JP2538209B2 - Image forming device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a document illumination lamp for certifying a document while moving relative to the document, and an optical system for forming an image of the document by illumination by the lamp. A detection means for detecting the size of the original by comparing the level of the reflected light obtained by the illumination by the original illumination lamp with a predetermined level, and illuminating the original with the original illumination lamp, The present invention relates to an image forming device in which the size of a document is detected by the detecting means prior to an image forming operation for forming an image by forming an image by the optical system.

2. Description of the Related Art Generally, in a copying machine, since the copy magnification is set according to the size of the original, the size of the original is automatically detected by the above-mentioned detecting means. Various types of image forming devices have been proposed as image forming devices employing such a document size detection method.
In any of these formats, the original illumination lamp illuminates the original, and the reflected light obtained by the original illumination lamp is detected before performing the image forming operation in which the image of the original is formed by the optical system. The size of the document is detected by guiding the reflected light level to a predetermined level, and an image forming operation is performed according to the detection result.

Here, conventionally, when the original illumination lamp is turned on to detect the original size, the lamp voltage is kept constant so that the brightness of the original illumination lamp is kept constant so that the amount of reflected light becomes constant. Was in control.

Therefore, for example, in a copying machine in which the copy density is changed depending on the amount of light when illuminating a document to form an image, the brightness of the document illumination lamp is detected during the document size detection and during the image forming operation. That is, complicated control of switching the lamp voltage is required. Also, after detecting the document size,
If the original image is immediately formed and the copy operation is performed, if there is a large difference between the lamp voltage at the time of detecting the original size and the lamp voltage at the copy operation, the lamp voltage overshoots when switching. As a result, instability of the brightness control of the lamp is caused, and the image forming operation is adversely affected.

OBJECT The object of the invention is to provide an actuating device of the type described at the outset, which eliminates the above-mentioned disadvantages of the prior art.

To achieve the above object, the present invention controls the brightness of the original illumination lamp to be constant in the image forming apparatus of the type described at the beginning when detecting the original size and during the subsequent image forming operation. If the brightness of the original illumination lamp during image formation is changed to adjust the image density,
There is provided an image forming apparatus including control means for controlling so as to change the predetermined level in the detection means when detecting the original size according to the changed brightness of the original illumination lamp.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a basic configuration example of an image forming apparatus to which the present invention is applied will be clarified.

In the image forming apparatus shown in FIGS. 1 to 3, the document 1 is placed on the contact glass 2 as a document table at the reference position P _0.
Is set with reference to and is pressed by the document cover 3.
During the image forming operation, the document 1 is illuminated and scanned by a scanner 7 equipped with a reflecting mirror 4, a document illumination lamp 5 that illuminates the document in the width direction, and a first mirror 6, and the reflected light from the document 1 is first scanned. An electrostatic latent image is formed by forming an image on a photoconductor (not shown) through the mirror 6, the second mirror 8 and a lens (not shown). The scanner 7 is connected to a drive wire 11 that is wound between pulleys 9 and 10, and according to a drive pulley 13 that is rotated by a drive motor 12, illuminates and scans one surface of a document from a reference position P ₀ side at a predetermined speed, and thereafter. , Return operation to the reference position P ₀ side. In this way, the document illumination lamp 5 moves relative to the document 1 and proves the document 1. The mirrors 6 and 8 and the lens form an optical system that forms an image of the original 1 by the certification by the original certification lamp 5. In this way, the image forming device executes the image forming operation by forming the image of the document by the optical system.

Here, in this embodiment, as shown in FIG. 2, a central reference method is adopted in which the original 1 is set with reference to the center mark 14 provided at the reference position P ₀ of the contact glass 2.
Also, in FIG. 2, the type of original used is A size, and A3 original 1a, A4 portrait original 1b, A4 landscape original 1c, A5 portrait original 1d, A5
A document 1 of any one of five types of horizontal document 1e is set.

Thus, the scanner 7 is equipped with a plurality of optical sensors 15a and 15b which are constituent elements of the detecting means 15 for detecting the document size. These optical sensors 15a and 15b detect the reflected light from the document 1 using the document illumination lamp 5 as a light source, and a slit 4a is formed in a part of the reflecting mirror 4. As described above, the detection means 15 has two optical sensors 15a and 15b such as photodiodes, and these optical sensors 15a and 15b are arranged at predetermined positions in the width direction of the document 1 with a space therebetween. , Pulley 9,10, drive wire 11
And a driving unit composed of a driving motor, and is supported so as to scan and move with respect to the document surface.

One optical sensor 15a is used for determining the amount of movement from the reference position P ₀ , and is arranged on the center reference line, that is, the line of the center mark 14. The other optical sensor 15b is used for determining the width of the document, and receives the reflected light from the edge of the A3 document 1a or the A4 landscape document 1c, but the A4 portrait document 1b, the A5 portrait document 1d and the A5 landscape document 1e. It is arranged at a position where the reflected light from is not received.

For these optical sensors 15a and 15b, as shown in FIG. 3, the light receiving range of the reflected light from the original 1 is reduced,
In order to improve the accuracy of size detection, for example, the range of reflected light that can be received by the light-shielding pipe 16 whose inner surface is black is attached and the like is restricted.

The detection unit 15 has a comparison unit (not shown) corresponding to each of the optical sensors 15a and 15b in addition to the above-described optical sensors 15a and 15b, and the amount of reflected light received by each of the optical sensors 15a and 15b is preset. The output of the comparison means turns ON when the amount of light is greater than the set reference light intensity, and OF when the amount of light is less than the reference light intensity.
F Considering this with or without the original 1, when the output of the comparison means is ON, it corresponds to the state where the original 1 is present (the state where the reflected light from the original 1 is received), and when it is OFF, it corresponds to the state where the original 1 is not present. . In this way, the detection unit 15 detects the size of the document 1 by comparing the level of the reflected light obtained by the illumination of the document illumination lamp 5 with a predetermined level. Hereinafter, a specific configuration example will be described.

An encoder 20 is connected to the drive motor 12. As a result, the encoder accompanying the rotation of the drive motor 12
The output pulse number of 20 is counted by a counter (not shown), and the movement amount 1 of the scanner 7 (and therefore the optical sensors 15a and 15b) from the reference position P ₀ is measured from the counted number when the output of the optical sensor 15a changes. A conversion unit (not shown) for converting the document length into a document length is provided.

The document size is detected by preliminary scanning of the scanner 7 prior to the start of the copying operation. That is, the scanner 7 performs preliminary scanning from the reference position while turning on the document illumination lamp 5. Here, consider a case where an A4 landscape original 1c is set on the contact glass 2, for example. In this case, at the reference position P ₀ , both the optical sensors 15a and 15b receive the reflected light from the original document 1c, and the output of each comparison means is turned ON. Then, the number of output pulses of the encoder 20 increases as the scanning of the scanner 7 progresses, and when the scanning of the scanner 7 reaches the end of the document 1c, the document 1c disappears and each optical sensor 15
Both outputs from the comparing means a and 15b are switched from ON to OFF. At this point, the output of the optical sensor 15a has changed, so that the counting of the number of output pulses from the encoder 20 is stopped and the movement amount l ₃ of the scanner 7 (optical sensors 15a, 15b) from the reference position P ₀ at that time is stopped. Is converted to. Original 1 set from the value of this movement amount l ₃ is A4
It is tentatively determined to be either the horizontal document 1c or the A5 portrait document 1d. However, at this point, the optical sensor for determining the original width
At the same time, in 15b, the output from each comparison means changes from ON to OFF. As a result, since the document width is A4 width, it is determined that the set document 1 is A4 width document 1c.

If the A5 landscape original 1d is set on the contact glass 2, the comparison means output of the optical sensor 15a is O.
When it is changed from N to OFF, it is tentatively determined that it is either the A4 landscape original 1c or the A5 landscape original 1d.
Is the same as when is set, but the optical sensor 15
Since the output of the comparison means of the optical sensor 15b has not changed at the time when the output of the comparison means of a has changed, it is determined that the combination of the outputs is A5 portrait original 1d in this case.

In this way, the movement amount l of the scanner 7 (optical sensors 15a, 15b) converted and calculated by the output change of the optical sensor 15a
Which size of the A1 original 1a, A4 portrait original 1b, A4 landscape original 1c, A5 portrait original 1d, A5 landscape original 1e is set depending on the combination of the output state of the optical sensor 15b at that time Can be determined. That is, the document size is determined based on the document width detected by using the optical sensor 15b and the document length converted by the conversion unit. More specifically, in this document size detecting device, the first movement amount (document length) from the reference position P ₀ at the time when the output of the comparing means of the optical sensor 15a changes from ON to OFF according to each document is
As shown in the figure, if l ₁ , l ₂ , l ₃ and l ₄ are set, it is determined as shown in the following table depending on whether the comparison means output of the optical sensor 15b is ON or OFF.

Size measurement table Case Moving amount Optical sensor 15b Size judgment l ₁ ON A3 original l ₂ OFF A4 portrait original l ₃ ON A4 landscape original l ₃ OFF A5 portrait original l ₄ OFF A5 landscape original In this way, according to this embodiment, By using the two optical sensors 15a and 15b that receive the reflected light from the original 1, the size of the five originals 1a to 1e can be determined, the detection mechanism is simplified, and the cost is low. Become.

In the present embodiment, the case where only the A version of the original 1 is described, but in the case where it is also used for the B version of the original, an optical sensor for determining the width of the B version of the original corresponding to the optical sensor 15b. You just need to add one.

When detecting the document size by the preliminary scanning of the scanner 7, as the return operation method of the scanner 7, two methods can be adopted. The first method is a method in which even after the document size is detected, scanning is performed for the maximum scanning length determined by the machine, and then a return operation is performed to the reference position P ₀ to set the copying operation standby state. is there. The second method is
If the document size is detected in the preliminary scan (optical sensor
When the output of the comparison means of 15a changes from ON to OFF), the scanner 7 is stopped and the scanner 7 is immediately returned from the position to the reference position P ₀ to be in the standby state for the copying operation. The first method has an advantage that the operation control system of the scanner 7 can be simplified, and the second method has an advantage that the time required for the preliminary scanning of the scanner 7, that is, the time required for detecting the document size can be shortened. Especially, in the case of a small size original such as an A5 original, the time can be shortened significantly.

Further, in the above description as the document size detection method,
In the preliminary scanning, the document size is detected when the scanner 7 scans away from the reference position P ₀ , but it may be detected by moving in the opposite direction. That is, the document size is detected when the scanner 7 is in the scanning direction in which it returns from the maximum scanning position to the reference position P ₀ . In this system, by giving a size detection instruction from a scanning panel (not shown), the scanner 7 moves to the maximum scanning position and waits for the next instruction. Then, the scanner 7 starts scanning toward the reference position P ₀ according to the next instruction such as start of copying, and detects the document size during the movement. Also in this method, the positions of the optical sensors 15a and 15b are the same as in the case described above, but the operating states thereof are opposite. The maximum scanning amount is predetermined by the machine (therefore, the encoder 20 corresponding to the maximum scanning amount is
The number of output pulses is also determined.) Therefore, the document size (length) can be easily calculated by subtracting the moving length of the scanner 7 from the maximum scanning amount.

As described above, in the image forming apparatus of this example, the detection unit 15 that detects the size of the document compares the level of the reflected light obtained by the illumination of the document illumination lamp 5 with a predetermined level to determine the size of the document. Is detected, and the size of the document is detected by the detection means 15 prior to the image forming operation in which the document illumination lamp 5 illuminates the document and the image of the document is formed by the optical system. Is configured to detect.

In the image forming device shown in FIG.
The detection means 31 is a combination of the optical sensor 15a and the optical sensor 15b. One end of the optical fiber 30 serves as a light introducing portion 30a and is supported by the scanner 7 so that the reflected light from the document 1 can be introduced into the optical fiber 30. The optical sensors 15a and 15b are arranged in the fixing portion 32 of the device, and are optically connected to receive the light transmitted by the optical fiber 30 from the other end of the optical fiber 30. The optical fiber 30 is provided for each of the optical sensors 15a and 15b. The other structure and its basic operation are the same as those of the embodiment shown in FIGS. 1 to 3, and it is the same that the document size is detected by the detecting means 31 prior to the image forming operation. . In the configuration example shown in FIG. 4, since the scanner 7 is not equipped with the optical sensors 15a and 15b, the optical sensors 15a and 15b are not affected by the thermal effect of the document illumination lamp 5 and the temperature drift of the sensor. Is greatly reduced,
The reliability of size detection is improved.

Further, in the case of the configuration example shown in FIG. 4, by providing the lens 33 in the light introducing portion 30a of the optical fiber 30 as shown in FIG. 5, the reliability of the document size detection can be further improved. For example, from the tip of this lens 33 to the original 1
When the distance to the surface is set to 5.5 mm and the lens 33 having an outer diameter of 3 mm is used, the document size detection accuracy can be set to 1 mm. In this case, it is possible to discriminate up to a document length difference of 1 mm. In this respect, without using the lens 33, the optical fiber
The detection accuracy is 3 to 4 mm when the distance between the tip of the light introducing portion 30a of 30 and the surface of the original 1 is set to 5.5 mm. Also, optical fiber 3
Since 0 is used, the optical sensors 15a and 15b are not affected by the heat of the document illumination lamp 5.

By the way, in most copying machines of recent years, the image density of a copy is changed by changing the brightness of the original illumination lamp, that is, the lamp voltage. In such a copying machine, when detecting the document size as described above,
Not only does it require extra control to switch the lamp voltage to a voltage different from when the original is illuminated, but if the copy operation is performed immediately after the original size is detected, the lamp voltage during original size detection If the difference between the lamp voltage during the copy operation and the lamp voltage during the copy operation is large, there is a problem in that the lamp brightness control becomes unstable due to overshoot of the lamp voltage and the copy image is adversely affected at the time of switching. .

Therefore, in this example, the image forming apparatus having the above-described configurations is configured so that the original size can be detected without changing the lamp voltage during the original size detection and during the copy operation. That is, the control unit (not shown) controls the brightness of the document illumination lamp 5 to be the same when detecting the document size and during the subsequent image forming operation. More specifically, in a copying machine of the type in which the image density of a copy is changed stepwise to multiple levels by changing the voltage of the original illumination lamp, while the original voltage is maintained, the original The size is detected. by this,
It is possible to eliminate the adverse effects caused by switching the lamp voltage as described above.

However, in that case, the original illumination lamp 5 at the time of copying
If the brightness of the original is changed and set, the lamp voltage at the time of the operation of detecting the original size, that is, the brightness of the original illumination lamp will be different accordingly. There is a risk that it will not be obtained. Therefore, if a plurality of levels of detection detection levels for the presence or absence of a document are provided to the comparison means side of the detection means 15 and 31 with respect to the reflected light of multiple levels of lightness, the problem is solved. Therefore, the size of the original can be accurately detected.

Since the reflected light is large when the original illumination lamp is bright (when the copy density is low), increase the predetermined judgment level voltage in each comparison means of the detection means 15 and 31 when detecting the original size. If it is dark (when the copy density is high), the control such as lowering the predetermined determination level voltage when detecting the document size may be performed. When the brightness of the original illumination lamp is adjusted stepwise to adjust the image density, the predetermined level of each comparison means in the detection means 15, 31 is adjusted, that is, the threshold of the detection level is adjusted. It is changed step by step according to.

For example, if the output voltage for the light received by the light receiving element that constitutes the optical sensor is higher than V, it is detected that there is paper (ON), and if it is lower than V, there is no paper (OFF).
That is, what voltage is used as a threshold value, and the threshold voltage may be changed according to the switching of the lamp voltage. Such control means can be implemented by, for example, a microcomputer program or the like that can select the threshold value according to the selected concentration information.

In this way, by providing the detection means with a plurality of judgment detection levels according to the plurality of density levels, it is not necessary to switch the lamp voltage for both the original size detection and the copy operation. It is possible to eliminate the adverse effect on the image due to the overshoot or the like accompanying the lamp voltage switching.

As described above, in this example, the control unit controls the brightness of the document illumination lamp to be the same when detecting the document size and during the subsequent image forming operation, and the image density is adjusted in order to adjust the image density. When the brightness of the original illumination lamp during operation is set to be changed, control is performed so as to change the predetermined level in the detection means for detecting the original size according to the changed brightness of the original illumination lamp. Of.

Effect According to the present invention, it is possible to eliminate the need for control such as switching the brightness of the document illumination lamp between the document size detection and the image forming operation, and eliminate the adverse effect associated with the switching. In addition, it is possible to accurately detect the document size.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an embodiment of the present invention, FIG. 2 is a plan view showing dimensional relationships, FIG. 3 is a vertical side view showing an enlarged view of the vicinity of a scanner, and FIG. FIG. 5 is a side view showing a modification thereof. 1 ... manuscript, 5 ... manuscript illumination lamp, 15 ... detection means,
31 …… Detection means

Claims (1)

(57) [Claims] 1. A document illumination lamp for illuminating the document while moving relative to the document, an optical system for forming an image of the document by the illumination by the lamp, and an illumination by the document illumination lamp. A detection unit for detecting the size of the original by comparing the level of the obtained reflected light with a predetermined level, the original is illuminated by the original illumination lamp, and the image of the original is formed by the optical system. In the image forming apparatus for detecting the size of the original document by the detecting means prior to the image forming operation for forming an image, the brightness of the original illumination lamp is detected at the time of detecting the original size and the subsequent image forming operation. If the brightness of the original illumination lamp during image forming operation is changed and set to control the same and the brightness of the original illumination lamp is changed. An image forming apparatus comprising: a control unit that controls the detection unit to change the predetermined level when detecting the document size.