JPH026977A - Image scanner - Google Patents

Abstract

PURPOSE:To appropriately suppress the raise of the temperature of an original platen by predicting the raise of the temperature of the original platen based on an original scanning mode, a value detected by a temperature sensor detecting the temperature of the original platen and various types of data obtained from a scanner, and driving and controlling a cooling means according to the prediction. CONSTITUTION:Based on the original scanning mode, the value detected by the temperature sensor 26 detecting the temperature of the original platen 1 and various types of temperature-raise-related data obtained from the scanner, the raise of the temperature of the original platen 1 is predicted, and the cooling means, a cooling fan 27 in this embodiment, is driven and controlled according to the prediction. As a result, noise is reduced in a normal operating mode, while in a special mode, cooling ability is improved by accelerating the rotation of the cooling means to appropriately suppress the raise of the temperature of the original platen.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an image scanning device used in a copying machine, an image processing apparatus, a facsimile machine, etc. Regarding temperature rise prevention technology for glass).

[Prior Art] Conventionally, in copying machines, etc., originals are placed on a glass platen,
Since the document is illuminated from below by the illumination lamp, the temperature of the document table glass tends to rise. However, in such an apparatus, the temperature of the document table is not allowed to rise above a certain temperature, as stipulated in the safety standards of the Electrical Appliance and Material Control Law, primarily to maintain the safety of the user.

Therefore, in conventional devices, the air flow rate (rotation speed) of the cooling fan and various control amounts of the document scanning system (optical system) are determined in advance in order to satisfy the above safety standards in the operating mode where the temperature of the document table is the highest. Ta.

[Problem to be Solved by the Invention 1] However, in the copying mode that is normally frequently used, the temperature of the document table does not rise that much, and there is a considerable margin with respect to the temperature specified in the above-mentioned stability standard. Nevertheless, conventional devices are based on operating modes with severe temperature conditions as described above, so they sacrifice optimal control of cooling fans, etc. in normal operating modes for the sake of this very special operating mode. There was a drawback that there was.

For example, the temperature of the document table generally increases significantly when a large number of copies are made continuously in the enlargement mode, but even in this case, the temperature increase is not a problem if the number of copies is small.

However, assuming that originals are changed one after another and copied continuously, control is necessary to prevent temperature rise problems even when making a large number of copies, even if the copy mode is for a small number of copies. There must be.

However, the operating noise of the cooling fan in particular is annoying, and if it is always rotated at maximum speed, the noise of the entire device increases.

Therefore, the present invention eliminates the above-mentioned drawbacks and makes it possible to make the device as low as possible in the normal operating mode,
Another object of the present invention is to provide an image scanning device that can perform image scanning with optimal control no matter what operating mode (original scanning mode) it is in.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an image scanning device that reads and scans a document placed on a document table.
A cooling means for cooling the document table; a prediction means for predicting a temperature rise of the document table based on at least one of the operation mode of reading scanning and data obtained from within the apparatus during scanning; and prediction by the prediction means. The present invention is characterized by comprising a control means for driving and controlling the cooling means according to the result.

[Function 1] With the above-described configuration, the present invention is based on the operation mode for document scanning, the detected value of the temperature sensor 6 that detects the temperature of the document table, or various data obtained from within the device related to the temperature rise of the document table. The system predicts the upper temperature limit of the document table and controls the cooling means (such as a cooling fan) according to this prediction, so it is quiet in normal operation mode and quiet in special mode. Since the rotational speed of the cooling means is increased, the cooling capacity is increased and the rise in temperature of the document table can be appropriately suppressed.

〔Example〕

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

FIG. 1(8) shows the basic configuration of an embodiment of the present invention.

In this figure, a denotes a cooling means (for example, a cooling fan) that cools at least the document table in an image scanning device that reads and scans a document placed on a document table. b is a prediction means for predicting the temperature rise of the document table based on at least one of the operation mode of the reading scan (for example, each fffi copy mode) and data obtained from within the apparatus in conjunction with the scan; be. Control means C drives and controls the cooling means a according to the prediction result of the prediction means A.

The data used for the prediction is, for example, the detected value of the temperature detection means (temperature sensor) that detects the temperature of the document table, the operation time and stop time (calculated values) of the reading scan, and the set output density. It is characterized in that it is at least one of a value or a supply voltage value to a lamp for document illumination.

FIG. 1(B) shows the internal structure of a copying apparatus according to an embodiment of the present invention. In this figure, an original on an original platen glass (original platen) 1 is illuminated by an illumination lamp 2 and an auxiliary reflector 3, and the reflected light from the original 1 passes through a slit 4 into a first.
Second. Third. The fourth mirrors 5, 6, 7.8 and the zoom lens 9 expose the photosensitive drum 10, which is the recording medium of the image forming means. These lighting lamps 22 reflectors 3
゜Slit 4. 1st. The second mirror 5.6 and the zoom lens 9 constitute the original scanning system (original scanning optical means) of this embodiment.

The photosensitive drum IO, which rotates at a constant speed, is uniformly charged by a negative charger 11 and then subjected to image exposure, and charges in non-image areas are erased by exposure from a blank exposure lamp 12. Thereafter, the electrostatic latent image on the photoreceptor drum IO is visualized by the developing device 13, and this visualized image is transferred to the cassette 1.
The image is transferred onto a transfer material (paper) 17 fed by a paper feed roller 15 and a registration roller 16 from the transfer roller 11F by being charged by a transfer 11F electric device 18.

The transfer material 17 on which the image has been transferred is conveyed by a conveyor belt 19, fixed by a fixing device 20, and discharged onto a tray 22 by a discharge roller 21.

After the transfer, the photosensitive drum 10 is charged with residual toner by a charger 23, cleaned by a cleaner 24, and roughly removed by an erase lamp 25 to prepare for the next copying.

Reference numeral 26 denotes a temperature sensor (temperature detection means) arranged inside the document table glass 1 outside the image scanning area to detect the temperature of the document table glass 1. Reference numeral 27 designates a cooling fan (cooling means) that cools the document table glass 1 and the entire document scanning system, 35 a stepping motor that drives the document scanning system, and 37 a main motor that drives the photosensitive drum 10 and the like.

FIG. 2 shows the circuit configuration of the control system of the copying apparatus shown in FIG. 1(B). In this figure, numeral 30 constitutes the control means and prediction means of the present invention, and is a control section that controls the entire apparatus, and includes a CPU (central processing unit) using a microcomputer, and FIGS. , a ROM (read only memory) storing control procedures according to the present invention as shown in FIG. 6, a RAM (random memory) used as a work area, etc. are built in. Reference numeral 31 denotes an operation unit for performing various keys such as a copy start key and a manual magnification key and various displays, and reference numeral 32 denotes the above-mentioned temperature sensor 26 and the transfer material 1.
7, various sensors (detectors) necessary for process control such as position detection, temperature detection of the fixing device 20, and document density.

34 is a drive circuit that drives a stepping motor 35 for driving the document scanning system, and 36 is a control unit that performs PLL control of a main motor (DC motor) 37 that drives the photoreceptor tram IO and the like. The control section 36 changes the rotation speed of the main motor 37 depending on the reference clock signal output from the CPU of the control section 3G. Further, 33 is an FV (frequency-voltage) conversion circuit that rotationally drives the cooling fan 27 at a speed corresponding to the voltage output from the control section 30.

A. Embodiment 1 Next, the operation procedure of the control section 30 according to the embodiment of the present invention will be described with reference to the flowchart of FIG. This flowchart is a control task (task program) that is activated whenever the main unit is powered on. In this embodiment, as described below, the temperature rise of the document table glass 1 is predicted based on the temperature detected by the temperature sensor 26, and the rotation speed of the cooling fan 27 is controlled to be changed in stages from 7 to the maximum speed. It is.

When the power is turned on, the process first proceeds to step 3-1, and it is determined whether or not a copying operation is in progress (copying in progress). If copying is in progress, the process proceeds to step 3-2; if copying is not in progress, step 3-1 is performed.
At step 7, turn off the cooling fan 27 and stop it.

In step 3-2, the detected value (detected temperature) T read from the temperature sensor 26 is compared with a predetermined upper limit temperature value X set in advance. It is preferable to set the value of X to a value several percent lower than the temperature specified by safety standards, for example.

If the temperature T detected by the temperature sensor 25 is higher than the predetermined value X, the process proceeds to step 3-5, where the cooling fan 27 is rotated at the maximum speed, and the process returns to step 3-1. Here, the rotational speed of the cooling fan 27 is controlled by changing the frequency of the clock signal 8 outputted from the control section 30 to the FV conversion circuit 33. For example, the higher the frequency of the clock signal 38, the cooler the cooling fan 27 is. The fan 27 rotates at high speed,
If you set it low, it will rotate at a low speed.

On the other hand, if the temperature T detected by the temperature sensor 26 is lower than the predetermined value X, the process moves to step 3-3, where the temperature T detected by the temperature sensor 26 is compared with a predetermined lower limit temperature y. It is assumed that y<<) (.If the detected temperature T is higher than the predetermined value y, proceed to step 3-6, rotate the cooling fan 27 at a medium speed, return to step 3-1, and perform the detection If the temperature T is lower than the predetermined value y, proceed to step 3-4 and rotate the cooling fan 27 at a low speed.
Return to step 3-1.

In this way, the rotational speed of the cooling fan 27 is appropriately controlled through the FV conversion circuit 33 according to the detected value of the temperature sensor 26, so that the cooling fan 27 rotates at the lowest speed in the normal operating mode. Therefore, the generated noise can be suppressed to a low level, and the temperature rise of the document table glass 1 can be suppressed by rotating the cooling fan 27 rapidly only in a very special operation mode. In this embodiment, the rotational speed of the cooling fan 27 is shown in three stages: high, medium, and low; however, the present invention is not limited thereto, and the set value (x) to be compared is used.

Of course, it is also possible to increase y) for finer control.

B. Embodiment 2 In the above-mentioned Embodiment 1, program control is performed by the CPU of a microcomputer, so relatively fine control is possible. However, the present invention is not limited to this, and an analog circuit as shown in FIG. It can be configured using only hardware.

In FIG. 4, Ql is a comparator, and R2, R3 and R4 are transistors. Further, Sl is a detection signal from the above-mentioned temperature sensor 26, and the comparator Ql compares the level of the signal Sl with the reference voltage v0 generated by the resistors R1, [2, and based on the comparison result, the transistor Q2 Turn ON or OFF.

That is, when SL>Vo, transistor q2 is turned on. Depending on whether this transistor Q2 is turned on or off, the subsequent transistor Q3 is also turned on or off. The driving voltage applied to the cooling fan 27 by turning on and off the transistor Q3 is V or Vl (assuming Vl>Vl)
becomes. Further, the transistor Q4 is turned ON or OFF by the cooling fan 0N10FF signal S2, which is also a signal indicating that the copy operation is in progress, and starts or stops the cooling fan 27.

With the above circuit configuration, the cooling fan 27 maintains the temperature detected by the temperature sensor 26 (S1) during the copy operation (while the fan is rotating).
It is driven with a driving voltage of vl or V depending on the voltage. Therefore, by appropriately setting the resistance values of the resistors R1 and R2 and the values of the drive voltages V, Vl, etc. according to the characteristics of each device, it is possible to achieve the same optimal control operation as in the above embodiment. It becomes possible to obtain.

C0 Embodiment 3 Next, an embodiment of the present invention in which the cooling fan 27 is controlled according to the operating time will be described.

The operation time of the copying operation depends on the copying size (dimensions of the transfer material 17)
, if the copy magnification is the same, it can be determined by the number of copies. Therefore, an example in which the copy size is A4 (print) and the copy magnification is 100% will be described below.

As the number of copies increases, the lighting time of the halogen lamp 2 for document illumination also increases proportionally. That is, there is a proportional relationship between the number of copies and the temperature rise of the document table glass 1. Therefore, the driving voltage of the cooling fan 27 is first switched depending on whether or not the number of copies is continuous copying of 10 or more sheets. Further, the longer the stop time of the document scanning device is, the colder the document table glass 1 becomes, so the stop time and the temperature of the document table glass 1 are inversely proportional.

Therefore, the driving voltage of the cooling fan 27 at the time of the next copying is changed depending on whether the apparatus is stopped for more than 5 minutes or less than 5 minutes.

An example of the operation for controlling the drive of the cooling fan 27 based on the above criteria will be described with reference to the flowchart in FIG.

The Kiguchi movement is the movement at the start of copying.

First, in step 5-1, it is determined whether a five-minute timer that is always started when the copying operation is stopped is counting up. Here, if the determination is negative, the number of copies of this copy operation is 1 in the next step 5-2.
It is determined whether the number is 0 or less. If the judgment is negative here, the stop time is within 5 minutes and the number of copies is 10 or more, so
Proceeding to step 5-3, the driving voltage of the cooling fan 27 is set to the highest level, and the copying operation begins in step 5-7.

If the above step 5-1 is affirmative, it means that the copy operation has been stopped for 5 minutes or more, so step 5-4
Then, it is determined whether the number of copies is equal to or less than 0 per month. If the determination is negative, the stop time is 5 minutes or more and the number of copies is 10 or more, so proceed to step 5-5, set the driving voltage of the cooling fan 27 to the middle level, and then step 5-7.
to start copying operation.

If the above step 5-4 is affirmative, the stop time is 5.
Since the number of copies is more than 10 minutes and the number of copies is 10 or less, the process proceeds to step 5-6, sets the driving voltage of the cooling fan 27 to the lowest level, and performs the copying operation of step 5-7.

The above control operation makes it possible to suppress the rise in temperature of the document table glass 1 to within an appropriate temperature range.

D. Embodiment 4 Next, an embodiment of the present invention in which the cooling fan z7 is controlled according to the operation mode will be described.

There are various operating modes related to document scanning, and it would be complicated to describe all the cases, so here we will focus on the copy magnification and document illumination halogen lamp 2, which have the greatest effect on the temperature rise of the document table. Control regarding two modes of lighting voltage will be described.

First, regarding the copy magnification, the larger the copy is, the slower the original scanning speed of the original scanning system becomes, and the shorter the scanning distance becomes. Therefore, the temperature of the document table glass 1 near the home position of the document scanning system increases rapidly.

Furthermore, when attempting to reduce the copy density, the temperature of the halogen lamp 2 increases in order to increase its lighting voltage, and the temperature of the original platen glass 1 increases accordingly. For example, if the target range of the copy density setting switch (not shown) on the operation unit 31 is set from Fl to F9, the standard density is F5, and in the case of a device with a power supply voltage of 100μ, the halogen lamp at F5 The lighting voltage is 65V
And the lighting voltage is 82.2V for Fl,
At F9 it is 70.2V.

Therefore, please refer to the flowchart in FIG. 6 for an example of the operation of switching the drive of the cooling fan 27 depending on the operation mode of whether the copy is enlarged by 120% or more and whether the lighting voltage of the halogen lamp 2 is 67V or more. and explain.

The cutting edge operation is performed at the end of the copying operation as in the case of FIG.

First, in the first step 6-1, it is determined whether the magnification of the enlarged copy is 120% or more. If the determination is affirmative here, the process moves to the next step 6-2, and it is determined whether the lighting voltage of the halogen lamp 2 is 67V or higher. If the determination is affirmative here, the copy is enlarged by 120% or more and the lighting voltage is 67V or more, so the process proceeds to step 6-3 and the driving voltage of the cooling fan 27 is set to the highest set voltage. Thereafter, the process moves to the copy operation in step 6-6.

If the above step 6-2 is negative, this means that the copy is enlarged by 120% or more and the lighting voltage of the halogen lamp 2 is 67 V or less, so the process proceeds to step 6-4 and the cooling fan 27 is Set the drive voltage to the medium setting voltage. Thereafter, the process moves to the copy operation in step 6-6.

Further, when the above-mentioned step 6-1 makes a negative determination, the magnification ratio is 120% or more and the lighting voltage of the halogen lamp 2 is 67 V or less, so the process proceeds to step 6-5 and the cooling fan 27 is driven. Set the voltage to the lowest setting voltage. Thereafter, the copy operation of step 6-6 is performed.

[Effects of the Invention] As described above, according to the present invention, the operation mode of document scanning, the detected value of the temperature sensor that detects the temperature of the document table, or the value obtained from within the device related to the temperature increase of the document table is determined. The system predicts the temperature rise of the document table based on the various data received, and controls the cooling means (e.g. cooling fan) according to this prediction, which reduces noise and makes the machine quieter in normal operation mode. In addition, in the special mode, the rotational speed of the cooling means is increased, so that the cooling capacity is increased and the temperature rise on the document table can be appropriately suppressed.

[Brief explanation of the drawing]

FIG. 1 (8) shows the basic configuration of the embodiment of the present invention.
7 [2] 0-i/'f IfJ', FIG. 1 (B) is a sectional view showing the internal structure of the copying apparatus according to the embodiment of the present invention, and FIG. 2 is the embodiment of the present invention shown in FIG. 1 (11). Figure 3 is a block diagram showing the circuit configuration of the control system of the present invention.
Figure 4 is a circuit diagram showing a control circuit of another embodiment of the wooden invention, and Figures 5 and 6 are flowcharts 1 and 6 respectively showing the operating procedure of still another embodiment of the wooden invention. . DESCRIPTION OF SYMBOLS 1... Original table glass, 26... Temperature sensor, 27... 7-control fan, 30... Control part, 31... Operation part, Ql... Comparator, Q2. Q3. Q4...Transistor. Figure 1 (A) Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1) An image scanning device that reads and scans a document placed on a document table, comprising: a cooling means that cools the document table; and a control means for driving and controlling the cooling means in accordance with the prediction result of the prediction means. Characteristic image scanning device. 2) The data used by the prediction means for prediction includes the detection value of the temperature detection means for detecting the temperature of the document table, the operation time and stop time of the reading scan, and the set output density value or document illumination lamp. 2. The image scanning device according to claim 1, wherein the voltage supplied to the image scanning device is at least one of the voltage values supplied to the image scanning device.