JPS5868760A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To permit adequate potential control for photoreceptors having different contrasts and sensitivites by providing plural grids to the secondary electrostatic charger of a corona discharger and controlling applied voltages individually. CONSTITUTION:The developed images formed by forming latent images on a photosensitive drum 1 consisting basically of a conductive layer, a CdS photoconductive layer and an insulation layer with a secondary electrostatic charger 19 for simultaneous exposure and destaticization from the light images scanned over an original placing plate 3 and developed 41 said images are transferred from the rear surface of the transfer paper 51 held in a transfer section 55 by a corona discharger 59. Three sets of control grids 191, 193, 195 are provided to the charger 19, and positive, negative and ground potentials are applied to these grids respectively and are controlled individually according to the potential of the drum 1 measured with the probe 43 of an electrometer. The electrostatic charging capacity of the charger 19 is made controllable over a wide range without producing any irregular charging when it is desired to change the contrast largely as in color copying or in the stage of compensating the change in the sensitivity of the photoreceptor.

Description

[Detailed description of the invention]

Main part 1 is to measure the surface electric potential and potential of the light body from one shot to the next in order to find the optimal control when controlling the image forming conditions. I was struck by the electrophotographic device that I was using as my guide. Conventionally, the lighting voltage end of an electronic document illumination lamp is designed to collect the surface potential of the N I' photosensitive sensor and use it as a detection signal to converge the dark potential and bright potential of the light body to their respective target values. is controlled to bring the dark potential and bright potential to target values. In this surface potential automatic control, in order to achieve complete control for different target values of dark area potential or bright area potential, secondary frosting, charging fb control of LtNti image exposure simultaneous charging is required. I increased the range by enough v1. Also, in order to obtain a constant dark area potential or bright area 7 (I position) due to variations in the IQ or 21 citrus of the light-relaxing body, it is necessary to widen the control range of the secondary band.
) −1 ta [7 or 2 quadratic band? In order to expand the control range of II,
When the 11 change rlj of the current (711, FF, A) or the current is increased, the following problem occurs as it approaches its maximum value (1111 or minimum value). In other words, if the current 111 is small, uneven charging is likely to occur, resulting in image stains. It varies depending on the configuration, but for example, M.1-y'7. In a case where the discharge wire diameter is 60~+((1/zm), approximately 350 μA is the boundary value in a two-polarity zone. Also, if the current value is large (e.g., 1000 μAJ or more), ozone generation may occur. It becomes a problem of increase, and even more takaishi, sweat,
Is there a problem with the increase in current Rkt due to leakage from the charger or 1u of the high voltage transformer?
is. The present invention solves the above problems and improves J8! In the automatic control of human blood, which can be set to different dark potentials or bright areas,
] The present invention provides a device that can converge the potential of the IJ discharge to a predetermined dark area while keeping the control range 11 of each flow within an appropriate range. The present invention also provides a device that can perform appropriate t1 position control even for light sources having different sensitivities or contrasts. -' It is an object of the present invention to provide a device that can perform appropriate potential control even if the distance between the wire and the surface of the photoreceptor varies. In step 6, a photoreceptor having a basic structure of a conductive layer, a photoconductive layer, and an insulating layer is used, and a photoreceptor is equipped with a plurality of grids for applying different IL pressures. detecting the latent image forming means and the surface potential of the photoreceptor;
and means for controlling the corona discharge means. In a preferred configuration of the present invention, 1, iY+ notation: 1+' control means controls the ml UJ discharge 1
It is characterized by controlling the river voltage and the applied voltage Lr: of the grid. Further, in a further configuration 1 of the present invention, the control means controls a grid to which a voltage near the dark potential is applied. Hereinafter, the misfire 1-1 will be explained in detail based on the drawings. FIG. 2 is a diagram showing a configuration of an embodiment device a of the present invention. In addition to full-color copying of @i;J, IJit manuscripts using separate exposure for each color (blue, green, and red), it is also possible to make single-color copies using white (ND filter) exposure. At 11 in Figure 2,
On the surface of an optical drum 1 11 rotating in the a direction, a photoreceptor 1 having a basic structure 1 including a conductive layer, an OdS light-extinguishing layer, an electric layer, and an insulating layer is formed. A document to be copied is placed on the document table crow 3L and illuminated by the illumination lamp 5. Scanning mirrors 7 and 9 that scan the original scan the original in synchronization with the rotation of the drum 1, and mirrors 7 and 9 scan the original, respectively.
', 9' place ■ Move to 6 and i (1 light lamp 5
also moves to the 5' position. Scanned &'tfk optical image It, lens 11. An image is formed on the photoreceptor surface of the photoreceptor drum 1 through a mirror] 32-color separator 15 and a mirror) -17, and a secondary charger 19 for simultaneous removal and weight removal of bζ light. A latent image is formed by such a light source.
Here, the color separator 15 selects a blue filter 15B according to each color separation. It consists of a green filter 15G, a red filter 15R, and an ND filter 15N, and the previous color separation is performed by rotating and switching the stiff filter. The surface of the photoconductor of the photoconductor drum 1 is preliminarily coated with a blade cleaner 31.
The previous latent image is removed by the pre-exposure lamp 33 and the pre-removal device 35. Next, the photoreceptor surface is uniformly charged with a negative charger 37 to have a uniform potential. The charged photoreceptor surface is neutralized by the secondary charger 19 together with the IfiL draft image, and then the entire surface is uniformly illuminated with light by the entire surface exposure lamp 39, so that the photoreceptor surface has a high contrast electrostatic potential. An image is formed. Between the entire surface exposure lamp 39 and the developing device 41, a static 1
It is designed to detect the magnitude of the image, that is, the electrostatic potential. Developing device 4 ] 14 consists of a yellow developing device 374 ] Y, a magenta developing device 41 M, a cyan developing device 410 and a black developing device 4 . Each color developer (toner) is delivered to the transfer section 55 4 ] and a non-optical clipper is used. 57 is a transfer part (4 without gripping the tip of 51). The developed image on the surface of the photosensitive drum 1 is transferred onto the transfer paper 51 which has been maintained B by a corona discharge from the back side of the paper by a transfer IJ' corona discharge device 59. In the case of monochrome copying, immediately after defrosting the separation static eliminators 60 and 61, the separation claw 63 is operated to separate the transfer paper 51 from the transfer unit 55. Number J1 should be reproduced in case of predicted coffee 2~
3. Hold the transfer paper 51 without opening the gripper 57 of the transfer section 55 and without operating the separation claw ( ) 3 until the transfer of the three-color developed image is completed.3. When the transfer is completed, the transfer paper 51 is separated from the transfer unit (55) by the operation of the separation claw 63, and sent to the heating roller fixing device 67 by the conveyor belt 65.
The transfer paper 51 on which the image is fixed is placed in the tray 6.
9 and 11j). After the transfer '7f is completed, the toner remaining on the surface -1 of the photo-jt tram 1 is cleaned by the flade cleaner 31 in preparation for the next transfer/copying cycle. FIG. 4 is a sectional view showing a schematic configuration of the secondary charger 19 shown in FIG. -134450), the grid wires are arranged at predetermined intervals (for example, 1Ili'L+
nn・) are strung up in large numbers. Also, the distance between the grid wire group and the surface of the photosensitive drum 1 should be set appropriately (for example, approximately 1 mm).
) is maintained. Each grid wire group is divided into three groups, a negative grid 191, a positive grid 193, and a zero grid 195.
00V, +30~+250V for positive grid 193
bias %t, no pressure is applied, and zero grid 19
5 is grounded. TIF 19o is corona discharge wire,
197 is a shield plate. The above electrophotograph v<Gj conductive layer, light guide πf, Jsl
A step of charging the surface of the photoreceptor with a predetermined polarity using a photoreceptor having an insulating layer as its basic structure, and a reverse polarity step of applying a corona discharge 1 having an IJV portion of polarity opposite to the polarity while irradiating the surface of the photoreceptor with a light image. '-JU1sujj (a step of further irradiating the photoreceptor surface with a light image while reducing or substantially stopping the effect on the ITii ball culm and the corona discharger that cures the opposite polarity component; It is characterized by having a step of applying a corona discharge similar to the reverse polarity corona discharge step to the surface of the photoreceptor while regulating the discharge and amount,
The purpose of n1 is to expand the luminance re-viewing range beyond the conventional method.
It is something that can be done. The slope of the characteristic that shows the relationship between

[, teIR'74'
A: By improving reproducibility, it is possible to create a bright inflection point in the latent image characteristics and increase the slope of the background density area (approximately less than 0.3) of the original to prevent fog from occurring. That is. FIG. 2 shows an example a (solid line) of latent image potential 1 due to the ND filter spectroscopy under automatic potential control of the present invention. The horizontal axis is the original density (DO), and the vertical axis is the surface curve. (■8), and the dark area target potential V, which will be described in detail later. (persimmon), bright area target potential (VSL) is 400V each.
, corresponds to -130V, and the negative grid bias of the secondary charger at this time is -140V%.
(ground potential). In addition, the stability shown by the broken line and the dashed-dotted line C is obtained by finely adjusting the potential automatic control post-stop grid bias (it is possible to finely adjust it from the VR axis adjustment after automatic control using the switch SW), and the broken line indicates the positive grid high- f Scar) -30V, the dashed dotted line is +250V Te property. In the case of the coating film according to the present invention, three levels of frost are set to the first level, and a full-color dark area (If (bright lamp 5 is turned off)), an intermediate density area (lamp 5 is turned on at an intermediate level), and 31 , extension ffj... (Lamp 5 at maximum rated voltage A1) 1 standard for σ (u'i '1ir, place v
DO*VWLO and ■SLO are set as shown in Table 1 below. , Table 1, FIG. 3 is a block diagram of a circuit that controls the potential. In the figure, a drum clock pulse 105 corresponding to the rotation angle of the photosensitive drum 1 is outputted from a photointerrupter 103 by a clock 101 for detecting the rotation angle of the photosensitive drum 1. This clock pulse 105 is
- This is counted by the sequence controller 107 and controls information signals necessary for copying, such as information such as the set number of seconds. A controller 107 supplies a microcomputer 109 for potential control with timing signals necessary for switching the high-voltage yahalogen photocopper and timing signals for measuring the dark potential VD + intermediate density potential "Wl, +" and the bright potential VSL. The latent image potential detected by the electrometer probe 43 is measured by the surface potential measuring circuit 111 at a value of ]/30 of the surface potential.
It is measured as a potential of 0, is digitally converted by an A-D converter 113, and then supplied to a computer 109. The computer 109 stores the potential measurement value on the switch board 1.
Calculations are performed according to the control formula in order to converge to the target value selected in step 15. The signal resulting from the blasphemy is supplied to the DA converter 119 via the pass line 117 and converted into analog. Analog converted signals 1, high voltage control circuit 1
21, 123, 125 and mix circuit 127. The computer 109 also sends a control signal 131 to the analog multiplexer 129, and sends a control signal 131 to the analog multiplexer 129. j & tone board 1
The image fine adjustment signal from 33 and 35 is switched and supplied to any of the high voltage control circuits 121 to 125 and the mix circuits 11!1i127. High voltage control circuits 121, 123
, at 125? r-+ analog signal 137T,
137G, I:17v and ■l! Addition voltage signals 139T and 139G with Ir image fine adjustment signal 135
, 139V is the high voltage transformer 141 , 143 ,
At 145, after boosting the voltage, the charger 37. Secondary zone 11
Negative grid of L device 191. They are each supplied to a secondary charger 19. In this case, it can be suppressed by controlling the primary charge voltage and secondary charge voltage instead of controlling the primary charge voltage, current, and secondary charge voltage. Also,
A mixed signal 139 If of the analog signal 137H and both image fine adjustment signals 135 from the mix circuit 127 is supplied to the halogen control circuit 155 to control the halogen voltage VHt applied to the illumination (halogen) lamp 5. Further, the computer 109 supplies a digital signal to the (10) driver 16 via the pass line 117. This r10 driver]61 sets it to (standard). Next, a target value is set using a target value setting changeover switch (connected to the switch board 115) provided outside the copying unit. After performing these operations, a control button (not shown) is pressed to activate the control circuit. The control operation U is performed according to the flowchart shown in FIG. First, turn on the serious crime of the Tora 2nd place control circuit (Block 4
01). Next, potential cleaning is performed by pre-rotating the photosensitive drum 1 (block 403). In this state, the voltage VH7 of the document illumination lamp 5 is turned on at the maximum rated voltage, and the light emission of this lamp 5 is maximized. The document image light with such maximum light intensity is transmitted to the ND filter 1 of the color separator 15.
The color separator 15 is set as a filter to transmit 5N. In addition, constant values of negative grid bias and positive grid bias of secondary charging current and secondary charging are output. This constant value is shown in ■ in Table 1. It is designed to be switched in accordance with each potential target value of (1) and (2). Examples are shown in Table 2. Table 2 Next, in order to measure the bright area potential, the white light drum 1 was rotated to expose the surface of the photoreceptor. With the potential probe 43,
Block 405) detects the bright area potential VSL on the surface of the photoconductor of the photoconductor drum 1, supplies the detection signal to the potential measurement circuit 111, and measures the bright area vsr.
. Here, if the control value in ■2 is the maximum value (790 μA) or the final judgment, the measured bright area potential vS L and bright ms
Target value in %■ Difference from sLO (1vSL-' VsL
ol) is within the tolerance (cl) or not (
block 407). If the judgment is negative, the secondary charging current (the connected high voltage transformer has constant current characteristics)19
The secondary charging voltage ■2 is controlled by the valley 1 at ■2-δVSL.
-3 control (block 4o9). Then, the process returns to block 405 and the operation is repeated. Blocks 405, 406, 407 until the bright area potential VST, obtained again by the secondary charging current 2 controlled by block 409, falls within the tolerance limit and converges to its target (i('fVsL.).
The operations at and 409 are repeated. If the result is within the allowable error C, and an affirmative determination is made in block 407, the color separator 15 is rotated and the blue filter 15B is set so that the original image light passes therethrough (block 411). Note that in this step, the filters are switched in the order of green, red, ND, green, and red. Next, in order to measure the dark potential VD, the illumination lamp 5 is turned off and the photosensitive drum 1 is rotated once without exposing the original. The surface potential of the photoconductor surface of the photoconductor drum 1 is dark area potential VII.
Therefore, this dark potential VD is detected and measured by the electrometer probe 43. (Block 413). Next, I! <! The light pump 5 emits light at the maximum rated voltage to maximize the exposure amount of the original. # Rotate the optical drum 1 and expose the surface of the photoreceptor to the brightest light. In this state, the bright area potential vsr', which is a surface potential, is detected and measured by the electrometer probe 43 (block 419). The difference between the measured dark potential VD and its target value VDO (IVDVDDOI
) is within the tolerance C2 and the measured bright area potential VS
Difference between L and its target value VSLO (IVSL - VSLOI
) or within the tolerance 03 (block 421). If the judgment is indeterminate,
- Single charger (The connected equal voltage transformer has constant current characteristics.) The single charge current ■1 of 37 is controlled by the control method △■l-
control according to the mother-in-law vD (block 417). Also, the negative grid (connected transformer) at the secondary charging current 17 is determined (block 423). Here, VQ-
is controlled in the range of -30V to -300V. The process then returns to block 413 to repeat the loop. The bright area potential VS■a has an allowable error C with respect to its target value V SLO.
If it converges within 3, a positive judgment is made at block 421, and the loop is exited. Illumination lamp 5 is placed in the middle cylinder, pressure halogen electric Elt VHn
7, and set the original exposure amount to the standard light amount. The photosensitive drum 1 is rotated under such an amount of light to expose the surface of the photosensitive member. The 5th potential on the surface of the photoreceptor is the intermediate density potential VWI
, and this potential VWIL is measured by the electrometer probe 43 and the potential measurement circuit 111 (block 425). The difference between the measured intermediate concentration potential VWL and its target value (IVWL-VWLOI) is determined to be within the tolerance C4 (block 427). If the judgment is negative, ri429). The process then returns to block 425 to modify the roof motion. Medium dark) 0go SIS 'f-K (☆v
W L or its target A] (j ■ If each error of ¥1 for WLO converges within C4, block 427 returns a positive 5if judgment. In steps 411 to 427, the primary charging voltage VQ- and the halogen pressure VH in the blue filter 15B are controlled and set based on blocks 411 to 427. Next, the color separator 15 It is determined whether the filter set in is the last one (block 431). In this case, since the determination is negative, the process returns to block 411. In block 411, color separator 1 is selected in the order of blue → green → red → book.
Turn 5 to switch and set the ZC filter. The operations of blocks 413 to 429 are performed each time the filter is set, and the primary charging current "I" and the negative grid pressure V in the filter are determined.
f+- and halogen voltage V117 are controlled and set. Such a loop operation is repeated, and when the control of each voltage is completed for the most popular filter, a standard decision is made in block 431, and the control operation of the control circuit is concluded (a). In this way, the voltage relationship is established so that the field <In potential of the three colors of blue, green, and red and the single color of white (NII) is set to a predetermined value. Then, under the set control phase relationship, 1 l of the original placed on the original glass platen 3.
111 image or close-up color photograph on transfer paper 51. In addition, for example, by deceiving the changeover switch of the pine device a, the three colors of blue, green, and red and the monochromatic color of white (N - 1) are set to the first few stages for each of the three colors, e.g. It would be good to be able to set it to 3 levels. In the case of the device of this example, there are three switching settings as shown in Table 1. 1 village I (immediately, the potentials are S Umezakuzu 2, respectively) set in this way. The measurement of
This is done after a standard reflective surface such as transfer paper is placed on the original width table glass 3, and the original document is scanned at the same speed as normal copying to form 1111 positions. Also, the coefficients δ, α7βl and β2 . γ indicates the value of the function according to each flash formula. FIG. 6 is a flowchart of the m-position control of the light pulse, and shows that the lamp 'i (f It) is illuminated on the document illumination surface at a pressure of 111 at the frontmost position. That is, at 501 in FIG. Start copying, 502
It is difficult to judge the one-band 'Llf output. - In the case of charging output, the primary control value mentioned above in 503 is 11j.
If yes/good, the primary (IY power output is turned off (504). Secondary'l) The same operation is performed in steps 5 () 5 to 507 for the I city output, and the 50
8, the output of the amount of light is determined. When outputting the light amount, set 509 to 71 for each color during exposure (light amount control value X FB,
a. Showa IDX-output. For example, as mentioned above, FB=1.21, ■-゛G=1.23. PR = 1.3 (1, FND = 1.28. If it is not a photometric output, it is turned off at 510. Next, it is determined whether or not the copy is completed (511), and if it is white, it is set at 50.
Steps 2 or less are repeated X, and if 1 is the end of copying, the process goes to step 512 and the copying ends. In order to explain the present invention in detail, FIG. Figures 8 and 9 show I2 in ND filter exposure.
VST, characteristics listed. Figures 7, 8, and 9 show the characteristics when VQ is -150V, -50V, and -250V, respectively, and VD = 500V and VD, respectively.
= 320V. As shown in Figure 7 (if VG = -150V, VD
= vsr at 320V, = -100V and VSL = -200V at VD =500V
To control I2 is 330μA to 1,010μA
requires a variable range. At this time, when I2=330 μA, image staining occurs due to discharge unevenness. Further, when I2 = 1,010 μA, the generation of ozone increases, and problems such as dielectric breakdown of the insulation part of the charger and pinholes in the photosensitive drum due to high voltage application tend to occur. However, in the case of vG = -50V in Fig. 8, VD = 32
To control VSL ==-100V at 0V, I2
should be 430μA, and v(1=-25(
'IV, then VD = 50 (in IV, v
To control S I, = -2 + IOV, X2 is 790μ
A is sufficient, and the problem in each boundary area in the case shown in FIG. 7 does not occur in either case. Next, an ND filter actually obtained by applying the present invention (
Examples of city and position control values for light (white) are shown in Tables 3 and 4.
1° VDOVWI and 0VSLO in Table 3 are 1 standard i < i tif, Q7 in Table 1, and Table 4 is the value after completion of potential control. Table 3 Table 4 Here, 12■ of Table 3 is the initial voltage of the high voltage current of the secondary charger +
fft, I+■ is the initial value of the high voltage current of the primary charger, vG
−■ is the initial value of the grid bias voltage of the secondary charger, V
2O is the initial value of the illumination lamp voltage for obtaining vwr, o, and is a value stored in the microcomputer. Table 3 (D?/J period value (12■7 ■l■+ vG-
■. va■) and the control value in Table 4 after potential control ("2+'1■
When compared with G-9 (a), the characteristics of the photoreceptor subjected to this potential control are that the sensitivity is slightly lower than that of the standard photoreceptor, and the electrostatic contrast is also low. 2 in Table 4 is 790 .mu.A, which is the maximum value of the control range of 2, and the amount exceeding the control range of 20 will continue to be controlled by VQ-. As a result, vQ-=-250V, VST, LJ
: , converges to the target value potential (vsLo). In the following-1-1 specific example, 1 (,! revealed vll<according to the present invention, a wide range of potential target values is achieved, and ■11th place 1
1i11? +lii is possible, and secondary: 10
Adjust the current and current values ■: Can be kept within the range. Thus, in the present invention, there is no image staining, the generation of ozone can be reduced, and the leakage of charging currents can also be prevented. It is also possible to prevent variations in the bright area potential due to variations in the distance between the photosensitive drum and the grid of the secondary charger. Therefore, it is particularly effective when copying is often done with different contrasts, such as when making color copies. Even if there is a change in the development resistance of the toner over time, the image density can be kept constant within the 11 standard range, and it is also possible to easily prevent the occurrence of fog during development.

[Brief explanation of drawings]

Figure 1 shows a demonstration of a color electrophotographic experiment according to the present invention.
4:1 Latent image electric potential after automatic control of the surface potential of the present invention; 1) Diagram showing the special stab; 3rd figure:
1 is a block diagram of the control circuit in the system shown in FIG. FIG. 6 is a flowchart showing the operation of FIG. 3 during copying. Figure 7.8.9 shows "2" in each ND filter exposure.
' This is a diagram showing STJ characteristics. 1. Photosensitive drum 3 Document table glass 5.. Illumination lamp 15.. Color separator 19... Secondary band li device
4)・Developer 43...〒[I level meter probe 51・
・Transfer paper 55...Transfer section 59...Transfer corona discharger 67...Heating roller fixing device 10 Tochotsupashik 107...Main sequence controller 109...
- Microcomputer 111...Surface adjustment and position measurement circuit 115...Switch board 133...Fine adjustment board 16]...R10 driver 163...Display unit 171...Diode switch board. Applicant: Canon Co., Ltd. -375- From Beard/--7hehehe (A7 between X/θ0 (liA) ×10θ A

Claims (1)

[Claims] (1) In a photographic device that uses a photoreceptor repeatedly to form a latent image, a photoreceptor whose basic structure is a conductive layer, a light conductive layer, and an insulating layer is used, and different voltages are applied to the photoreceptor. A latent image forming means having a corona discharge means having an initial number of grids to apply light and a light image irradiation means, and a means for detecting the first outer surface of the light and controlling the corona discharge means. electrophotographic equipment. (2. In the invention of indigo in claim 1, Kura 11
The control means controls corona discharge control of the corona discharge means;
1. An electrophotographic apparatus characterized in that the voltage and the voltage applied to the grid are controlled. (8. In the device set forth in claim 1 or 2, the control means controls a clid that applies a voltage closer to the bright area potential.) (4) In the discovery 1 described in claim 1, 2, or 3, the control means controls the corona discharge voltage of the pre-metered corona discharge means, A ν14-copy copy characterized by the fact that there is no internal control.