JPH07111607B2 - Image forming apparatus temperature control method - Google Patents

Description

The present invention relates to a temperature control method for preventing a temperature rise of a table glass and an optical system in an apparatus for forming an image by scanning an original.

(B) Conventional Technology In some devices that form an image by scanning an original, the temperature of the table glass or the optical system becomes extremely high. For example, an image forming method disclosed in Japanese Patent Laid-Open No. 58-88739 discloses a light-receiving sheet in which microcapsules encapsulating a colorless dye and a photocuring agent are uniformly dispersed on a sheet, and an image-receiving sheet coated with a developer. This is a method of forming an image by using and, but a light source of high brightness is required because the sensitivity of the light receiving sheet is not sufficient, and the original scanning speed cannot be increased. For this reason, there is a problem that the temperature of the table glass and the optical system rises extremely quickly and the saturation temperature thereof becomes very high. For example, the document scanning speed is 5m / sec
The halogen lamp is rated at 500W, 20lm /
It is possible to finally obtain an appropriate image brightness by using two sec secs at 1000W and a brightness of 20,000 lm / sec, but in this case 1000W of power is consumed, so the table glass surface And the temperature rise of the optical system rises extremely quickly, and the saturation temperature becomes extremely dangerous at 85 ° C when the number of continuous copies of A4 original is 20. In particular, in such an image forming method, the condition becomes more severe in a full-color image forming apparatus using a light-receiving sheet in which three types of microcapsules each exhibiting eight colors of cyan, yellow, and magenta are uniformly dispersed. There is a problem in that continuous copying cannot be practically performed without doing so.

In order to solve this problem, a method has conventionally been proposed in which a motor for air flow formation is installed in the image forming apparatus and the optical system is cooled by the air flow during the copying operation. In addition, a method has also been proposed in which an infrared cut filter is installed in front of the copy lamp to absorb heat rays.

(C) Problems to be Solved by the Invention However, these methods are extremely insufficient for lowering the temperature of the table glass or the optical system that rises to 85 ° C. to a safe temperature range. There is also a risk of promoting deterioration and, in some cases, destroying the infrared cut filter due to abnormally high temperature and further causing burns to the operator.

An object of the present invention is to provide a temperature control method capable of preventing an abnormally high temperature of a table glass and an optical system during a continuous copying operation in an image forming apparatus of this type in which the optical system consumes a large amount of power. To do.

(D) Means for Solving the Problems In the invention according to the first aspect, the maximum continuous number of copies is automatically set based on the original scanning width and the magnitude of the input voltage applied to the copy lamp. Whenever the number of continuous copies reaches an integral multiple of the maximum number of continuous copies during the copy operation, the original scanning is forcibly stopped to shift to the interrupt mode of the copy operation, and the interrupt mode is released after a predetermined time elapses. It is characterized by shifting to the normal mode.

(E) Function In the invention according to the first aspect, the maximum number of continuous copies is automatically set based on the original scanning width and the magnitude of the input voltage applied to the copy lamp. The temperature rise is likely to increase as the document scanning width becomes shorter, that is, the document size becomes smaller, and the copy lamp applied voltage increases. The applied voltage of the copy lamp can be selected by an operator into several types. If the applied voltage is increased, the brightness of the obtained image becomes bright, and conversely, if the applied voltage is lowered, the brightness becomes dark. The operator can select an image having an appropriate brightness by switching the applied voltage according to the type of the original and the preference. When the document scanning width and the voltage applied to the copy lamp are determined in this manner, the maximum number of continuous copies is automatically set based on them. The maximum number of continuous copies is relatively small when the document scanning width is short or the set copy lamp application voltage is high. On the contrary, if the document scanning width is long or the set copy lamp applied voltage is small, the document scanning width becomes relatively large. The method of determining the maximum number of continuous copies is determined in advance according to the characteristics of the device.

When the maximum continuous copy number is automatically set as described above, if the continuous copy number reaches the maximum continuous copy number during the next copy operation, the original scanning is forcibly stopped at that point and the copy operation is stopped. Enter suspend mode. In this case, the interruption mode is entered regardless of whether or not the number of copies remains. At the stage of shifting to the interruption mode, the scanning of the original is stopped and the copy lamp is also turned off, so that the temperatures of the optical system and the table glass gradually decrease. When a predetermined time elapses, that is, when the temperatures of the optical system and the table glass decrease to a certain temperature, the interruption mode is released and the normal mode is entered. In this normal mode, when the number of remaining copies is present, the copy operation may be automatically started, or the ready state may be restored.

(F) Embodiment Configuration of Image Forming Apparatus FIG. 2 is a schematic configuration diagram of an image forming apparatus in which the temperature control method according to the present invention is implemented.

This image forming apparatus uses the image forming method disclosed in JP-A-58-88739. To outline this known image forming method, a light-receiving sheet in which microcapsules encapsulating a colorless dye and a photo-curing agent are uniformly dispersed, and an image-receiving sheet coated with a developing material are used. To support full-color, microcapsules containing cyan, yellow, and magenta colorless dyes are uniformly dispersed, and the cyan capsule contains a red light curing agent, the yellow capsule contains a blue light curing agent, and the magenta capsule contains a magenta capsule. Use a green light curing agent enclosed in each. Then, when the image-receiving is performed on the light-receiving sheet, a selectively cured image is formed,
The light receiving sheet and the image receiving sheet on which the selectively cured image is formed are overlapped and pressed, whereby development and transfer are performed at the pressing point. That is, a colored image is formed on the image receiving sheet. If a full-color type light-receiving sheet is used, a full-color colored image is formed on the image-receiving sheet by one pressing step.

In FIG. 2, a table glass 2 is provided on the upper surface of the image forming apparatus main body 1. An optical system for scanning a document is arranged below the table glass 2, and the optical system is composed of one halogen lamp 3, reflection mirrors 4 to 7 and a lens 8.

Pressure rollers 10 and 11 are provided substantially in the center of the image forming apparatus main body 1, a light receiving sheet roll 12 is arranged on the left side thereof, and an image receiving sheet cassette 13 is provided on the right side thereof. The cartridge of the light receiving sheet roll 12 is integrally provided with a winding roller 13 for winding a used light receiving sheet. The light receiving sheet 14 is conveyed from the roll 12 by some rollers to the exposure point P1 where it is subjected to imagewise exposure. Further, the image receiving sheet 15 is fed from one of the image receiving sheet cassettes 13 by the sheet feeding roller 16, and is superposed on the light receiving sheet 14 at the position of the roller 17 so as to be overlapped with the pressure roller 1.
It is sent to the pressure point P2 of 0 and 11. Pressure point
After being developed and transferred by P2, the used light-receiving sheet is wound around the winding shaft 13 by the guide member 20, and the image-transferred sheet is transferred to the conveyor belt 21 and the heat roller 22. It passes and is discharged to the paper discharge tray 23. The image receiving sheet is coated with a thermoplastic resin. The heat roller 22 is for melting the thermoplastic resin to make the surface of the color image a uniform glossy image.

When the copy switch is pressed down in the above configuration, the light receiving sheet 14 is conveyed and the original is scanned by the optical system. Document scanning is performed by moving the halogen lamp 3 and the reflecting mirror 4 in the direction of arrow A. The document scanning width is set in advance to the length of the document size designated by the operator, and when the document scanning is completed, the original home position is returned at that time. The pressure rollers 10 and 11 are driven at the same time as the scanning of the document, and the light receiving sheet 14 is conveyed. At this time, imagewise exposure is performed at the exposure point P1, and a selective cured image is formed. The light receiving sheet 14 that has passed the exposure point P1 is superposed on the image receiving sheet 15 conveyed from the paper feed cassette 13, is pressed at the pressure point P2 (developed and transferred), and is wound while being guided by the guide member 20. It is wound around the shaft 13.

On the other hand, the image receiving sheet 15 is heated by the conveyor belt 21 as a heat roller.
It is conveyed to the sheet 22, heated here, and discharged to the sheet discharge tray 23. In the case of multi-copy (continuous copy), the above operation is continuously performed.

Although not shown, the operation unit is provided with a key for designating the brightness of the image so that the operator can select an appropriate brightness of the image. The control unit selects a copy lamp application voltage corresponding to the designated brightness and supplies the voltage to the halogen lamp 3. A key for designating the size of the document placed on the table glass 2 is also provided, and the control unit reads the size of the document designated by the operator to determine the document scanning width of the optical system.

Description of Temperature Control Method FIG. 1A shows the temperature rise characteristic of the table glass surface with respect to the number of continuous copies in the above image forming apparatus. For the sake of clarity, the number of parameters is reduced in this figure. That is, the parameters are the document size (A4, A3) and the copy lamp applied voltage (image brightness) input and set by the operator. Characteristics V1 to V3 shown by solid lines are characteristics when the document size is A4 and the copy lamp applied voltage is 80V, 70V, and 60V. Further, v1 to v3 indicated by the chain double-dashed line show the characteristics when the document size is A3 and the copy lamp applied voltage is 80V, 70V, 60V. The temperature T1 is the maximum allowable value of the table glass surface temperature. The temperature T2 is an arbitrary value that is sufficiently lower than the maximum allowable temperature of the table glass. The number of copies M1 at the intersection of the table glass temperature maximum allowable value T1 and the characteristic V1 is A4
The size represents the maximum number of continuous copies when the voltage applied to the copy lamp is 80V. Similarly, m1 which is the number of copies at the intersection of T1 and v1 is A3 size original and the voltage applied to the copy lamp is 80V.
Represents the maximum number of continuous copies. The control unit (not shown) controls the number of copies M1 to M3 and m1 at each of the intersections of the characteristics V1 to V3 and the characteristics v1 to v3 and the table glass temperature maximum allowable value T1.
.About.m3 is stored as the maximum continuous copy number, and the maximum continuous copy number is selected (set) from these based on the original scanning width and the input voltage setting of the copy lamp applied voltage. Then, when the number of continuous copies reaches the set maximum number of continuous copies during the continuous copy operation, the original scanning is forcibly stopped and the copying operation interruption mode is entered. The changes in a to e of the figure represent changes in the temperature of the table glass from the time of shifting to the interruption mode. Then, when the temperature of the table glass reaches the temperature T2, the interruption mode is released to shift to the normal mode.

 Operation of Control Unit FIG. 3 is a flowchart showing the operation of the control unit.

In step n1, the operator inputs copying conditions such as the number of copies a1 and paper size from the operation panel. When the operator presses the print switch at n2, it is determined whether the document scanning width is A4 or less. This document scanning width is determined according to the document size or is set from the size of the selected paper feed cassette and the copy magnification. At n4 and n5, it is determined whether the applied voltage V of the copy lamp is equal to or higher than the reference voltage V2. In order to facilitate understanding, there are two types of copy lamp applied voltage. That is, the voltage is divided into two types of voltages that are equal to or higher than the reference voltage V2 (in FIG. 1A, they are divided into three types of voltages). Then, in n6 to n9, the maximum continuous copy number is set to N1 based on the magnitude of the voltage applied to the copy lamp (n4, n5) and the document scanning width (n3). For example, when the document scanning width is A4 or less and the copy lamp applied voltage is set to V2 or more, the maximum continuous copy number N1 is set to 5 (n6). At n10, the contents of N1 are transferred to N, at n11 a copy cycle is executed, and at n12, the number of copies completed is counted by the counter a. Then, in n13, it is determined whether or not the copy number a is an integer multiple of N (the maximum continuous copy number N1 at first), and when it becomes an integer multiple, the interruption mode is set in n14. In this interruption mode, the timer t is started at n15 and n16 and waits for the predetermined time T to elapse. Of course, in this interruption mode, the supply of the applied voltage to the copy lamp is stopped. In this interruption mode, the temperature of the table glass gradually decreases.

As described above, the predetermined time T is set to the time until the temperature of the table glass reaches T2 in FIG. When the predetermined time T elapses, the content of N + N1 is reset to N at n17, and the interruption mode is released at n18 to shift to the normal mode. When the mode is shifted to the normal mode, it is judged at n19 whether or not the copying operation for a1 sheets is completed, and if not completed, n11 and subsequent steps are executed again.

In the operation shown in FIG. 3, in order to facilitate the time, the scanning width is distinguished by two types, that is, A4 or less (first type).
(In the figure (A), A4 size or A3 size is used for explanation.)
However, you can make the conditions for n3 more detailed, and
It is also possible to make the conditions of n4 and n5 more detailed. Similarly, the conditions of n6 to n9 can be finely set.

In the operation shown in FIG. 3, for example, the copy number a1 is 24
It is assumed that the copy magnification is set to 1 ×, the paper size is set to B5, and the copy lamp applied voltage is set to V2 or less. In this case, since the original scanning width is B5 and the copy lamp applied voltage is V2 or less, the maximum continuous copy number N1 is set to 10 (n7). N is also set to 10. When 10 copy cycles are repeated, n = 10 and N = 1 at n13
Since it is 0, the copy cycle is suspended for a fixed time T. Then, when that time elapses and the temperature of the table glass falls below a predetermined temperature (T2 in FIG. 1), the value of N is set to 20 (n17), and 10 copy cycles (11 to 20) are performed again.
Repeat). Then, at n13, n = 20 and N = 20, so the copy cycle is interrupted again for the time T. Then the value of N is set to 30. Then, the remaining four copy cycles are performed, and all copy cycles are completed and ended.

Other Embodiments In the above temperature control method, the maximum number of continuous copies is set based on the original scanning width and the magnitude of the voltage applied to the copy lamp, and the transition to the interruption mode and its cancellation are performed with reference to the values. However, it is also possible to directly detect the temperature of the table glass or its peripheral portion and control the transition to the interruption mode and its cancellation based on the detection result.

FIG. 1B shows the temperature change of the table glass and the temperature change of the reflector with respect to the number of copies. The reflector is provided at a position covering the halogen lamp 3 in FIG. As shown in the figure, the reflector temperature characteristic and the table glass temperature characteristic have a certain correlation, and when the table glass temperature is high, the reflector temperature is also high. Therefore, the temperature of the table glass can be known by detecting the temperature of the reflector. Figure 4 shows the reflector 30
An example is shown in which the thermistor 31 is attached to the upper end of the reflector 30 to detect the temperature. In FIG. 1 (B), the temperature T1 is the upper limit temperature of the table glass. Therefore, when the temperature detected by the thermistor 31 reaches t1, it can be known that the table glass has reached the upper limit temperature. In the figure, the temperature of the table glass reaches the upper limit temperature when the number of continuous copies reaches 10.

The temperature T2 in FIG. 1 (B) is a temperature corresponding to T2 in FIG. 1 (A). That is, it is an arbitrary temperature sufficiently lower than the maximum allowable value T1 of the table glass temperature. The temperature t2 indicates the temperature of the reflector when the table glass temperature T2 is reached. In this embodiment, when the reflector temperature reaches t1 during the continuous copying operation, the original scanning is forcibly stopped and the copying operation is suspended. Then, when the reflector temperature reaches t2 in the suspend mode, the suspend mode is canceled and the normal mode is entered. The changes in f and g in the figure indicate that the reflector temperature and table glass temperature are decreasing in the interruption mode, respectively. Then, at the point Q1, the suspend mode is released and the mode shifts to the normal mode. If there are remaining copies, it will be automatically re-copied from this point Q1. It should be noted that it is possible to set the ready state at this point Q1.

Operation of Control Unit FIG. 5 is a flowchart showing the operation of the control unit when carrying out the control method based on the temperature detection by the thermistor 31.

At n20 in the figure, it is determined whether or not the temperature of the table glass has reached the table glass temperature maximum allowable value T1. This determination is made from the detection value of the thermistor 31. If the temperature exceeds T1, the interruption mode is set at n21, and at n22, the temperature is lowered to the lower limit temperature T2 (see FIG. 1 (B)). When the lower limit temperature T2 is reached, the suspend mode is released (n23),
Switch to normal mode. If there is a remaining number, the copy cycle for the next number is automatically performed.

Other Embodiment 2 FIG. 6 shows another embodiment. In this embodiment, at n30, even if the table glass temperature exceeds the maximum allowable value T1 and the remaining number of copies is equal to or less than the constant number a (k is set to a small number), the copy cycle is continued. It was done. This determination is made by n31. If this is done, the table glass temperature will reach the maximum allowable value.
Even if the temperature becomes T1 or higher, the remaining copy can be completed without increasing the temperature much higher than that temperature, which is efficient.

Other Modifications In addition, an infrared cut filter may be provided in the above embodiment to prevent temperature rise. FIG. 7 shows the mounting position when the infrared cut filter is provided.
In the figure, 32 is an infrared cut filter and a reflector.
It is located at a position facing 30. Although the thermistor 31, which is a temperature sensor, is attached to the reflector 30 in the figure, it is of course possible to directly attach the thermistor 31 to an appropriate portion of the table glass.

(G) Effect of the Invention As described above, according to the present invention, particularly in an image forming apparatus that requires high illuminance for scanning an original, when a dangerous temperature is reached, the copying operation is automatically and automatically suspended. Since the transfer is ensured, the safety of the image forming apparatus is ensured, and the thermal stress on the peripheral parts can be reduced, so that deterioration of the parts can be prevented.

[Brief description of drawings]

FIGS. 1A and 1B are views for explaining a temperature control method of an image forming apparatus for carrying out the inventions of claims 1 and 2, respectively. FIG. 2 is a schematic configuration diagram of the image forming apparatus, FIG. 3 is a flowchart showing the operation of the control section of the apparatus for carrying out the invention of claim 1, and FIG. 4 is a thermistor of the apparatus for carrying out the invention of claim 2. FIG. 5 shows the arrangement state, FIG. 5 is a flow chart showing the operation of the control unit of the image forming apparatus for carrying out the invention of claim 2, and FIG. 6 shows the operation of the control unit of another embodiment of the invention of claim 2. It is a flowchart shown. Further, FIG. 7 shows an example of reducing the temperature rise of the table glass. 1 ... Image forming apparatus main body 2 ... Table glass 3 ... Copy lamp

Claims (1)

[Claims] 1. A maximum continuous copy number is automatically set based on the original scanning width and the input copy lamp applied voltage, and the continuous copy number is an integer of the maximum continuous copy number during continuous copy operation. The temperature of the image forming apparatus is characterized in that the scanning of the original is forcibly stopped and the mode is changed to the interruption mode of the copy operation every time the number of times reaches double, and the interruption mode is released and the mode is changed to the normal mode after a predetermined time elapses. Control method.