JPS58196552A - Copying apparatus - Google Patents

Abstract

PURPOSE:To reduce errors and to enable control of exposure, by forming a latent image corresponding to an original on a photoreceptor through a preliminary scanning, and controlling the exposure of an image in a main copying process using the latent image. CONSTITUTION:Reference voltage is applied to an original illumination lamp 22 in the preliminary scanning of a preliminary copying process. Potential of a latent image formed ona drum 1 is detected with an electrometer 17, and sent to a conversion circuit. The potential of said latent image is integrated with this circuit, and the voltage to be applied to the lamp 22 at the copying scanning in the main copying process is determined by calculation on this basis. The use of the integrated signal raises the detection accuracy of the potential information on the latent image of the original consisting mainly of characters and thin lines, and permits obtainment of a beautiful faithful copy from such an original.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an original scanning type copying apparatus which is capable of obtaining appropriate copying depth regardless of the density of the LIC liquid type.

Conventionally, this type of electronic copying machine with an automatic degree system has been used.
As disclosed in Publication No. 2134 of 1982, etc., the light receiving element provided in the optical path of the original was used.

Measure the original once.1. These conventional devices are known to carry out copying while adjusting and supplying the obtained signal to the original illumination fan.
It is unavoidable to place it in the optical path of the reflected light of the original to the photoreceptor.
Light to the photoconductor: 1 t is cut and the light increases. Another disadvantage is that it becomes mechanically complicated in order to enter the optical path only during measurement. Furthermore, not only does it require a complicated process of correcting the difference between the spectral characteristics of the light-receiving element and the spectral characteristics of the photoreceptor, but also when the characteristics of the photoreceptor change due to the number of times it is used, the environment in which it is used, etc. It has a major drawback that its control ability is inadequate.

The main object of the present invention is to provide a copying apparatus that can solve the above-mentioned problems.

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

Fig. 1 shows an example of an electrophotographic copying apparatus to which the present invention can be applied. It has nine electrophotographic photoreceptors laminated to each other. This electrophotographic photosensitive drum
According to the (b) rotation, it is first uniformly charged by the DC corona emitter w/L device 2, and then receives the original horizontal jt and image sulin) 3111 light by the optical system described later, and at the same time discharges in 3.
tic receives ACl or DC corona radiation of opposite polarity to discharger 2, and is then uniformly exposed in rung 4.

As a result, a high-contrast static image 1w corresponding to the original is formed on the drum 1. (1) The present invention can also be applied to Carlson type electrophotography & C, in which case 3.
Method 4 is not necessary. ) In the copy book process, the 31* device 5 is activated and the developing sleeve 6 is rotated.
As a result, the latent image is developed and a toner image is obtained. This toner image is attached to a rope 7°8 in the copying process.
Transfer paper P supplied from ↓ - C supply tsr tlt
To.

The image is transferred by the action of the transfer charger 9. Transfer paper P is separated from drum l by separation roller lO.

Sent to fix ill. The toner image is fixed on the transfer paper P by this fixation 1i11, and after fixing, the toner image is discharged onto the tray 13 by the paper discharge roller 2.

On the other hand, the toner remaining on the drum 1 after transfer is removed by a cleaning blade 14, and the drum 1 is then uniformly exposed to light using a lamp 15 and actuated by a static eliminator 16 to erase the light history and charge history. Delete all. The drum l is then used again for the imaging process.

In the preliminary copying process, during the image forming process, the developer 5 does not operate (that is, the developing sleeve 6 does not rotate) and toner is supplied to the drum 1.1. In addition to the fact that the paper P'ft is not supplied to the transfer station because the rows 27 and 8 do not operate,
The same operation as in the above-mentioned self-adjusting and forming process is performed, and a latent image corresponding to the original is formed on the drum 1 after being illuminated by the lamp 4.

The potential of the latent image is then detected by an electrometer 17 at a position in front of the development station. The output of the lamp 22 is controlled based on the signal from the electrometer 17°.

Now, the original O is placed on the original table 18, and this original 0 is scanned by mirrors 19, 20, and 21. That is, the mirrors 19, 20, 21 #i move back and forth between the real position and the broken line positions 19', 20', and 21' in the figure. mirror 1
9 and the mirror 20.21 is the l: axis. The original 0 is mounted on a mirror 19 by a halogen lamp or the like which moves back and forth between the solid line position and the broken line position 22' in the figure.
illuminated by. Light from original 0 IT mirror 19.
It is reflected in the order of 20.21, passes through the lens 23, is reflected by the mirror 241C, and is emitted into the drum lKm. In other words, the optical image of the original is slit-exposed onto the drum l.

In the apparatus shown in FIG. 1, when Fi, the mirrors 19, 20, and 21 move to the right in the copying machine.

The lamp 22 is turned on, the original O is scanned, and an optical image formed by the reflected light of the original is slit-exposed onto the drum 1. When the scanning of the original is completed and the mirrors 19.degree. 20.21 reach the dotted line positions, the mirrors 1920.21 move back to the dotted line positions in the figure. On the other hand, the ** obtained by the gIig light during the forward movement of the -h mirror is developed with toner as described above, and the toner image is transferred to the paper P.
A preparatory copying process is performed before the copying process described above. At this time, document 0 is also scanned. That is.

The mirrors 19, 20, and 21 move forward to the right from the solid line position in the figure, and when the forward movement is completed, they move back to the left. Then, during this forward movement to the right, or to the left during evening movement in summer, the lamp 22 is turned on, and at this time, the drum l is slit-exposed by the reflected light from the document O through the optical system. be done. In any case, by lighting the lamp 22 and scanning the document by moving the mirror forward or backward, the drum I
A latent image corresponding to the original is formed in K. The surface potential of this latent image is detected by the potential needle 17'.

1. The subject book process referred to in this specification means that the document light g1 is applied to the photoreceptor.
The process of exposing a document to light to form a latent image and forming a copy from that latent image is carried out, and the scanning of the document carried out in the copy process is called copy scanning. On the other hand, the copying preliminary process is a process in which a photoreceptor is irradiated with light from the original to form a latent image corresponding to the original, but a public copy is not formed from that latent image. The scanning of the original document to be performed will be referred to as full preliminary scanning.

Now, as mentioned above, the potential of the latent image formed on the drum l is detected in the preliminary scan. A reference voltage is applied. That is, as shown in FIG. 2, in the copy preliminary process, the switch 23 is connected to the contact 23' side. The signal from the reference signal generation sub-path 24 is applied to the lamp drive circuit 25, thereby applying the reference voltage V· to the lamp 22. By applying this reference voltage Vo, the lamp 22 emits a strong WL strain, illuminating a plain document with a predetermined color density, and then illuminating a plain document with a predetermined surface potential 2 with an intensity of 1, for example, a standard white plain color. The intensity is such that when the original is illuminated, a surface potential m1tt is formed such that toner does not adhere to it.

Then, the original O is preliminarily scanned while the original s40 is illuminated with the second reference potential Vot applied by the scanner 22.

As a result, a latent image corresponding to the density of the original is formed on the drum l, and the potential of this formed a is measured by the electrometer 17.
However, the signal from the potential 117 is detected as a voltage - through the switch 26 which is closed as shown in FIG. The current is transmitted to the current conversion circuit 27. It was formed by this circuit 27. The current corresponding to the potential of the latent image is 1 circuit 2
8 and held.

In other words, the circuit 28Fi forms a signal equivalent to the average potential υ of the latent image in the area measured by the electrometer 17.

This signal is then transmitted to the arithmetic circuit 29, and the circuit 2
9 calculates and determines the voltage v1 to be applied to the rung 22 during copy scanning in the book copy process. For example, the circuit 29 is
Vl is determined based on the proportional equation: VB-αυ"-hato. Kotoa4□04. -□74f! k (
E-V*f! k ) is a constant determined corresponding to '. When the original O is illuminated with the lamp 22 to which a voltage of vl is applied, a distance of 4146 m without any tension can be obtained. In other words, rung 22 to which voltage ■l is applied
When a latent image is formed by illuminating the original flat, the a
The average potential of the image is such that it does not attract toner or only a small amount of toner is attracted, so it is cool.
The 40 characters, lines, etc. are clearly copied.

On the other hand, no capri occurs in the area corresponding to the ground portion that occupies most of the area of the manuscript.

For example, assume that the photoreceptor shown in FIG. 1 has fkE -■ characteristics as shown in FIG. 3. Under normal conditions, this photoreceptor is E-
vIIIIII! Used in areas where the slope is linear. On the other hand, the portion of the straight line taffi+ is approximately linearly proportional to the lamp lighting voltage. Therefore, when a photoreceptor having the EV characteristic shown in FIG. 3 is used, one circuit 29 uses a signal corresponding to the average potential υ to calculate the voltage . Calculate 1. Then, when the original is illuminated by the lamp 22 turned on with this voltage ■,
The average potential of am formed on the drum l is approximately O volts (i.e., a potential that does not attract toner), and the drum l has no ground force blur.
Clear Enoki copies of letters and lines can be obtained. In addition, when copying a single character, thin line original with many solid black areas, solid gray areas, and many solid areas, apply a voltage equal to the value of V+ minus △■ to the lamp 22. good. By doing this, the light emission intensity of the lamp becomes slightly smaller, and the average potential of a'ta becomes ^, so that even solid parts can be copied without blurring.

In any case, the signal of the calculation result obtained by the calculation circuit 29 is stored in the storage circuit 30.

The memorized good signal is then applied to the lamp drive circuit 25 through the switch 23i which switches to the contact 23'' during the copying process, thereby causing the lamp 22 to maintain the voltage Vr K.
Lights up more.

The operations of the above apparatus are summarized in FIG. 4, which shows a timing chart of the operations of the main means.

When the belly photography switch is turned on, the drum l begins to rotate, and the charger 2.3.9.16 and lamps 4 and 15 are energized.

Next, mirrors 19, 20, 21. Uynia'22 begins its forward movement. Just before this forward movement starts, contact 23' of switch 23
is connected, and the lamp 22 is lit at the reference voltage ■. Thus, the forward movement of the optical system forms an # image corresponding to the oak Ill' on the drum l, and this potential is detected by the electrometer 17 and integrated by the integrating circuit 28 as described above.

In this embodiment, the switch contact 23' is opened during the forward movement of the scanning optical system, and the lamp 22 is turned off.

W, only the potential of the # conductor (that is, the a-image of a part of the document in the scanning direction) up to the point in the middle of scanning the document is adjusted (generally the average of the entire document and the average of the part of the document (There are few cases where the density differs significantly, so this is sufficient for practical use.) However, by keeping the switch contact 23' closed until the forward movement of the blue scanning optical system is completed, the latent image corresponding to the entire length of the document is The potential t-m may be fixed. In any case, the arithmetic circuit 29 uses the lamp 2 during copy scanning based on the IS number corresponding to the latent image potential obtained in the -H period potential measurement.
Calculate the voltage to be applied to 2. Meanwhile, the scanning optical system Fi, which had completed its forward movement, returned to the ship.

Next, the copying process begins.

In the copying process, the contact 23' of the switch 23 is connected, and a voltage is applied to the lamp 22 based on the above calculation result, so that the lamp 22 is turned on with an intensity corresponding to the average # degree of the original. Then, as soon as this lamp is turned on, the scanning optical system starts to move forward, and the document is scanned. In the copying process, since the scanner 5 operates, the latent image of the original obtained by the J copy scanning is subject to tax control. On the other hand, in the copying process, the paper P is sent to the transfer station by actuating the actuator 1''-28, so that the toner particles obtained by the development described above are transferred to the paper P and fixed thereon to obtain a copy. 1. A beautiful copy without capri can be obtained.

In addition, an electric potential is formed that lights up the lamp 22 when the scanning optical system moves back and forth during the forward movement of the scanning optical system in the case of copy preparation in the example described above. 'Determine the lighting voltage.1. However, as shown in Figure 4, the lamp 22 (z) lights up at 0II7Ih of the scanning optical system during copy preparation - 1, and this forms the image corresponding to the original, and the flI of Jin. The arithmetic circuit 29 may be used to determine the lighting pressure during copy scanning based on the potential of the image. Although it is possible to detect m It '1 m corresponding to the entire length, it is preferable to detect the potential of a part of the document (in the scanning direction) and give that information to the arithmetic circuit.
Good too.

In addition, when the scanning optical system is moved back and forth in the preliminary copying process, 1
The potential of the m-image may be detected and the information may be provided to the transformer circuit.

In the above example, the lamp lighting voltage is determined by proportional calculation using the information obtained by integration, but the lamp lighting voltage is determined by comparing the signal obtained by integration with the reference signal 121 and the difference between the two. You may also do so. in any case.

Since Integral No. 4S is used, the detection accuracy of the potential information of the latent image of originals containing mainly letters and thin lines (in practice, most of the originals are such) is high, and therefore it is possible to detect beautiful and faithful images from originals such as the one above. A copy can be obtained.

Further, in the above example, the lamp 22 is turned on by the reference voltage in the copy preliminary process. This makes it easy to calculate the lamp lighting voltage during copy scanning, and it is possible to set a voltage that satisfies the original density.

In the above examples, the lighting voltage of the lamp 22 is controlled, but by adjusting the aperture provided in the lens 23 or the slit opening provided in the middle of the optical path, it is possible to control the original image on the photoreceptor. The exposure amount may be automatically controlled in accordance with the density of the original. In this case, in the preliminary copying process, the aperture amount of the diaphragm or slit is set to a reference value (a value that allows a latent image of a predetermined potential to be formed when a plain original of a predetermined density is exposed), and the original is thereby formed. The potential of the latent image corresponding to is detected, an integral signal is obtained, and the aperture amount of the aperture or slit is fully corrected based on this signal.

As described above, according to the present invention, a latent image corresponding to the original is formed on the photoreceptor through preliminary scanning, and the latent image is used to control the image exposure amount in the copying process, so that the exposure amount can be controlled with less error. It is something.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a copying machine to which the present invention can be applied, Fig. 2 is an explanatory diagram of a lamp control circuit, and Fig. 3 is an explanatory diagram of a photoconductor E-V%.
FIG. 4 is an explanatory diagram of the operation of an embodiment of the device according to the present invention. 1 is an electrophotographic photoreceptor, 2 is a charger, 17 is an electrometer, 19
, 20. 21 is a scanning mirror, 22 is an original illumination lamp, 2
8 is an integrating circuit, and 29 is an arithmetic circuit. Applicant Canon Co., Ltd. Agent Gi Marushima −

Claims (1)

[Claims] A copying device 1 of the Ryoten running type [in which Ryo Tachibana? Preliminary scanning is performed on the stl to be scanned to form a 11L layer on the photoreceptor, and the potential of this latent image is detected. Integrate the signal.Based on the integral value, calculate the image side original cover for the photoreceptor@
↓It is a copying machine that can be used as an image.