JPS63121870A - Electrophotographic color image forming machine - Google Patents

Abstract

PURPOSE:To fix a proper image on a light transparent film by switching the driving speed of a transfer drum according to the 1st conveyance fixation condition and the 2nd conveyance fixation condition in synchronism with the end of a transfer process of final color. CONSTITUTION:When a print button is pressed in overhead projector (OHP) mode, a main control part sends an operation command 36 and the 1st speed command 37 for driving a motor at the 1st speed to a motor control circuit, and the motor begins to rotate at the 1st speed; and respective process parts are controlled at predetermined timing and the main control part sends the 2nd speed command to the motor control circuit in synchronism with the end of the transfer process of the final color to vary the rotating speed of the motor to the 2nd speed, i.e. slow speed, thus obtaining an excellent OHP image. The 1st speed command is sent out again after a fixing process and the rotating speed of the motor is reset to the 1st speed. All processes are carried out at the 1st speed except in the OHP mode. Consequently, the transparency of the OHP film is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an electrophotographic color image forming machine such as a copying machine, a printer, or a facsimile machine, and particularly relates to an improvement in a fixing mechanism that contributes to miniaturization of the entire apparatus.

(Prior Art) Generally, this type of color image forming machine is used for copying machines, printers,
Used for recording devices such as printing machines or facsimiles.

In a particularly typical copying machine, a toner image is formed on a photoreceptor, and this toner image is electrostatically supported on a paper surface.
Thereafter, a full color image or a monochromatic color image is obtained by heating and pressurizing the image between a pair of rollers.

However, in recent years, in addition to the use of plain paper (thick letter, postcard paper, second original drawing, release paper), it has become important for this type of device to record images on transparent film used for overhead projectors (hereinafter abbreviated as ○HP). It has become a thing.

However, despite this extremely high requirement, images projected onto transparent films were opaque, making it impossible to obtain practical color tones. For example, a projected image using yellow toner will appear dark overall, and particularly high-contrast areas will become gray. In addition, the other color tones also seemed dark overall.

These developments were caused by the roughness of the surface of the color toner layer on the film, which caused the OHP projection light to be refracted and scattered when it passed through the toner layer.

Various methods have been proposed to solve this problem. For example, JP-A-59-188673, JP-A-60-86
According to Japanese Patent No. 574, when using OHP paper, the peripheral speed of the fixing roller is lowered and the amount of heat given to the toner is increased to sufficiently melt the toner and make the surface of the toner mirror-like.

Further, when specifically implementing the method as an apparatus, Japanese Utility Model Application Laid-Open No. 59-192158 proposes a method in which the position of the transfer material is detected in a conveying section before fixing and the speed of the fixing device is varied.

However, as mentioned above, providing the conveying section has the disadvantage that the apparatus becomes larger.

FIG. 2 is an overall configuration diagram of a conventional color copying machine.

In the figure, 1 is an illuminator, 2 is a lens, 3 is a color separation filter, 4 is an optical system fan, 5 is a photosensitive drum, 6 is a charger, 7 is a static eliminator, 8 is an eraser, 9 is a magenta developer, 10 is a cyan developer, 11 is a yellow developer, 12 is a pre-transfer static eliminator, 13 is a transfer drum, 14 is a transfer section, 15
1 is a separating section, 16 is a pre-cleaning static eliminator, 17 is a cleaning section, 18 is a paper feeding section, 19 is a registration roller, 20
2 is a fixing section, and 21 is a paper discharge tray.

In this way, in the conventional example, the conveying section 22 is provided between the transfer drum 13 and the fixing section 20, and the transfer paper is transferred to the transfer drum 13.
Since it is necessary to reduce the speed of the conveying section 22 and the fixing section 20 from a position completely away from the transfer paper, the distance is naturally required to be equal to the maximum transfer paper size.

(Purpose) The present invention was made based on this background,
The present invention is based on a color image forming machine having a transfer drum and a photosensitive drum, and an object of the present invention is to propose a color image forming machine capable of fixing a suitable image on a transparent film without increasing the size of the device.

(Structure) For this purpose, the present invention reduces the rotation of the transfer drum after the toner on the photoreceptor is transferred to the transfer material, and the distance between the transfer section and the fixing section is set to approximately the length of the transfer material. This enabled significant miniaturization.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic diagram of a color copying machine according to the present invention. Components similar to those in FIG. 2 are given the same reference numerals.

During the image forming operation, the photoreceptor 5 is charged, exposed by the exposure section 1, and developed by the developer 11. On the other hand, the transfer material is fed from the paper feed section 18, wrapped around the transfer drum 13 with a clamp (not shown), and the transfer charger 14 transfers the toner onto the transfer material.

The photoreceptor 5 is cleaned in the cleaning section 17, and then charged, exposed, developed, transferred, and cleaned again.
Create a color image. The transfer paper on the transfer drum 13 on which the three-color or four-color image has been created is peeled off from the transfer drum 13 by the separating section 15, enters the fixing section 20, and is fixed.

In the case of plain paper, the situation is as described above, and the linear speeds of the transfer drum 13 and the fixing section 20 may be approximately the same.

Next, in the case of a transparent film such as OHP, the linear speed of the fixing section 20 is slow. Specifically, in the case of 9 papers, it is about 1/2. As mentioned above, this is to increase the amount of heat given to the toner.

Therefore, in the present invention, after the transfer is completed, the transfer drum 13 is
The fixing unit 20 is also dropped at approximately the same speed.

By doing the above, transfer C' The distance between the drum and the fixing section can be significantly shortened.

FIG. 3 shows an embodiment of the main control circuit of the copying machine main body according to the present invention. Centered around the CPU, ROM, RAM
, and 110 parts, where the 110 part is a driver for driving loads such as the motor, charger, clutch, solenoid, etc. of the copying machine main body, and signals from sensors installed in various parts of the copying machine main body. Input circuit for inputting information, serial interface circuit for reading manual keys on the operating unit and controlling the display, serial interface circuit for servo control of the drive motor of the copier main body, RDF, ADF, sorter , an option board interface for controlling peripheral devices such as a duplex unit and a paper feeder, and a non-volatile RAM interface for storing data such as image forming conditions and operation modes.

FIG. 4 shows an embodiment of a motor control circuit according to an embodiment of the control method of the present invention.

In the figure, a microcomputer 34 has a built-in PWM control counter and ROM, reads an operation command signal 36 (motor's ○N10FF signal) and a speed command signal 37 from the main control unit via an interface circuit 35, and outputs an encoder 38. The motor rotation speed is measured using the speed command signal 37, and the motor voltage (current) is calculated using the speed command signal 37.
WM control.

The output of the encoder 38 is obtained as a two-phase pulse train,
This encoder output is increased in resolution 39 and counter 40
to obtain the motor speed.

At the same time, the direction of rotation is also detected (41).

The motor driver 42 calculates the motor speed data obtained here and the speed command signal 37 from the main control section.
By adjusting the duty ratio of the pulse signal applied to the motor, it is possible to obtain a constant rotation that always matches the speed command signal.

The copying machine of this embodiment has a ○T (P selection mode button) on the operation section, and after pressing this OI-r T' selection button to switch to OHP mode, pressing the print button allows you to The machine is controlled in HP mode.

Now, if the pudding 1 button is pressed in HP mode, the main control unit issues a driving command to the motor control circuit and a first speed command to drive the motor at the first speed. , the motor begins rotating at a first speed. Each process section is controlled according to predetermined timing, and in synchronization with the end of the final color transfer process, the main control section sends a command to the motor control circuit to drive the motor at the second speed. A second speed command is issued, and the rotation speed of the motor changes from the first speed to the second speed.

Here, a second speed command is issued, and the motor rotation speed is set to the first speed command.
The second speed becomes lower than the above speed, and a good OHP image can be obtained. After the fixing process is completed, the first speed command is issued again, and the motor rotation speed returns to the first speed.
Prepare for the next print operation. Note that when not in the OHP mode, all strokes are executed at the first speed.

FIG. 5 is a flowchart showing the control operation according to the present invention.

In the figure, in step 1 (same as below), display control of the operation section, manual key processing, etc. are performed. OHP mode key 0N
10FF is also checked by this routine and OH is stored in RAM.
Stores whether it is in P mode or not. In step 4, when the print SW is pressed, a first speed command is issued to drive the motor at the first speed, the driving command is sent from the main control section to the motor control circuit, and the motor is driven at the first speed. It starts rotating at speed. In step 6, when the transfer of the final color is completed, it is checked whether or not the OHP mode is set. If it is the ○HP mode, the second speed command is output from the main control section to the motor control circuit, and the motor is set to the first speed. speed to a second speed. When not in OHP mode, the speed is not changed. Further, in step 7, when the ejection of the transfer paper is completed, it is checked whether or not copying for the set number of sheets has been completed, and if it has not been completed, the first speed command is output again and the motor is set to the first speed. Starts the next copy operation.

If the set number of copies have been completed, a copy end process is performed, the operation command is turned off, the motor is stopped, and the machine returns to the standby state.

(Effects) The present invention is as described above, and according to the color image forming apparatus according to the present invention, it is possible to reduce the size of the apparatus and improve the translucency of the OHP film.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a color copying machine according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a color dispenser according to a conventional example, and FIG. 3 is a block diagram showing an example of a main control circuit. , FIG. 4 is a diagram showing one embodiment of a motor control circuit, and FIG. 5 is a control flowchart according to the present invention. 5... Photosensitive drum, 13... Transfer drum. M1 nephew

Claims (2)

[Claims] (1) An electrophotographic color image forming machine equipped with a photoconductor drum, a transfer drum, and a fixing device, a means for setting the first conveyance and fixing conditions that can fix toner on a recording material of plain paper, and a recording material of resin film. In an image forming machine having a means for setting a second conveying and fixing condition that can fix toner, the transfer drum is driven under the first conveying and fixing condition and the second conveying and fixing condition in synchronization with the end of the final color transfer process. An electrophotographic color imaging machine that features switching speeds. (2) In the case of the second transport fixing condition, the driving speed of the transfer drum is reduced to approximately half.
) The electrophotographic color image forming machine described in item ).