JPH034911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device using an electrophotographic method or an electrostatic recording method, and more particularly to a printing device that can improve the transfer efficiency of a toner image and obtain a clear transferred image.

FIG. 1 is a perspective view showing the configuration of a laser printer device.

A latent image forming medium (photosensitive drum) 1 is driven by a motor 2 at a constant speed in the direction of an arrow 4 via a deceleration mechanism 3. Reference numeral 5 denotes a pre-charger for uniformly charging the photosensitive drum 1, and then a laser optical unit 6 forms a latent image.

After the latent image is formed, a developer 8 is applied to the latent image on the surface of the photosensitive drum by a roller 9 in a developing device 7 in order to visualize the latent image, and a visible image is formed by the toner in the developer. Afterwards, transfer the paper 10 to the transfer guide 11.
The transfer charger 12 applies an electric charge to the paper 10 from the back side of the paper 10 in the gap of the transfer guide 11 to perform transfer.

After the transfer, the photosensitive drum 1 has its charge removed by a static eliminator 13, and a cleaning section 14 collects residual toner on the surface of the photosensitive drum.

The paper 10 is transported from the hopper 15 to the paper feed tractor 1
6, passes through a transfer guide 11, is fixed in a fixing device 17, and is then folded and stored in a stacker 18. The paper feed tractor 16 is a paper feed motor 19
The paper is fed at a constant speed via the deceleration mechanism 20. When printing is performed using such a configuration, conventionally, the speed at which the paper 10 is moved by the photosensitive drum 1 and the paper feed tractor 16 is the same.

However, if the speeds of the conventional photosensitive drum 1 and paper 10 are the same, and the thickness or type of paper changes significantly, the toner image may be transferred only by the electrostatic force or magnetic force of the transfer charger 12 during transfer. As a result, a peeling phenomenon occurs in the vicinity of the photosensitive drum 1 of the toner image, resulting in transfer failure, or the central portion of the pixel of the toner image is not transferred at all.

FIG. 2 is a sectional view showing a state in which toner on a photosensitive drum peels off during transfer. A toner image 8' with a positive charge is attached to the photosensitive drum 1 as shown in FIG. 2A, and a negative charge is applied to the paper 10 by the transfer charger 12 as shown in FIG. 2B, as shown in FIG. 2C. When the paper 10 separates from the photosensitive drum 1, in some cases, the toner image 8' remains on the drum surface, causing toner dropout 21 in the toner image transferred to the paper surface, resulting in poor transfer, and a clear transferred image cannot be obtained. There was a problem that I was told was not there.

The present invention has been made in view of the above-mentioned problems, and its object is to provide a printing device that can improve transfer efficiency and obtain clear transferred images.

The above object is to provide a latent image forming medium that is moved at a constant speed, an electrostatic latent image forming apparatus that forms an electrostatic latent image on the latent image forming medium, and an electrostatic latent image forming apparatus that forms an electrostatic latent image on the latent image forming medium. A developing device that creates a visible image using charged toner and the latent image forming medium are provided in a non-contact state, and the toner image on the latent image forming medium is charged with an electric charge having a polarity opposite to that of the toner image. a transfer charger that transfers the image onto a recording medium by emitting a discharge charge; A printing device comprising a recording medium transport means for transporting the latent image forming medium, the transport speed of the latent image forming medium being:
This is achieved by a printing apparatus characterized in that the transfer speed is set to be faster within a range of about 1% to 2% than the transfer speed of the recording medium by the recording medium transfer means.

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

In FIG. 1, the rotational speed of the photosensitive drum 1 is increased by changing the reduction ratio of the speed reduction mechanism 3 of the photosensitive drum 1. As a result, the latent image produced by the laser optical unit 6 extends in the rotational direction of the photosensitive drum 1 (in the direction of arrow 4), but misalignment occurs at the transfer section guide 11 due to the speed difference between the photosensitive drum 1 and the paper feed tractor 16. As a result, an image of the normal size appears on the paper 10. However, due to a change in the rotational speed of the photosensitive drum 1, the transfer start position 22 moves forward slightly. For this purpose, it is necessary to correct the transfer position or paper stop position.

In this way, as a result of experiments, good printing was obtained by increasing the speed difference of photosensitive drum 1 by about 1.6%.
Further, if it is less than 1.0%, there is almost no effect on the transfer efficiency, and if it is more than 2%, image shift will gradually occur.

As explained above, in the printing apparatus according to the present invention, by increasing the moving speed of the photosensitive drum and the recording paper within the range of approximately 1.0% to 2% relative to the recording paper, the electrostatic force during transfer is increased. In addition, a frictional force is applied between the paper and the outer periphery of the photosensitive drum to peel the toner image from the photosensitive drum surface. Even when using a transfer charger that performs transfer by discharging electric charges, it is possible to improve the transfer efficiency and obtain a clear transferred image.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the structure of a laser printer device, and FIGS. 2A to 2C are cross-sectional views of a state in which toner on a photosensitive drum peels off during transfer. In the figure, 1 is a photosensitive drum (latent image forming medium);
2 is a photosensitive drum drive motor, 3 and 20 are speed reduction mechanisms, 4 is an arrow indicating the rotation direction of the photosensitive drum, 5 is a front charger, 6 is a laser optical unit, 7 is a developing device, 8 is a developer, and 8' is a Toner image, 9 is a roller,
10 is a recording paper (recording medium), 11 is a transfer guide,
12 is a transfer charger, 13 is a static eliminator, 14 is a cleaning unit, 15 is a hopper, 16 is a paper feed tractor, 17 is a fixing device, 18 is a stacker, 19 is a paper feed motor, 21 is a toner missing, and 22 is a transfer unit. Indicates the starting position.

Claims (1)

[Scope of Claims] 1. A latent image forming medium 1 that is transported at a constant speed; Electrostatic latent image forming media 5 and 6 that form an electrostatic latent image on the latent image forming medium 1; The latent image forming medium A developing device 7 that visualizes the electrostatic latent image on the latent image 1 with charged toner is provided in a non-contact state with the latent image forming medium 1,
a transfer charger 12 that transfers the toner image on the latent image forming medium 1 to the recording medium 10 by discharging charges having a polarity opposite to the charging polarity of the toner image; Recording medium transport means 11, 16, 19, 20 for transporting in the same direction as the transport direction of the latent image forming medium 1 while in contact with the latent image forming medium 1 at the transfer position by the device 12;
A printing apparatus having the following, wherein the moving speed of the latent image forming medium 1 is about 1% to 2% lower than the moving speed of the recording medium 10 by the recording medium transporting means 11, 16, 19, and 20. A printing device characterized by: being set at a high transfer speed within a range of %.