JPH04140765A - Image forming device - Google Patents

Abstract

PURPOSE:To keep power consumption at the time of standby small and to shorten a waiting time by performing timing control so that processing is started before a thermal fixing device attains a temperature at which thermal fixing can be performed. CONSTITUTION:When the power source of a page printer turned on, a control temperature T0 is set at a standby temperature T2, for instant, about 150 deg.C. When a printing command is transmitted, the control temperature T0 is set at a thermal fixing temperature T1. The surface temperature T of a heating roller 25a gradually rises. In the case that the surface temperature T becomes a previously set actuation permission temperature T3, a main motor is actuated, and printing actions are performed by successively starting the supply of a recording paper 21 by a paper supply roller 23, the electrostatic charging of a photosensitive drum 11 by a main charger 12, exposure by an LED array 13, development by a developing device 14, and the transfer of a toner image by a transfer charger 15 in specified timing. When a specified time elapses in a state where the printing command is not transmitted, the control tempera ture T0 is recovered to the standby temperature T2 again, and the power con sumption is made to become smaller, then the same control is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, such as a page printer or a copying machine, which forms an image by an electrophotographic process.

Image forming devices such as page printers transfer a toner image formed by electrostatic action to a recording medium, and then heat it in a heat fixing device to obtain a printed image. It has become.

By the way, it takes a considerable amount of time to heat the above-mentioned heat fixing device from room temperature to a temperature that allows heat fixing, so if you heat it from room temperature every time you form an image, you will have to wait until a printed image is obtained. It takes a long time. On the other hand, in order to constantly maintain the heat fixing device at a temperature that allows heat fixing, a considerable amount of power is consumed.

Therefore, this type of image forming apparatus generally attempts to reduce power consumption and shorten waiting time by controlling the temperature of the heat fixing device in two stages: a standby temperature and a heat fixing temperature.

In other words, normally the standby temperature is set slightly lower than the heat fixing temperature to reduce power consumption, the temperature of the heat fixer is further increased after a printing command is issued, and the electronic photo is processed after the heat fixing temperature is reached. It is supposed to start the process.

However, in the above-mentioned conventional image forming apparatus, if the power consumption during standby is to be kept low, the standby temperature is lowered, so that the time required to reach the heat fixing temperature becomes longer. Therefore, there has been a problem in that it is difficult to significantly shorten the waiting time until the electrophotographic process is started while reducing power consumption.

In view of the above points, it is an object of the present invention to provide an image forming apparatus that can shorten the time from when a printing command is issued until the start of an electrophotographic process while reducing power consumption during standby. The purpose is

In order to solve the above-mentioned problems, the present invention provides an image forming apparatus that is equipped with a heat fixing device and forms an image on a recording medium using an electrophotographic process, by controlling the temperature of the heat fixing device. The apparatus is characterized by comprising a temperature detection means for detecting the temperature, and a control means for controlling the timing so that the electrophotographic process can be started before the temperature of the heat fixing device reaches a temperature capable of heat fixing. .

According to the above configuration, the control means starts the electrophotographic process based on the detection result of the temperature detection means before the temperature of the heat fixing device reaches a temperature at which heat fixation is possible. Perform timing control to obtain.

As an embodiment of the present invention, an example of a page printer will be described below with reference to FIGS. 1 to 3.

Figure 1 is a cross-sectional front view showing the configuration of a page printer;
Figures (a) and (b) are flowcharts showing control operations of the control device, and Figure 3 is a graph showing changes in temperature of the heat fixing device.

In FIG. 1, 11 is a photosensitive drum, 12 is a main charger, 13 is an LED (light emitting diode) array,
14 is a developing device, 15 is a transfer charger, 16 is a cleaner, 17 is a static elimination lamp, 21 is a recording paper, 22 is a paper feed cassette, 23 is a paper feed roller, 24 is a recording paper conveyor, 25 is a heat fixing device, 25a is a heat roller, 25b is a heater lamp, 25c is an opposing roller, 31 is a temperature sensor, 32 is an A/
D converter 33 is a control device.

The photosensitive drum 11 is formed by forming a photosensitive conductive layer on the outer periphery of a cylindrical conductive base, which is uniformly charged by a main charger 12 and then selectively exposed to light by an LED array 13. An electrostatic latent image is formed.

The developing device 14 forms a developed toner image by developing the electrostatic latent image with toner, that is, by attaching toner to the photosensitive drum 11 according to the charged state. .

The transfer charger 15 is configured to transfer the toner image onto recording paper fed from the paper feed cassette 22 via the paper feed roller 23. The recording paper 21 is further sent to a thermal fixing device 25 via a recording paper conveyor 24, and the toner image is thermally fixed thereon.

Furthermore, after residual toner is removed by a cleaner 16 from a portion of the photoreceptor drum 11 where the toner image has been transferred, the charge is removed by a charge removal lamp 17 to prepare for the next image forming operation.

The control device 33 controls the main charger 12 and the developing device 1.
4, the transfer charger 15, the static elimination lamp 17, the paper feed roller 23, the recording paper conveyor 24, the main motor (not shown) that drives the photosensitive drum 11, etc. are controlled.

Further, the control device 33 controls the LED array 13 based on print commands, print data, etc. from the host computer, and exposes the photosensitive drum 11 according to the print data.

Further, the heater lamp 25b is controlled based on the surface temperature T of the heat roller 25a detected from the temperature sensor 31 via the A/D converter 32, and the heater lamp 25b is controlled.
The temperature of the heat roller 25a is set to the standby temperature or the heat fixing temperature, and when switching from the standby temperature to the heat fixing temperature, the operation timing of each of the above parts is controlled based on the temperature of the heat roller 25a.

In the above configuration, the control device 33 performs the following control.

First, when the power of the page printer is turned on, as shown in Figure 2 (
The main routine shown in a) is started, and the control temperature To is set to a standby temperature T2 of, for example, about 150°C (Sl
l).

Therefore, each time the timer interrupt routine shown in FIG. 2(b) is started, if the surface temperature T of the heat roller 25a is lower than the control temperature T - allowable temperature range α (S31), the heater is activated. Turn on the lamp 25b (S32
) On the other hand, if it is higher than the control temperature TO + allowable temperature range α, (
333), turn off the heater lamp 25b534)
, if it is within the allowable range, return as is. That is, the surface temperature T of the heat roller 25a is controlled so as to reach the standby temperature T2, as shown in FIG.

In the main routine, it is next determined whether or not a print command has been sent from the host computer (S]2), and when the print command has been sent, the control temperature To is set to the heat fixing temperature T1 (S13). Therefore, the heater lamp 25b is maintained in the ON state by the timer interrupt routine, and the surface temperature T of the heat roller 25a gradually increases.

Eventually, when the surface temperature T reaches the preset operating permission temperature T3 (S14), the main motor is activated and the recording paper 21 is fed by the paper feed roller 23.
Charging of the photosensitive drum 11 by the main charger 12,
Exposure by the LED array 13, development by the developer 14,
Transfer of toner images by the transfer charger 15 is sequentially started at predetermined timing, and a printing operation is performed (315).

Here, the operation permission temperature T3 is set, for example, from 170 to 18, in anticipation of the time required from the start of the printing operation until the recording paper 21 reaches the position of the thermal fixing device 25.
The heat fixing temperature TI is set to about 160°C, which is lower than the heat fixing temperature TI, which is about 0"C. That is, the above S15 is executed immediately after the surface temperature T reaches the operation permission temperature T3, and the recorded toner image is transferred. When the paper 21 is conveyed to the position of the heat fixing device 25 by the recording paper conveyor 24, the surface temperature of the heat roller 25a reaches the heat fixing temperature T1, ensuring that heat fixing is performed. .

When printing for one page is completed (51, 6), the operation of the main motor etc. is stopped to stop the printing operation (S1
7) If the next print command is sent (S18), the steps from S15 onward are repeated, while if a predetermined time elapses without a print command being sent (S19), the process returns to Sll and the control temperature To is set to the standby temperature again. After returning to T2 and reducing power consumption, the same control is repeated.

As described above, even if the surface temperature T of the heat roller 25a does not reach the heat fixing temperature T1, the recording paper 21 will not reach the heat fixing unit 25.
Since the printing operation is started at the timing when the heat fixing temperature T1 is reached when the position is reached, the waiting time after the printing command is sent can be suppressed to the necessary minimum.

In the above embodiment, an example was explained in which the printing operation is started when the surface temperature T of the heat roller 25a reaches the preset operating permission temperature T3, but the invention is not limited to this. The change in surface temperature T is predicted by linear interpolation, quadratic curve interpolation, logarithmic curve interpolation, etc. based on the surface temperature T at each time.
The timing at which the printing operation is started may be controlled by estimating the time required for the printing operation to occur.

Furthermore, when the surface temperature T reaches the operation permission temperature T3, the printing operation may not necessarily be started, but a print data transfer permission signal may be output to the host computer, etc., or when applied to a copying machine. In this case, a display may be displayed to the operator indicating that the copying operation is possible, and a state may be maintained in which the copying operation can be started immediately when the copying start switch is operated.

As described above, according to the present invention, the control means performs timing control so that the electrophotographic process can be started before the temperature of the heat fixing device reaches a temperature that allows heat fixing. Since the electrophotographic process can be started with the minimum necessary waiting time, it is possible to easily achieve both reduction in power consumption and shortening of waiting time. .

[Brief explanation of the drawing]

Figure 1 is a cross-sectional front view showing the configuration of a page printer;
Figures (a) and (b) are flowcharts showing control operations of the control device, and Figure 3 is a graph showing changes in temperature of the heat fixing device. 21... Recording paper, 25... Heat fixing device, 31... Temperature sensor, 33... Control device

Claims (1)

[Claims] (1) In an image forming apparatus that is equipped with a heat fixing device and forms an image on a recording medium using an electrophotographic process, the temperature detection means for detecting the temperature of the heat fixing device and the temperature of the heat fixing device can be thermally fixed. 1. An image forming apparatus comprising: a control means for controlling timing so as to start an electrophotographic process before the temperature reaches a certain temperature.