JPH05333627A - Cooling controller for original reader - Google Patents

Abstract

PURPOSE:To obtain a cooling controller for an original reader capable of stably controlling a temperature in an optical unit, without the rising of cost caused by the installation of a new part. CONSTITUTION:When the reading of an original is started and a halogen lamp 11 is turned on, a SCON (system controller) 1, adds a prescribed additional value to a counter value stored in a nonvolatile RAM 4, every prescribed period, and stores the obtained value in the nonvolatile RAM 4. When the halogen lamp 11 is turned off, the SCON 1 subtracts a prescribed subtractive value from a set value stored in the nonvolatile RAM 4, every prescribed period. and stores the obtained value in the nonvolatile RAM 4. When the counter value stored in the nonvolatile RAM 4 exceeds a prescribed value, the SCON 1 rotates and drives a cooling sector fan motor 10 only for a prescribed period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling control device for a document reading device, which controls a cooling device of a document reading device for convectively dissipating heat emitted by an illumination lamp which is driven to scan along a document surface by a cooling fan. ..

[0002]

2. Description of the Related Art Generally, in a copying machine, the surface of an original document placed on a contact glass is illuminated by a lamp, and the reflected light is directly guided to the surface of a photosensitive member to form a latent image of the original image. The photoelectric conversion element converts the signal into an electric signal, and after performing a predetermined process, the light emitting element is modulated by the recording signal and the modulated light is guided to the surface of the photoconductor to form a latent image of the original image. A halogen lamp that emits a large amount of light is used as a lamp for illumination, but since it also generates a large amount of heat at the same time as it emits light, it raises the temperature of the entire optical unit for reading the original, causing optical path errors, and causing a scan drive Or the display element arranged in front of the top surface of the device may deteriorate early,
There is also an inconvenient aspect in that the contact glass may be overheated, and the operator may be surprised or feel uncomfortable due to the high temperature when the operator manually touches the original. Therefore, in order to dissipate the heat generated by the halogen lamp, a cooling fan is provided in the vicinity of the halogen lamp, and air is blown to the halogen lamp to forcibly cool it. The larger the air volume, the higher the cooling efficiency.However, when the air volume increases, dust such as toner and paper dust rises, contaminating the surface of the mirror body arranged in the optical unit for optical path refraction, and The reduction in the amount of exposure light reaching the surface lowers the contrast of the formed image and causes image deterioration such as background stain. It is conceivable to install a dust filter to purify the air, but in order to compensate for the decrease in wind speed due to that, the cooling fan must be driven by a more powerful fan motor, and noise during operation increases.

[0003]

In order to eliminate such inconvenience, for example, as disclosed in Japanese Patent Laid-Open No. 58-16254, a thermistor is arranged at a predetermined position in the optical unit, and thereby, A method is known in which a fan motor is intermittently operated based on the detected temperature information to control the temperature inside the optical unit. However, for that purpose, circuit element parts such as temperature detection circuit and temperature control circuit, and circuit board, and new parts such as connection bus bar for connecting these are required, which leads to an increase in the unit price of the device and causes for some reason. When the thermistor causes a short circuit, a break, or the like, the temperature inside the optical unit becomes uncontrollable.
SUMMARY OF THE INVENTION The present invention is intended to solve such a problem of the prior art, and provides a document reading apparatus capable of stably controlling the temperature in the optical unit without causing a price increase due to the addition of new parts. An object is to provide a cooling control device.

[0004]

In order to solve the above-mentioned problems, the present invention stores in a storage means a setting value, an addition means for adding a setting value stored in the storage means, and a storage means. The subtraction means for subtracting the set value and the set value stored in the storage means for each predetermined period while the illumination lamp is on are added by the addition means by the predetermined addition value and stored in the storage means. Then, while the illumination lamp is off, the set value stored in the storage means is subtracted by the predetermined subtraction value by the subtraction means for each predetermined period and stored in the storage means, and stored in the storage means. When the set value exceeds a predetermined value, it has a control means for controlling to drive the cooling fan to rotate for a predetermined period.

[0005]

When the reading of the original is started and the illumination lamp is turned on, the control means adds the set value stored in the storage means every predetermined period by the predetermined addition value by the addition means and stores it in the storage means. When the illumination lamp is turned off, the control means subtracts the set value stored in the storage means for each predetermined period by the predetermined subtraction value by the subtraction means and stores it in the storage means. When the set value stored in the storage means exceeds a predetermined value, the control means rotationally drives the cooling fan for a predetermined period.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the main part of the overall control of a copying machine according to the first embodiment of the present invention. The control of the main part will be briefly described with reference to the drawings. The system controller (SCON) 1 that controls the entire copying machine includes an operation unit / power supply CPU 2, a scanner (SC) CPU 3, and a non-volatile RA.
It exchanges signals with M4 and controls each. The operation unit / power supply CPU 2 controls the fixing heater 8 based on the detection output of the fixing thermistor 9 which is provided near the fixing roller (not shown) via the AC drive circuit 5 and detects the temperature of the fixing roller. The SCON 1 controls the fan motor 10 of the cooling fan via the gate array (GA) 6. The SCCPU 3 receives the document size information SZ detected by the document size sensor 12, and controls the halogen lamp 11 via the halogen lamp (HL) drive circuit 7.

FIG. 4 is a flow chart for setting the counter value when the power is turned on. First, after initializing the CPU including SCON1 and peripheral I / O (S-1), the nonvolatile RA
The counter value P stored in M4 and the fixing thermistor registration value THr representing the temperature of the fixing thermistor 9 when the power is cut off are read (S-2, S-3). Next, the current temperature detection value THp of the fixing thermistor 9 is read (S
-4), (THr-THp) are calculated, and the difference is set as the fixing temperature difference registration value D (S-5). Below, the fixing temperature difference registered value D
Is checked, and the value of the correction registration value M is set according to the value. That is, if D <15 (No in S-6), M = 0
(S-12), if 15 ≦ D <30 (N in S-7)
o), M = 600 (S-13), if 30 ≦ D <60 (No in S-8), M = 1000 (S-14), 60 ≦
If D <100 (No in S-9), M = 2000 (S
-15), if 100 ≦ D (Yes in S-9), the lower limit value P is set to 1000 (S-10), and the counter value P is decremented at a predetermined interval while the apparatus is on standby.
After starting the second timer (S-11), the process returns to the beginning. When the setting of the corrected registered value M is completed when D <100, (PM) is calculated, and the difference is set as the value of the counter value P (S-16). And the value of the counter value P is 10
It is determined whether or not it is smaller than 00 (S-17), and if the determination result is Yes, the lower limit value P is set to 1000 (S-1).
8) After starting the timer for 10 seconds (S-1
9) Return to the beginning. As described above, the larger the difference between the fixing thermistor registered value THr and the temperature detection value THp of the fixing thermistor 9, the smaller the counter value P is, so that the temperature of the optical unit decreases during the power-off state. The contribution is reflected in the counter value P. When the value of the counter value P set in this way exceeds a predetermined threshold value, the rotation of the fan motor 10 for driving the cooling fan is started.

FIG. 5 is a flow chart of cooling fan drive control. Halogen lamp 11 during startup or standby of the device
Is not lit, the temperature of the optical unit gradually decreases due to heat dissipation even if the optical unit is heated. Therefore,
First, it is determined whether the cooling fan is driven (S-2
0) If the determination result is Yes, the value of the counter value P is checked, and if P ≦ 2400 (Yes in S-21), it is determined whether or not the 5-minute timer has finished counting (S-2.
2) If the determination result is Yes, the 5-minute timer is stopped and reset (S-23). Then, the cooling fan is stopped (S-24). If the decision result in the step S-20 is No, the value of the counter value P is checked and 3000 ≦ P
If so (Yes in S-25), after starting the 5-minute timer (S-26), the driving of the cooling fan is started (S).
-27). In this way, once the cooling fan is driven,
It is operated continuously for 5 minutes. This prevents short-term intermittent operation of the fan motor 10,
And the starting load on the bearing of the cooling fan is reduced. Even if the correspondence between the counter value P and the temperature in the optical unit is deviated, the temperature in the optical unit at the start of driving the cooling fan will be slightly different, and the temperature in the optical unit within the predetermined range will be small. There is no hindrance to temperature control. Figure 6
6 is a flow chart for setting a counter value while the apparatus is starting up or is on standby. First, the temperature detection value THp of the fixing thermistor 9 is stored in the nonvolatile RAM 4 (S-28).
Next, it is determined whether or not the 10 second timer has finished counting (S-29), and if the determination result is Yes, it is determined whether or not the cooling fan is driven (S-30), and the determination result is Y.
If it is es, the value of the correction registration value C is set to 40 (S-
32). If the determination result is No, the value of the correction registration value C is set to 1
It is set to 0 (S-31). Next, (PC) is calculated, the difference is set as the value of the counter value P (S-33), and it is determined whether the value of the counter value P is less than 1000 (S-34). If the determination result is Yes, the lower limit value P = 1
000 (S-35), and after starting the timer for 10 seconds, start (S-36). As described above, when the cooling fan is driven, the temperature decrease rate of the optical unit increases, so the subtraction value (obtained by actual measurement) of the counter value P is set to a large value. Further, the registration thermistor registration value THr is updated at regular intervals in order to enable the counter value setting process at power-on regardless of the timing at power-off.

FIG. 7 is a flow chart for setting the counter value during the copying operation. Even during the copying operation, the subtraction processing of the counter value P is performed at regular time intervals as in the standby state. When the halogen lamp 11 is turned on, the addition processing of the counter value P is performed based on the lighting time and the driving voltage. Done. First, it is determined whether an image forming operation is in progress (S-3
7) If the determination result is Yes, it is determined whether or not the halogen lamp 11 is turned on (S-38).
If the determination result is Yes, the document size information SZ detected by the document size sensor 12 and the driving voltage VL of the halogen lamp 11 are read (S-39). Next, based on the correction registration value determination data table shown in FIG. 8, the correction registration value Q corresponding to the document size information SZ and the driving voltage VL of the halogen lamp 11 is set (S-4).
0). Further, (P + Q) is calculated, and the difference is set as the value of the counter value P (S-41).

Next, the present invention is provided with a clock that is independently driven even when the power is cut off, and the time of the power cut-off state is measured by the clock to correct the counter value P. A second embodiment will be described. FIG. 9 is a flowchart of setting the counter value when the power is turned on. First, SCO
After performing the initialization processing of the CPU including N1 and the peripheral I / O (S-51), the counter value P stored in the nonvolatile RAM 4 and the time To when the power is cut off are read (S-51).
-52, S-53). Next, the current time Tp is read (S-54), (Tp-To) is calculated, and the difference is set as the time difference registration value D '(S-55). Below, the time difference registration value D '
Is checked and the value of the corrected registration value M ′ is set according to the value. That is, if D '<5 (No in S-56),
If M ′ = 0 (S-61), 5 ≦ D ′ <10 (S-5
7 No), M '= 500 (S-62), 10≤D'<
If 50 (No in S-58), M '= 1000 (S-
63), if 50 ≦ D ′ <120 (N in S-59)
o), M ′ = 2000 (S−64), and 120 ≦ D ′ (Yes in S-59), the lower limit value P = 1000 is set (S
-60) After starting the timer for 10 seconds (S-6
8) Return to the beginning. In the case of D '<120, after setting the value of the corrected registration value M', (PM ') is calculated, and the difference is set as the value of the counter value P (S-65). Then, it is determined whether the value of the counter value P is smaller than 1000 (S-66), and if the determination result is Yes, the lower limit value P = 1
000 (S-67), after starting the timer for 10 seconds (S-68), the process returns to the beginning.

FIG. 10 is a flow chart for setting a counter value while the apparatus is starting up or is on standby. First, the current time Tp is stored in the nonvolatile RAM 4 (S-71). Next, it is determined whether the 10 second timer has finished counting (S-72). If the determination result is Yes, it is determined whether the cooling fan is being driven (S-73), and the determination result is Y.
If it is es, the value of the corrected registration value C'is set to 40 (S
-75). If the determination result is No, the value of the corrected registration value C'is set to 10 (S-74). The total copy number Nc stored in the non-volatile RAM 4 is read (S-76), and it is determined whether the value of the total copy number Nc is 70000 or more (S).
-77), if the determination result is Yes, the correction coefficient registration value E
Is set to 0.7 (S-78). Judgment result is No
Then, it is further determined whether or not the value of the total number of copies Nc is 50000 or more (S-79), and if the determination result is Yes, the value of the correction coefficient registration value E is set to 0.9 (S-8).
0). If the determination result is No, the value of the correction coefficient registration value E is set to 1.0 (S-81). Next, the coefficient registration value F =
C ′ × E is calculated (S−82), and further (P × F) is calculated. This product is used as the counter value P (S-8
3), it is determined whether the counter value P is less than 1000 (S-84), and if the determination result is Yes, the lower limit value P is set to 1000 (S-85), the timer is cleared for 10 seconds, and then the start is performed. (S-86). As described above, in this embodiment, deterioration of the use of the dustproof filter and the cooling fan,
The counter value P is reduced in accordance with the operating amount of the copying machine in consideration of the factor of temperature rise in the optical unit due to deterioration over time.

By the way, the temperature rise change amount Degu and the temperature fall change amount Degd in the optical unit are respectively given by the following equations. Degu = R × I (1-e ^{−t / RC} ) Degd = R × I × e ^{−t / RC} where R: thermal resistance, I: heat flow, C: heat capacity The heat flow I is proportional to the amount of heat generated by the halogen lamp 11. Because
It can be associated with the lighting time of the halogen lamp 11 and the drive voltage VL, and the value of the heat capacity C is substantially constant.
On the other hand, the value of the thermal resistance R fluctuates greatly due to the blinking of the halogen lamp 11, but the thermal resistance is experimentally measured by measuring the saturated region of the temperature increase and the temperature decrease in the lighting state and the extinguished state of the halogen lamp 11. The amount of change in the value of R can be obtained. FIG. 3 is a graph showing changes in the temperature t in the optical unit and the temperature detection value THp of the fixing thermistor 9 with respect to the time T after completion of the copying operation. FIG. 2 is a graph showing changes in the temperature t (a) in the optical unit and the counter value P (b) with respect to the time T when the continuous copying operation is performed with the cooling fan stopped. The solid line shows the case where the driving voltage VL of the halogen lamp 11 is large, and the broken line shows the case where it is small. The counter value P is the threshold value P ₁
When the temperature exceeds t ₁ , the temperature t in the optical unit exceeds t ₁ and enters the saturation region. FIG. 11 is a graph showing a specific example of temperature control of the optical unit according to the present embodiment in association with the actual measurement value. The horizontal axis represents time T, the vertical axis represents the temperature t in the optical unit, and the vertical axis represents the counter value P. The power of the copying machine was turned on at time T = 0, the reading of an A4 size document was started at time T = T ₁ , and the reading was finished at time T = T ₃ . Time T = T ₂ is the rotation start time of the cooling fan, time T =
T ₄ is the rotation end time. Time T = T ₅ is the standby end time, and time T = T ₆ is the next cooling fan rotation start time.

[0013]

As described above, according to the first aspect of the present invention, while the illumination lamp is on, the setting value stored in the storage means is added to the predetermined value by the adding means every predetermined period. The values are added one by one and stored in the storage means, and while the illumination lamp is off, the set value stored in the storage means is subtracted by a predetermined subtraction value by the subtraction means and stored in the storage means every predetermined period. Then, when the set value stored in the storage means exceeds a predetermined value, the cooling fan is driven to rotate for a predetermined period, so that a price increase due to the addition of new parts is not caused, The temperature inside the optical unit can be controlled stably.

According to the second aspect of the invention, the subtraction value subtracted by the subtraction means during the period when the cooling fan is rotationally driven is set to a value larger than the subtraction value during the period when the cooling fan is stopped. Therefore, the temperature when the optical unit is cooled can be controlled more stably.

According to the third aspect of the present invention, when the document reading device and the image forming device are turned on again, the temperature of the fixing roller stored in the storage means and the temperature detection means actually detect the temperature. According to the difference in the temperature of the fixing roller, the setting value stored in the storage unit is subtracted and stored in the storage unit.Therefore, the temperature detection unit of the fixing roller included in the image forming apparatus is used. By predicting the cooling state of the optical unit during the power-off period even when the power is turned on again, the temperature inside the optical unit can be controlled stably.

According to the invention described in claim 4, when the power of the document reading device is turned on again, the time when the power stored in the storage means is cut off, and the time measuring means actually measures the time. Since the set value stored in the storage means is subtracted and stored in the storage means in accordance with the difference in the time, the time measurement means provided in the control means is used to turn on the power again. By predicting the cooling state of the optical unit during the power-off period, the temperature inside the optical unit can be controlled stably.

According to the fifth aspect of the invention, the subtraction value subtracted by the subtraction means is set to a smaller value in accordance with the operation amount determined by the operation amount determination means. It is possible to perform fine temperature control in the optical unit in consideration of deterioration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of overall control of a copying machine according to a first embodiment of the present invention.

FIG. 2 is a graph showing changes in temperature and counter value in the optical unit with respect to time when a continuous copying operation is performed with the cooling fan stopped.

FIG. 3 is a graph showing changes in the temperature inside the optical unit and the temperature detection value of the fixing thermistor with respect to the time after the end of the copying operation.

FIG. 4 is a flowchart of setting a counter value when the power is turned on.

FIG. 5 is a flowchart of cooling fan drive control.

FIG. 6 is a flow chart of setting a counter value during standby.

FIG. 7 is a flowchart of setting a counter value during a copying operation.

FIG. 8 is a table showing a modified registration value determination data table.

FIG. 9 is a flow chart of setting a counter value at power-on according to the second embodiment of the present invention.

FIG. 10 is a flow chart of setting a counter value during standby.

FIG. 11 is a graph showing a specific example of temperature control of the optical unit in association with actual measurement values.

[Explanation of symbols]

 1 System Controller (SCON) 2 Operation Unit / Power Supply CPU 3 Scanner (SC) CPU 4 Nonvolatile RAM 8 Fixing Heater 9 Fixing Thermistor 10 Fan Motor 11 Halogen Lamp 12 Original Size Sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 1/04 101 7251-5C

Claims (5)

[Claims] 1. A document is provided inside a document reading device provided with an illumination lamp which is driven to scan along the document surface while illuminating the document surface, and the heat emitted by the illumination lamp is convected by a cooling fan. In a cooling control device of a document reading device for controlling a cooling device of a document reading device to be dissipated, storage means for storing a set value, addition means for adding the set value stored in the storage means, and the storage means The subtraction means for subtracting the stored set value and the set value stored in the storage means are added by the predetermined addition value by the addition means every predetermined period while the illumination lamp is turned on. Stored in the storage means, and while the illumination lamp is off, the set value stored in the storage means is subtracted by a predetermined subtraction value by the subtraction means in the storage means every predetermined period. Record In addition, when the set value stored in the storage means exceeds a predetermined value, the original reading apparatus has a control means for controlling the rotation of the cooling fan for a predetermined period. Cooling control device. 2. The control means sets the subtraction value subtracted by the subtraction means during the period when the cooling fan is rotationally driven to a value larger than the subtraction value during the period when the cooling fan is stopped. Item 3. A cooling control device for a document reading device according to item 1. 3. A temperature detecting means for detecting a temperature of a fixing roller of an image forming apparatus for forming an image read by a document reading apparatus on a recording paper, and a memory means, together with a set value, detected by the temperature detecting means. The temperature of the fixing roller is also stored, and the storage function is maintained even when the power supply of the document reading device and the image forming apparatus is cut off. When the power supply of the document reading device and the image forming device is turned on again,
The control means sets the set value stored in the storage means in accordance with the difference between the temperature of the fixing roller stored in the storage means and the temperature of the fixing roller actually detected by the temperature detection means at that time. 2. The cooling control device for a document reading apparatus according to claim 1, wherein control is performed so that the subtraction is performed and the result is stored in the storage unit. 4. A time measuring means for continuously measuring time even when the power source of the document reading apparatus is cut off, and a storage means, together with a set value, a time measured by the time measuring means when the power source is cut off. When the power source of the document reading device is turned on again, the control means measures the time when the power source is shut off, which is stored in the storage means, and the time measuring means actually measures the time. The cooling control device for a document reading apparatus according to claim 1, wherein control is performed such that the set value stored in the storage unit is subtracted and stored in the storage unit according to a time difference. 5. An operating amount determining means for determining an operating amount of an image forming apparatus for forming an image read by a document reading device on a recording sheet, wherein the control means responds to the operating amount determined by the operating amount determining means. 2. The cooling control device for a document reading apparatus according to claim 1, wherein the subtraction value set by the subtraction unit is set to a smaller value.