently, when high-speed operation is required, the 1st mode is selected and then the process is performed three times to complete recording, which is therefore finished in a short time (about a half as long as in the 2nd mode). When an original has faithful gradation over a wide density range like a photograph, the 2nd mode is selected and then the process is performed plural times (normally twice) for each color, so recording is performed with nearly ideal characteristics and an image faithful to the original image is reproduced.

Description

[Detailed description of the invention] CField of invention 1 The present invention relates to an electrostatic transfer type color recording device.

Especially regarding improving image quality.

[Prior Art] In an electrostatic transfer type recording device, for example, an electrostatic copying machine, a series of processes such as charging, exposure, development, fixing, etc. are performed to record a copy of an original image on a predetermined recording paper. In this type of recording apparatus, it is preferable to reproduce an image that is as faithful to the original image as possible. Therefore, with regard to gradation, it is sufficient if the density (or density) of the original image and the density of the recorded image are in a proportional relationship.

However, in a typical copying machine, the relationship between original density and copy density is not linear, as shown in FIGS. 6a, 6b, and 6c. In particular, the copy density is saturated in areas where the original density is high. Gradation is not reproduced in areas where the copy density is saturated. Furthermore, in a color copying machine, when the density is saturated, the color balance is disrupted, resulting in a difference between the color of the original image and the color of the recorded image. The relationship between the original density and the copy density is shown in Figure 6a (characteristics with adjusted developing bias voltage), Figure 6b (*Light amount 1 [adjusted characteristics), and Figure 6C (characteristics adjusted).
As shown in FIG. 3), the charging voltage of the photoreceptor can be changed in various ways by adjusting various parameters related to the recording process. However, as can be seen from these drawings, no matter what adjustment is performed, it is not possible to make the relationship between original density and copy density linear over a wide density range.

For this reason, conventional copying machines have been provided with a large number of parameter adjustment means to adjust various parameters wR so as to obtain the most preferable image depending on the type of document image. Therefore, in order to obtain a good copy, it is necessary to take a large number of test copies, and even if AM is performed strictly, the image quality will not be sufficient for originals with a wide range of gradation changes such as photographs. I can't get it.

[Purpose of R-light] The purpose of the present invention is to improve the quality of recorded images.

[Structure of the Invention] For example, by adjusting the exposure amount, the original density-copy density characteristic can be shifted with respect to the original density value, as shown in FIG. 6b. Therefore, characteristics A and B shown in FIG. 6d can be respectively realized. When characteristic A and characteristic B are combined (characteristic A + B), characteristics close to ideal characteristics can be obtained over a wide concentration range.

To achieve this, it is necessary to adjust the parameters to
Set the copying machine to the state of , perform the first image formation and transfer, readjust the parameters and set the state of characteristic B,
The second image formation and transfer can be performed.
A high quality image is recorded on the recording sheet according to the characteristics of A and B.

Y (yellow) for color recording.

The first and second image formation and transfer may be performed for each of the developed colors of C (cyan), 2M (magenta).

By the way, when reproducing one recorded image by performing image formation and transfer a plurality of times, it is necessary to accurately align the positions of the first image and the second image. Therefore, in one aspect of the present invention, a transfer drum is disposed close to a charge carrier such as a photosensitive drum, and the transfer drum is provided with a holding means for holding a recording sheet. According to this, since the recording sheet can be fixed on the transfer drum, if the image is transferred in synchronization with the rotation of the transfer drum, the first image and the second image can be accurately aligned. Since no misregistration occurs, the imaging and transfer process can be repeated by successively changing the developer color to obtain a color image.

However, when image formation and transfer are performed twice for each color as described above, in the case of full-color recording, 6
You need to run the process once.

Recording time becomes longer. For example, assuming that the time required for each image formation and transfer process is 4 seconds, the process is repeated 6 times, so it takes at least 24 seconds to make one copy.

Therefore, in the present invention, a recording mode changeover switch means is provided to enable selection of a plurality of operation modes. 1st
In the first mode, one imaging and transfer process is performed for each color, and in the second mode, multiple (usually two) imaging and transfer processes are performed for each color. As a result, when high-speed operation is required, the first
If you select this mode, the process will be executed three times before recording ends, so you can complete the recording in a short time (about 1/2 of the time in the second mode), and it will be faithful to the original over a wide density range like a photograph. If you require excellent gradation, select the second mode and the process will be executed multiple times (usually twice) for each color, so recording will be performed with characteristics close to ideal characteristics. Images that are faithful to the original image can be reproduced.

By the way, since the transfer drum that holds the recording sheet is generally made of a dielectric film, when a transfer operation is performed and a current is passed through it, the transfer drum becomes saturated in charge.

Therefore, if the transfer operation is repeated, the transfer efficiency decreases each time.

Therefore, in conventional color copying machines, the first time is 150 μA (Y) and the second time is 250 μA (C).
The transfer current value was changed stepwise for each transfer process, such as 400 μA (M) for the 933rd time.
This prevents a decrease in transfer efficiency. When repeating the process six times as described above, it is necessary to set six current steps. However, if the maximum value of this current is too large, lightning strikes, reverse transfer (toner on the recording sheet is pulled toward the photosensitive drum), deformation of the transfer drum (the surface becomes dented), etc. may occur. Therefore, since the width of the current step has to be made smaller, the later the transfer efficiency becomes, the lower the transfer efficiency becomes.

On the other hand, when characteristic A and characteristic B are combined as shown in Fig. 6d, recording is performed over the entire area of original density in characteristic A, but in characteristic B, the recording area is in the area with high original density. Limited. In other words, the part recorded by characteristic A is larger than the part recorded by characteristic B.
This has a large effect on the entire recorded image.

Therefore, in a preferred embodiment of the present invention, recording according to characteristic A, which has a large effect on the entire recorded image, is performed in the first process, and recording according to characteristic B (high density area recording) is performed in the second process. No. Thereby, deterioration in image quality due to a decrease in transfer efficiency can be minimized.

By the way, when a predetermined alternating current voltage is applied to a separation electrode provided to separate the recording sheet from the transfer drum, the transfer drum is neutralized and the saturation current becomes small. but,
Because the recording sheet is only partially held mechanically on the transfer drum.

If separation static electricity removal (stripping static electricity removal) is performed during process execution,
The recording sheet rotates away from the transfer drum, staining the transferred image or causing trouble with the device. Therefore, in a preferred embodiment of the present invention, when three recording processes are completed, a voltage at a level lower than the peeling level of the recording sheet is applied to the separation electrodes to perform intermediate charge removal. Thereby, the step width of the transfer current can be increased, and a decrease in transfer efficiency can be prevented.

[Example] The present invention will be described in detail below with reference to one drawing.

FIG. 2 shows a mechanical section of one type of color copying machine embodying the present invention. This will be explained with reference to FIG.

40 is a contact glass on which the original is placed.

An optical scanning system is provided below the contact glass 40. The optical scanning system includes an exposure lamp 3. 1st mirror 4.
2nd mirror 5. Third mirror 6, lens 7, fourth mirror 8
A two-color separation filter 9 and the like are provided. Exposure lamp 3
The light emitted from the contact glass 40 hits a document (not shown) on the contact glass 40, and the reflected light is reflected by the first mirror 4. 2nd mirror 5. The light passes through the third mirror 6, lens 7, fourth mirror 8, and color separation filter 9, and enters the surface of the photosensitive drum 1.

The color separation filter 9 has three filters, R (red), G (green), and B (blue) arranged at an angle of 120 degrees to each other.
Equipped with two filter plates.

One of the filter plates is selectively inserted into the optical path of the optical scanning system.By driving a filter motor M5, which will be described later, the one-color separation filter 9 is rotated, and the selection of the filter plate is changed. R,G.

By sequentially inserting the B filter plates into the optical path and scanning the original, an original image separated into the basic colors of R, G, and B (three primary colors of light) is obtained.

In this example, filter plates are selected in the order of B, R, and G. In order to know the position of the filter plate, a home position sensor (5E5 to be described later) is provided to detect whether the blue filter plate is inserted into the optical path.

Near the circumferential surface of the photoreceptor drum l, a charger (main charger) lO, an eraser 11. Magenta (M) curse, image roller 12. Cyan (C) developing roller 13. Yellow (Y) gl, image roller 14. Transfer drum 2. Transfer charger 18. Static neutralization charger before cleaning 19. It is equipped with a cleaning unit 20°, a static elimination charger 21, etc.

In FIG. 2, the photosensitive drum 1 rotates counterclockwise, and the transfer drum 2 rotates clockwise. The transfer charger 18 is arranged inside the transfer drum 2 at a position close to the photosensitive drum 1 .

The cylindrical portion of the transfer drum 2 that holds the recording sheet is
It is made of a dielectric film, and comes into contact with the surface of the photoreceptor drum 1 via the recording sheet when performing a recording operation. Two separate chargers 22 and 23 are arranged downstream of the transfer charger 18 of the transfer drum 2 so as to sandwich the peripheral wall of the transfer drum 2 .

The paper feeding system is equipped with two paper feeding cassettes 26 and 27, one of which is selected. The lower paper feed section has a calling roller 28. A paper feed roller 29 and a reversing roller 30 are provided, and the recording sheets are fed one by one from the paper feed cassette 26 by driving these rollers. The same applies to the upper sheet feeding section.

The recording sheet 41 fed from the upper or lower paper feed cassette stops at the position of the registration roller 31, and is moved to the transfer drum 2 in synchronization with the rotation timing of the transfer drum 2 as shown in FIG. 3b. sent to.

One clamp plate 2a is provided on the outer circumferential surface of the transfer drum 2 in parallel with its rotation axis. This clamp plate 2a is
Although it is normally closed, it is opened and closed by a cam mechanism 2b by driving a motor M7, which will be described later. In other words,
When feeding the recording sheet 41, open the clamp plate 2a,
When the recording sheet 41 enters between the clamp plate 2a and the transfer drum 2.

The clamp plate 2a is closed to clamp (hold) the leading end of the recording sheet 41. It should be noted that since the transfer drum 2 is charged by passing the transfer current, an electrostatic attraction force is applied, and thereby the portion other than the leading edge of the recording sheet 41 is also held on the transfer drum.

When all image transfer is completed, the charge is removed by applying a predetermined AC voltage to the separation chargers 22 and 23, and at the same time, the clamp plate 2a is opened to separate the recording sheet 4I from the transfer drum 2.

As shown in FIG. 3a, the photoreceptor drum l and the transfer drum 2
are connected to each other by gears 45 and 46,
Gear 45 is connected to main motor M1 via transmission mechanism 42. This transmission mechanism 42 is equipped with a home position sensor HPI.

Referring again to FIG. The recording sheet is separated from the transfer drum 2 by passing between the transfer chargers 22 and 23,
The fixing roller 32 and pressure roller 3 of the fixing section located downstream
The paper is ejected after being thermally fixed through the paper.

The operation board OP1 of the color copying machine shown in FIG.
As shown in the figure. Referring to FIG. 4a, this operation board includes a display DPI, a numeric keypad KT, a magnification key Kl, a paper key 2. 3 on the clear stop key. 4. to the interrupt key. 5. to the print key. Density adjustment knob AJ, mode selection key KM
A. K.M.B.

It is equipped with KMC, KMD and mold indicator DP2.

In this example, by operating mode selection keys KMA, KMB, KMC, and KMD, the copying process can be executed with five types of preset density characteristics. Immediately after the device is powered on, normal mode (or first mode) is selected, and each mode selection key KMA, KMB, KMC, and KMD
By pressing A mode (second mode), B mode (third mode), C mode (fourth mode) and D
mode (fifth mode) is selected.

In order to set the characteristics of each mode, this color copying machine is provided with a color balance setting board OP2 shown in FIG. 4b. This setting board OP2 is the operation board OP
Although it is located near I, it is usually covered with a cover (not shown).

Referring to FIG. 4b, the color balance setting board OF2 is provided with a large number of keys and a display section DP3. The six keys KGL control the developing bias voltage, Y, C, M.
(TJP.

The six keys KG2 change the applied voltage of the main charger IO to Y.

The six keys KG3 are used to adjust each of C and M, and the six keys KG3 adjust the light level of the exposure lamp 3 to Y, C,
This is for adjusting each of M. 6 on key
is a memory key for storing the values updated by the keys KGI, KG2, and KO2 in the memory of the specified mode. Key 7 is a key for selecting between full color mode and single color mode.

The display section DP3 is equipped with nine 7-segment numerical displays, and displays nine parameters, namely, development bias Y,
C, M, Y for main charger voltage.

One display digit is assigned to each of C, M, and exposure level Y, C, and M. Each display digit has a value of 0°1.2,
3, 4, 5, 6, 7, 8, 9. A, B.

Since C, D, E, and F can be displayed, each of the nine parameters can be displayed in 16 levels. In other words, this color balance setting board ○P2 allows 16 levels of level adjustment for each parameter.

Reference is made to FIGS. 5a, 5b, 5c, 5d, and 5e which schematically show the electrical circuit configuration of the color copying machine of FIG. 2. A main control board 100 controls the entire device. The main control board 100 is connected to sensors and motors via various units.

Solenoids etc. are connected.

Referring first to FIG. 5a, a paper feed unit 110 is connected to the main control board 100. As shown in FIG. Paper feeding unit 110
, a resist detection sensor 111°, a paper end sensor 113, 118 . Limit position sensor t14, 119.
A sensor group including paper size sensors 115, 120, etc.
Paper feed roller stop solenoid 5OL3. Call flow control solenoid 5OL4, 5OL5. Registration motor M2. A paper feed motor M3 and a paper feed table motor (for pressure) M4 are connected.

Referring to Figure 5b, the main control board ■00.

A development control plate 120 is connected. Development control plate 120
are connected to Y, C, and M developing units 122, 123, and 124, and various clutches. ,I! The A image control board 120 is equipped with a microcomputer 121 inside, and the developing roller and pumping roller of each developing unit are connected to a high-voltage power supply as shown in FIG. Power output lines B-8 and B-D of the unit 130 are connected.

Referring to FIG. 5c, the main control 1fitoo includes high voltage power supply units 130, 140, 150 and the eraser 1.
1 is connected. The high voltage power supply unit 130 outputs a charging voltage output line C2, a transfer current output line T, and a charging voltage output line C2 based on a 6-bit charging control signal, a 4-bit transfer control signal, and a 5-bit developing bias control signal from the main control board 100. Development bias voltage output line B-[), B
- to 8.

A predetermined amount of power is supplied to each. High pressure 1! source unit 1
30 obi ff1W! The extrusion line C is connected to the main charger 10, and the transfer current output line T is connected to the transfer charger 18.

The high-voltage power supply unit 140 applies a predetermined static elimination voltage to the static elimination chargers 19 and 21 when the static elimination charger on signal from the main control board 100 is turned on. When the separate charger on signal from the main control board 100 is turned on, the high voltage power supply unit 150 connects the separate chargers 22 and 2.
A predetermined separation voltage is applied between 3 and 3. In this example, the separated charge-on signal is 2 bits, and one separated voltage can be switched between 5.5 KV AC and 4 KV AC. When applying a voltage of 4 KV, the recording sheet is not peeled off from the transfer drum because the charge is not removed sufficiently.

Referring to FIG. 5d, an AC power supply unit 160 is connected to the main control board 100. AC power supply unit 1
60 performs voltage conversion, alternating current power switching, etc. AC power supply unit No. 160 is connected with a lamp regulator, a developing motor, a main motor Ml, a fixing heater, a fixing fan, a fixing drive motor, a power transformer, and the like.

A filter is provided inside the AC power supply unit 160.

It is equipped with a relay and a number of solid state relays.

Referring to FIG. 5e, the main control board 100 includes an operation board ○Pl, a color balance setting board OF2. Memory unit 170. +The fixing unit 180, lamp regulator 190, and motor control unit 200 are connected. In this example, the dimming level of the lamp regulator 190 is controlled by a 5-bit control (
It is configured to be set on the i issue.

The motor control unit 200 includes a filter motor M5.
Lens motor M6. Clamp motor M7, return motor M8, cleaning motor M9, and sensor SE that detects the home position of the mechanism driven by each motor.
5. SE6. SE7. SE8 and SF3 are connected. Filter motor M5 drives color separation filter 9,
The lens motor M6 drives the lens 7 to control the copying magnification, the clamp motor M7 drives the clamp plate 2a to open and close, the return motor M8 returns the optical scanning system (scanner), and the cleaning motor M9 controls the cleaning unit. 20 drives are performed.

Inside the main control board 100, a microprocessor,
It is equipped with ROM (read-only memory), RAM (read/write memory), Ilo, A/D converter, etc. The memory unit 170 is a memory equipped with a battery backup circuit, and is used to store data that needs to be retained even when the power of the apparatus is cut off, such as the values of various parameters set by the color balance setting board OP2. It is equipped with.

Next, the operation of the color copying machine shown in FIG. 2 will be explained, but first, characteristic parts will be briefly explained. In this example, normal mode, mode A.

In mode B and mode C, image formation and transfer processes are performed once for each color of Y, C, and M. However, if mode D is selected by pressing the mode key MD, mode B Characteristics (set parameters)
According to the steps, each process of Y, C, M image formation and transfer
After repeating the steps, Y, C again according to the characteristics of mode C.
, M are performed once each.

That is, in mode D, image formation and transfer are performed six times (in full color mode).

Therefore, if characteristic A shown in Figure 6d is set to mode B, and characteristic B is set to mode C, recording can be performed with characteristics A and B in Figure 6d by selecting mode D. .

FIG. 8 shows an outline of the operation of the copying machine shown in FIG. 2.

This will be explained with reference to FIG. When the power is turned on.

First, perform the initial settings. Specifically, after setting the output boat to its initial state and clearing the internal memory, the scanner,
Set the positions of the movable parts such as the variable magnification mechanism 9 color separation filters to the initial state (home position), and each process control unit.
Set to operational state. The normal mode is selected as the operation mode. In the normal mode, all indicators DP2 on the operation board OPI are turned off.

After the initial settings, the status of each part (fixing temperature, etc.) is checked repeatedly and the system waits until it becomes operational.

If there is an abnormality, proceed to abnormality processing. If the preparation is OK, "copy possible" is displayed on the display DPI of the operation board ○P1, and the status check of each part, key manual processing 9 indication process, etc. are repeatedly executed until 5 is pressed on the print key.

The "key manual processing" subroutine is shown in FIGS. 9aS, 9b, and 9c. Refer to each diagram for "key human processing"
Explain. In this subroutine, the presence or absence of key human power is checked, and if key human power is present, processing is performed accordingly.

When the numeric keypad KT is turned on, the number of copies is set according to the numerical value assigned to that key. When 2 is turned on in the paper key, the paper feed system selected during the copying operation is switched from the upper stage to the lower stage or from the lower stage to the upper stage. When 1 is turned on in the magnification key, magnification control is performed to change the 1 magnification. When 5 is turned on to the print key, a print start flag is set.

Next, the processing of keys related to density parameters will be explained, but before that, the configuration of the memory (part of the memory unit 170) that stores each parameter will be explained. FIG. 11 shows the memory map of that part. Referring to FIG. 11, this memory block 07 includes memories Mr I, Mr2 . MI3. MNI, M
N2. MN3°MAI, MA2. MA3. MB 1. M
B2. MB3, MCI, MC2, MC3, MDI, MB
2 and MB3 are slightly smaller. Memory MIn (n=1~
3) stores the data being input, M N n .

M A n , M B n , M Cn and MDn
Normal mode, Mode A, Mode B, respectively.
Mode C and mode D data are stored. Memory M
The data stored in the areas n=L, n=2, and n=3 of In, MNn, MAn, MBn, MCn, and MDn are the developing bias voltages, respectively.

Corresponds to the main charger's applied voltage and exposure amount.

Referring again to Figures 98@, 9b and 9c.

When key KGI (any of the six keys) is turned on, it is first determined whether it is on the up (U) side or the down side (D). If it is on the up side, the contents of the memory Ml 1 (only the one corresponding to the key turned on among Y, C, and M) is incremented (+1). However, if the content before update is 15, that value is retained. If it's on the down side.

Decrement (-1) the contents of memory MI 1 (only the one corresponding to the key turned on among Y, C, and M). However, if the content before update is 0, that value is retained.

When key KG2 (any of the six keys) is turned on, it is first determined whether it is on the up (U) side or the down side (D). On the up side, increment (
+1). However, if the content before update is 15, that value is retained. If it's on the down side.

Decrement (-1) the contents of the memory MI 2 (only the one corresponding to the key turned on among Y, C, and M).

However, if the content before update is 0, that value is retained.

When key KG3 (any of the 6 keys) is turned on,
First, it is determined whether it is on the up (U) side or the down side (D). If it is on the up side, the contents of the memory MI 3 (only the one corresponding to the turned-on key among Y, C, and M) is incremented (+1). However, if the content before update is 15, that value is retained. On the down side, memory MI 3 (Y, C
, M that corresponds to the key turned on) is decremented (-1). However, if the content before update is 0, that value is retained.

When the KGI, KO2 and KO2 keys are pressed.

Each time the contents of the memory are incremented or decremented, a predetermined period of time is waited. Therefore, when the KGl, KO2, and KO2 keys are pressed, the value in the memory M I n is repeatedly updated at a rate of 1 every predetermined time. The range of variation is between 0 and 15.

When the memory key 6 is turned on, the contents of the register R6 are referred to and processing according to the value is performed.

Register R6 stores values according to the operating mode selected at that time, and 0, 1, 2.3, and 4 correspond to normal mode, mode A, mode B, mode C, and mode D, respectively. . In normal mode, memory M
II, MI2 and MI3 respectively to memory MNI.
, MN2 and MN3, and if mode A, memory M
The contents of tl, M■2 and MI3 are respectively stored in memory M.
A.I.

Store in MA2 and MA3, and if mode B, memory MI
The contents of I, MI2 and MI3 are stored in the memory MBI, respectively.
Store in MB2 and MB3, and if mode C, memory Ml
1. The contents of MI2 and MI3 are stored in memory MCI.
, MC2 and MC3, and if mode D, memory M
I 1. The contents of MI2 and MI3 are stored in each memory MD.
Store in L, MD2 and MC3.

When the mode key is turned on, the following processing occurs depending on the pressed mode key. If the mode key is KMA, set the mode register R1 to 1, and transfer the contents of memories MAI, MA2, and MA3 to the memories Ml 1. MI2 and M
Store in I3. If the mode key is KMB, set the mode register R1 to 2, and set the memory MBI, MB2 and MB.
3 are stored in the memories MII, MI2, and MI3, respectively. If mode key KMC, mode register R1
is set to 3, and the contents of memories MCI, MC2, and MC3 are transferred to memories MII, M?, respectively. 2 and MI3. If the mode key is KMD, set 4 in mode register R1 and select memory MDI.

The contents of MC2 and MC3 are respectively stored in memory MII.

Store in MI2 and MI3.

i.e. mode key KMA, KMB, KMC or KM
When a mode is selected with D, the parameters of the selected mode are transferred to the memory M I n , and the parameters of the selected mode are transferred to the memory M I n
The contents of are updated by operating the keys KGI, KG2 and KO2, and when 6 is pressed on the memory key, the updated contents of the memory M I n are transferred to the memories MNn, MAn, MBn, MCn according to the operating mode at that time. Or M.D.
Transferred to n and set. Note that once a mode other than normal mode is selected, normal mode cannot be selected again unless the power is turned off.

When mode D is selected as described above, the first process (Y, C, and M) is executed using the parameters of mode B, and then the second process is executed using the parameters of mode C. By updating the parameters of mode B and mode C, the parameters of the first process and the second process of mode D can be WRm independently. by this.

The degree of freedom in adjusting density characteristics (original density - copy density) in mode D is increased.

Note that the memories M B n and M Cn (n = 1 to
3), values such that the composite characteristic (A+B) shown in FIG. 6d is closest to the ideal characteristic are automatically set at the time of initial setting. At this time, the contents of the memory MBn are set to a characteristic in which the recording area covers the low density area or the entire area, as shown by the characteristic A in Fig. 6d, and the contents of the memory MCn are set to a characteristic as shown by the characteristic B in Fig. 6d. In this case, the fli recording area is set to a characteristic that is limited to a high concentration area. What data will be edited at this time?

It is stored in advance in the read-only memory (ROM) of the main control board 100. Therefore, even if the concentration parameters are not adjusted after the power is turned on, if mode D is selected, theoretically preferable characteristics are automatically set. Note that 8 is set in all memories M D n at the time of initial setting.

Referring again to FIG. When 5 is pressed on the print key, that is, when the print start flag is set by the above-mentioned "r key manual processing", the copy process is started. When you start the copy process, the "Scanner Control", "
Exposure lamp control”.

"Charging control", "Transfer control", "Separation control".

The subroutines of "developing bias control,""filtercontrol," and "clamper control" as well as other controls are repeatedly executed in short cycles until copying is completed.

The "scanner control" subroutine will be described with reference to FIG. 10a. First, it is determined whether mode D is selected. That is, since the current mode state is held in register R1, it is determined whether it is 4 (mode D) by referring to register R1. In the case of mode D, when the content of counter CNI is less than 6, mode D
Otherwise, when the content of CNI is less than 3, the following processing is performed. The contents of counter CNI are as follows.

Cleared to 0 when starting the copy process.

When the scanner start timing comes, the forward scanning drive of the scanner is started. In this example, the scanner is driven by the main motor Ml during forward scanning. Also,
When the scanning end timing is reached, forward scanning of the scanner is stopped and scanner return driving is started. In this example,
During return driving, the scanner is driven by a dedicated return motor M8. Either one of the drive system of the main motor M1 and the drive system of the return motor M8 is selectively connected to the scanner by a clutch (not shown).

When the home position sensor SE8 of the scanner detects the home position, the return drive is stopped and the counter CNI is incremented by I-(+1). In other words, in mode D, 6
In other modes, scanning is repeated three times.

Various timings are grasped by counting the number of pulses from a timing generator (not shown) that outputs pulses synchronized with the drive of the main motor from the start of copying.

The "exposure lamp control" subroutine will be explained with reference to FIG. 1 Ob. First, the contents of register R1 are referred to and processing is performed according to the value. If the contents of R1 are 0, 1, 2, and 3, register R2 is stored in memory MN3. M.A.
3. Load the contents of MB3 and MC3. The contents of R1 are 4. That is, in mode D, a value corresponding to the contents of counter CN2 is loaded into R2. The contents of counter CN2 are:

Indicates the number of times the exposure lamp has been lit since the start of copying. Therefore, the contents of counter CN2 are cleared to 0 at the start of copying. If the content of counter CN2 is less than 3, M
The calculation result of B3+ (MD3-8) is loaded into R2, and if the content of CN2 is 3 or more, MC3+ (MD3-8)
) is loaded into R2.

Next, it is determined whether the mode is D, and if mode D, the following process is executed when CN2 is less than 6, and if it is other than mode D, the following process is executed when CN2 is less than 3. That is, when the exposure start timing is reached, the dimming level of the exposure lamp 3 is set according to the contents of the register R2, and the exposure lamp is turned on.

Further, when the exposure end timing is reached, the exposure lamp is set to OFF and the counter CN2 is incremented.

Therefore, in mode D, exposure is repeated six times, and mode D
Otherwise, repeat the exposure three times.

As mentioned above, the density parameter, that is, the dimming level, set in mode D is MB 3 + (MD 3-8) in the first process (CN2 depth 0-2), and MB 3 + (MD 3-8) in the second process (CN2 depth 0-2). 2 = 3 to 5), MC3+
(MD3-8). Therefore, if you adjust the parameter settings in mode D, the first process and the second
Both parameters of the process are corrected. The correction amount is given as a deviation from the standard value (8) of the mode D parameter.

In other words, if the parameters of mode B and mode C are set in advance so that the composite characteristic (mode D) is close to the ideal characteristic, the composite characteristic can be changed by simply adjusting the parameter of mode D (MD3). The overall characteristics, that is, the characteristics of both the low concentration region and the high concentration region can be adjusted. This makes adjustments easier and reduces the number of test copies.

The "charging control" subroutine will be explained with reference to FIG. 10e. First, the contents of register R1 are referred to and processing according to the value is performed. If the contents of R1 are Q, 1, 2, and 3, the memories MN2 . MA2. M
Load the contents of B2 and MC2. The contents of R1 are 4.
That is, in mode D, a value corresponding to the contents of counter CN3 is loaded into R3. The contents of the counter CN3 indicate the number of times the charger is energized since the start of copying.

Therefore, the contents of counter CN3 are cleared to 0 at the start of copying. If the content of counter CN3 is less than 3, MB
The calculation result of 2+ (Mn2-8) is loaded into R3,
If the content of CN3 is 3 or more, MC2+ (Mn2-8)
The calculation result is loaded into R3.

Next, it is determined whether the mode is D, and if mode D, the following process is executed when CN3 is less than 6, and if it is other than mode D, the following process is executed when CN3 is less than 3. That is, when the timing to start energizing the electrification charger comes, the voltage to be applied to the electrification charger 10 is set according to the contents of the register R3, and the voltage is applied. Also, when charging is completed.

The applied voltage is set to 0 and the counter CN3 is incremented. Therefore, in mode D, the relay charger energization is repeated six times, and in modes other than mode D, the charger energization is repeated three times.

As mentioned above, the concentration parameter set in mode D, that is, the voltage applied to the charger, is MB2+ (Mn2-8) in the first process (CN3=0 to 2), and MB2+ (Mn2-8) in the second process (CN3=3). ~5), MC2+(Mn
2-8). Therefore, when the parameter settings are adjusted in mode D, the parameters of both the first process and the second process are corrected without adjusting the parameters in mode B and mode C. The correction amount is given as a deviation from the standard value (8) of the mode D parameter.

In other words, if the parameters of mode B and mode C are set in advance so that one composite characteristic (mode D) is close to the ideal characteristic, the entire one composite characteristic can be changed by simply adjusting the parameter of mode D (Mn2). That is, the characteristics of both the low concentration region and the high concentration region can be adjusted. This makes adjustments easier and reduces the number of test copies.

The "transcription control" subroutine will be explained with reference to FIG. 10d. First, it is determined whether the mode is D or not. Mode D
Then, when the value of counter CN5 is 5 or less, if the value of CN5 is other than mode D, when the value of CN5 is 2 or less, load data corresponding to the value of + CN5 into register R5, and at each current switching timing, the value of register R5 is changed. The current value of the transfer charger is changed according to the current value. When switching the current value, the counter CN5 is incremented. Also counter CN5
is cleared to O at the start of copying. Therefore.

The content of CN5 means the number of process executions in the transfer process. When the transfer process is completed 6 times in mode D, and when the transfer process is completed 3 times in modes other than mode D, the transfer charger is turned off (the current value is set to 0).
). In this example, the energizing current of the transfer charger is set as follows.

Other than mode D: 1st process (Y) ... 150 μA 2nd process (
C) ...250μA 3rd time (M) ...400μA Mode D = Process 1st time (Y) ...150μA 2nd time (
C) ...250μA 3rd time (M) ...400μA 4th time (Y) ...250μA 5th time (C) ...400μA 6th time (M) ...600μA Every time the process changes as described above The reason why the current value is updated is that when the transfer process is executed, the transfer drum is charged, and the subsequent transfer efficiency is reduced. If static elimination is not performed at all, it is necessary to sequentially increase the current value in six steps in mode D, but in this example, intermediate static elimination is performed after the third process, as will be described later.

The fourth transfer current is set to a smaller value than the third transfer current.

The "separation control" subroutine will be explained with reference to FIG. 10e. In this subroutine, an AC voltage of 5.5 KV is applied between the separated chargers 22 and 23 when one separation timing is reached, and the voltage is set to 0 when the voltage release timing comes. Also.

At the intermediate neutralization timing, an AC voltage of 4 KV is applied between the one-separation chargers 22 and 23.

When the transfer process is executed, the surface of the transfer drum 2 is charged to the following potential.

1st time... approx. 500v 2nd time... 1000~1500V 3rd time...
- 2000-3000 V Therefore, in this example, when the third transfer process is completed, 4 volts is applied to the 1-separation charger.
An alternating current voltage of KV is applied to eliminate static electricity from the transfer drum 2. During this process, when M# electricity is applied, the surface potential of the transfer drum is 500.
-100OV. Therefore, the subsequent transfer current can be reduced by tJ% compared to the case where intermediate charge removal is not performed. Since the transfer drum 2 is not completely neutralized after performing the intermediate static elimination, the recording sheet will not be peeled off from the transfer drum 2 by performing the intermediate static elimination. When an AC voltage of 5.5 KV is applied to the separation charger, the surface potential of the transfer drum 2 drops to approximately Ov, and the recording sheet is peeled off from the transfer drum 2.

The "developing bias control" subroutine will be explained with reference to FIG. 10f. First, the contents of register R1 are referred to and processing according to the value is performed. RI content is 0.1.2
and 3, respectively, the memory MNI,
MA1. Load the contents of MBI and MCI. If the content of R1 is 4 and the mode is D, a value corresponding to the content of counter CN4 is loaded into R4. The contents of the counter CN4 indicate the number of times the process has been executed since the start of copying in the development process. The contents of the secondary counter CN4 are cleared to O at the start of copying. Counter CN4
If the content of is less than 3, MB 1 + (MD l-8)
The operation result of is loaded into register R4, and if the contents of CN4 are 3 or more.

The calculation result of MCt 10 (MD t-8) is loaded into R4.

Next, it is determined whether the mode is D, and if mode D, the following process is executed when CN4 is less than 6, and if it is other than mode D, the following process is executed when CN4 is less than 3. That is, when the developing bias voltage application timing comes, register R
The applied voltage is set according to the contents of step 4, and the voltage is applied to the developing electrode.

Furthermore, when the voltage release timing comes, the applied voltage is set to 0 and the counter CN4 is incremented. Therefore, in mode D, voltage application is repeated six times, and mode D
Otherwise, repeat the voltage application three times.

As mentioned above, the density parameters set in mode D, that is, the development bias voltage, are set in the first process (CN
4=O~2), MB l +(MD l-8), second
In the process (CN4=3 to 5), MC1+
(MDI-8). Therefore, if you adjust the parameter settings in mode D.

Without adjusting the parameters of mode B and mode C,
The parameters of both the first process and the second process are corrected. The correction amount is given as a deviation from the standard value (8) of the mode D parameter.

In other words, if the parameters of mode B and mode C are set in advance so that the composite characteristic (mode D) is close to the ideal characteristic, the entire composite characteristic can be adjusted by simply adjusting the parameter (MDI) of mode D.

That is, the characteristics of both the low concentration region and the high concentration region can be adjusted. This makes adjustments easier and reduces the number of test copies.

The "filter control" subroutine will be explained with reference to FIG. 10g. In this subroutine, the contents of the counter CN1 that holds the number of scans by the scanner are referred to, and the color of the color separation filter 9 is selected according to the result. That is, if the counter CNI is 0 or 3, it is checked whether the color separation filter is at the home position, and if it is not at the home position, the filter motor M5 is driven until the home position is detected. When the home position is reached, the filter motor M5 is stopped and the counter CN6 is cleared to 0.

If counter CNI is 1 or 4, check the contents of counter CN6. If CN6 is not 1, the filter motor M5 is driven to rotate the color separation filter 9 by 120 degrees and the contents of the counter CN6 are incremented. If counter CNI is 2 or 5, check the contents of counter CN 6. If CN6 is not 2, filter motor M
5 to rotate the color separation filter 9 by 120 degrees and increment the contents of the counter CN6.

As a result, when the counter CNI is 0 or 3.

A blue (B) filter plate is inserted into the optical path.

When the counter CNI is 1 or 4, a red (R) filter plate is inserted into the optical path, and the counter CNl is 2 or 5.
When , a green (G) filter plate is inserted into the optical path.

In addition, in the color copying machine shown in FIG. 2, Y, C.

Although a monochrome copy operation of any one of the M colors is also possible, the monochrome mode is omitted in the flowchart shown in the drawing. In the monochrome mode, the image formation and transfer process is performed once for each copy, but as in the case of the full color mode, the process can be repeated twice for the monochrome copy.

FIG. 1 and FIG. 7 show operation timings in mode D and other modes, respectively. Referring to FIG. 1, in mode D, the scanner scans and exposes the process in one copy cycle.

It can be seen that the charging process, development process, transfer process, etc. are repeated six times. On the other hand, the seventh
In the operating mode shown in the figure, the scanner scans and exposes the process in one copy cycle.

It can be seen that the charging process, development process, transfer process, etc. are repeated three times. By selecting Mode D, very good quality copies are obtained, but the copying speed is quite slow because the imaging and transfer process is repeated six times. Therefore, if the copy speed is an issue, by selecting an operation mode other than mode D, copying can be performed in about half the time of mode D.

Incidentally, in the past, density unevenness, as if swept by an ear of rice, sometimes appeared on the recorded image along the scanning direction of the copying machine (rotation direction of the photoreceptor drum). This phenomenon was not observed when the rotation mode (a mode in which each color is processed twice) was selected. In other words, by performing the recording process multiple times for the same color, density unevenness is also eliminated.

The meanings of special symbols shown in each drawing are as follows.

HP... Home position (home position) PP...
Power back (power supply) SOLl... Solenoid MC... Electromagnetic clutch In addition, in the above embodiment, the light emission level of the exposure lamp is used as a parameter related to image reading, but a means for reducing the amount of light is provided in the optical path of the optical scanning system. It is also possible to provide a filter and use the squeeze amount as a parameter.

In the above embodiment, an analog type color copying machine is shown, but the present invention can be applied to various other recording apparatuses that perform a similar electrostatic transfer type recording process.

[Effects] As described above, according to the present invention, the high image quality mode (Mode D in the embodiment) capable of reproducing an image faithful to the original image and the high speed recording mode can be arbitrarily selected with a switch, so the operation can be performed according to the purpose. By using different modes, color copying machines and the like can be used for various purposes.

[Brief explanation of drawings]

FIG. 1 is a timing chart showing an example of the operation of the color copying machine according to the embodiment in mode D. FIG. 2 is a front view showing the configuration of the mechanism section of the device of the embodiment. 3a and 3b are perspective views showing a part of the apparatus shown in FIG. 2. FIG. 4a and 4b are plan views showing the appearance of the operation board ○P1 and the color balance setting board ○P2 of the apparatus shown in FIG. 2. 5a, 5b, 5c, 5d, and 5e are block diagrams showing the electrical circuit configuration of the device of FIG. 2. FIG. FIGS. 6a, 6b, and 6c are graphs showing changes in the yK original density-copy density characteristics when the developing bias voltage, exposure amount, and charging voltage are changed, respectively. FIG. 6d is a graph showing a method for bringing the original density-copy density characteristic closer to the ideal characteristic. FIG. 7 is a timing chart showing an example of the operation of the device shown in FIG. 2 in normal mode. Figures 8a, 9a, 9b, 9c, 10a, iob, 10c, and 10d. FIG. 1 Oe, FIG. 10F, and FIG. 1OG are a flowchart 1- showing the operation of the electric circuit of the device shown in FIG. FIG. 11 is a memory map showing a portion of the allocation of each memory in the memory unit 170. l: Photosensitive drum (charge carrier) 2: Transfer drum 2a: Clamp plate 2b: Cam mechanism 3: Exposure lamp 4: First mirror
5: Second mirror 6: Third mirror 8: Fourth mirror 7: Lens 9: Color separation filter LO
: Charger 11: Eraser 12, 13, 14
:Developing roller (developing means) 18: Transfer charger 20: Cleaning unit 21: Static neutralization charger 22.23: Separation charger 26.27: Paper feed cassette 2゛8: Call roller 29: Paper feed roller 30: Reverse roller 31 Ni resist Roller 32: Fixing roller 41: Recording sheet 42: Transmission mechanism 4
5.46: Gear OP1: Operation board ○ P2: Color balance setting board 5 Niblint key 6: Memory ink KMA, KMB, KMC, KMD: Mode selection key (
Recording mode changeover switch means) KGI, KO2, KO2: keys DPI, DP2. DP3: Display unit 100: Main control board (electronic/control means) 170: Memory unit 190: Lamp regulator Ml: Main motor M2 resist motor M3:
Paper feed motor M4: Paper feed table motor M5: Filter motor M6: Lens motor M7: Clamp motor M
8: Return motor M9: Cleaning motor

Claims (7)

[Claims] (1) Charge carrier; An electrostatic latent image forming means for forming an electrostatic latent image on the charge carrier; Equipped with multiple color developers for visualizing the electrostatic latent image, disposed close to the charge carrier. a developing means; a transfer drum comprising means for holding a recording sheet and disposed close to the charge carrier; recording mode switching means; and a recording sheet held on the transfer drum; The process of forming an electrostatic latent image on the surface, making the latent image visible using the developing means, and transferring the visible image onto the recording sheet on the transfer drum is repeated several times while sequentially changing the color of the developer. An electrostatic transfer type color recording apparatus, comprising: electronic control means for switching the number of image formation and transfer process executions for each color of developer to one or more times in accordance with the setting of a recording mode changeover switch means. (2) When the process of image formation and transfer for each color developer is executed a plurality of times, the electronic control means controls the electrostatic latent image forming means and the The electrostatic transfer color recording apparatus according to claim 1, wherein at least one image forming parameter of at least one of the developing means is changed. (3) The electronic control means sets the image forming parameters such that the image recording area in the second process is limited to a higher density part of the image than in the first process. The electrostatic transfer color recording device according to scope (2). (4) The electrostatic transfer color recording according to claim (2), wherein the image forming parameter includes at least one of a document image reading level, a charging voltage of a charge carrier, and a developing bias voltage. Device. (5) When the number of image formation and transfer processes performed for each color developer is plural, the electronic control means performs the second process after performing the first process for each color developer.
Claim No. (1)
3. The electrostatic transfer color recording device according to item (2), item (3), or item (4). (6) The electronic control means prohibits static electricity removal from the transfer drum at the recording sheet peeling level from the start of the recording operation until all image formation and transfer processes are completed for the developers of all colors. An electrostatic transfer type color recording apparatus according to claim 1, wherein a recording sheet is held on the transfer drum. (7) When the number of image formation and transfer processes performed for each color developer is plural, the electronic control means performs the second process after performing the first process for each color developer.
According to the above-mentioned claim (1), the transfer drum is subjected to static electricity removal to a level that the recording sheet does not peel off from the transfer drum when the first process for all color developers is completed. 1) The electrostatic transfer type color recording device as described in item 1).