JPH01167773A - Exposure device for copying machine - Google Patents

Abstract

PURPOSE:To synchronize the images of a digital exposure system with those of a light lens exposure system and to remove failures such as deviation in position, etc., by setting a distance from a detection means to a exposure starting point of an original and a distance from the exposure starting position of the digital exposure system to the exposure starting position of the light lens exposure system equal to or exceeding it. CONSTITUTION:A detection means S1 is provided on a position P1 obtained when the scanning means of the light lens exposure system 4 attains a certain speed since said scanning means starts scanning and the exposure of a photosensitive body 10 by a digital exposure system 12 is started with signals from the detection means S1. A distance l2 from the detection means S1 to the exposure starting point P2 of an original and a distance L from the exposure starting position of a photosensitive body 10 by the digital exposure system 12 to the exposure starting position P2 of the photosensitive body by the light lens exposure system 4 are set equal to or exceeding it. Therefore, the positions can be surely synchronized with each other. Thus, the failures such as the overlap of the images formed by the digital exposure system on the images formed by the light lens optical system and the occurrence of the deviation in position can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure apparatus for a copying machine having a digital exposure system and a light lens exposure system.

[Conventional technology]

Conventionally, copiers that use an electrophotographic method that creates two types of electrostatic latent images on a photoreceptor in a single exposure process have an exposure system that uses a digital method and a light system that uses an exposure lamp or lens. A lens exposure system is commonly used.

The digital exposure system uses an image signal to expose the photoconductor using a raster output scanner (hereinafter referred to as RO5) using an LED, and the electrostatic latent image formed by this digital exposure system is transferred to the first developer. After being developed by a second developing device, the photoreceptor is exposed again by a light lens exposure system to form another electrostatic latent image on the photoreceptor, and this electrostatic layer is developed by a second developing device and then transferred to the paper in a transfer process. If different color developers are stored in the first developing device and the second developing device in advance, two-color copying is possible.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional exposure apparatus, it is difficult to align the electrostatic latent image formed by the first exposure using the digital exposure system and the electrostatic latent image formed by the second exposure using the light lens exposure system. There is a problem that a positional shift of ~5 degrees occurs.

This is because when the electrostatic latent image formed on the photoconductor by the digital exposure system reaches the exposure position by the light lens exposure system, there is a fluctuation in the scanning speed of the light lens exposure system, and this is shown in Figure 3. To explain, the light lens exposure system follows the curve Va
Assuming that is the normal rising speed at the start of scanning, variations occur in the rising speed as shown by curves Vb and Vc with the start of scanning, and as a result, the scanning starting point of document a changes from the scanning starting point (home position) Po shown in FIG. 4. Since there are variations in the time t2 until P2 is reached, the electrostatic latent image formed by the light lens exposure system may be misaligned with respect to the first electrostatic latent image on the photoconductor rotating at a constant speed. This positional shift causes problems such as parts of the images overlapping and the original image not being able to be copied in the desired arrangement.

[Means and effects for solving the problem] This invention was made for the purpose of improving the above-mentioned problems, and after exposing the photoreceptor using a digital exposure system, another image is placed on the photoreceptor again using a light lens exposure system. In an exposure device of a copying machine that exposes to light, a detection means is provided at a position where the scanning means of the light lens exposure system reaches a constant speed, and a detection signal from the detection means starts exposure of the photoreceptor by the digital exposure system. In addition, the distance from the detection means to the exposure start point of the document and the distance from the exposure start position of the photoreceptor by the digital exposure system to the photoreceptor exposure start position of the light lens exposure system are set to be the same or greater, It is an object of the present invention to provide an exposure device for a copying machine in which an image formed by a digital exposure system and an image formed by a light lens exposure system are synchronized.

〔Example〕

An embodiment of the present invention will be described in detail with reference to the drawings.

In the figure, 1 is the main body of the copying machine, and the original 2 to be copied is on the top.
A light lens exposure system 4 is provided below the platen 3.

A light lens exposure system 4 is connected to a document 2 placed on a platen 3.
an exposure lamp 4a that illuminates the copy surface of the document 2, and a copy mirror 41*42+ that guides reflected light from the original 2 onto the optical path 6.
43 + condensing lens 4b provided on the optical path 6
and a plurality of mirrors 44 that refract the light focused by the lens 4b toward the photoreceptor 10 and form an image on the photoreceptor 10.
+ 45 + 46, and the exposure lamp 4a and mirrors 41+ 42+ 43 are installed on a carriage (not shown), and are at a home position P shown by a virtual line. It is movable along the lower surface of the platen 3.

Further, around the photoconductor 10, there is a digital exposure system 12 consisting of a charger 11 that uniformly charges the surface of the photoconductor 10 and a ROS 12a, and an electrostatic potential formed on the surface of the photoconductor 10 by the digital exposure system 12. a first developing device 13 for developing an image;
An exposure point of a light lens exposure system 4 provided at a distance from the exposure point of the digital exposure system 12, a second developer 14 for developing an electrostatic latent image formed by the light lens exposure system 4, and a feeder (not shown). A copying machine 15 that transfers the developed toner image onto a sheet 20 fed from a paper device, a conveyance means 16 that conveys the sheet 20 peeled off from the photoreceptor 10 after transfer to the fixing device 17, and a transfer means 16 for the photoreceptor 10 after transfer. A cleaning device 18 for removing untransferred toner remaining on the surface of the photoreceptor 1
They are arranged in the above order along the rotation direction of 0.

The partially digital exposure system 12 has a mirror 121 behind the half mirror 46 provided in the light lens exposure system 4 that guides a part of the light transmitted through the half mirror 46 to the reading device 12b.
．． It has 122.

The image data read by the reading device 12b is
The ROS on signal and the first detection rIS are sent to the ROS controller 12c shown in the figure.

When a detection signal is input, it is simultaneously sent to the ROS 12a, and an electrostatic latent image is formed on the photoreceptor 10 by the RO 812a.

Further, the first detector S is located between the home position P0 of the light lens exposure system and the second detector S2 provided at the exposure start point P2 of the original 2, and the first detector S is located between the home position P0 of the light lens exposure system and the second detector S2 provided at the exposure start point P2 of the original 2. The distance g1 from the first detector S1 to the second detector S1 is the amount of movement commensurate with the time t1 from when the carriage starts moving from the home position Po until the carriage stabilizes, and the distance fI2 from the first detector S1 to the second detector S2 is ,
From the exposure point of the digital exposure system 12 to the light lens exposure system 4
It is set to be equal to the distance to the exposure point (ff2=L), and when the diameter of the photoreceptor 10 is Dp.

Next, to explain the operation, the original 2 to be copied is placed on the platen 3.
Place it on the top and press the start button to return to the home position P.
The carriage of the light lens exposure system 4, which had been stopped at position o, starts moving.

The above-mentioned carriage does not have a stable rising speed from the home position po until a certain time t due to changes in the drive motor characteristics and load, but the speed stabilizes by the time it reaches the first detector S1 and passes the first detector S1. do.

The first detector S sends a detection signal to the RO8 control device 12c as well as detecting the carriage, and sends a detection signal to the RO8 control device 12c.
c inputs the signal from the first detector S1 and the ROS ON signal as well as the image data stored in the memory in advance.
312a to start exposing the photoreceptor 10.

Thereafter, the carriage reaches the exposure start point P2 of the original 2 at a constant speed v1 and starts exposing the original 2, and the second detector S2 detects this and sends an exposure start signal to the control system of the copying machine main body 1. is output.

On the other hand, while the carriage of the light optical system 4 is traveling at a constant speed v1 from the first detector S to the second detector S2, the photoreceptor 10 is exposed by the digital exposure system 12. The formed electrostatic latent image is developed by the first developing device 13.

Then, the carriage moves to the document 2 provided with the second detector S2.
When reaching the exposure start point P2 of When the light lens exposure system 4 reaches the exposure point of the lens optical system 4 and starts exposing the original 2, the light lens exposure system 4 exposes the photoconductor 1.
Since the exposure of 0 is started, the exposure start position of the digital exposure system 12 on the photoconductor IO and the exposure start position of the light lens exposure system 4 are completely synchronized.

Thereafter, the electrostatic latent image formed by the light lens exposure system 4 is developed by the second developing device 14, and then reaches the transfer device.
, the toner images developed by the second developing device are simultaneously transferred onto the paper 20 fed from a paper feeding device (not shown). After the transfer is completed, the paper 20 is peeled off from the photoconductor 10 and sent to the fixing device 17 by the conveying means 16 for fixing. 18 is removed.

Therefore, if developers of different colors are stored in the first and second developing units 13 and 14 in advance, two-color copying can be performed in one copying process.

〔Effect of the invention〕

As described in detail above, in this invention, a detection means is provided at a position where the scanning means of the light lens exposure system reaches a constant speed after starting scanning, and a signal from the detection means is used to detect the photoreceptor by the digital exposure system. At the same time, the distance from the detection means to the exposure start point of the document and the distance from the photoconductor exposure start position of the digital exposure system to the photoconductor exposure start position of the light lens exposure system are set to be the same or greater. , it is possible to reliably synchronize these positions.

This makes it possible to eliminate problems such as overlapping or misalignment between the image formed by the digital exposure system and the image formed by the light lens optical system.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a copying machine according to an embodiment of the present invention, Fig. 2 is a block diagram of its control system, Fig. 3 is a diagram showing changes in speed of the scanning system, and Fig. 4 is a conventional explanation. It is a diagram. 2 is a document, 4 is a light lens exposure system, 10 is a photoreceptor, 1
2 is a digital exposure system. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masaaki Yonehara

Claims (1)

[Claims] In an exposure device of a copying machine that exposes a photoconductor 10 by a digital exposure system 12 and then exposes another image onto the photoconductor 10 again by a light lens exposure system 4, the scanning means of the light lens exposure system 4 is kept at a constant speed. A detection means is provided at the position reached, and a detection signal from the detection means causes the digital exposure system 12 to start exposing the photoreceptor 10, and also determines the distance l_2 from the detection means to the exposure start point of the original 2 and the digital exposure. An exposure device for a copying machine in which the distance L from the sighting start position of the photoreceptor 10 by the system 12 to the photoreceptor exposure start position of the light lens exposure system 4 is the same or greater.