JPH0434567A - Printing position correcting device - Google Patents

Abstract

PURPOSE:To immediately detect a shift in printing position and automatically restore it by controlling exposure start timing and an LD(laser diode) driving frequency according to the output signal of detection sensors which detect a shift in LD irradiation position. CONSTITUTION:The position detection sensors 8 and 8' which receive the light beam outputted by an exposure part 3 as an LD unit, detect the position shift of the beam light on a photosensitive drum 1, and outputs specific position shift information are mounted on the same lines of both end parts of the photosensitive drum 1. The signals of those sensors are received by a control mechanism 9 and the exposure start timing of the exposure part 3 and the LD frequency are controlled. Consequently, trouble resulting from variation in printing width due to temperature variation and variance in the fitting positions of the LD unit and device can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing position correction device for a printing press using an electrophotographic method.

[Prior Art] Conventionally, in this type of printing device, the printing timing is set to a constant value for each device, and fluctuations due to variations in LD units or temperature changes are not controlled at all.

[Problem to be solved by the invention]

In the conventional printing device described above, the printing timing is set to a constant value, so if there is a temperature change, the printing width may deviate from the designed value as shown in Figure 4, or the LD unit and device mounting position may change. A situation has arisen in which the printing width deviates from the designed value due to variations in the printing width. For this reason, as shown in FIG. 4, the guaranteed range of printing width becomes narrower, and as shown in FIG. 5, the printing position becomes smaller than the design value S. It had the inconvenience of getting tangled.

[Purpose of the Invention] The present invention improves the disadvantages of the conventional example, and even if there is a misalignment of the printing position due to temperature changes or machine characteristics, it is possible to immediately detect this and automatically repair it. The purpose of the present invention is to provide a printing position correction device that can perform the following steps.

[Means for Solving the Problems] In the present invention, in a printing machine using an electrophotographic method having an LD (laser diode) unit for exposure, the LD
at least two positional deviation detection sensors arranged near the irradiation surface of the LD for detecting positional deviation of the LD irradiation position; and a mechanism for controlling the exposure start timing and the LD drive frequency based on the output signals of the positional deviation detection sensors. It has a configuration that has the following. This aims to achieve the above-mentioned purpose.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 1 indicates a photosensitive drum, and reference numeral 2 indicates a charger. A developing device 4 is disposed on the right side of the photosensitive drum 1 in FIG. Reference numeral 5 indicates a transfer device. A printing paper 11 is placed between the transfer device 5 and the photosensitive drum 1.
There is a passageway.

Further, at the upper end of the photosensitive drum 1 in FIG.
A cleaning plate 6 is provided on the upstream side in the rotational direction of the photosensitive drum 1 near the charger 2 where the exposure section 3 as a unit is provided.

Furthermore, a position detection sensor 8 receives the light beam outputted from the exposure section 3 described above, detects the positional deviation of the beam on the photosensitive drum l, and outputs predetermined positional deviation information.
, 8' are installed on the same line at both ends of the photosensitive drum 1. Reference numeral 9 indicates a control machine that regulates the operation of the printing device. In this configuration, the surface of the photosensitive drum 1 is negatively charged by the charger 2. Thereafter, the print information is exposed by the exposure section 3, and a latent image is formed on the surface of the photosensitive drum 10. This latent image is developed with toner conveyed by the developing device 4. Finally, the printing information is transferred onto the paper 11 by the transfer device 5, and the printing operation is completed.

In the second case, in this embodiment, positional deviation detection sensors 8 (on the left side of printing) and 8゛ (on the right side of printing) are installed near the photosensitive drum 1, which is the LD irradiation surface, to detect deviations in the LD irradiation position. . Then, the control mechanism 9 receives the signal from the sensor, and the exposure start timing of the exposure section 3 and the LD
Control frequency. This effectively prevents the print width from varying due to temperature changes and variations in the mounting positions of the LD unit and the device.

Next, the operation of the print position correction device will be explained using FIG. Misalignment detection sensor 8 (left side of printing), 8°
The signal detected at the right side of the print is sent to the control mechanism 9. In the control mechanism 9, due to the time difference (interval) between the positional deviation detection sensors 8 and 8, for example, when the time is short as shown in FIG. The exposure section 3 is driven by delaying the start timing and advancing the LD drive frequency.

(2) When printing based on the LD irradiation position shift detection sensors 8, 8', the exposure unit 3 is driven by advancing the start timing and increasing the LD drive frequency.

Here, FIG. 3 shows changes in print width when the present print position correction device is not used. LD! 2 is driven by a constant signal from the control mechanism 9 to emit light. That light is polygon mirror 13
A latent image is formed on the photosensitive drum 1 through the lens 10. However, if the exposure section 3 is too far away from the photosensitive drum 1, for example, the print width becomes wide. By providing this embodiment, such inconveniences can be effectively alleviated.

〔Effect of the invention〕

As explained above, the present invention provides a printing apparatus using an electrophotographic method having an LD unit for exposure, in which at least two positional deviation detection sensors are provided near the LD irradiation surface, and the detection time difference between the sensors is By having a mechanism for controlling the exposure start timing and the LD drive frequency, it is possible to improve the problem caused by the print width changing due to temperature changes and variations in the mounting position of the LD unit and the device.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an example of the operation of the print position correction mechanism, and FIGS. FIG. 3 is an explanatory diagram showing changes in print width and print position. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 2... Charger, 3... Exposure section, 4... Developing device, 5-... Transfer device, 6... Cleaning blade, 7... Erase lamp, 8 ,8゛...
- Positional deviation detection sensor, 9...control mechanism. Applicant Japan Electric Co., Ltd. Agent Patent Attorney Takahashi Square Tube Diagram 4 Diagram

Claims (1)

[Claims] (1) In a printing machine using an electrophotographic method having an LD (laser diode) unit for exposure, at least two positional deviations for detecting the positional deviation of the LD irradiation position placed near the irradiation surface of the LD. A printing position correction device comprising a detection sensor and a mechanism that controls exposure start timing and LD drive frequency based on an output signal of the positional deviation detection sensor.