JPS63142378A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate an image defect and to prevent the temperature in a machine from rising by providing a temperature detecting means which detects the developing device temperature of an image forming device, and interrupting image forming operation when the developing device temperature is higher than a set temperature and cooling the developing device by a cooling means during this period. CONSTITUTION:If the detected temperature of a temperature sensor 3 rises above the set temperature in continuous copying operation, the output signal 9 of a comparing circuit 8 rises to H to put a fan driving circuit 16, thereby operating a fan. The signal 9 and a signal 11 are both H, so the output signal 12 of an AND gate 10 is H, a delay circuit 13 operates and a signal 14 rises to H, and a controller 15 interrupts the image forming operation including electrostatic latent image formation and development. Then when the developing device 2 is cooled by the fan 4 until the detected temperature of the temperature sensor 3 drops to the set temperature or less, the output signal 9 of the comparing circuit 8 falls to L and the image forming operation is restarted. Consequently, troubles such as the blocking development of toner caused by a rise in the temperature of the developing device by a heat source are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image forming apparatus that forms an electrostatic latent image and develops it with toner.

[Technical background] Image forming apparatuses that use electrostatic latent images use fine particle toner as a developing material.There are two types of toner: heat-fixable toner and pressure-fixable toner. is the mainstream,
It has become. This toner is stored in the developing device, but the higher the image forming apparatus, especially the high-speed machine, the more likely it is that the toner will solidify in the developing device due to heat generated by a document illumination lamp, or so-called blocking.

This blocking causes the latent image holding member (
Toner does not adhere to electrophotographic photoreceptors (electrophotographic photoreceptors, etc.), resulting in poor images. It also caused the gear that transmits the drive to the developing cylinder to become chipped.

[Purpose] The present invention is capable of eliminating image defects due to toner blocking inside the developing machine, which are the drawbacks of the above-mentioned conventional example, and at the same time, making it possible to prevent the temperature inside the machine from rising and keep the temperature below a certain level. .

[Structure] In the present invention, a developing device temperature detecting means is provided, and when the developing device temperature exceeds a set value, the image forming operation is stopped and the developing device is cooled by the cooling device.

In Figure 1, 1 is an image-holding tram (6-element photosensitive drum, etc.) of the image forming apparatus, 2 is a developing device that develops an electrostatic latent image with toner, and 3 is inside the developing device. A temperature sensor is provided at 4, and 4 is a fan for cooling the developing device. The temperature sensor 3 and fan 4 are installed at optimal positions where other obstacles will not occur.

FIG. 2 is a control circuit block diagram when a thermistor is used as the temperature sensor 3. 5 and 6.7 are resistors, respectively, and the temperature is set by the resistor 6.7. Reference numeral 8 denotes a comparison circuit, and when the temperature detected by the temperature sensor 3 is higher than the set temperature, the output signal 9 of the comparison circuit becomes H. 10 is and Kate,
11 is a copy signal from the controller 15 to the ant gate 10, which is H during copying and L during standby.

12 is the output signal of the ant gate 10; 13 is a delay circuit; when the output signal 12 is H, the delay circuit operates; otherwise, it does not operate.

14 is a signal from the delay circuit to the controller, which is L during the delay operation and when the H1 delay operation is not performed. 15
is a signal from a controller that controls a well-known copy sequence (image forming operation); 4 or H does not start the copy sequence, and signal 14 causes the copy sequence to start. Reference numeral 16 denotes a fan drive circuit, which operates when the output signal 9 is H to operate the fan 4.

For example, if the temperature detected by the temperature sensor 3 becomes higher than the set temperature during continuous copying, the output signal 9 of the comparator circuit 8
becomes H, the fan drive circuit 16 is operated, and the fan 4
Activate. Signal 9. Since the signals 11 are both H, the output signal 12 of the AND gate 10 becomes H, and the delay circuit 13 acts, causing the signal 14 to become H, and the controller 15 performs image forming operations including electrostatic latent image formation and development. middle school 11
d. Then, the developing device 2 is cooled by the fan 4,
When the temperature detected by the temperature sensor 3 becomes lower than the set temperature, the output signal 9 of the comparison circuit 8 becomes L, and the image forming operation restarts.

[Effects] As described above, the present invention is effective in solving problems such as the toner blocking phenomenon caused by the temperature rise in the developing device due to a heat source such as an optical lamp.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is a block circuit diagram of an embodiment of the present invention. 1 is an electrophotographic photoreceptor, 2 is a developing device, 3 is a temperature sensor, 4
is a cooling fan.

Claims (1)

[Claims] An image forming apparatus comprising a temperature detecting means for detecting the temperature of a developing device of the image forming apparatus, and when the temperature of the developing device exceeds a set temperature, image forming operation is stopped, and during this period, the developing device is cooled by a cooling means.