JPH0659546A - Blank lamp controller for copying machine - Google Patents

Abstract

PURPOSE:To execute the trimming and masking of a photosensitive body by a blank lamp without missing an image on a peripheral part, even if the electrostatic charging voltage of the photosensitive body is different. CONSTITUTION:When the electrostatic charging voltage of the photosensitive body 8 is high, LED lamps 101, 102, 201 and 202 outside the area La of the photosensitive body 8 are destaticized by a part whose luminous intensity is high, but when the electrostatic charging voltage is low, only the LED lamps 101 and 202 outside the area La are turned on, destaticization outside the area La is executed by the parts of the rays of faint irradiating light L1f and L202f emitted by the LED lamps 101 and 202 of the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blank lamp control device for a copying machine, and more particularly, to a peripheral portion or a portion of a copy document copied by electrostatic copying for trimming the peripheral portion or a part thereof. TECHNICAL FIELD The present invention relates to a blank lamp control device that irradiates light onto a lamp to attenuate the charging voltage.

[0002]

2. Description of the Related Art As is well known, an electrostatic electrophotographic copying machine comprises unit processes of charging, exposing, developing, transferring and fixing. In such a structure, copying is performed by the following process. First, an electrostatic latent image is created by exposing reflected light of the original image through the optical system to the surface of the photoconductor that has been uniformly charged by the charger charger, and the toner (developer) is statically charged on the electrostatic latent image. Electrodeposit and develop to form a toner image on the photoconductor, then transfer the toner image onto the recording paper by static electricity of the opposite polarity to the toner image applied to the transfer body, and remove the transferred toner on the recording paper. An image corresponding to the original image is fixed on the recording paper by fixing by heating and pressing. In addition to the basic structure of the copying machine configured as described above, many functional elements are added for the purpose of improving image quality and improving the efficiency of copy image formation, and the blank lamp also achieves the above-mentioned purpose. It is one of the additional functional elements. The blank lamp is used to prevent deterioration of image quality due to copying of an image other than the copy original, and to trim or mask a part of the copy original according to the purpose.

The blank lamp is arranged on the downstream side of the electrostatic charger for charging the photosensitive member in the moving direction of the photosensitive member and on the upstream side of the exposure position for exposing the reflected light of the copied image toward the photosensitive member. A linear light source for projecting light, for example, a large number of LEDs on the linear light source in a direction perpendicular to the movement of the photoconductor.
A minute light source such as a (light emitting diode) is provided. The blank lamp thus formed turns on the selected micro light source only in the area of the electrostatic latent image designated by the purpose formed on the moving photoconductor or in a portion outside the area, and the photoconductor is turned on. It has a function of preliminarily attenuating the charging voltage in the range to prevent the toner from adhering to this portion. However, the conventional blank lamp has a function of illuminating and extinguishing when it reaches a specified range portion of the photoconductor that moves regardless of the charging voltage of the photoconductor. The charging voltage of the photoconductor is constantly charged by the charging charger, but the charging voltage is selected depending on the type of the original image. For example, in the photo mode, lower the charging voltage of the photoconductor compared to the normal mode,
By lowering the light amount of the exposure optical system and further lowering the toner adhesion density in the high density portion of the original, the toner adhesion density in the halftone can be made relatively high. Therefore, the charging voltage of the photoconductor is higher in the photo mode than in the normal mode.
The charging voltage of the photoconductor is lowered as a whole. For example, 660V is set in the normal mode, while 300V is set in the photo mode. Therefore, in the photographic mode, even weak light is easily affected.

[0004]

When the charging voltage on the photoconductor is higher than a predetermined value, the influence of the lowering of the charging voltage in the light projection range is not exerted, but when the charging voltage is low,
There is a problem that the stray light of the blank lamp also lowers the charging voltage in a portion other than the designated portion, and the image in the peripheral portion of the designated trimming or masking area is lost.

[0005]

In order to solve the above problems, the present invention provides (1) a photoconductor, a charger for charging the surface of the photoconductor to a predetermined voltage, and a copy original on the charged photoconductor. Exposure optical system for forming an electrostatic latent image by exposing an optical image corresponding to the image of the image, and one of copy originals that are disposed facing the photoconductor between the charging charger and the exposure position and are determined according to the purpose of copying. A blank lamp that is turned on in a width on the photoconductor corresponding to a portion or an outer peripheral portion, and a blank lamp control unit that makes the lighting width of the blank lamp variable according to the magnitude of the charging voltage of the charging body, Further, (2) in the above (1), a large number of minute light sources arranged within a range beyond the image forming range of the photoreceptor on a line perpendicular to the moving direction of the photoreceptor, and the minute light sources Projected toward the photoconductors, which are arranged in each A blank lamp having a reflector, and when the charging voltage of the photoconductor is equal to or higher than a specified voltage, only a minute light source outside the image forming range in the direction perpendicular to the moving direction of the photoconductor is turned on, and when the voltage is lower than the specified voltage, an image A blank lamp control means for turning on a micro light source excluding a micro light source in a predetermined range close to the image forming range among the micro light sources outside the formation range; and (3) in (1) above, the photoconductor. A plurality of minute light sources arranged on a line perpendicular to the direction of movement of the photoconductor in a range beyond the image forming range of the photoconductor, and projecting light toward the photoconductor provided in each of the microlight sources. When the charging voltage of the blank lamp having a reflector and the photoconductor is a specified voltage, the blank lamp is turned on or off when the moving photoconductor reaches the image forming range, and the voltage is lower than the specified voltage. And it is characterized in that delaying the lighting timing of light when passing through advancing the off time to turn off when it reaches the image formation range, the image formation range.

[0006]

The light amount of each minute light source such as an LED lamp constituting a blank lamp is substantially constant near the center of the minute light source, but sharply attenuates as it goes away from the center. On the other hand, the charging voltage of the photoconductor decreases substantially in inverse proportion to the irradiation intensity when the photoconductor is irradiated with light, so when the charging voltage of the photoconductor is high, the charging voltage decreases due to the minute peripheral light amount of the blank lamp. The drop voltage of is small,
Although the voltage drop has a small effect on the image, it is affected when the charging voltage is low.Therefore, when the charging voltage of the photoconductor is lower than the specified voltage, the charging voltage of the photoconductor in the image forming range depends on the amount of ambient light. The time to turn off the minute light source on the side that affects the light or to turn on or off the blank lamp according to the movement of the photoconductor is adjusted.

[0007]

1 is a view for explaining an example of a copying machine to which the present invention is applied. An original placing table 23 made of hard transparent glass is arranged at the upper end of the copying machine 30. . An original document (not shown) placed on the original document table 23 is reflected by the original light emitted from the lamp unit 1 from the mirrors 2, 3 and 4, the lens unit 5 and the mirrors 6 and 7. Through the photosensitive drum 8 rotating in the direction of arrow B
Exposed. In the above, the scanner is composed of the lamp unit 1, the mirror 2 and the like.

A charging charger 14 for uniformly charging the surface of the photosensitive drum 8 is provided in the rotation region of the photosensitive drum 8 prior to exposure, and an electrostatic latent image is formed on the exposed portion. Further, on the downstream side of the charging charger 14, a blank lamp 22, a developing device including a black developing tank 9, a yellow developing tank 10, a magenta developing tank 11 and a cyan developing tank 12, a transfer belt 15, a cleaning unit 17, and The static elimination lamp 13 is arranged in this order. Toners of a corresponding color are stored in the developing tanks 9 to 12 of the developing device.

In the above arrangement, color copying is performed by the following operation procedure. When the charging charger 14 uniformly charges the surface of the photosensitive drum 8, the scanner 1
The second scan (scanning) is performed, and the reflected light from the document passes through the color separation filter (not shown) and the charging charger 14
Slit exposure is performed on the surface of the photosensitive drum located between the image-to-image eraser (not shown), and a blue electrostatic latent image is formed on the exposed portion. Then, the blank lamp 22 erases the portion corresponding to the non-image area of the electrostatic latent image,
Yellow toner is supplied from the yellow developing tank 10 to the electrostatic latent image in the image area that is not erased, and a toner image of the same color is formed.

Then, the toner image is circulated in the direction of arrow C, and a high negative DC voltage is applied to the first transfer roller 21 to the transfer belt 15 part of which is pressed against the surface of the photosensitive drum 8. Transcribed. At this time, a part of the toner that does not contribute to the transfer remains on the surface of the photoconductor drum 8, but the cleaning unit 17 scrapes off the remaining toner. Then, the static elimination lamp 13 eliminates the residual charges on the surface of the photosensitive drum.

When the above steps are completed, the charger 1
4 uniformly charges the surface of the photosensitive drum again, and the reflected light from the original obtained by the second scan is slit-exposed to form a green electrostatic latent image. Similarly, the non-image area is erased by the inter-image eraser, and magenta toner is supplied to the electrostatic latent image from the magenta developing tank 11 to form a toner image of the same color. Then, this toner image is transferred to the transfer belt 15 and the images are superimposed.
After that, when the same processing as described above is performed, the charging charger 14 charges the surface of the photoconductor drum again uniformly, and thereafter, cyan toner is supplied from the cyan developing tank 12 to the photoconductor drum 8 in the same manner, and a toner image of the same color is obtained. Is formed. Then, this toner image is transferred to the transfer belt 15, and final image superposition is performed. After that, the second transfer roller 16 which has not been in contact until now is brought into pressure contact with the transfer belt, and the toner image on the transfer belt 15 on which the images are superimposed is transferred to the copy sheet. A negative voltage higher than the transfer belt surface potential is applied to the second transfer roller 16. The copy paper on which the toner image has been transferred is then transported to the fixing device 19 by the suction transport portion 18, where the toner is fixed there, and then discharged by the discharge roller 20 to the outside of the machine. on the other hand,
Black-and-white copying is performed by supplying black toner to the electrostatic latent image on the photoconductor drum 8 from the black developing tank 9 and transferring the toner image onto a copy sheet via the transfer belt 15.

2 (a) and 2 (b) are views for explaining the structure of the blank lamp 22 according to the present invention. FIG. 2 (a) is a front view seen from the photosensitive member side, and FIG. 2 (b) is (a). ) Is a view taken along the line BB in the figure, where 31 is a substrate, 32 is a reflector,
Reference numerals 101, 102, ..., 202 denote LED (light emitting diode) lamps, and parts having the same functions as those in FIG.

In the figure, LED lamps 101, 102, 103, ..., 2 of the same standard as a minute light source are formed on the surface of the substrate 31 having a length substantially equal to the width of the photosensitive body 8 facing the photosensitive body 8.
Reflectors 3 are arranged at equal intervals in a straight line and further surround each LED lamp and open toward the photoconductor 8.
2 are provided. The blank lamp 22 formed in this manner has, for example, a distance a (≈1 mm: millimeter) between the photoconductor 8 and the reflector 32, and an interval b (≈) between the LEDs 101, 102, ... 202 of the reflector 32.
1 mm).

FIG. 3 is a diagram showing the light distribution of a general LED lamp, showing the relationship of the light quantity of the LED lamp with respect to the distance from the center of the lamp. As shown in the figure, the LED lamp has a substantially constant lamp light amount up to a predetermined distance from the center, but the light amount attenuates rapidly as the distance from the center of the lamp increases.

FIG. 4 shows the general relationship between the amount of lamp light entering the photosensitive member and the general amount of attenuation of the surface voltage. As shown in the figure, the amount of light entering the photoconductor is proportional to the amount of attenuation of the charging voltage of the charged photoconductor. From the relationship between the light amount characteristic of the LED lamp shown in FIG. 3 with respect to the light emitting position and the attenuation amount of the photosensitive member surface potential with respect to the lamp light amount shown in FIG.
It is inferred that the greater the distance from the center of the D lamp, the lower the amount of attenuation of the surface potential. Therefore, when the charge voltage of the photoconductor is high, the decrease voltage of the photoconductor charge voltage which is attenuated by the light in the peripheral portion away from the center of the LED lamp is a negligible voltage which is very small compared with the charge voltage, and it depends on the light of the LED lamp. The range of the charge removal effect of the photoconductor is only in the vicinity of the central portion of the LED lamp. On the other hand, when the charging voltage of the photoconductor is low, the decrease voltage of the charging voltage of the photoconductor, which is attenuated by the light around the center of the LED lamp, becomes a level that has a sufficient effect compared with the charging voltage, and the photoconductor by the light of the LED lamp The effect of static elimination appears in a portion relatively far from the central portion of the LED lamp. Therefore, the blank lamp 2
When 2 is used, the reflector 32 is provided as shown in FIG. 2, and the surrounding light is cut around the LED lamps 101, 102 ,.

FIG. 5 is a diagram for explaining an example of a light irradiation area from an LED lamp having a reflector. The LED lamp shown is the LED lamp 102 when the portion of the LED lamp 102 shown in FIG. 2 is taken out. Photoconductor from 8
Light irradiation ranges L ₁ and L ₂ are shown. Even when the reflector 32 is provided as shown in the figure, the light irradiation ranges L ₁ and L ₂ actually irradiated by the LED lamp 102 spread to a width c wider than the width b of the reflector 32 on the surface of the photoconductor 8. When the charging voltage of the photoconductor is low, the spread portion also removes the charge, and the influence of the spread of the LED lamp cannot be completely removed.

FIG. 6 is a diagram for explaining an example of the operation of the blank lamp control device of the copying machine according to the present invention. In FIG. 6, L _a is an image area, and the parts having the same functions as those in FIGS. The same reference numerals as in FIGS. 1 and 2 are attached.

The photoconductor 8 in FIG. 6 shows a case of charge elimination by light irradiation by moving in a direction perpendicular to the paper surface in the image area L _a remaining portion of the photosensitive member 8. Position range of disposed the LED lamp in the blank lamp 22 corresponding to the image area L _a is, the LED lamp 2 from the LED lamp 103
00 in the range of, LED lamps 101, 102 and LED lamps 201 and 202 corresponds to a portion of erasing charge voltage of the photosensitive body part other than the image area L _a.
That is, in the conventional blank lamp control, the LED lamps 101, 10 are always operated without considering the charging voltage of the photoconductor 8.
2 and 201, 202 were lit. In the present invention, when the charged body 8 is charged to a high voltage, as described above, the range of L _{1 to} L ₂ is on the left end side of the drawing, and the range of L _{200 to} L ₂₀₂ is on the right end side of the drawing. The static electricity is eliminated by the spreading irradiation light, and the lighting area of the LED lamp and the static elimination area coincide with each other. On the other hand, when the charging voltage of the photosensitive member 8 is low, the LED lamps 101, 102 and 20 are used as in the case of the high charging voltage.
Since 1,202 and to the the light L ₂ of the low intensity portion of the LED lamp 102 and 201 from L ₂ d and L ₂₀₀ lights L ₂₀₁ d is neutralization affects the image area L _a, in the present invention, the charging of the photosensitive member When the voltage is low, the LED lamps 102 and 201 close to the image area L _a to be affected are turned off and only the outer LEDs 101 and 202 are turned on, so that the low-luminance irradiation lights L ₁ f and L ₂₀₂ f are displayed. area L _a
The range, i.e., it is possible to remove the portion of the image area L _a to originally charge elimination. The present invention is applied, for example, when making a photo mode copy having a low charging voltage. In this way, by varying the lighting width of the blank lamp that lights according to the charging voltage of the photoconductor, it is possible to prevent chipping of the peripheral portion of the image.

FIG. 7 is a diagram for explaining the case of removing the charge voltage of the photoconductor in a region perpendicular to the moving direction of the photoconductor, in which 301 is a blank lamp lighting region, 3
Reference numeral 02 denotes a static elimination boundary area. It is assumed that the photoconductor 8 is moving in the direction of the arrow P, and when the charge is discharged outside the area 302 in the figure, the blank lamp 22 turned on at the side 303 to be erased first is turned off by the width w ₁ . The blank lamp is turned on, the erase turn-on timing on the side 304 to be erased next is delayed by the time for moving the width w ₂ to set the blank lamp as a turn-on area.
The blank lamp is turned on outside the frame 01. As described above, the lighting width of the blank lamp 22 is narrowed in the lateral direction of the photoconductor, and the lighting width is varied by adjusting the control timing of the blank lamp 22 in the image advancing direction.

FIG. 8 is a diagram for explaining a control circuit of the blank lamp control device of the copying machine according to the present invention. In the figure, 400 is an IC, 401 is a control circuit inside the IC, and 402 is a shift register inside the IC. , 403
Is a buffer circuit inside the IC, 404 to 408 are LEDs
Lamps, 409, 410, 411 and 412 indicate control signals of the IC, the signal of 409 is a clock signal to the IC, 410 is a data signal to the IC, and 511 is the IC.
The data input enable signal 512 indicates an IC reset signal.

The IC 400 is controlled by a control circuit (not shown) using the clock signal 409, the data signal 410, the data input enable signal 411 and the reset signal 412. Now, assuming that data is sent from the control circuit, the control circuit releases the reset signal 412, activates the enable signal 411, and then the clock signal 4
The data signal 410 is transferred in synchronization with 09. The data sent in this manner is stored one by one from the shift register 402 corresponding to the LED 404, and the data that comes in in synchronization with the next clock is again sent to the LED 404.
Stored in the shift register 402 corresponding to
The data stored in the shift register 402 corresponding to D404 corresponds to the shift register 40 corresponding to the LED 405.
It shifts to 2 and is stored. The data thus sent is sequentially shifted from the left to the right in the drawing and stored. At the same time, the data sent from the shift register 402 is sequentially output to the buffer 403, and if the data output from the shift register 402 is H level at this time, L data is output.
The ED lights up. In this way, the blank lamp 2 corresponds to the serial data sent from the controller.
The LED lamp in 2 lights up.

[0022]

As is apparent from the above description, according to the present invention, the blank lamp is turned on according to the charging voltage of the photoconductor charged to different voltages as in the case of copying in the photographic mode and the normal mode. Since the width is variable, it is possible to prevent the image around the trimming or masking area from being chipped.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of a copying machine to which the present invention is applied.

FIG. 2 is a diagram for explaining the structure of a blank lamp according to the present invention.

FIG. 3 is a diagram showing a light distribution of a general LED lamp.

FIG. 4 is a diagram showing a general relationship between a lamp light amount of a photoconductor and a surface voltage attenuation amount.

FIG. 5 is a diagram for explaining an example of a light irradiation area from an LED lamp having a reflector.

FIG. 6 is a diagram for explaining an example of the operation of the blank lamp control device of the copying machine according to the present invention.

FIG. 7 is a diagram for explaining a case where the charging voltage of the photoconductor in a region perpendicular to the moving direction of the photoconductor is removed.

FIG. 8 is a diagram for explaining a control circuit of the blank lamp control device of the copying machine according to the present invention.

[Explanation of symbols]

1 ... Lamp unit, 2, 3, 4, 6, 7 ... Mirror, 5
... Lens unit, 8 ... Photosensitive drum, 31 ... Substrate, 3
2 ... Reflector, 101, 102, ..., 202 ... LED
(Light emitting diode) lamp.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomiyuki Ishikawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation

Claims (3)

[Claims] 1. A photoconductor, a charging charger that charges the surface of the photoconductor to a predetermined voltage, and exposure optics that forms an electrostatic latent image by exposing an optical image corresponding to the image of a copy original on the charged photoconductor. A system, a blank lamp which is disposed between the charger and the exposure position so as to face the photoconductor, and which is lit in a width on the photoconductor corresponding to a part or an outer peripheral portion of a copy document determined according to the purpose of copying. A blank lamp control device for varying the lighting width of the blank lamp according to the magnitude of the charging voltage of the charging body. 2. A plurality of minute light sources arranged on a line perpendicular to the moving direction of the photoconductor in a range beyond the image forming range of the photoconductor, and the photoconductors arranged on each of the microlight sources. A blank lamp having a reflector for projecting light toward the body, and when the charging voltage of the photoconductor is equal to or higher than a specified voltage, only a minute light source outside the image forming range in a direction perpendicular to the moving direction of the photoconductor is turned on and specified. 2. A blank lamp control means for turning on a micro light source except for a micro light source in a predetermined range close to the image forming range among the micro light sources outside the image forming range when the voltage is lower than the voltage. Blank lamp control device for copiers. 3. A plurality of minute light sources arranged on a line perpendicular to the moving direction of the photoconductor in a range beyond the image forming range of the photoconductor, and the photoconductors arranged on each of the microlight sources. A blank lamp having a reflector for projecting light toward the body, and when the charging voltage of the photoconductor is a specified voltage, turning on or off the blank lamp when the moving photoconductor reaches the image forming range, 2. The blank of a copying machine according to claim 1, wherein when the voltage is lower than a specified voltage, the turn-off timing of turning off when reaching the image forming range is advanced, and the turn-on timing of turning on when passing the image forming range is delayed. Lamp control device.