JPH03279977A - Copying machine - Google Patents

Abstract

PURPOSE:To perform exposure with a light quantity in accordance with the density of an original by providing a liquid crystal shutter in the optical path of reflected light from the original to a photosensitive body and changing the light quantity for the exposure. CONSTITUTION:A scanning unit 102 scans the original Or in a direction shown by an arrow under an original platen 103, and the liquid crystal shutter 101 for correcting the light quantity for the exposure is provided on the optical path inside the scanning unit 102. When an original area specifying signal is inputted in a liquid crystal shutter control means 100 by the operation of an editing panel or key, the means 100 makes the part of the area where the reflected light passes in a light shielded state so that the specified level of light quantity may be obtained. Namely, when 1/2 light quantity is necessitated, 1/2 part where the reflected light passes is made in the light shielded state. Thus, the specified area of the original is exposed with the appropriate exposing light quantity in accordance with the variable density and an image is faithfully reproduced.

Description

[Detailed description of the invention] (a) Industrial application fields The present invention relates to an electrophotographic copying machine.

fb) Conventional technology Recently, there has been a remarkable development in image forming apparatuses that employ electrophotographic processes, such as copying machines. (e.g.), so-called copying machines with editing functions are provided.

The principle behind this is that before the original image obtained by exposure scanning is formed on a charged photoreceptor, areas of the original that do not need to be copied or areas where halftones such as photographs are desired are copied as is. The charge potential of the area on the photoreceptor corresponding to the desired area is lowered to an appropriate level according to the desired density rail, and the adhesion of toner in each area-1 is adjusted. 63-23169) (c + Problems to be Solved by All Inventions) However, as mentioned above, simply specifying the potential on the photoreceptor corresponding to a specified area of the document and lowering it to In other words, if the exposure light amount for a high potential and the exposure light amount for a low potential are mixed, the quality of the image in the middle tone will be affected by the standard exposure light amount, but the exposure light amount for the middle tone will not be accurate. If so, the standard image quality will be degraded.

Specifically, when the photoconductor is charged at a high potential for standard copying, the quality of the reproduced image is good if the exposure light amount is standard, but at a low potential for halftones such as photographs, the quality of the reproduced image is good. In some cases, if the exposure light level remains at the standard level, the quality of the image will deteriorate, such as the reproduced image being too bright, text becoming thin, text skipping over thin originals such as pencils, and low-density areas of photographs not being reproduced. come. If the amount of exposure light is set to be appropriate for a low potential for halftones such as photographs, problems such as fogging and darkening of the background will occur in the high potential area of the photoreceptor. In any case, there is a problem in that it is not possible to faithfully reproduce the original by simply changing the potential of the photoreceptor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a copying machine that can faithfully reproduce an original by partially changing the amount of exposure light.

(d) Means for Solving the Problems The copying machine of the first invention according to this application is characterized in that a liquid crystal shutter for correcting the amount of exposure light is provided on the optical path of the reflected light of the document leading to the photoreceptor.

In the copying machine of the second invention according to this application, the liquid crystal shutter control is configured to drive the liquid crystal shutter so that the amount of light exposed to the area on the photoreceptor corresponding to the designated area in the document becomes a predetermined amount of light. It is characterized by having a means.

(e) Effect In the first invention of this application, since the liquid crystal shutter is provided on the optical path of the light reflected from the light source to the photoreceptor, the liquid crystal shutter can be completely or partially in a light-shielding state. Therefore, the amount of light for exposure can be changed in whole or in part.

FIG. 1 is a configuration diagram of the second invention according to this application. The scanning unit 102 scans the original Or below the original table 103 in the direction of the arrow. A liquid crystal shutter 101 is provided on the optical path inside the scanning unit 102 to correct the amount of light for exposure. When a document area designation signal is input to the liquid crystal shutter control means 100 through an editing panel (not shown) or key operation, the liquid crystal shutter control means 100 puts the area into a light-shielding state so that the area I is present. For example, if 1/2 the amount of light is required, only 1/2 of the passing portion is shielded from light. By doing so, it is possible to expose the designated area of the document with an appropriate amount of exposure light according to its shading, and faithfully reproduce the image.

(f) Embodiment FIG. 5 is a schematic diagram of the main parts of a copying machine which is an embodiment of the present invention. This copier uses an electrophotographic process, and controls the charged potential on the photoreceptor using an area-designated photo mode lamp to control blank (erase), photo mode (
It has an editing function that allows you to select and specify standard modes.

An original table lO is provided on the upper surface of the main body 1, and an original document Or is placed on it. An editor 11 is attached in place of the cover of the document table 10, and as described later, area designation, blank space, photo mode (Hahetone), and standard mode are designated by this editor 11. A scanning unit 20 of the optical device 2 is arranged below the document table 10. The scanning unit 20 includes a light [21, a slit 22, a liquid crystal shank 24]
, a first mirror 23, and the like. The liquid crystal shutter is provided on the optical path between the slit 22 and the first mirror 23. Further, the optical device 2 includes the second to fifth mirrors 2
6 to 29, a sixth mirror 25, a lens 200, etc.
The light reflected from the sixth mirror 25 illuminates the photoreceptor 30. The photoreceptor 30 rotates in the direction of the arrow in the figure, and around it are area designation photo mode lamps 31 blank lamps 32.
is arranged, there is an exposure point P downstream thereof, and a developing device 33
is installed. Further, a transfer charger 34, a peeling charger 35, a cleaning device 36, a static elimination lamp 37
is installed. At the lower right side of the main body 1, there is disposed a paper feed section 4 consisting of a cassette for storing paper 41, a paper feed roller, a timing roller, etc., and the paper is conveyed to the transfer section as indicated by arrow B in the figure. . A fixing device 5 is provided on the left side of the photoreceptor 30, and a paper discharge section 6 is provided on the left side thereof.

FIG. 2 is a perspective view of the main parts of the liquid crystal shutter 24. As shown in FIG. 5, the light emitted from the light source 21
The light is reflected by the document Or on the 0, passes through the slit 22, and reaches the first mirror 23 via the liquid crystal shutter 24. arrow a
The direction is the axial direction of the photoreceptor, and the direction indicated by the arrow is the circumferential direction of the photoreceptor. The length p is the width of the slit 22. The device used is a twisted nematic transmissive liquid crystal panel, which transmits incident light when a voltage below a threshold voltage is applied, and blocks the incident light when a voltage above the threshold voltage is applied. Such liquid crystal panels were arranged in a seven-trick pattern, two rows in the circumferential direction of the photoreceptor, and N+1 panels arranged in the axial direction. Then, by selectively applying a voltage higher than a threshold value to any liquid crystal in one column, light is blocked and the amount of exposure light in a designated area is halved. That is, if everything is in the standard mode, it remains as is, but if the photo mode is specified, a voltage higher than the threshold is applied to one of the two rows of the area of the liquid crystal shank through which the light reflected from that area passes. This blocks half of the reflected light, making the exposure light amount half that of the standard mode. 24a is a designated area of the standard mode that transmits all the reflected light, and area 24b is a designated area of the photo mode that blocks only half of the light that passes through the slit.

FIG. 4 is an explanatory diagram of halving the amount of exposure light for a designated area using a liquid crystal shutter.

When the N+1 liquid crystal panels in one column are numbered O to N from the left, and a voltage above the threshold is applied to the CD liquid crystal panels from the end time of timer XA to the end time of timer XB, the following figure is obtained. The amount of reflected light irradiated into the area of the photoreceptor corresponding to the shaded area is halved, and the amount of exposure light is halved.

As shown in FIG. 6 and 11, which will be described later, the editor 11 includes a tablet 110 consisting of a large number of resistance wires arranged at intervals of about 1 in each of the X-axis direction and the Y-axis direction, and an erase (blank)
key 111, photo mode key (halftone) 112,
It is composed of a clear key 113, an end key 114, and an all clear key 115. An arbitrary point on the tablet is pressed, and the resistance value determined by the X and y coordinates of the arbitrary point is detected as a voltage level.

Erase key 111 is a key for specifying erasing within a specified area, photo mode key 112 is a key for specifying halftone (halftone), and clear key 113 is a key for specifying erase within a specified area.
This key is used to erase data in the memory related to the photo mode area. The end key 114 is a key for ending the area designation, erasure, and photo mode designation.

The all clear key is a key for erasing memory data related to all photo mode areas.

FIG. 3 is a perspective view of the main parts of the area designation photo mode lamp.

As shown in FIG. 5, the area 1h fixed photography mode lamp is disposed close to the photoreceptor between the charger 38 and the blank lamp 32. The figure shows the state when the casing is removed, and the LED light emitting elements 31a are arranged in one row.
It forms an ED array. By selectively causing any LED light emitting element to emit light with a predetermined amount of light,
The charge on the corresponding area on the photoreceptor is removed or reduced, and the electrostatic latent image in that area is brought to O or low potential. The principle of removing or reducing the charge in a designated area is the same as that described in FIG. 4 for the liquid crystal shutter described above.

The operation of the copying machine configured as above will be explained based on FIG. 5 and the other figures mentioned above.

First, the scanning unit 20 of the optical device 2 moves back and forth along the lower surface of the document table 10 by a drive mechanism (not shown), and scans the surface of the original for exposure during the forward movement. The speed is V/, where V is the circumferential speed of the photoreceptor and k is the copying magnification. The second mirror 26 and the third mirror move at V/2 in conjunction with the scanning unit 20 in order to keep the optical path length constant. Further, the lens 200, the fourth mirror 28, and the fifth mirror 29 are moved to set the magnification. The reflected light from the original passes through the slit 22 and the liquid crystal shutter 24 as shown by the two-dot chain line in the figure, and hits the first mirror 23, the second mirror 26, and the third mirror 2.
7. The light is reflected by the sixth mirror 25 via the lens 200, the fourth mirror 28, and the fifth mirror 29, and is irradiated onto the photosensitive pair 30 to form an image on its surface. At this time, if a designated photo mode signal is input by the editor 11, half of the liquid crystal shutter 24 is shut off, and the amount of light to the designated area is halved.

The photoreceptor 30, which can be rotated in the direction of arrow A, passes through a charging charger 38 to be charged, and when in the area photography mode, passes through an area designation photography mode lamp 31 to slightly remove static electricity from the designated area and bring it to a designated low potential. During reduction copying, the portion outside the original image is neutralized by passing through the blank lamp 32. In this way, the surface of the photoreceptor 30 is charged to a potential depending on the purpose, and the optical device 2
Toner is attached to the formed electrostatic latent image in the developing device 33, and the attached toner is transferred from the paper feed section 4 by the transfer charger 34. The images are transferred onto the paper 41 fed in at the same timing. In addition, in the area of the specified area photo mode, the amount of toner that adheres is smaller than usual due to the low potential (the reproduced image density is lighter than usual, the characters in the area are thin, and the faint characters such as pencils are skipped). etc. will not occur.

After the development and transfer, the photoreceptor 30 has residual toner removed by a cleaning device 36, and the charge is removed by a charge removal lamp 37. On the other hand, the sheet 41 on which the image has been transferred is peeled off from the photoreceptor 30 by the peeling charger 35 and conveyed, subjected to heat treatment by the fixing device 5 to fix the image, and then discharged to the sheet discharge section 6.

FIG. 6 is a block diagram of a portion of the control section of the copying machine.

The CPU 90 has a ROM 91. RAM92 is connected. In addition, the main motor drive unit 96 via l1093
, a developing motor drive section 97, a timing roller/clutch 98, an electrostatic charger drive section 94, a transfer charger drive section 95, and other process units are connected thereto. Further, an l1080 is connected to the CPU 90.

A program is written in ROM91 in advance, and RAM9
2 is assigned other working areas such as a timer. The CPU 90 reads data from the ROM 91 and RAM 92 in response to key input or sensor input, and controls the entire copying machine, such as driving the copying section, paper feeding section, and paper ejection section, and controlling temperature.

The CPU 90 inputs specified coordinate data from the editor 11 via the I1080 and the A/D converter 81, and also inputs signals from various keys 111/115 of the editor 11. Further, the light emission and amount of light from each LED light emitting element of the area designated photo mode lamp and the voltage applied to each liquid crystal panel of the liquid crystal shutter are individually controlled. Note that the coordinate data, LED light amount data, liquid crystal panel voltage data, etc. are written into the memory &2.

The area photography mode lamp control circuit 300 includes a shift register 311, a latch 312, and a driver 313, which are controlled by a signal transferred from the l1080 to control on/off of each drive transistor Tr.

The control circuit 240 of the liquid crystal shutter is a shift register 241
, latch 242, liquid crystal panel 243, l1080
The voltage applied to each liquid crystal panel is controlled to be above or below the threshold value.

FIG. 7 is a flowchart of control operations related to the 'trA collection function of the copying machine. FIG. 8 is a diagram showing an example of specifying coordinates on the editor of the copying machine. When processing is started by turning on the power, an initial state is first set (nl). That is, set the start address of the memory of the specified coordinate data to the memory address, set the value ffl of the counter that counts the cumulative number of times of coordinate specification to 0, and change the stored coordinate data to be arranged in ascending order (ascending order) with respect to the y coordinate. These include setting the code i for calculation to O, lowering each flag, and clearing each memory. At n2, the input/output is activated, and at n3, an end flag is used to determine whether or not the coordinate designation, the static elimination potential designation for each designated area, and the exposure light amount designation have been completed.

If the end flag is not set at n3, the above-mentioned designation has not been completed, and the process proceeds to step 118, where it is determined whether the (Xy) coordinate data has been input twice. If it is determined that the input is required, the coordinate data input at the violet 19 is stored in the memory address MA. In this example, the coordinate data for each area is specified at both ends of the diagonal line of the rectangular area (the 8th
(see figure), each area is entered twice.

Next, it is determined whether or not the photo mode key has been input for that area (n1o), and if it is determined that it is an input line, the photo mode (half erase) flag (H, F) is set (nil), and the The light amount data of the area designated photographic mode lamp is taken in (n12), and the voltage data to the liquid crystal shutter is taken in (n13), and the process proceeds to n20.

If it is determined in nlo that there is no input, the process proceeds to n14, where it is determined whether or not the erase key has been input. If it is determined to be an input line,
Set erase flag (E, F) (n 15) n 2
Proceed to. If it is determined in n14 that there is no input, the process advances to n16 and it is determined whether or not the clear key has been input. If the input line is determined, the coordinate data for the specified area with the memory address, the light amount data of the area specified photo motor lamp, and the voltage data for the liquid crystal shutter are cleared (n17). If there is no input at n16, the process advances to n18 and it is determined whether or not the end key has been input. If it is determined that it is an input line, set the end flag (En, F) (n 19), and if it is determined that there is no input, rr 20
Proceed to and determine whether or not the all clear key has been input. If there is an input, the process returns to nl; if there is no input, the process returns to n2.

As described above, the coordinate data, the light amount data of the area-designated photo mode lamp, and the voltage data of the liquid crystal shutter are stored for each area.

! If it is determined in step 13 that the end flag (En, F) is set, the input of each data for all areas has been completed, so proceed to step n4, and check whether the copying machine is in the process of copying. judge.

FIG. 8 shows the case where n areas are specified, and the total number of times the coordinates are specified, 84m, is 2n because each area is specified twice. And the coordinates of the last nth area are (X5
-1+ya-1) and (xm, ya). Further, the y-axis direction is the scanning direction, and scanning is performed from the side with the smaller y-coordinate. Note that if the code when y is arranged in ascending order as described above is 1, then i=1 to m.

If the copying operation is in progress, if i is 0 in n5, the coordinate data, area specification photo mode lamp light intensity data, and liquid crystal shutter voltage data are sorted in descending order of the y coordinate (n6), and i is set to 1. Start from (nl)
.

At n21, it is determined whether the photo mode flag is set. If you are standing, proceed to rr 22 and set the light intensity voltage ■8 for the photo mode of the area specified photo mode lamp, and set the voltage VL (above the threshold) to be applied to the liquid crystal panel in the photo mode in n23. do. When the y coordinate is y (n24), Xi~X. Turn on the lamp of 1 (n25), half open the LCD panel of xmX i+1 (n26), when the y coordinate is yo, 1 (t127),
X= ~x1, turn off the lamp of 1n28), x, ~
Xi.

Fully open the LCD panel (rr29).

If the photo mode flag is not set on n21, I)
At step 30, it is determined whether the erase flag is set. ■ Light intensity voltage for full erase of area specified photo motor lamp if standing.

Please set r131), where the y coordinate is y, (n
32) Please turn on the Xi "Xi++" lamp.I)
33), where the y coordinate is y,,1 (n34), xm
x8. , turn off the lamps (n35). In addition, each LCD panel has a standard voltage (below the threshold) unless specified.
VN is applied and the liquid crystal shutter is fully open.

Similar processing is repeated until the value of i becomes m-1 (n36), and the process returns to nl.

With the above configuration, nlo~n13, n23, n26, n2
9 corresponds to the liquid crystal shutter control means of the present invention.

By controlling as described above, when copying an original containing a mixture of text and photographs, as shown in FIG. The original can be faithfully reproduced by copying the character part O1 in the standard mode using CS.

In this embodiment, area specification is done using an editor.

However, other methods are also possible. Furthermore, the editor is equipped with trimming keys, masking keys, etc., allowing you to diversify your editing functions.

(Effects of the Invention As described above, according to the present invention, a liquid crystal shank is provided in the optical path to the photoreceptor for reflecting yellow on the original, and the amount of light for exposure can be changed. The combined amount of light can produce 6 lights.

Furthermore, it has been made possible to control the light irradiated to the area on the sensitive body that corresponds to the specified area on the manuscript. This results in
The density can be changed according to the density tone of each area, making it possible to copy the original document with great fidelity and significantly improving reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the second invention of this application. Second
The figure is a perspective view of a main part of a liquid crystal shutter commonly used in a copying machine which is an embodiment of the present invention. FIG. 3 is a perspective view of the main parts of the area designation photo mode lamp of the copying machine. FIG. 4 is an explanatory diagram of halving the amount of exposure light for a designated area using a liquid crystal shutter. FIG. 5 is a schematic diagram of the main parts of the copying machine. FIG. 6 is a partial diagram of the control section of the copying machine. Figure 7 shows
3 is a flowchart of control operations related to the editing function of the copying machine. FIG. 8 is a diagram showing an example of specifying coordinates on the editor of the copying machine. FIG. 9 is a diagram showing an example of specifying a mode for each area when copying a document containing a mixture of text and photographs. Or-original, 20-scanning unit, 21-light source, 24-liquid crystal shutter, 30-photoreceptor.

Claims (2)

[Claims] (1) A copying machine characterized in that a liquid crystal shutter for correcting the amount of exposure light is provided on the optical path of reflected light from the original to the photoreceptor. (2) A liquid crystal shutter control means for driving the liquid crystal shutter so that a predetermined amount of light is exposed to an area on the photoreceptor corresponding to a designated area in the document. Copying machine according to item 1.