JP2000098795A - Image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a noise due to the rotation of a fan motor by rotating the fan motor by the absolute minimum number of rotations while taking the balance of temperature rising inside the machine and a fan noise into consideration. SOLUTION: The temperature of a fixing roller is determined based on a detected signal from a thermistor 12 by a control circuit 20 before recording operation. And also the rotational speed of the fan motor 14 is set based on the number of fan rotations corresponding to a temperature obtained from a table stored in a RAM 22. For instance, when the detected temperature of the thermistor 12 at the time of starting is 0-24 deg.C, the fan motor 14 is set to be in a stopped state until the temperature of the fixing roller reaches 120 deg.C by being heated by a heat lamp 11. When it is >=120 deg.C, the fan motor 14 rotation is decreased by 50%. Then, when printing is finished and the detected temperature of the thermistor 12 becomes 120 deg.C, the fan motor 14 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus having a heat fixing device for fixing a toner image on paper by heating.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic image recording apparatus is provided with a heat fixing device for fixing a toner image on a sheet by pressing and heating the sheet on which a toner image has been transferred. A fan motor for cooling the heat fixing device is provided in order to prevent adverse effects on members nearby due to heat generated by the fixing device.

Further, as a conventional technique of this kind, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 8-123298. The publication describes a control of changing the number of revolutions of the fan motor by continuous printing or single printing.

[0004]

By the way, in order to reduce the size of the image recording apparatus in recent years, the image recording apparatus is located near the heat fixing device.
For example, there is a configuration in which a toner storage unit that stores toner collected by cleaning the photoconductor is disposed. Here, since the toner hardens at a temperature of 50 ° C. or more, at least a portion of the heat fixing device close to the toner containing section is cooled by a fan motor so that the inside of the toner containing section does not rise to 50 ° C. or more. Need to be controlled.

When cooling with a fan motor,
If the number of rotations of the fan motor per unit time is increased, cooling can be performed more reliably. However, a problem arises that increasing the number of revolutions leads to an increase in noise.

The present invention solves such a problem and reduces the noise due to the rotation of the fan motor by rotating the fan motor at the minimum necessary number of revolutions in consideration of the balance between the temperature rise inside the machine and the noise of the fan. It is an object of the present invention to provide an image recording apparatus that realizes the above.

[0007]

In order to achieve the above object, the present invention provides a cylindrical fixing roller, a heat lamp disposed inside the fixing roller, and a temperature for detecting the temperature of the fixing roller. A heating element having a detection element and an energization control unit for controlling energization to the heat lamp so that the fixing temperature can be maintained based on the temperature detected by the temperature detection element during fixing; and In an image recording apparatus having a fan motor for suppressing an ambient temperature to a predetermined temperature or less, a control unit for setting a rotation speed of the fan motor according to a temperature detected by the temperature detection element before recording is started. It is characterized by. According to such a configuration, the rotation speed of the fan motor can be set to the minimum necessary speed before the start of recording according to the temperature of the portion to be cooled.

Further, the invention is characterized in that the control means variably controls the number of rotations of the fan motor during rotation according to a recording operation time. With such a configuration,
Control such as increasing the number of revolutions of the fan motor in accordance with a rise in the temperature around the heat fixing device during the recording operation can be performed.

Further, the present invention is characterized in that the control means performs variable control of the number of revolutions of the fan motor based on the temperature detected by the temperature detecting element after the end of the recording operation.
With such a configuration, the rotation speed of the fan motor after the end of the recording operation can be set to the minimum necessary speed.

Further, the present invention is characterized in that the number of revolutions of the fan motor after the end of the recording operation is variably controlled in accordance with the recording operation time. With such a configuration, the rotational speed of the fan motor can be set to the minimum necessary speed while balancing the amount of temperature decrease around the heat fixing device and the amount of cooling by the fan motor.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a side view showing an internal structure of an image recording apparatus according to a first embodiment of the present invention, wherein 1 is a main body of the image recording apparatus, 2 is a photoreceptor, and 3 is light on the surface of the photoreceptor 2. An optical writing device for forming an electrostatic latent image by irradiating
A developing roller for supplying toner to the electrostatic latent image of the photoconductor 2 to make it visible, a transfer roller 5 for transferring a toner image formed by supplying toner to the electrostatic latent image on the photoreceptor 2 onto paper, and A waste toner storage unit 7 for storing collected waste toner such as toner on the photoconductor 2 that has not been used for forming,
Hopper section for storing new toner to be supplied to printer, 8
Denotes a cartridge in which a waste toner storage unit 6, a toner hopper unit 7, a charging device for charging the photoconductor 2 and a static elimination device for neutralizing the photoconductor 2 are integrated, and 9 denotes a heat fixing device. Reference numeral 9 denotes a cylindrical fixing roller 10, a heat lamp 11 inserted inside the fixing roller 10, a thermistor 12 for detecting the surface temperature of the fixing roller 10, and a contact with the fixing roller 10 under a predetermined pressure. A pressure roller 13 and the like in contact with each other are provided. Reference numeral 14 denotes a fan motor for air-cooling a portion of the exterior housing of the heat fixing device 9 facing the waste toner storage unit 6, reference numeral 15 denotes a paper feed cassette for storing image recording paper, and reference numeral 16 denotes an automatic document feeder for automatically feeding a document. Reference numeral 17 denotes an image reading device for reading an image of a document conveyed by the automatic document conveying device 16.

The paper fed from the paper feed cassette 15 is
It is conveyed to the transfer roller 5 via a conveyance roller and a guide,
Further, it is sent from the transfer roller 5 to the fixing roller 10. At this time, since the photoconductor 2 rotates along the moving direction of the sheet, the developing roller 4 is positioned upstream of the transfer roller 5 in the rotation direction of the photoconductor 2, and the toner hopper 7 is positioned near the developing roller 4. I have. Further, a cleaning member for the photoconductor 2 and a waste toner container 6 are located downstream of the transfer roller 5 in the rotation direction of the photoconductor 2. Here, since the heat fixing device 9 is located on the downstream side of the transfer roller 5 in the sheet conveying direction, the waste toner container 6 is located near the heat fixing device 9.

FIG. 2 is a block diagram showing a control system of the fan motor. Reference numeral 20 denotes a control circuit; 21, a recording motor for rotating the photosensitive member 2; 22, a RAM storing a table of various set values; 4 shows a ROM storing a control program. The control circuit 20 controls the energization of the heat lamp 11 and the rotation of the fan motor 14 per unit time based on the temperature detected by the thermistor 12 in order to maintain the fixing roller 10 at a predetermined temperature and cool the heat fixing device 9. The number (hereinafter, simply referred to as the rotation speed) is controlled. Further, the rotation speed of the fan motor 14 is controlled by a PWM (pulse width modul).
ation) control.

The RAM 22 stores setting values as shown in (Table 1) and (Table 2). Table 1 shows an example of the relationship between the temperature of the fixing roller at the start of recording and the fan rotation speed, and Table 2 changes the temperature of the fixing roller and the rotation speed of the fan motor at the start of recording. 4 shows an example of the relationship between the transition times up to and including:

[0016]

[Table 1]

[0017]

[Table 2]

Next, the rotation control of the fan motor 14 will be described.

First, before the recording operation, the control circuit 20 stores the fan rotation speed corresponding to the temperature detected by the thermistor 12 in the RAM.
The rotation speed of the fan motor 14 is set based on a table stored in the storage 22. Then, the recording operation is started, the clocking of the recording operation time is started, and the fan motor 14 is rotated when the temperature detected by the thermistor 12 rises to a predetermined temperature. Then, the fan motor 14 is stopped when the detected temperature drops to a predetermined temperature after printing is completed.

For example, if the temperature detected by the thermistor 12 at the start of recording is less than 25 ° C., the fixing motor 10 is heated by the heat of the heat lamp 11 and the fan motor 14 is stopped until the temperature reaches 120 ° C. When the temperature becomes higher than or equal to ° C., the fan motor 14 is rotated at 50% rotation speed as shown in (Table 1). Control is performed such that the fan motor 14 is stopped when the temperature of the fixing roller 10 is reduced to 120 ° C. by the end of printing and the heat generation of the heat lamp 11 is stopped.

Similarly, if the detected temperature of the thermistor 12 at the start of recording is 25 ° C. or more and less than 120 ° C., the fan motor 14 is stopped until the detected temperature becomes 120 ° C. 70 fan motors
%, And after printing, the detected temperature is 120
When the temperature reaches ° C, the fan motor 14 is stopped. The temperature detected by the thermistor 12 at the start of recording is 120 ° C.
In this case, the fan motor 14 is stopped until the detected temperature reaches 120 ° C., and when the detected temperature reaches 120 ° C. or higher, the fan motor 14 is rotated at 100% rotation speed. When the fan motor 1
4 is stopped.

Here, when the recording operation time is short, cooling is performed at the number of revolutions of the fan motor 14 set at the start of recording, but when the recording operation time is long, the temperature around the heat fixing device 9 is reduced. It is necessary to increase the cooling amount in accordance with the rising amount. Therefore, control is performed so that the rotation speed is increased when a predetermined transition time has elapsed since the rotation of the fan motor 14 started.

For example, if the detected temperature of the thermistor 12 at the start of recording is lower than 25 ° C., the fan motor 14 is rotated at 50% rotation speed when the detected temperature becomes 120 ° C. or higher. If more than 5 minutes have passed since the detection temperature reached 120 ° C, (Table 2)
As shown in the figure, after 5 minutes, the number of rotations is increased from 50% to 100%.
Change to After printing is completed, control is performed to stop the fan motor 14 when the temperature detected by the thermistor 12 drops to 120 ° C.

When the temperature detected by the thermistor 12 at the start of recording is 25 ° C. or more and less than 120 ° C., the rotation speed is increased from 70% to 100% three minutes after the temperature detected by the thermistor 12 becomes 120 ° C. %, And when the detected temperature of the thermistor 12 at the start of recording is 120 ° C. or higher, there is no change in the rotation speed.

As described above, for example, when the temperature detected by the thermistor 12 before the recording operation is low, the temperature around the fixing roller 10 is low, so that it is not necessary to cool the fan motor 14 by rotating the fan motor 14 at a high rotation speed. Therefore, by setting the rotation speed of the fan motor 14 in accordance with the temperature detected by the thermistor 12 before the recording operation, the rotation speed of the fan heater 13 can be kept low.
4 can reduce the noise.

In the apparatus of the first embodiment, the fan motor 14 is stopped when the temperature detected by the thermistor 12 reaches 120 ° C. after the end of the recording operation. However, when the fan motor 14 is rotating at 100% rotation speed, the detected temperature of the thermistor 12 becomes 12
The rotation continues until the temperature reaches 0 ° C., and the rotation noise of the fan motor 14 is generated. In the second embodiment of the present invention described below, in order to further reduce the noise of the fan motor 14, the rotation speed of the fan motor 14 after the end of the recording operation is controlled in accordance with the recording operation time.

Table 3 shows an example of the relationship between the recording operation time and the number of revolutions of the fan motor when the detected temperature of the thermistor reaches 150 ° C. after the end of the recording operation. Note that the control before the end of the recording operation in the second embodiment is the same as that in the first embodiment, and thus the description is omitted.

[0028]

[Table 3]

When the temperature detected by the thermistor 12 reaches 150 ° C. after the end of the recording operation, the fan motor 1 to be set from the set values shown in Table 3 and stored in the RAM 22 (Table 3).
Call the number of rotations of 4. In the apparatus according to the second embodiment, as shown in (Table 3), the fan operation time is reduced to 50% when the recording operation time is less than 3 minutes, 70% when the recording time is 3 minutes or more and less than 6 minutes, and 80% when the recording operation time is 6 minutes or more. The number of rotations is controlled to decrease.

FIG. 3 is a graph showing an example of the rotation control of the fan motor in the apparatus according to the second embodiment, in which the recording operation time is 5 minutes and the recording start temperature is less than 25 ° C. First, since the detected temperature of the thermistor 12 at the start of recording is lower than 25 ° C., the fan motor 14 is stopped until the detected temperature reaches 120 ° C., and when the detected temperature exceeds 120 ° C., the fan motor 14 is turned off by 50%. Rotate at the speed. Further, when the recording operation time has passed 3 minutes, the fan motor 14 is rotated at 100% rotation speed. When the recording operation is completed and the temperature detected by the thermistor 12 decreases to 150 ° C., the rotation speed of the fan motor 14 is reduced to 70%, and the temperature detected by the thermistor 12 decreases to 90 ° C. At this point, the fan motor 14 is stopped.

With this configuration, the fan motor can be rotated at the minimum necessary rotation speed by controlling the rotation speed of the fan motor in consideration of the detected temperature and operating time of the thermistor. The rotation noise of the motor can be reduced, and the noise can be reduced. As a result, for a user who does not use the apparatus very frequently, the apparatus can be used with little fan motor noise.

[0032]

According to the present invention constructed as described above, the rotation speed of the fan motor can be set to the minimum necessary speed before the start of recording according to the temperature of the portion to be cooled. In addition, noise caused by rotation of the fan motor during operation of the apparatus can be reduced.

Further, since the number of revolutions of the fan motor is made variable according to the recording operation time, it is possible to control such that the number of revolutions of the fan motor is increased in accordance with a rise in the temperature around the heating and fixing device during the recording operation. The rotation speed of the fan motor can be reduced to a necessary minimum while balancing the amount of temperature rise around the fixing device and the amount of cooling by the fan motor.

Further, the number of revolutions of the fan motor is variably controlled based on the temperature detected by the temperature detecting element after the end of the recording operation, so that the rotation speed of the fan motor after the end of the recording operation can be reduced to a minimum necessary speed. Noise of the fan motor after the end of the recording operation can be reduced.

In the variable control of the number of revolutions of the fan motor after the end of the recording operation, the recording operation time is taken into consideration, so that the amount of temperature reduction around the heat fixing device and the amount of cooling by the fan motor are balanced. The rotation speed of the motor can be set to the minimum necessary speed.

[Brief description of the drawings]

FIG. 1 is a side view showing an internal configuration of an image recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a control system of a fan motor.

FIG. 3 is a graph showing rotation control of a fan motor in the device of the second embodiment.

DESCRIPTION OF SYMBOLS 1 Main body 2 Photoconductor 3 Optical writing device 4 Developing roller 8 Cartridge 9 Heat fixing device 10 Fixing roller 11 Heat lamp 12 Thermistor 13 Pressure roller 14 Fan motor 17 Image reading device 20 Control circuit 21 Recording motor 22 RAM 23 ROM

Claims (4)

[Claims] An image forming apparatus comprising: a cylindrical fixing roller; a heat lamp disposed inside the fixing roller; a temperature detecting element for detecting a temperature of the fixing roller; Based on the above, there is provided a heat fixing device having an energization control means for controlling energization to the heat lamp so as to maintain the fixing temperature, and a fan motor for suppressing the temperature around the heat fixing device to a predetermined temperature or less. The image recording apparatus according to claim 1, further comprising control means for setting a rotation speed of the fan motor in accordance with a temperature detected by the temperature detection element before the start of recording. 2. The image recording apparatus according to claim 1, wherein the control unit variably controls the number of rotations of the fan motor during rotation according to a recording operation time. 3. The image recording apparatus according to claim 2, wherein the control unit performs variable control of the number of revolutions of the fan motor based on a temperature detected by the temperature detection element after the end of the recording operation. 4. The image recording apparatus according to claim 3, wherein the number of revolutions of the fan motor after the end of the recording operation is variably controlled according to a recording operation time.