JPS6026206B2 - Method for adjusting photoreceptor exposure light amount in a copying machine with original reading function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photoreceptor exposure light amount adjustment method in a copying machine having an original drafting function.

As is well known, in order to copy an original and obtain a good copy, the amount of light emitted from the photoreceptor must be adjusted depending on the condition of the original.

However, in general copying machines, the exposure light amount is adjusted manually by the machine operator, but the operator makes the adjustment based on his/her intuition. It became necessary to redo the process, and there was room for waste in terms of materials and time.

On the other hand, recently, copying machines having a document reading function have been put into practical use in combination with an electrophotographic process.

Copying machines of this type generally have the function of forming a static latent image corresponding to the information pattern on a document by charging and exposing a photoconductive photoreceptor, and developing this image. It has at least the function of scanning and converting an information pattern into an image signal.

An object of the present invention is to automatically adjust the amount of light exposed to the photoconductor during the copying process in a copying machine having a document capture function that performs slit exposure of the photoconductor and uses a solid-state image sensor to capture the document. The objective is to provide a method for adjusting the

The present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a copying machine/reading/recording device to which the present invention is applied.

That is, in the figure, reference numeral 1 is a photoconductive photoreceptor, reference numeral 2 is a charger, reference numeral 3-1 is an illumination lamp, and reference numeral 3 is a photoconductor.
-2, 3-3, 3-5 are reflecting mirrors, 3 and 4 are mirror lenses, 4 is a moisture developing device, 5 is a stacker, 6 is a transfer charger, and 7 is a turn loaf. -, the reference numeral 8 designates a static elimination lamp, the reference numeral 9 a cleaning device, and the reference numeral 10 a document layer glass, respectively.

Further, the reference numeral 11 indicates an imaging lens system, the reference numeral 12 indicates a solid-state image sensor, the reference numeral 13 indicates a CRT, and the reference numeral 14 indicates an east concentrating optical transmission body array.

The photoreceptor 1 is formed into a drum shape and is arranged so as to be able to be rolled around a shaft in the direction of the arrow.

charger 2, developing device 4, registration roller 5, transfer charger 6, turn-roof 7, static elimination lamp 8,
The cleaning devices 9 are arranged in the above order in the circular direction of the photoreceptor 1 so as to thread the photoreceptor 1 . The illumination lamp 3-1, reflecting mirrors 3-2, 3-3, 3-5, and mirror lenses 3-4 constitute an optical system for exposing the photoreceptor. , 3-5, and the mirror lens 3-4 constitute an exposure optical path from the document surface on the document placement glass 10 to the photoreceptor exposure section.

The illumination lamp 3, reflecting mirrors 3-2, 3-3, and imaging lens system 11 constitute an optical system for reading the original. An optical path for reading the original is constructed from the image sensor 12 to the solid-state image sensor 12. The CRT (sword ray tube) 13 and the convergent transmitter array 14 constitute a line scanning mechanism,
These are provided between the photoreceptor exposure section and the developing device 4 so as to scan the photoreceptor surface in a line.

First, each of the copying process, original copying process, and recording process using image signals by the apparatus will be explained.

First, the copying process will be explained.

Set up the device for the copying process and place the original to be copied ○
When the photoreceptor 1 is placed on the document display glass 10 and the device is activated, the photoreceptor 1 begins to rotate in the direction of the arrow, and at the same time, the charger 2 starts corona discharge.

In this way, the peripheral surface of the photoreceptor 1 is uniformly charged by the corona discharge of the charger 2, and moves toward the photoreceptor exposure area. During this time, the lighting lamps 3-1 emit light,
The upper part of the reflecting mirror 3-2 is illuminated in the form of a slit whose longitudinal direction is perpendicular to the drawing. When the uniformly charged surface of the photoreceptor 1 reaches the exposed area, the illumination lamp 3-1
integrally with the reflecting mirror 3-2 moves to the left in the figure parallel to the original lectern glass 10 at a speed equal to the moving speed of the periphery, and scans the original ◯ with illumination light.

At this time, the reflecting mirror 3-3 moves in the direction of the arrow at a moving speed that is 1/2 of the moving speed of the reflecting mirrors 3-2 to keep the optical path length of the exposure light east constant. A part of the reflected light from the slit-shaped illuminated part of the document ○ is guided to the photoconductor exposure part by the optical system for exposing the photoconductor, and is illuminated by the action of the in-mirror lens 3-4. is formed on the photoreceptor 1. In this way, the photoreceptor 1 is exposed to slit light, and the photoreceptor 1
A static latent image is formed in accordance with the information pattern of document 0. The formed static exposure latent image moves with the rotation of the photoreceptor 1, is wet-developed by the developing device 4, and is visualized. During this time, the recording sheet S is conveyed within the apparatus and is waiting with its leading end held against the registration rollers 5.

The registration rollers 5 send the recording sheet S to the transfer section in accordance with the movement of the visible image, and superimpose it on the visible image.

The transfer charger 6 discharges corona toward the recording sheet S superimposed on the visible image, thereby causing the recording sheet S to
The visible image on the photoreceptor is transferred onto the recording sheet by the action of the electric charge applied to the photoreceptor.

After the visible image has been transferred, the recording sheet S is separated from the photoreceptor 1, transported by a turn roller 7, subjected to necessary processing such as drying, and then discharged from the apparatus as a copy. .

Thereafter, the photoreceptor 1 is neutralized by a neutralizing lamp 8, and residual toner is removed by a cleaning device 9.

In this way, the copying process is completed. Next, the manuscript collection process will be explained.

When the apparatus is set for the document reading process, a document ○ is sent as shown in the figure, and the apparatus is operated, the illumination lamp 3-1 emits light.

The reflected light from the nuclear illumination part of the document ○ is guided by the reflecting mirrors 3-2, 3-3 and the imaging lens system 11, and is reflected onto the light receiving castle of the solid-state image sensor 12, at the illuminated part, and onto the drawing. A reduced image of a document area having a fixed straight line whose length direction is the vertical direction is formed by the action of the imaging lens system 11 . The solid-state image sensor 12 has a large number of very small light-receiving elements arranged closely in a line, and is integrated to provide a self-scanning function. Each time it is driven by a clock pulse, the information of the document portion imaged on the light receiving castle is converted into a time-series electric signal by self-scanning. The illumination lamp 3-1 and reflecting mirrors 3-2 and 3-3 move in the direction of the arrow to illuminate and scan the document 0, as in the copying process. As a result, the part of the original that forms a striped image on the light-receiving castle of the solid-state image sensor 12 changes sequentially, and as the self-scanning of the solid-state image sensor 12 is repeated due to short-cycle clock pulses, the information pattern on the original ○ is sequentially changed in chronological order. is converted into an electrical signal. Now, the electric signal obtained by the solid-state image sensor 12 is applied to a shift register and a signal processing circuit (both not shown in FIG. 1) for each scan.

A shift register maintains applied electrical signals in chronological order. On the other hand, the signal processing circuit detects the maximum signal among the released electric signals, that is, the maximum output value Vmax due to the self-scanning of the solid-state image sensor 12, and sets it to an appropriate value of 1>B>0. 8 and the above Vm
axBVmboard x is applied as a binary comparison signal to a comparator (not shown). Solid-state image sensor 12
However, when the next self-scanning is performed and the resulting electrical signal is applied, the electrical signal from the original self-scanning held in the shift register is output and applied to the comparator.

The comparator binarizes the applied electrical signal and compares it with the bell BVmax, and detects a signal larger than this.
Binarize the signal to a logic value of "1" and a small signal to a logic value of "0".

This process is repeated for each self-scan of the solid-state image sensor 12, and the information pattern on the document ○ is converted into a time-series binary signal. Of course, the output of the solid-state image sensor 12 increases in proportion to the amount of light received by the light receiving element. Next, a recording process using image signals will be explained.

The CRT 13 has a face plate that is elongated in a direction perpendicular to the drawing and is disposed to face the circumferential surface of the photoreceptor 1 at a predetermined distance from the circumferential surface of the photoreceptor 1 in the direction of the photoreceptor rotating wheel. .

The east-focusing optical transmitter array 14 is an east-focusing optical transmitter (generally known by the trade name "Self-Otsuk") with a diameter of about one square.
A large number of them are arranged in a length that can form an erect, life-size image, and are bundled in parallel and close together in the direction perpendicular to the length direction, in the closest possible arrangement, and each The aggregate surface of the minute end faces of the energy-concentrating optical transmitter is integrated to form an elongated slit-like end surface, and the arrangement direction of the energy-gathering optical transmitter is oriented perpendicular to the drawing to form the slit-like end face. One of the end faces of C
One of the two faces toward the face plate of the RT 13, and the other face faces the circumferential surface of the photoreceptor 1. When the apparatus is set for a recording process and operated, the photoreceptor 1 rotates in the direction of the arrow and is uniformly charged by the charger 2.

If the recording is performed by scanning the original to convert the information pattern into an image signal and using this image signal, the above-mentioned discussion process will start at the same time, and even if the recording process is such that the image signal comes from outside the device. If so, the original stripe reading mechanism will not operate.

In the recording process of reading a document, the exposure light beam is blocked by a suitable light shielding plate. The image signal is CRT
13, it modulates the intensity of the electron beam being scanned in a direction perpendicular to the drawing, and converts it into a spatially arrayed optical signal by means of dot emission on the total optical film of the faceplate.

This optical signal is transmitted to the photoreceptor 1 by the converging transmitter array 14.
An image is formed on the charged peripheral surface of the electron beam, and a line scan of the photoreceptor 1 is performed by an optical signal for each scan of the electron beam.
A static latent image corresponding to an image signal is formed on the photoreceptor 1. This electrostatic image and photoreceptor 1 are then processed in exactly the same manner as in the copying process described above. Now, in order to apply the present invention to such an apparatus, the following procedure is performed.

In order to obtain a copy image of an information pattern by copying a document, the information pattern must be printed on a color or white background area to which the photoreceptor is sensitive due to its spectral sensitivity characteristics, or on a black or white background area to which the photoreceptor is sensitive. It must be written in a color that does not exist.

At this time, the contrast between the information pattern image and the background portion in the obtained copy image depends on the contrast between the two in the original document and the color of the background portion. Obtaining a good copy image is nothing more than 'optimizing the contrast between the background part and the information image part in the copy image.
Since the information pattern is written in black or a color to which the photoreceptor is not sensitive, in order to obtain proper contrast, when the light image is illuminated on the photoreceptor,
'The part of the photoreceptor corresponding to the background part needs to be exposed with an appropriate amount of light.

In other words, there is an appropriate value for the amount of radiant light in the portion of the photoreceptor corresponding to the background portion. In the exposure conditions in the copying process, the optimum value of the exposure light amount, that is, the light intensity corresponding to the optimum exposure amount is assumed to be ■. On the other hand, in this apparatus, when the photoreceptor is exposed due to the configuration of the optical system, a portion of the reflected light from the illuminated portion of the document is inevitably guided to the light receiving castle of the solid-state image sensor.

Since the light reflected by the document 0 is generally diffused light, the light intensity on the light receiving element of the solid-state image sensor 12 and the corresponding photoreceptor intensity are in a proportional relationship to each other. In other words, the light intensity of the light image projected onto the photoreceptor at a portion corresponding to the background portion of the original and the output value of the solid-state image sensor 12 relative to the background portion of the original are in a proportional relationship. Therefore, if the solid-state image sensor 12 were to self-scan when the photoreceptor was exposed using the optimum light intensity (3), the output value corresponding to the background portion of the document that would be obtained is set as the reference value Vo. According to the present invention, the amount of light exposed to the photoreceptor is adjusted as follows.

That is, in the copying process, while the original 0 is being scanned for illumination and the photoreceptor is being exposed, the solid-state image sensor 12 is caused to self-scan, and its signals are applied to the signal processing circuit 15 as shown in FIG. It is.

Then, since the maximum output Vmax of the group image sensor 12 obtained from the signal processing circuit 15 corresponds to the intensity of reflected light from the background of the document in a general document, this means that the solid-state image sensors 1 and 2 This is nothing more than detecting the intensity of light reflected from the background part of the document each time it scans itself. When the above Vmax is equal to the above Vo, the photoreceptor 1 is correctly exposed.
Now, from the signal processing circuit 15, the solid-state image sensor 1
Vmax obtained for each scan of 2 is applied to the comparison circuit 16.

The reference value Vo is applied to the comparison circuit 16,
Comparison circuit 16 compares Vmax and Vo, and (Vm
ax-Vo). This output signal is applied to the illumination lamp light emission control circuit 17. The illumination lamp light emission control circuit 17 controls the amount of light emitted from the illumination lamp 3-1 according to the applied signal.

That is, if (Vmax-Vo) is positive, the illumination lamp light emission control circuit 17 sets the light emission amount of the illumination lamp 3-1 to (Vmax-Vo).
max-Vo) according to the absolute value of (Vmax
-Vo) is negative, the amount of light emitted from the illumination lamps 3-1 is set to (V
The value is increased according to the absolute value of m(red x−Vo). Fluctuations in the amount of light emitted from the illumination lamp 3-1 are determined by the solid-state image sensor 12.
As a result of the self-scanning, a variation in Vmax is immediately detected, and the control amount of the light emission amount changes accordingly, and eventually the light emission amount of the illumination lamp 3-1 is controlled to a value that provides an appropriate amount of light for exposing the photoreceptor. Since the self-scanning of the solid-state image sensor 12 is extremely rapid compared to the illumination scanning of the document ○, extremely appropriate exposure of the photoreceptor can be achieved by controlling the amount of light emitted from the illumination lamp.

Furthermore, even if the reflectance of the background part of the document changes midway through, the amount of flashing light is automatically adjusted. As described above, according to the present invention, it is possible to provide a method for adjusting the amount of exposure light on a photoconductor in a copying machine having a document sampling function.
Note that in the above explanation, the pupil of the solid-state image sensor does not change between the copying process and the manuscript copying process;
The position of the solid-state image sensor may be different between the copying process and the original document taking process, and may be shifted from the position for taking the document to the position for detecting the exposure amount during the copying process.

[Brief explanation of drawings]

FIG. 1 is a front view schematically showing only the main parts of an example of a copying machine/recording apparatus to which the present invention is applied, and FIG. 2 is a diagram for explaining the present invention. 1... Photoreceptor, 12... Solid-state image sensor, I
5... Signal processing circuit, 16... Comparison circuit. Little brother I diagram N ship

Claims (1)

[Claims] 1 A photoconductive photoreceptor is slit-exposed to form an electrostatic latent image corresponding to the information pattern on the document, and when this electrostatic latent image is developed, the document is read and scanned by a solid-state image sensor. , a device having at least the function of converting an information pattern on a document into an image signal, when the device is configured for a copying process, converts a portion of the reflected light from a slit-shaped illuminated portion of the document into an image signal. , a reduced image of a part of the illuminated area is formed on the light receiving area of the solid-state image sensor, and at the same time as the photoreceptor is exposed to the slit, the solid-state image sensor reads and scans the document. The output of the solid-state image sensor is input to a signal processing circuit, and the signal processing circuit detects the maximum output value Vmax of the solid-state image sensor for each scan, and determines the optimum exposure amount of the photoreceptor for the background of the original. A comparison circuit compares the reference position V_0, which has been converted in advance to the output value of the image sensor, and the maximum output value, and adjusts the output of the comparison circuit so that the maximum output value Vmax becomes equal to the reference position V_0. Accordingly, a photoreceptor exposure light amount adjustment method is characterized in that the amount of light emitted from a document illumination lamp is controlled.