JP2724050B2 - Cooling fan control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling fan control method for controlling the temperature inside an image forming apparatus constituting an electrophotographic printer, a copying machine or the like.

[0002]

2. Description of the Related Art Generally, an image forming apparatus constituting an electrophotographic printer, a copying machine or the like has many heating elements in the apparatus. Among the heat generating elements, the heat fixing device generates a particularly large amount of heat and determines the temperature in the apparatus.

FIG. 3 is a sectional view of a heat fixing device. The heat fixing device 1 includes a heat roller 2 and a pressure roller 3 which are pressed against each other with a sheet feeding surface therebetween. A halogen lamp is provided as a heater 5 in a pipe 4 made of an aluminum material or the like in which the surface of the heat roller 2 is coated with a fluororesin. A temperature sensor 6 such as a thermistor is provided in contact with the surface of the heat roller 2. The heater 5 is controlled by a control unit (not shown) based on an output signal of a heating signal generating means set corresponding to the reference temperature so that the surface temperature of the heat roller 2 is kept within a control temperature range. The heating signal generating means will be described later. The reference temperature includes a reference temperature in a standby state and a reference temperature in a printing state. The surface of the heat roller 2 is maintained in a low temperature range in the standby state and is maintained in a high temperature range in the printing state. In the printing state, the heat roller 2 and the pressure roller 3 are each rotating in the direction of the arrow. When the paper 7 is transferred from the photoreceptor (not shown) to a toner image and fed from the direction of arrow A, the pressure contact portion between the heat roller 2 and the pressure roller 3 dissolves the toner of the paper 7 with heat and heats the paper 7. Crimp to

In the printing state, the temperature around the heat fixing device becomes high. Therefore, the cooling fan provided near the heat fixing device 1 is rotated at a high speed to adjust the temperature inside the apparatus. Further, in the standby state, the cooling fan is rotated at a low speed because it is only necessary to cool the power supply and the control circuit, which are other heating elements generating less heat than the heat fixing device 1.

That is, in the conventional image forming apparatus, the number of rotations of the cooling fan is controlled to be switched between two stages (low speed, high speed) according to the operation state (standby, printing).

[0006]

In the conventional cooling fan control method, switching control is performed in two stages (low speed, high speed) in the operation state (standby, printing) of the cooling fan device for adjusting the temperature inside the device. I was FIG. 4 shows that the outside air temperature is room temperature (for example, 25
° C) and the surface temperature of the heat roller and the heater O
FIG. 5 is a state diagram showing a change with time in N / OFF operation. When the temperature of the surface of the heat roller falls below the reference temperature (point B), the heater is turned on, and the temperature of the surface of the heat roller exceeds the reference temperature (point C). And the OFF state.

However, as shown in FIG. 5, when the outside air temperature is low by using cooling or the like, when the heater is turned off, the temperature of the surface of the heat roller rapidly drops, and when the heater is turned on again, the heat roller is turned on again. Since the surface temperature rises slowly, the heater ON time is E,
There is a problem that the time is longer than the time D in the ON state of the heater shown in FIG. 4 and power consumption is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling fan control method for preventing unnecessary power consumption while always keeping the temperature inside the device within a control temperature range in the operation state of the device.

[0009]

In order to achieve the above object, a cooling fan control method according to the present invention comprises a heating time measuring means for measuring a heating time of a heating element by a heating signal, and a preset standard heating time. And a fan rotation control means for rotating the cooling fan at a lower speed when the heating time is longer than the standard heating time, when the heating time is longer than the standard heating time.

[0010]

According to the cooling fan control method of the present invention, the heating time measuring means measures the heating time of the heating element based on the heating signal, and the fan rotation control means outputs the preset standard heating time and the output of the heating time measuring means. When the heating time is longer than the standard heating time, the cooling fan is rotated at a lower speed than when the heating time is shorter than the standard heating time.

Therefore, according to the present invention, it is possible to prevent unnecessary power consumption while always keeping the temperature inside the device within a certain frame in the operation state of the device.

[0012]

An embodiment of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals.

FIG. 1 is a block diagram showing the configuration of the embodiment. The heating signal generating means 10 comprises a thermistor 6 and a comparing circuit 11. The reference voltage corresponding to the reference temperature shown in FIGS. On the other hand, the thermistor 6 shown in FIG. 6 is input to the non-inverting input terminal. When the surface temperature of the heater 2 becomes higher than the reference temperature, the inverting input voltage becomes higher than the non-inverting input voltage, and the output voltage of the comparison circuit 11 outputs the level "L". If the surface temperature of the heater 2 is lower than the reference temperature, the inverting input voltage becomes lower than the non-inverting input voltage, and the output voltage of the comparison circuit 11 outputs the level "H". Heating time measuring means 1
2 comprises an AND circuit 13 and a counter 14. The input side of the AND circuit 13 receives a system clock signal and a heating signal from the heating signal generator 10. The counter 14 counts the system clock signal while the heating signal is outputting the level “H”.

The fan rotation control means 9 comprises a table storage means 15, a driver selection data reading means 17, and a driver selection means 18. The table storage means 15 is a main storage device, and includes a program area 15a in which a control program is stored and a data area 15b in which a table including driver selection data corresponding to heating times divided by standard heating times is stored. The driver selection data reading means 17 includes a microprocessor 17a and an input / output port 17b. The microprocessor 17a is connected to the table storage means 15 and the input / output port 17b by a bus line. The driver selecting means 18 comprises a decoder 19 and power transistors 20, 21, 22. The input terminal of the decoder 19 is connected to the input / output port 17b by a bus line, and the output terminals Y ₀ , Y ₁ , and Y ₂ are connected to the base terminals of the power transistors 20, 21, and 22, respectively. The collector terminals of the power transistors 20, 21, and 22 are connected to the supply voltage lines of 5 V, 15 V, and 30 V, respectively, and the emitter terminals are connected to the input terminals of the cooling fan motor 24, respectively. The input / output port 17b is connected to the output terminal of the counter 14 and the logical product circuit 1
3 is connected to one input terminal.

Next, the operation will be described with reference to FIG.
FIG. 2 is a flowchart of the embodiment, and shows steps of cooling fan control which the microprocessor 17a processes according to a control program. In Step S ₁ checks whether the standby state. If the standby state proceeds to step S _6, not in the standby state, i.e. if the print state proceeds to step S _2. When the operation proceeds to step S ₆ , the microprocessor 17 a reads out the driver selection data “X ₃ ” from the table storage unit 15 and outputs it to the driver selection unit 18. The driver selection means 18 inputs the driver selection data “X ₃ ” to the decoder 19 and drives the power transistor 20. As a result, the cooling fan motor 24 is supplied with the supply voltage of 5 V via the power transistor 20, and rotates at a low speed. When step S _2, the microprocessor 17a reads the standard heating time T ₁ from the table memory unit 15 is set to a first register (not shown). Microprocessor 17a in step S ₃ is stored in the second register (not shown) the heating time T of the heating time measuring means 12 via the output port 17b is measured.
Microprocessor 17a at Step S ₄ compares the contents of the first register and the second register. As a result of the comparison, if the heating time T is longer than the standard heating time T ₁ the process proceeds to step S _5, the heating time T standard heating time T ₁
If following the process proceeds to step S _7. Step If S ₅ advanced, the microprocessor 17a is a table storing means 15
And outputs the driver selection data “X ₂ ” to the driver selection means 18. The driver selection means 18 inputs the driver selection data “X ₂ ” to the decoder 19 and
The power transistor 21 is driven. As a result, the cooling fan motor 24 is supplied with the supply voltage of 15 V via the power transistor 21 and rotates at a medium speed. Step S ₇
When the processing has proceeded to (1), the microprocessor 17a reads the driver selection data “X ₁ ” from the table storage means 15 and outputs it to the driver selection means 18. The driver selection means 18 inputs the driver selection data “X ₁ ” to the decoder 19 and drives the power transistor 22. As a result, the cooling fan motor 24 is supplied with the supply voltage of 30 V via the power transistor 22 and rotates at high speed.

The standard heating time T ₁ is the heating time at normal temperature. This embodiment has a plurality of drivers,
A driver was selected based on the result of comparison between the heating time and the standard heating time to control the rotation speed of the cooling fan.
Data corresponding to the voltage to be supplied to the cooling fan is stored in a table storage means, and the digital value is converted into an analog value by a digital / analog converter, further amplified through an amplifier, and the cooling fan is rotated. You may.

In this embodiment, the rotation speed of the cooling fan is controlled by the heating time in the printing state. However, if the rotation speed of the cooling fan is controlled by the heating time in the standby state, further power consumption is achieved. Be reduced.

[0018]

Since the present invention is configured as described above, the following effects can be obtained.

When the heating time is longer than the standard heating time, the cooling fan is rotated at a lower speed than when the heating time is shorter than the standard heating time. This has the effect of preventing an increase in the heating time due to the cooling effect that occurs when the temperature is low, thereby reducing power consumption.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an embodiment.

FIG. 2 is a flowchart showing the operation of the embodiment.

FIG. 3 is a cross-sectional view of the heat fixing device.

FIG. 4 is a heater ON / OFF state diagram when the outside air temperature is normal temperature.

FIG. 5 is a heater ON / OFF state diagram when the outside air temperature is low.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal fixing device 2 Heat roller 3 Pressure roller 6 Temperature sensor 7 Paper 9 Fan rotation control means 10 Heating signal generation means 12 Heating time measurement means 15 Table storage means 17 Driver selection data reading means 18 Driver selection means 23 Cooling fan

Claims (1)

(57) [Claims] 1. A heating signal is generated when a temperature of a heating element is lower than a reference temperature, and is stopped when the temperature exceeds the reference temperature.
In a cooling fan control method that controls the rotation of a cooling fan according to the temperature of a heating element to adjust the temperature inside the device, the heating time of the heating element is measured by a heating signal, and the heating time and a preset standard heating time A cooling fan rotating at a lower speed when the heating time is longer than the standard heating time, when the heating time is longer than the standard heating time.