JPS63242570A - Light-emitting diode printer - Google Patents

Abstract

PURPOSE:To enable printing with a fixed printed density to be performed through obtaining a required light emission luminance output even in the case of a long-time operation, by providing an LED printing head with a temperature sensor, and providing a breaking circuit for turning ON and OFF a cooling fan according to a signal from the sensor. CONSTITUTION:An LED printing head 3 is provided with a temperature sensor 22, and is connected to a cooling fan 21 through a breaking circuit so that the driving of the fan 21 is stopped in a range not exceeding an allowable operating temperature of LEDs or the like. By this, the driving time of the fan 21 is minimized, resulting in that the amount of a fine toner powder, paper dust, other dusts and the like carried to the surface of a focusing rod lens array 12 by an air flow from the fan 21 and adhered to the surface of the array 12 is made to be extremely small. Therefore, a required light emission luminance output can be obtained even in the case of long-time use, and printed density remains constant. In addition, the allowable operating temperature of the LEDs or the like is not exceeded, and, accordingly, reliability of the device is high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an LED printer using an LED array.

[Conventional technology]

U.S. Patent No. 43 is applied to the printing process of electrophotographic printers.
There is a technique shown in No. 76282. This will be explained below using the explanatory diagram of FIG. In the figure, 1 is a photosensitive drum;
2 is a charger, 3 is an LED? 'IJ head, 4
is a developing device, 5 is a transfer device, 6 is a fixing device, 1 is a static elimination lamp,
8 is a cleaner, 9 is paper, 10 is a cooling fan wind, 11 is an LED array, and 12 is a focusing rod lens array.

According to such a configuration, the photosensitive drum 1 uniformly charged by the charger 2 is selectively emitted by the LED print head 3, and an electrostatic latent image is formed on the surface thereof.

Therefore, toner adheres to the photosensitive drum 1 from the developing device 4 corresponding to the electrostatic latent image. The toner adhering to the photosensitive drum 1 normally has an electric charge, and by applying a high voltage having a polarity opposite to the electric charge to the transfer device 5, the toner adhering to the photosensitive drum 1 is transferred to the paper 9. Further, the toner transferred to the paper 9 is fixed by a fixing device 6 including a pressure roller, a heat roller, or the like.

Further, the entire surface of the photosensitive drum is then irradiated with uniform light by the static eliminating lamp 7, so that the electrostatic latent image formed in the previous process is erased. Furthermore, the toner remaining on the photosensitive drum 1 is removed by the cleaning device 8, and the cycle starts from the next charging cycle.

Next, the prior art of the LED print head is disclosed in Japanese Unexamined Patent Publication No. 61-209176, which will be explained using the side view of FIG. 4. In the figure, 1 is a photosensitive drum, 2 is a charger, 3 is an LED print head, 4 is a developer,
The LED print head 3 includes a plurality of LED arrays 11.
The basic structure is a converging rod lens array 12. 13 is a ceramic substrate, 14 is a paste, 15 is a heat sink, 16 is a ceramic substrate holder, 17 is a flexible printed wiring board, 18 is a common board, 19 is a control circuit board, and 2o is a focusing rod lens array holder.

With this configuration, light emitted from the LED array 11 passes through the convergent rod lens array 12 and forms an image on the photosensitive drum 1.

The above-described LED print head 3'f and attached electrophotographic printer cause a temperature rise during printing, and the measurement results of the temperature inside the LED print head 3 are shown in the graph of FIG.

Here, temperature rise refers to how many times the temperature has risen from the initial printing state, and also refers to the printing duty 1 in the figure.
00% and 50% are the number of dots emitting light from the LED as a percentage. 50% printing duty means, for example, that the number of LED dots in the LED print head 3 is 230.
If there are 4 dots, this corresponds to a state in which 11'52 dots are always lit during printing. Based on this measurement result, LE
The temperature inside the D print head 3 is 100% printing duty.
It can be seen that a temperature rise of about 30° C. occurs at a print duty of 50%, and a temperature rise of about 20° C. occurs at a printing duty of 50%.

In addition, the environmental temperature of the LED print head 3 is 5 to 45 degrees Celsius.
Therefore, for example, if printing is performed at 100% printing duty when the environmental temperature is 45°C, the temperature of the LED print head 3 will be 45°G + 3 (similar to) 75°C.
The guaranteed operating temperature of ICDr, etc. exceeds 70°C.

Therefore, in order to guarantee the reliability of the LED print head 3, specifically to prevent malfunctions, it is necessary to
When the print head 3 needs to be cooled, the air 10 from the cooling fan passes inside the LED print head 3 and between the converging rod lens array 12 of the LED print head 3 and the photosensitive drum 10.

[Problem that the invention seeks to solve]

According to the conventional technology described above, the air from the cooling fan contains fine powder from the developing device inside the printer, paper powder, and general dust. Fine toner powder, paper powder, and dust continue to adhere to the surface of the photosensitive drum side of the array.
After about 100 hours of actual operation of an optical printer (about 1 month), the amount of LED light that passes through the focusing rod lens array and reaches the photosensitive drum decreases, and the brightness output necessary for printing is insufficient, resulting in a thinner print density. However, if the problem worsens, printing becomes impossible.

[Means for solving problems]

The present invention provides an LED printer having a cooling fan for cooling an LED print head, in which a temperature sensor is disposed on the LED print head, and a cutoff circuit is provided to turn the cooling fan ON/OFF based on a signal from the temperature sensor. It is characterized by:

[Effect]

According to the above configuration, in order to cool the LED print head, the air from the cooling fan passes inside the LED print head and between the converging rod lens array of the LED print head and the photosensitive drum. fine powder, paper dust, and general dust are trapped and adhered to the surface of the focusing rod lens array, and over a long period of time the LED light emission brightness output necessary for printing cannot be obtained. Therefore, by using a temperature sensor, the LED
By stopping the driving of the cooling fan within a range that does not exceed the guaranteed operation temperature, it is possible to prevent fine toner powder, paper powder, and dust from adhering to the focusing rod lens array more than necessary, even during extremely long operation times. It is possible to obtain a device that can obtain the necessary luminance output, perform printing without changing print density, and also has high reliability without exceeding the guaranteed operation temperature of the LED.

〔Example〕

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

FIG. 1 is a front view of the LED print head, and FIG. 2 is a side view. In the figure, 1 is a photosensitive drum, 2 is a charger,
3 is an LED print head, 4 is a developer, 21 is a cooling fan, 10 is a cooling fan wind, 11 is an LED array, 1
2 is a focusing rod lens array, 13 is a ceramic vine substrate, 14 is a paste, 15 is a heat sink, 16 is a ceramic S plate holder, 17 is a flexible printed wiring board, 18
19 is a common board, 19 is a control circuit board, 20 is a focusing rod V lens array holder, and 22 is a temperature sensor.

This temperature sensor 22 is
N, which also serves as a cutoff circuit and is connected to the cooling fan 21.

According to the above groove bottom, for example, if printing is performed with a printing duty of 100% when the environmental temperature is 45°C, the cooling fan 21 of the LED printer will be turned off until the temperature of the LED print head 3 reaches 65°C, and the temperature will reach 65°C. When this temperature is reached, the temperature sensor 22 is turned on, the cooling fan 21 is turned on, and the LED print head is cooled by the wind 10 of the cooling fan.

As a result, the operating temperature of LEDs, ICDrs, etc. is guaranteed to be 70°C.
It never exceeds ℃.

In addition, the operating conditions that are usually common, that is, the environmental temperature 25
When the printing duty is 10% in °C, the temperature of the LED print head has not reached 65 °C, so the temperature sensor 22
is OFF, that is, the cooling fan 10 is OFF. Therefore, the adhesion of fine toner powder, paper powder, and general dust to the surface of the convergent rod lens array 12 caused by the cooling fan's wind 10 is minimized, and printing can be performed even when the LED printer has been operating for about 600 hours (about half a year). The necessary luminance output can be obtained and the print density will not become thinner.

Furthermore, the reliability of the device is guaranteed because the guaranteed operating temperatures of LEDs, ICDrs, etc. are not exceeded.

〔Effect of the invention〕

According to the present invention described above, a temperature sensor is disposed on the LED print head and connected to the cooling fan via a cutoff circuit, so that the driving of the cooling fan is stopped within a range that does not exceed the guaranteed operating temperature of the LED, etc. As a result, the driving time of the cooling fan is minimized, and as a result, the adhesion of fine toner powder, paper powder, dust, etc. carried to the surface of the focusing rod lens array by the wind of the cooling fan is extremely reduced. It is possible to obtain the necessary luminous brightness output and the print density does not change even if it is used for a long time.
Since the operation guaranteed temperature of the ED, etc. does not change, the reliability of the device can also be guaranteed.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of the present invention, Fig. 2 is a side view, Fig. 3 is an explanatory diagram of the printer, and Fig. 4 is a conventional LED.
FIG. 5, a side view of the printhead, is a graph showing the temperature rise within the LED printhead. 1... Photosensitive drum 2... Charger 3... LED
Print head 4...Developer 11...LED array 12...Focusing rod lens array 21...
Cooling fan 22...Temperature sensor patent applicant: Oki Electric Industry Co., Ltd., agent: Kyoji Kanakura, patent attorney

Claims (1)

[Claims] 1. In an LED printer having a cooling fan for cooling the LED print head, a temperature sensor is disposed on the LED print head, and the cooling fan is turned on/off based on a signal from the temperature sensor. An LED printer characterized by being equipped with a cutoff circuit.