JP3073271B2 - Cooling fan control device - 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 device for an image forming apparatus provided with a cooling fan for cooling the heat generated in a scanner section when an exposure lamp is turned on.

[0002]

2. Description of the Related Art An original is illuminated by an exposure lamp such as a halogen lamp, and the reflected light is imaged on a photoreceptor to form an electrostatic latent image, which is then visualized by a developing device and transferred onto transfer paper. In such an image forming apparatus, the scanner unit generates heat by turning on the exposure lamp. Excessive rise in temperature of the scanner part that generates heat and other unit parts to which the heat is transmitted deteriorates the performance and durability of each part, and it is dangerous to touch it by hand. Juan is cooling the scanner.

In this case, the continuous lighting of the exposure lamp causes
Even if the temperature in the vicinity of the scanner becomes the highest, if the cooling fan is constantly rotated with an air volume that can be sufficiently cooled, power will be wasted when the temperature is lower than that, and noise will be generated. A technique has been proposed in which fan control is performed according to the number of copies, or fan control is performed according to the copy count number. In addition, as a technique related to these, Japanese Patent Application Laid-Open No. 61-219966,
3-159873, JP-A-63-214770, JP-A-61-86750, JP-A-61-9
No. 2953, and the like.

[0004]

However, in the conventional apparatus, there is a risk that a temperature sensor is required or that a malfunction of the temperature sensor causes erroneous detection. Further, there is a problem that the actual temperature rise cannot be accurately measured only from the copy count number. That is, the degree of temperature rise varies depending on whether or not continuous copying is performed or the magnification (the scan length corresponding to the lamp lighting time varies depending on the magnification).

The present invention has been made based on such a background, and a cooling fan control device capable of judging an actual temperature rise in accordance with an operation state of an image forming apparatus and performing cooling more accurately is provided. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION The above objects are achieved by a cooling fan control device for controlling the cooling capacity of the cooling fan for cooling the heat generated Sukiyana portion by the exposure lamp on the image forming apparatus, depending on the magnification of the formed image Set the number of continuous copies
Control means for predicting the temperature rise of the scanner section based on the number of continuous copies and the scaling ratio of the formed image, and controlling the cooling fan based on the value, and controlling the cooling fan based on a command from the control means. This is achieved by a first means including power variable means for changing power supply to the drive motor. In this case, the power changing means includes a cooling fan tap switching mechanism, a voltage switching mechanism, a duty switching mechanism, and the like .

[0007]

[Action] control means and a continuous number of copies and the magnification ratio, to predict the temperature increase of Sukiyana the vicinity due to the lamp lighting the Sukiyana part, taps and the drive motor on the basis of the value,
By switching the voltage and the duty of the control signal, the number of rotations of the cooling fan and, accordingly, the air volume are switched.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a configuration diagram of the copying machine. To explain only the parts related to the present invention, 1 is an optical unit, 2 is a scanner, 3 is an exposure lamp, 4 is a cooling fan, 5 is a photosensitive drum, and 6 is a paper feed cassette. By the way, many recent copiers have a variable magnification function. At the time of zooming, the speed of the scanner 2 is changed to perform zooming in the vertical (sub-scanning) direction. For example, when reducing to 50%, the speed of the scanner 2 becomes twice as high as 100% (at the same magnification), and when expanding 200%, the speed of the scanner 2 becomes 100%.
That is, it becomes 1/2 of the time of%. Therefore, for example, the same A4
When a copy is made on a sheet of paper, the scanning is performed at a speed of 1/2 at a distance of 1/2 at the time of enlargement, and at a speed of 2 times at a time of reduction at the time of reduction.

In this case, as shown in FIG. 8, the temperature of the scanner and its surrounding parts (for example, contact glass) have different rising curves depending on the magnification. Therefore, it is not necessary to switch the air volume of the cooling fan 4 with the same continuous number of sheets uniformly for each magnification.

Further, in recent copying machines, it is common practice to scan only a required scan length depending on the size of a document and the size of a transfer sheet, thereby increasing the copy speed of a small size. Therefore, as shown in FIG. 9, the rise curve of the temperature of the scanner portion or the temperature of the surrounding parts (for example, contact glass) differs depending on the scan length. In this example, the rising curve is steeper for the small size. This is because short distances are scanned more frequently than long distances. Therefore, it is not necessary to switch the air volume of the cooling fan 4 with the same continuous number of sheets uniformly for each size.

[0011] From such a background, in the present invention, the number of continuous copies at the time of switching the air volume of the cooling fan 4 is set according to the magnification or the scan length. 1 and 2,
FIG. 3 is a control block diagram of the cooling fan control device according to the embodiment of the present invention.

First, in the embodiment shown in FIG. 1, reference numeral 10 denotes an operation unit, 11 denotes a CPU, 12 denotes a relay, and 12a denotes a switching piece. In this embodiment, the CPU 11 outputs a fan-on trigger (FO) to drive the cooling fan 4, and outputs a power-up trigger (PU) to operate the relay 12, so that the switching is normally performed at a lower speed. Piece 12
By switching a to the high-speed side, the drive motor 7 of the cooling fan 4 is rotated at high speed, and the fan airflow is increased. If only the fan-on trigger is output, the switching piece 1
Since 2a is on the low-speed side, the cooling fan 4 rotates at low speed, and the fan air volume can be kept small.

In a modification of the embodiment shown in FIG.
c is a connection piece of the relay 12, and 13 is an amplifying transistor. In this embodiment, a fan-on trigger is output from the CPU 11, the normally open connection piece 12c is closed, and the cooling fan 4 is closed.
And the power up trigger is turned on, and the drive motor 7 of the cooling fan 4 is
The fan airflow is increased by increasing the voltage supplied to the fan. If only the fan-on trigger is output from the CPU 11, the air volume of the cooling fan 4 becomes small.

In another modified example of the embodiment shown in FIG. 3, the fan is turned on at a high speed by rotating the cooling fan 4 at a high speed by flowing a fan-on trigger in a state of always GND in FIG. 4A. In addition, by flowing the fan-on trigger in the state of the pulse division shown in FIG. 4B, the cooling fan 4 is rotated at a low speed and the fan air volume is reduced.

FIG. 6 is a flowchart according to an embodiment of fan control in accordance with the magnification and the number of continuous copies. In the present embodiment, the relationship between the scaling factor and the number of continuous copies for fan air volume switching is as follows: when the scaling factor is 50% to 90%, the number of switching sheets is 20, when the scaling factor is 91% to 140%, the switching number is 15 sheets. When the scaling ratio is 141% or more, the number of switching sheets is 10.

First, a check is made as to whether copying is in progress (S1), and if copying is not in progress, the fan motor is turned off (S2). During copying, the magnification is 50% to 9
0% (Y in S3), when 20 or more continuous copies are made (Y in S4), or when the magnification is 91% to 140% (Y in S5), and 15 or more continuous copies are made (Y in S6) If there are more than 10 continuous copies at other magnifications, the fan air volume control is performed to increase the fan air volume (S8). In cases other than the above, conversely, the fan air volume is kept small (S9).

FIG. 7 is a flowchart according to an embodiment of fan control in accordance with the scan length and the number of continuous copies.
In this embodiment, the relationship between the scan length and the number of continuous copies for switching the fan air volume is as follows: when the scan size is A3, the number of sheets switched is 20, when the scan size is B4, the number of sheets switched is 15, and when the scan size is A4 or smaller, the switch The number is ten.

First, a check is performed to determine whether copying is in progress (S11). If not, the fan motor is turned off (S12). During copying, the scan length is A3 (Y in S13), when 20 or more continuous copies are made (Y in S14), or when the scan length is B4 (Y in S14).
15; Y), when 15 or more continuous copies are made (Y in S16), or when the scan length is smaller than B4 but not A4 or less (N in S17), and 15 or more continuous copies are made (Y in S16), Further, when the scan length is A4 or less (Y in S17) and 10 or more continuous copies are made (Y in S18), the fan air volume is increased (S19).
In cases other than the above, on the contrary, the fan air volume is kept small (S
20).

[0019]

According to the first aspect of the present invention, a formed image is formed.
By setting the number of continuous copies according to the
And a continuous number of copies and the magnification Te, because they Gyotsu the air volume control of the cooling fan, the actual temperature rise in accordance with the magnification mode, it is possible to control the fine cooling fan, noise, Power loss can be eliminated, and a highly reliable cooling fan control device can be provided. Claims 2 to 4
ADVANTAGE OF THE INVENTION According to the described invention, the apparatus which changes the electric power supply to the drive motor of a cooling fan can be made into an easy and efficient structure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a control circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a control circuit according to a modification of the embodiment.

FIG. 3 is a block diagram showing a control circuit according to another modification of the embodiment.

FIG. 4 is a waveform diagram of a control signal according to another modification.

FIG. 5 is a configuration diagram illustrating an example of a copying machine.

FIG. 6 is a flowchart of fan control according to the magnification and the number of continuous copies in the embodiment.

FIG. 7 is a flowchart of fan control according to the scan length and the number of continuous copies in the embodiment.

FIG. 8 is a characteristic diagram showing a relationship between the number of continuous copies and a scanner temperature for each magnification.

FIG. 9 is a characteristic diagram showing the relationship between the number of continuous copies and the scanner temperature for each scan length.

[Explanation of symbols]

 2 Scanner 3 Exposure lamp 4 Cooling fan 7 Drive motor 11 CPU 12 Relay 13 Amplification transistor

Claims (4)

(57) [Claims] A cooling fan control device for controlling a cooling capacity of a cooling fan for cooling heat generated in a scanner unit by turning on an exposure lamp of an image forming apparatus, wherein the number of continuous copies is set according to a magnification of a formed image.
Depending on the number of continuous copies and the magnification of the formed image,
Control means for predicting the temperature rise of the scanner section and controlling the cooling fan based on the value; and power variable means for changing the power supply to the drive motor of the cooling fan in accordance with a command from the control means. A cooling fan control device. 2. The cooling fan control device according to claim 1 , wherein the electric power varying means comprises a tap switching mechanism for switching the driving force of the driving motor. 3. The cooling fan control device according to claim 1 , wherein the electric power varying means is constituted by a voltage switching mechanism for changing a voltage supplied to the drive motor. 4. The cooling fan control device according to claim 1 , wherein the power varying means is constituted by a duty switching mechanism for changing a duty of a control signal of the drive motor.