JPH02249667A - Led printer - Google Patents

Abstract

PURPOSE:To prevent missing of a word due to problems of a circuit in a substrate by switching the supporting direction of an LED printing head in a manner that said head is at a predetermined position when printing is performed, at a position opposite to an elongated light receiving sensor when said head is detected to be abnormal and at a position where a Selfoc lens is directed upwards when said head is cleaned. CONSTITUTION:An LED printing head 8 is supported by a head holder 10a at both sides thereof. The holder 10a is coupled to a stay 10b at both sides thereof and hinged rotatably to a stand 13. The LED head 8 is at a position (C) when the printing apparatus is at rest, and moved to a position (B) by a motor 11a when a REDY signal becomes 1. The head 8 is brought opposite to an elongated light receiving sensor 14 which detects an accident of the head 8, thereby making it possible to check before printing. When a printing start signal, i.e., CPF-P is set, the head is moved to a position (A) in preparation for printing. The head 8 is kept at this position (A) during the printing time. Accordingly, every time printing is temporarily stopped, the head 8 can be checked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to improving the reliability and maintainability of a printing device using an LED print head.

[Background of the invention]

FIG. 1 shows a conventional example in which an LED print head is used in the optical system of an electrophotographic printing apparatus.The surface of a photosensitive drum 1 is uniformly charged by a charger 2,
A latent image of print data is formed by the D print head 8 . The latent image is developed in a developing device 3, and the toner image on the photosensitive drum is transferred onto the printing paper 4 side by a high voltage of a transfer device 5. The toner image transferred to the printing paper 4 is fixed to the printing paper 4 by being partially heated and pressed in a fixing process (not shown). On the other hand, after the transfer process, the photosensitive drum 1 is charged with an erase lamp 6, removed with a cleaner 7 to remove remaining toner on the photosensitive drum 1, and uniformly charged with a primary charger 2, and then used for the second and subsequent times. Repeat the printing operation.

This type of printing device using the LED print head 8 has the disadvantage that (i) the surface of the SELFOC lens 8C gets dirty with toner and the print quality deteriorates; Since this method is fixed in place, there is an inconvenience that the entire LED print head 8 must be attached and detached in order to clean the self-cleaning lens 8C.

Furthermore, (it) the LED array 8a includes approximately 3.5 LEDs (light emitting diodes) in a horizontal row corresponding to each tod of printing.
If there are 00 LEDs lined up and one of the LEDs fails, it will cause an error, but it is difficult to detect the failure of each LED in the LED print head 8, so it is difficult to detect the failure. It was common for them to be operated without such equipment.

However, in a computer-use printing apparatus that requires high reliability of print data, it is necessary to prevent the occurrence of such omission failures.

[Purpose of the invention]

An object of the present invention is to provide an electrophotographic printing apparatus using an LED print head, in which an LED array 8a or an LED
The printing apparatus of this method is designed to prevent characters from being omitted due to an open circuit failure in the D control board 8b, and to apply and develop this improvement measure to facilitate the cleaning work of toner stains on the SELFOC 8C part. The aim is to increase the reliability of

[Summary of the invention]

The present invention focuses on the fact that if the support of the LED print head 8 can be made rotatable, it is possible to perform operations that meet various requirements, and when performing a printing operation, a failure of the LED print head 8 is detected at a predetermined position. Sometimes, the long light receiving sensor 1
When cleaning the LED print head 8, the direction in which the print head 8 is supported is changed according to each request so that the Selfoc lens 8C is in the upward position ◎. .

[Embodiments of the invention]

An embodiment of the invention is shown in Figures 2a and 2b.

FIG. 2a is a schematic cross-sectional view in which the print head 8 is rotatably supported, and FIG. 2b is a plan view of the rotary support portion of the print head 8 of FIG. 2a.

The LED print head 8 includes an LED array 8a, an LED
An array controller plate 8b, a selfoc lens 8 for condensing the light from the LED array 8a and forming an image on the photosensitive drum 1.
C, heat radiation fins 8d, etc. The LED print head 8 is held on both sides by head holders 10a, both sides of the head holder 10a are connected by stays 10b, and rotatably supported by a stand 13. Stay 1
A gear 10c is fixed to one end of the head rotation source 11.
is combined with The head rotation source 11 is a motor lla.
and a motor gear 10b.

When the LED print head 8 is in the printing position (2), the head stopper 12 is engaged with the groove of the head holder 10a to eliminate play in the head support 10 and ensure positional accuracy during printing. There is. Head stopper 1
2 is composed of a stopper base 12a against which the head holder 10a is abutted to determine the position, and a stopper spring 12b for eliminating backlash.

A basic time chart for moving the position of the LED print head 8 is shown in FIG. 6. When the start-up operation of the printing apparatus is completed, the REDY-P signal becomes "1".

The LED print head 8 is kept at position O while the printing apparatus is at rest. When the REDY signal becomes "1", the motor lla is activated to move it to the position O.

A check is performed before the printing operation by facing the elongated light receiving sensor 14 that detects a failure of the LED print head 8.
The elongated light receiving sensor 14 is composed of a photodetecting element such as a solar cell, and is designed to cover the entire width of the LED array 8a so that each dot of the LED array 8a can be sequentially illuminated one by one for checking. .

When the print start signal CPF-P is set.

The motor lla is started again and moved to the position (3) in preparation for the printing operation. The print signal PRINT-P is set after a delay time Td from the CPF signal. delay time T
d is a time sufficient to stop the movement of the head support 10 and the vibrations generated during the movement. During printing, it remains held at the 1 position ■.

When the CPF-P signal is reset and the PRINT-P signal is reset after a delay time Td, the motor ll
Drive ``a'' is applied again, and the LED print head 8 is moved to position ``2'' to perform a diagnostic operation for detecting a failure.In this way, each time the printing operation is temporarily stopped, printing is performed while diagnosing a failure of the LED print head 8. Therefore, the printing operation is not continued in a state where a dot is missing. When the CPF-P signal is set again, the same operation is repeated.

The REDY-P signal is reset when the printing apparatus is put into a non-printing, dormant state after completing the required printing. At this time, the LED print head 8 moves to the 1 position ◎ and stands by in a state where cleaning work during maintenance and inspection can be easily performed.

Figures 3 to 5 are.

The gist of the present invention is specifically illustrated, and FIG. 3 corresponds to position 1, FIG. 4 corresponds to position 1, and FIG. 5 corresponds to position .

FIG. 7 shows an embodiment in which the LED print head 8 is moved using a cam. The lift cam 15 is configured to be able to move to one position, a position (■), and a position (◎) depending on the rotational position of the lift cam 15. The lift cam 15 is driven by a motor lla,
The basic time chart is the same as that shown in FIG.

〔Effect of the invention〕

According to the present invention, a failure of the LED print head 8 can be detected and the printing operation can be prohibited, so that it is possible to contribute to improving the reliability of the LED printing apparatus. Since the LED print head 8 can be held away from both the photosensitive drum 1 and the elongated light receiving sensor 14 for detecting failures when printing operations or failure detection operations are not performed, maintenance and inspection of the SELFOC lens 80 is possible. The parts can be cleaned easily, contributing to improved maintainability.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing a conventional embodiment of a printing device using an LED print head, Fig. 2a is a schematic cross-sectional view showing an embodiment of the present invention, and Fig. 2b is a schematic cross-sectional view showing an embodiment of the present invention. A plan view of the example, FIG. 3 is the position during printing when the present invention is implemented, FIG. 4 is the position at the time of failure detection when the present invention is implemented, and FIG. 5 is the rest position when the present invention is implemented. 6 shows the basic time chart of the present invention, and FIG. 7 shows a modified embodiment of the present invention. In the figure, 1 is a photosensitive drum, 2 is a charger, 3 is a developer, 4 is printing paper, 5 is a transfer device, 6 is an erase lamp, and 7
is the cleaner, 8 is the LED print head (whole), 8a
is I, ED array, 8b is LED array control board, 8c
1 is a SELFOC lens, 8d is a radiation fin, 9 is a head mounting base, 10 is a support body, 10a is a head holder, 1
0b is a stay, 10c is a gear, 11 is a head rotation source, 1
1a is a motor, llb is a motor gear, 12 is a head stopper, 12a is a stopper base, 12b is a stopper spring, 13 is a stand, 14 is a long light receiving sensor, 15
is a lift cam. Name of patent applicant Hitachi Koki Co., Ltd.

Claims (1)

[Claims] An electrophotographic printing device using an LED print head is equipped with a long failure detection sensor capable of covering the entire length of the LED array of the LED print head, and a support body holding the LED print head is rotatable. By switching the position of the LED print head between the position where the original printing operation is performed, the position facing the failure detection sensor mentioned above, and the position where the LED print head can be easily cleaned, the LED print head can be easily cleaned. An LED printer that is characterized by making failure detection possible and improving the cleaning performance of the LED print head, thereby improving the reliability of the LED printer.