JPH0354585A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain an energy-saving, inexpensive electrophotographic device which requires no heating waiting time and provides high printing quality with less transfer dislocation by bringing a recording sheet passing between a belt-like photosensitive body and a roller made of an elastic body into press-contact with a heating head via the belt-like photosensitive body and performing development. CONSTITUTION:In synchronization with the timing of when a laser scanner 4 writes a latent image onto the photosensitive body, the recording sheet 12 fed from a paper feed tray 11 is carried to a fixing position between the belt- like photosensitive body 1 and a pressure roller 8. Here, the recording sheet 12 is closely bonded by the pressure roller 8 with a toner image on a belt formed by a developing unit 6 in the position of a thermal head 7, and is heated by the thermal head 7 possessing a linear heating body extending in the main scanning direction. The toner image is transferred onto the recording sheet 12 by this heating and pressure of the pressure roller 8 and is fixed thereon, following which the recording sheet 12 is ejected to a paper ejecting tray 16. Toner remaining on the photosensitive belt 1 is cleaned out by a cleaning roller 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic apparatus, particularly an apparatus having a belt-like photoreceptor.

[Prior Art] Conventionally, as shown in FIG. 2, the electrophotographic process consisted of the following processes. In other words, the basic process is charging → exposure → development → transfer → fixing, and the means for separating the photoreceptor and recording paper, the means for conveying the recording paper after separation, the means for cleaning the photoreceptor, the auxiliary exposure means for the photoreceptor, etc. are also required in reality. It was equipped as an essential device. FIG. 2 shows an example in which a laser scanner 4 is used for exposure, and electrostatic separation is used for transfer separation between the recording paper 12 and the photoreceptor drum 19 using a transfer separation charger 20.21. Although there are methods such as a separation belt for image formation and separation and a belt for the photoreceptor, each method has the following drawbacks.

That is, l. It takes time to heat the fixing roller 25 → A waiting time is required when the power is turned on.

2. A large amount of power is required to heat the fixing roller.

3. When transferring an image to recording paper, misalignment between the recording paper and the photoreceptor tends to occur, and in order to maintain image quality, a highly accurate paper feeding mechanism is required, and the recording paper must be fed from the transfer position to the fixing position. A space of the same length in the direction is required, and a means of transporting the recording paper in between is required.

The above drawbacks have resulted in the device being bulky and expensive.

In addition, pressure fixing has been proposed to solve the problem 1.2 above, but the paper may become glossy.

[Problems to be solved by the invention] The present invention eliminates the above-mentioned drawbacks, eliminates wait time,
The purpose is to provide a high-quality, low-cost device that saves power, has little transfer misalignment, and has high print quality.

[Example] The embodiment shown in FIG. 1 will be described below.

In the figure, 1 is a photoreceptor belt, 2 is a pre-exposure LED that removes electrostatic afterimages, 3 is a primary charger that uniformly charges the photoreceptor, 4
5 is a laser scanner that irradiates a photoreceptor belt with laser in synchronization with image information to create an electrostatic latent image; 5 is a folding mirror 6 that guides the laser beam to the photoreceptor; a developer that develops toner on the electrostatic latent image; 7 heats the toner developed by a thermal head having a line-shaped heating element via a photoreceptor belt, and presses the photoreceptor with a pressure roller 8 whose surface is made of an elastic material and is longer than the length of the heating element. The toner image is transferred and fixed onto the recording paper 12 sandwiched between the belt 1 and the belt 1. 9 is a cleaning roller for the photoreceptor belt, lO is a tension roller for tensioning the photoreceptor belt, l1 is a paper feed tray that supplies recording paper, 13 is a feed roller that feeds the recording paper 12 from the paper feed tray, f4 is a recording A registration roller 15 that conveys the paper and removes skew is a registration sensor consisting of a photo interrupter that detects the passing of the recording paper in order to synchronize the image writing with the recording paper and a laser, and 16 is a registration sensor that discharges the recording paper l2. It's a tray. Reference numeral 17 denotes a power supply and control circuit, which are built into the cover 18 and constitute a laser beam electrophotographic printer.

The operation will be explained below.

In response to the recording start signal, the recording paper 12 is fed out from the paper feed tray 11 by the feed roller I3. The recording paper reaches the registration roller 14, and after the skew is removed, the rotation of the registration roller leads the recording paper to a recording section constituted by photoreceptor belts.

At this time, the registration sensor 15 detects the passing of the leading edge of the recording paper 12, and synchronizes the timing of writing the latent image onto the photoreceptor by the laser scanner.

In addition, prior to laser writing, the photoreceptor belt is transported clockwise in the figure by a driving means (not shown) so that its surface speed is equal to the recording paper feeding speed of the registration rollers, and an electrostatic afterimage caused by the pre-exposure LED 2 is transported. , and charging of the photoreceptor belt l by the primary charger 3 is also started. The recording paper l2 is brought into close contact with the image on the photoreceptor belt, which has been turned into a toner image by the developing device 6, at the thermal head 7 by the pressure roller 8. The thermal head is approximately 200 mm wide
μm. It consists of a single heating element with a length of 220 mm, and heats the image on the photoreceptor belt to about 280° C. at the same time as it passes through the heating element. Approximately 200μm
A photoreceptor belt based on a thick polyimide film transfers this heat to the toner image, rendering the toner in a semi-molten state, and the toner image is transferred and fixed onto the recording paper 12 by the pressure of the pressure roller. The surface of the photoreceptor bell 1 is coated with Teflon, and the image is approximately 10
Transferred to 0% recording paper 12. Thereafter, the recording paper 12 is discharged to a paper discharge tray l6, and the photoreceptor belt is cleaned by a cleaning roller 9 to remove a very small amount of remaining toner and dust such as paper dust. Since the photoreceptor belt 1 is heated only when it is in motion and only when there is an image, the deterioration in performance due to heat can be practically ignored.

In the above embodiment, the thermal head is a single heating element, but if multiple heating elements are provided in the main scanning direction and heating control is performed in accordance with image information not only in the sub-scanning direction but also in the main scanning direction, power consumption can be further reduced. It can be measured. Further, although this embodiment shows the case of image writing using a laser scanner, similar effects can be obtained in a copying machine or the like using an analog optical system using a conventional document table.

[Effects] As explained above, according to the present invention, 1. Since a transfer charger is not required, the cost is low and the process is highly stable.

2. Since the thermal head only needs to be heated when necessary, there is no waiting time when the power is turned on, which saves power and prevents damage to the photoreceptor belt.

3. Since the recording paper and photoreceptor are brought into close contact with each other by a pressure roller, transfer misalignment is less likely to occur.

It has the following advantages. Furthermore, it is possible to provide equipment with high image quality, low power consumption, and low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional copying machine. In the figure, l is a photoreceptor belt, 3 is a primary charger, 4 is a laser scanner, 6 is a developer, 7 is a thermal head, 8 is a pressure roller, 9 is a cleaning roller, 10
1 is a tension roller, 17 is a control circuit, 19 is a drum, 20 is a transfer charger, and 2l is a separation charger.

Claims (1)

[Claims] (1) In an electrophotographic apparatus having a belt-shaped photoreceptor,
It has a heating head having a line-shaped heating element extending in the main scanning direction, and a roller made of an elastic body disposed with respect to the heating element with a belt-shaped photoreceptor in between. An electrophotographic apparatus characterized in that a toner image on a photoreceptor is fixed to a recording paper by pressure contact with a recording paper in between.