JPS6365435A - Automatic exposing device for copying machine - Google Patents

Abstract

PURPOSE:To correct the fluctuation of control for the brightness of a light source and to always obtain clear copied images by setting up and inputting power supply value to a light source which is required not to form ground images for plural original images having different density. CONSTITUTION:A white level adjusting volume 5 and a halftone level adjusting volume 6 are fitted to a part of the inside of a copying machine body 11 and a reference power supply value to the light source 2 can be set up and inputted by operating these volumes 5, 6. Relation between original image density inherent in the copying machine and power supply values to the light source can be recognized by plural reference power supply values set up and inputted by an input means. At the time of a copying process based upon an automatic exposure mode, a power supply value corresponding to the output voltage of a silicon blue cell is found out from the relation between original reflecting density previously found out at every copying machine and power supply and the illumination of the light source 2 is controlled so that the ground of a copied image is turned to white independently of the density of the ground of the original, so that a clear image can be obtained.

Description

[Detailed description of the invention]! 8>Field of Industrial Application This invention relates to an automatic exposure device for a copying machine that controls power supplied to a light source according to the density of a document.

Summary of the Invention To summarize, the automatic exposure device for a copying machine according to the present invention includes an input means for setting and inputting a reference power supply value for forming appropriate copy images for each of a plurality of originals having different background densities. The light source is provided with a voltage suitable for the original image density based on the reference power supply value set by the input means, and the exposure amount is controlled with high precision by absorbing individual differences between copying machines. This is what I did.

(C) Conventional Technology In a copying machine, the relationship between the original image density and the copied image density is determined by the amount of exposure of the original to the light source provided in the optical system device. That is, even when copying the same original image, the density of the copied image can be changed by increasing or decreasing the exposure amount of the light source. Generally, in a copying machine, the exposure amount can be changed in several stages, so that an operator can form a copied image with a desired density. However,
The task of selecting an appropriate exposure amount according to the image density of the original is complicated, and adjusting the exposure amount while checking the image forming state increases the number of copies and reduces the operating efficiency of the copying machine.

For this reason, in conventional copying machines, a photoelectric conversion element receives the amount of light reflected from a document by a light source provided in an optical system.
Some devices were equipped with an automatic exposure device that controlled the power supplied to the light source according to the output voltage of the photoelectric conversion element. This automatic exposure apparatus was equipped with an input means for setting a reference power value in controlling the power supplied to the light source. This input means is used to set a power value such that no background image is formed when a document with a white background is copied.

When the reference supply power value set in this way is supplied to the light source, the output voltage of the photoelectric conversion element due to the reflected light from the white base original is maintained for any density of the original. Control power supply.

Therefore, as the density of the original increases and the output voltage of the photoelectric conversion element decreases, the power supplied to the light source increases until it is limited by the limiter. In other words, the background of the copied image is controlled to be white regardless of the background density of the original. The relationship between the original reflection density detected by the photoelectric conversion element and the power supplied to the light source is shown in Figure 5. The supplied power is proportional to the reflection density of the document from the reference value W1 set by the input means to the upper limit value Wmax regulated by the limiter.At this time, the value of the reference value W is adjusted by the input means. However, it is designed to absorb individual differences among copying machines caused by differences in sensitivity of photoreceptors, etc.

(d1) Problem to be Solved by the Invention Since the slope of the diagram showing the relationship between the original reflection density and the power supplied to the light source is determined by the control circuit, in the conventional automatic exposure device, the optical system of the copying machine It may not be possible to correct individual differences due to differences in light transmittance and reflectance of the lenses and mirrors that make up the system. The reference supply power values W, a and W
, b, and the relationship between the original reflection density and the supplied power is represented by the solid line and broken line in FIG. 6, respectively. The difference in the slopes of the two diagrams is an individual difference due to differences in the lenses and mirrors. If it is the same as that of aircraft A, then B
The power supplied to the light source is controlled according to the diagram indicated by the dashed line in the figure. For this reason, the brightness of the light source cannot be accurately controlled for medium-density originals, and clear copied images cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to set and input a power supply value to a light source necessary for not forming a base image for each of a plurality of original images having different densities, and to enable setting and input of a power supply value to a light source necessary for not forming a base image for each of a plurality of original images having different densities. An object of the present invention is to provide an automatic exposure device that can correct variations in brightness control of a light source caused by individual differences in light sources, and can always obtain clear copied images.

(e) Means for Solving the Problems The automatic exposure device of the copying machine of the present invention uses a photoelectric conversion element that receives reflected light from a light source from an original image, and whose output voltage changes depending on the density of the original image. In an automatic exposure device of a copying machine, which controls the power supplied to the light source according to the output voltage of the photoelectric conversion element, the standard power supply is used to form a copy image with a standard background density for each of a plurality of originals with different background densities. An input means for setting and inputting a value, and a calculation means for calculating a value of power supplied to the light source according to an output voltage of the photoelectric conversion element based on the relationship between the power supplied manually set by the input means and the image density of the original. It is characterized by having been established.

(f) Function According to the present invention, (1) A plurality of reference power supply values for obtaining a copy image of a reference background density for a plurality of background densities are manually set using the input means.

(2) The relationship between the original image density unique to the copying machine and the power supply value to the light source is known from a plurality of reference power supply values set and input by the input means.

(2) A calculation means calculates a power supply value adapted to the background density of the original based on the relationship between the original image density unique to each copying machine and the power supply value to the light source.

(Embodiment a) FIG. 2 is a schematic front sectional view showing the configuration of a copying machine equipped with an automatic exposure device according to an embodiment of the present invention.

A photoreceptor drum upper 12 is provided rotatably in the direction of arrow C in the center of the copying machine main body 11, and a charger 13, a blank lamp 14, a developing device 15,
Transfer charger 16, cleaner 17 and static elimination lamp 1
8 constitutes a copying process section 19. A paper ejection cassette 20, 21 is attached to one side of the copying machine main body 11, and a paper feed section 22 is configured. A paper ejection cassette 23 is attached to the other side of the copying machine main body 11, and constitutes a paper ejection section 25 together with a paper ejection roller 24 provided inside. A fixing roller 26 and a conveyance roller 27 are provided between the paper feed section 22, the copy process section 19, and the paper discharge section 25, forming a paper conveyance path 28.

A document table 29 is provided on the top surface of the copying machine main body 11. An optical system device 9 including a light source 2, mirrors 30 to 35, and a lens 36 is provided between the document table 29 and the copying process section 19.

The optical system device 9 moves back and forth in the direction of arrow A or B, and scans the image of the document placed on the document table 29.

When scanning an image of a document, the light from the light source 2 is distributed to the surface of the photosensitive drum 12 via mirrors 30 to 35 and a lens 36, as shown by dotted lines in the figure. is equipped with a white level adjustment volume 5 and a halftone level adjustment volume 6, and by operating these, a reference power supply value to the light source 2 is set and input. The white background level adjustment volume 5 and the halftone level adjustment volume 6 are input means of the present invention.

FIG. 1 is a schematic front view showing the optical system of the copying machine.

The optical system device 9 concentrates the light from the light source 2 onto the document table 29 using the reflector 3 . This reflected light from the original document is guided to the surface of the photosensitive drum 120 via mirrors 30, 31, etc., as shown by diagonal lines in the figure. Of the reflected light from the original, a position d ahead of the original position P2 guided to the photoreceptor drum 12 in the scanning direction indicated by arrow A, if P l
The reflected light from the slit 4 is shown by the dashed line in the figure.
is led to silicon blue cell 1. This silicon blue cell 1 is a photoelectric conversion element of the present invention, and the output voltage changes depending on the amount of reflected light. The distance d between the document positions P and P2 is the distance that the optical system device moves in the direction of arrow A in the time required to control the illuminance of the light source 2 according to the output voltage of the silicon blue cell 1. .

FIG. 3 is a block diagram of the IIJ control section of a copying machine equipped with the automatic exposure device.

A to the CPU 51 via the I10 interface 54.
The output data of the silicon blue cell 1 is input from the /D converter 56 . When adjusting the power supplied to the light source 2, the data of the white background level reference power value W1 and the halftone level reference power value W2 are obtained from the white background level adjustment volume 5 and the halftone level adjustment volume 6, respectively.
The signal is input from the /D converter 57 to the CPU 51 via the I10 interface 54. Each of the reference power values WI and W2 is stored in the battery-backed RAM5.
3 memory areas M1 and M2. CPU
51 calculates control data for the light source 2 according to the program stored in the ROM 52 based on the reference power value stored in the RAM and the detection data of the silicon blue cell l, and
10 interface 54 to the copy lamp driver 55. A part of the RAM 53 is allocated to a working area for this calculation.

The copy lamp driver 55 controls the power supplied to the light source 2 based on the control data.

FIG. 4 is a flowchart showing the operation of the copying machine.

When the power is turned on, warming up starts (n
l), when this warming-up is completed (n2),
Data and mode are available for input. At this time, a check is made to see if the mode is for setting and inputting the standard supply power value (n3), and if it is not the mode for setting and inputting the standard supply power value, the system waits for data input and print switch operation (n4). .n5). When in the standard supply power value setting input mode, white level adjustment volume 5
Then, the reference power value Wl of the white background level and the reference power value W2 of the halftone level are inputted by the halftone level adjustment volume 6 (n13, n14). This reference power value W and W2 are determined in advance by concentration, and D2 is R.
Settings are input for each of the white original and halftone original stored in the OM 52. Using this reference power value W and W, the slope of a linear function representing the relationship between the document reflection density and the supplied power is determined (n15). Furthermore, the intercept C on the Y axis of this -order number is found (11
16), this slope and intercept C are each stored in RAM53.
are stored in memory areas M3 and M4. When the setting input of the reference power supply value is completed in this way, and the data is input and the print switch is operated, the copying process is executed, and the optical system device 9 scans the image of the original. At the start of this copying process, it is checked whether or not the automatic exposure mode is set (n6), and if the automatic exposure mode is set, the reflection density of the document is detected by the silicon blue cell 1 (n9). Based on the detected document reflection density value and the slope value stored in memory areas M3 and M4, the supplied power value W is determined by a linear function expression expressed as W=hD+C (n
19). The power of this supplied power value W is output to the copy lamp 2 (nil). This operation is performed until the document scanning is completed (n12→n6), and the power suitable for the image density of the document related to the copying process is supplied to the copy lamp 2. , supplied to source 2.

On the other hand, if the automatic exposure mode is not selected, the manually input data is read and the power specified by this setting value is supplied to the light source 2 (n
? , n8. n1l) - nlO, n15. n
16 corresponds to the calculation means of this invention.

In this way, according to this embodiment, the slope and intercept C of the linear function representing the relationship between the document reflection density and the supplied power are calculated using the set reference power supply values W, , W, and The relationship shown by the solid line in Figure 5 is obtained.

During the copying process in automatic exposure mode, the power supply value corresponding to the output voltage of the silicon blue cell 1 is determined from the relationship between the original reflection density and the supplied power, which is determined in advance for each copying machine, and is First, the illuminance of the light source 2 is controlled so that the background of the copied image becomes white, and a clear image can be obtained.

Note that the response of the light source 2 is sufficiently slow compared to the time required to calculate the supplied power value according to the output voltage of the silicon blue cell 1, so the supplied power value for each document's background density converges to one value. .

(h1 Effects of the Invention According to this invention, it is possible to obtain a reference power supply value for forming a copy image with a reference background density for each of a plurality of originals having different background densities, and to obtain a reference power supply value for each copying machine with a reflection density of the original. It is possible to determine the relationship between the value of power supplied to the light source and the value of power supplied to the light source.This relationship includes individual differences between the optical system device and each device constituting the copying process section, and this relationship is set in advance for each copying machine. This makes it possible to prevent deterioration in the quality of copied images due to inappropriate supply power values caused by individual differences between each copying machine.

[Brief explanation of drawings]

Fig. 1 is a schematic front view showing the main parts of a copying machine equipped with an automatic exposure device according to an embodiment of the present invention, Fig. 2 is a schematic front sectional view showing the configuration of the copying machine, and Fig. 3 is a copying machine of the same A block diagram of the control unit of the machine, Figure 4 is a flowchart of the copying machine, and Figure 5 is a block diagram of the control section of the machine.
The figure shows the relationship between the original reflection density and the power supplied to the light source in the copying machine. FIG. 6 is a diagram showing the relationship between the reflected density of a document and the power supplied to the light source in a copying machine equipped with a conventional automatic exposure device. 1-Silicon blue cell, 2-Light source, 5-White background level adjustment volume, 6-Half-done level adjustment volume.

Claims (1)

[Claims] (1) Equipped with a photoelectric conversion element that receives the light reflected from the light source from the original image and whose output voltage changes according to the density of the original image, and controls the power supplied to the light source according to the output voltage of the photoelectric conversion element. In an automatic exposure device of a copying machine, an input means for setting and inputting a reference power supply value for forming a copy image with a reference background density for each of a plurality of original image densities having different background densities; An automatic exposure device for a copying machine, comprising: calculation means for calculating a power supply value to a light source according to an output voltage of a photoelectric conversion element based on a relationship between a supply power value and a document image density.