JPH0785181B2 - Copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a technique for increasing the copying speed at the time of continuous copying, as a part of increasing the speed of a copying machine.
The first reference density document and the second reference density document are provided on one side of the document table in the scanning direction.
A reference density original is arranged side by side in this order from the upstream side in the scanning direction, and a first detector for detecting the surface potential of the electrostatic latent image corresponding to the first reference original is provided around the photoconductor, A second detector for detecting the developing density corresponding to the second reference density original is provided, the light source light amount is controlled based on the detection result of the first detector, and the toner density is adjusted based on the detection result of the second detector. The present invention relates to an improvement of an optical system moving type copying machine configured to be controlled.

[Prior Art] In recent years, various speed-up measures have been taken in order to realize high-speed copying machines. However, due to the relationship with the power supply, it is said that speeding up is almost the limit with only these measures.

In view of such a current situation, the inventors of the present invention have studied the conventional copying machine in detail in order to further increase the speed of the copying machine, and as a result, as a result, the first reference is set on one side of the platen in the scanning direction. A density original document and a second reference density original document are arranged side by side in this order from the upper side in the scanning direction, and a first surface for detecting the surface potential of the electrostatic latent image corresponding to the first reference density original document is provided around the photoconductor. A detector and a second detector for detecting the developing density corresponding to the second reference density original document are provided, and the light source light amount is controlled based on the detection result of the first detector to obtain the detection result of the second detector. It was found that there is room for improvement in the following points in the optical system moving type copying machine configured to control the toner density based on the above.

That is, in the conventional copying machine described above, the exposure scanning start position of the optical system scanner is set below the first reference density original document (the position where exposure scanning is performed from the first reference density original document), and one copy is made. At any time, the optical system scanner starts moving from the position below the first reference density document and returns to the position below the first reference density document even when performing continuous copying of one document. Was configured.

By the way, the toner concentration (the ratio of the toner in the two-component developer consisting of toner and carrier) may fluctuate within a short period of time, so it is desirable to control it continuously and continuously. Therefore, in the current copying machine, the exposure scanning of the second reference density original is performed by the optical system scanner for each copying operation, and the exposure scanning of the second reference density original is performed each time.
Alternatively, for the purpose of saving toner consumption and reducing the load on the cleaning device, an image corresponding to the second reference density original is formed on the surface of the photoconductor at a rate of once every several exposure scans. The development density is optically detected by a detector such as a reflective photo sensor, and the toner density is controlled within a certain range by adjusting the toner supply amount to the developing device based on the detection result. ing.

On the other hand, since the change in the light amount due to the deterioration of the light source does not appear in a short period of time, the control of the light amount of the light source (so-called AVR correction) does not have to be performed for each copy operation unless the copy magnification is changed. By the way, in the current copying machine, only when a certain time or more (usually set to about 3 minutes) has passed since the end of the previous copying or when the copying magnification is changed, the first copying is performed. The AVR is corrected prior to the copying operation. In other words, by turning on the light source while the optical system scanner is stationary below the first reference density document, an electrostatic latent image corresponding to the first reference density document is created, the surface potential is detected, and the AVR is detected. Is configured to be corrected.

However, in the conventional copying machine, the exposure scanning start position of the optical system scanner is set below the first reference density original document as described above, and therefore, during the continuous copying operation, the exposure scanning of the first reference density original document is performed. The optical system scanner was designed to return to the position below the first reference density document, even though the light source light amount control (AVR correction) was not performed.

Therefore, in the above-mentioned conventional example, when continuous copying is performed, the moving path portion of the optical system scanner (the optical system scanner required for pre-scanning the first reference density original document) on the scanning direction upper side than the second reference density original document. (Path of movement)
Is irrelevant to the AVR correction and can be regarded as an unnecessary scan length during the continuous copying operation. The width of the first reference density original (width in the scanning direction) is at most several tens of millimeters at the longest, so the time required for the optical system scanner to move this portion is the copy time per sheet (one sheet). However, for example, when performing continuous copying of a large number of hundreds of sheets, the optical system scanner moves back and forth through the above-mentioned portion. It is clear that the resulting loss of time will be insignificant.

[Problems to be solved by the invention]

In view of the above-mentioned conventional drawbacks, the present invention reduces the scanning length of the optical system scanner by switching the exposure scanning start position of the optical system scanner between the start and end of the copying operation and the continuous copying operation. , It is intended to enable speeding up of continuous copying.

[Means for solving problems]

The technical means taken by the present invention to achieve the above object are as follows.

That is, according to the present invention, in the copying machine described at the beginning, the exposure start position of the optical system scanner is set to the first exposure scanning start position for performing exposure scanning from the first reference density original document at the start and end of the copying operation. On the other hand, during the continuous copying operation, a control means is provided for setting the exposure start position of the optical system scanner to the second exposure scan start position for exposure scanning from the second reference density original.

[Action]

According to the above configuration, if one copy is to be made,
The optical system scanner starts moving from the first exposure scanning start position, returns to the first exposure scanning start position, and stops, but during the continuous copying operation, the optical system scanner moves to the second exposure scanning start position. By returning, the movement in the scanning direction is started again from the second exposure scanning start position, the copying of the second and subsequent sheets is continued, and the first exposure scanning starting position is returned only when the copying of all the sheets is completed. Will stop.

〔Example〕

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

FIG. 1 is a schematic configuration diagram of an optical system moving type copying machine, FIG. 2 is a schematic configuration diagram of a main part showing an exposure scanning start position of an optical system scanner, and FIG. 3 is a movement control circuit (control) of the optical system scanner. (Means) is a flowchart executed.

In FIG. 1, 1 is a document table made of transparent glass or the like, 2
Is a document holder, 3 is an optical system of an optical system moving type, and an optical system scanner 6 including a light source 4 for slit exposure and a mirror 5,
It is composed of moving mirrors 7, 8, a fixed mirror 9, a zoom lens group 10, and the like. Reference numeral 11 is a drum-shaped photosensitive member that rotates in the direction of the arrow, and around it, a charging device 12, a developing device 13, a transfer device 14, a copy paper separating device 15, and a cleaning device 16 are arranged. Reference numeral 17 is a paper feeding / conveying device that conveys the copy paper in the paper feeding cassette 18 toward the transfer device 14, 19 is a paper ejection conveyance device that conveys the copy paper after transfer / separation to the fixing device 20, and 21 is a paper ejection tray. Is.

As shown in FIGS. 1 and 2, on one side of the document table 1 in the scanning direction, a first reference density document A and a second reference density document B are juxtaposed in this order from the upper side in the scanning direction. Has been done.
The first reference density original A and the second reference density original B
Is a suitable color (for example, the first reference density original A is gray and the second reference density original B is black), or an appropriate color is directly attached to the lower surface of one side of the original table 1 in the scanning direction. It is constructed by sticking small pieces colored in gray and black as described above.

Around the photosensitive member 11, a first detector 21a for detecting the surface potential of the electrostatic latent image corresponding to the first reference density original A.
And a second detector for detecting the development density corresponding to the second reference density original document B (as the second detector, for example, a reflection type photo sensor composed of a combination of a light emitting diode and a photo detector is used). 21b and are provided. Then, the light source light amount is controlled based on the detection result of the first detector 21a, that is, so-called AVR correction is performed, and the toner supply amount to the developing device 13 is adjusted based on the detection result of the second detector 21b. Thus, the toner density (ratio of toner in the two-component developer including toner and carrier) is controlled to be substantially constant. Reference numeral 22 denotes a blank cut lamp provided between the first detector 21a and the developing device 13, which is used for its original purpose, and the first reference density original A is applied to the first reference density original A by irradiating the photoconductor 11 with light. It is also configured to erase the corresponding electrostatic latent image. In FIG. 2, 23 is a holding plate for fixing the original table 1 to the upper surface of the copying machine main body, 24 is an original, 25 is a light source light amount control circuit, and 26 is a toner density control circuit.

In this embodiment, in the copying machine having the above-mentioned structure, the exposure scanning start position of the optical system scanner 6 is exposed from the first reference density original A at the start and end of the copying operation and during the continuous copying operation. It is characterized in that it is configured to switch between a first exposure scanning start position for performing exposure scanning and a second exposure scanning start position for performing exposure scanning from the second reference density original document B. More specifically, below the first reference density original A and below the second reference density original B, respectively,
Photo interrupters PI ₁ and PI _s for detecting the position of the optical system scanner 6 are provided, and at the start and end of the copying operation, the optical system scanner 6 is detected by the photo interrupter PI ₁ under the first reference density original A, Photo interrupter PI ₁
Is the first exposure scanning start position, and during other continuous copying operations, the optical system scanner 6 is detected by the photo interrupter PI _s below the second reference density original B, and the position of the photo interrupter PI _s is changed. The movement control circuit C is provided as control means for controlling the movement of the optical system scanner 6 so as to reach the second exposure scanning start position.

Next, the operation of the copying machine having the above structure will be described with reference to the flowchart shown in FIG. In the following, S _{1 to} S ₅ indicate steps in the flowchart.

First, place the original 24 on the original table 1 and turn on the print switch.
To do. In step S ₁ , the optical system scanner 6 is set to the first
It is determined whether or not it is at the exposure scanning start position, and when the optical system scanner 6 is not at the first exposure scanning start position, that is, the optical system scanner 6 is stopped at a position other than the first exposure scanning start position for some reason. In this case, the optical system scanner 6 is returned to the first exposure scanning start position (the position detected by the photo interrupter PI ₁ ).

When the optical system scanner 6 is at the first exposure scanning start position, it is detected by the photo interrupter PI ₁ (S ₁ ).
The exposure scan is started (S ₂ ). More specifically, in the configuration of the present invention, if the optical system scanner 6 is located at the first exposure scanning start position, the light source 4 is turned on at the same time when the print switch is turned on, and the optical system scanner 6 is located at the first exposure scanning start position. The first reference density document A
The electrostatic latent image corresponding to is formed on the photoconductor 11, the surface potential is detected by the first detector 21a, and the light source light amount is controlled (AVR correction) based on the detection result.

Next, the optical system scanner 6 exposes and scans the second reference density original document B to form an electrostatic latent image corresponding to the second reference density original document B on the photoconductor 11 and develops it by the developing device 13. Corresponding to the development density, that is, the second reference density document B, the photoconductor 11
The density of the visible image formed on the surface is optically detected by the second detector 21b, and the developing device is based on the detection result.
The toner is replenished to the toner 13, and the toner concentration in the developer is controlled so that the fluctuation is suppressed within a certain range. The toner of the image corresponding to the second reference density document B is removed from the surface of the photoconductor 11 by the cleaning device 16.

Thereafter, the copy paper is fed toward the transfer device 14, the original 24 is exposed and scanned, and the copy operation is performed on the copy paper.

After exposure scanning is finished to the end of the document 24 (s _3), in step S _4, whether the remaining number of copies is zero is determined. For example, if you want to make one copy,
Since the remaining number of copies is zero, the optical system scanner 6
Returns to the first exposure scan start position (the position detected by the photo interrupter PI ₁ ) and stops (S ₅ ), but if continuous copying is in progress, the remaining number of copies is not zero, so the optical system scanner The exposure scanning start position of 6 is switched to the second exposure scanning start position, and the optical system scanner 6 stops at the second exposure scanning start position (the position detected by the photo interrupter PI _s ) and starts the exposure scanning again. . In the copying machine, the toner density is controlled by the exposure scanning of the second reference density original document B for each exposure scanning, the toner consumption amount is reduced, and the load on the cleaning device 16 is reduced. As described above, some exposure scans may be performed once for some purposes. In the case of the latter copying machine, the exposure scanning of the second reference density original document B is performed for each copying operation, but the second scanning formed on the surface of the photoconductor 11
The electrostatic latent image corresponding to the reference density original document B is erased by the blank cut lamp 22, and the electrostatic latent image corresponding to the second reference density original document B is developed once every several exposure scans. It will be.

Then, when the number of remaining copies becomes zero, that is, when all the copies are completed, the optical system scanner 6 starts the first exposure scanning start position (position detected by the photo interrupter PI ₁ ).
Return to and stop (S ₅ ).

Therefore, when the scanning length of the optical system scanner 6 at the time of making the first copy is represented by L ₁ in FIG. 2, a portion corresponding to the width l ₁ of the first reference density original A during the continuous copying operation. Only, the scanning length L ₂ of the optical system scanner 6 is shortened, and continuous copying is speeded up.

In FIG. 2, the second exposure scanning start position is set at the boundary between the first reference density original A and the second reference density original B, but the present invention is not limited to this, and It is also possible to set a position slightly deviated to the upper side or the lower side in the scanning direction of the boundary as the second exposure scanning start position. That is, as shown in FIG. 4, the optical system scanner 6 has a high moving speed at the start of the movement, and after it has stabilized at a predetermined speed,
Normally, the exposure is performed after the reference density original B is set. On the other hand, the width l ₁ and the width l ₂ of the second reference density document B of the first reference density document A is usually each be set to about 25 mm, only the middle portion of the width of each l _1, l ₂ is the It is usually used for detection by the first detector 21a and the second detector 21b. Therefore, of the width l ₂ of the second reference density original document B, on the scanning direction upper side than the area actually used for detection by the second detector 21b and until the moving speed of the optical system scanner 6 falls within this area. In principle, it is possible to select the second exposure scanning start position as long as the position is apart from the region by a distance necessary for stable stability.

Further, in the above embodiment, the first exposure scanning start position and the second exposure scanning start position of the optical scanner 6 are set by using the two photo interrupters PI ₁ and PI _s that detect the position of the optical scanner 6. However, the present invention is not limited to this. For example, an encoder is used as a motor for driving the optical system scanner 6, and when the optical system scanner 6 moves in the scanning direction, the pulse number of the encoder is added to obtain the moving distance of the optical system scanner 6 in the scanning direction. In the copying machine in which the braking timing of the optical system scanner 6 is controlled by subtracting the number of pulses when the optical system scanner 6 is returned, the optical number during the continuous copying operation is set by setting the number of pulses to be subtracted. It is possible to set the stop position of the system scanner 6, that is, the second exposure scanning start position.

〔The invention's effect〕

The present invention is configured as described above, and during the continuous copying operation, the optical system scanner returns to the second exposure scanning start position to start the movement in the scanning direction from the second exposure scanning start position again. Since the second and subsequent copies are continued, the scanning length of the optical system scanner can be shortened and the speed of continuous copying can be increased.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a schematic view of the structure of an optical system moving type copying machine, and FIG. 2 is a structure of a main part showing an exposure scanning start position of an optical system scanner. FIG. 3 is a flow chart executed by the movement control circuit of the optical system scanner, and FIG. 4 is a diagram for explaining the movement speed of the optical system scanner. A: first reference density original document, B: second reference density original document, C
...... Movement control circuit, 1 ...... Document stage, 4 ...... Light source, 6 ......
Optical system scanner, 11 …… photoreceptor, 13 …… developing device, 21
a ... 1st detector, 21b ... 2nd detector.

Claims (1)

[Claims] 1. A first reference density document and a second reference density document are arranged in this order from one side in the scanning direction of a document table in this order from the upper side in the scanning direction, and the first reference density document and the second reference density document are arranged around the photosensitive member. A first detector for detecting the surface potential of the electrostatic latent image corresponding to the first reference density original document and a second detector for detecting the development density corresponding to the second reference density original document are provided. An optical system moving type copying machine configured to control a light source light amount based on a detection result and a toner concentration based on a detection result of a second detector, and an optical system scanner at the start and end of a copying operation. While the exposure start position of the optical scanner is set to the first exposure scanning start position where the exposure scanning is performed from the first reference density original document, the exposure start position of the optical system scanner is changed from the second reference density original document during the continuous copying operation. Set to the second exposure scanning start position for exposure scanning Copier characterized by comprising providing a control means.