JP2927819B2 - Image forming control device for copier - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming control apparatus of a copying machine in which a reference position signal generation time of a transfer sheet holder is used as a reference for various image forming operation timings.

2. Description of the Related Art Generally, in an image forming section of a copying machine, the surface of a photoconductor transferred in a certain direction is uniformly charged (charging step), and an image of a document is placed on the uniformly charged photoconductor. Is performed to form an electrostatic latent image (exposure step), and toner is supplied to the electrostatic latent image from a developing device to develop the electrostatic latent image ( (Developing step) A visible toner image is obtained. The obtained toner visible image is transferred to a transfer paper side by a transfer device (transfer step), whereby a final image is formed.

In a copying machine having a transfer paper holder such as a transfer drum as the transfer device, the leading end of the transfer paper is clamped and fixed by a clamper mechanism attached to the transfer paper holder, and the transfer paper is attached to the outer periphery of the transfer paper holder. Is wound and conveyed. Then, the transfer of the toner visible image is performed so that the leading end of the clamped transfer paper coincides with the leading end of the document.

In a software sequence of a copying machine equipped with such a transfer paper holder, each image forming process of charging, exposure, development and transfer is performed based on the rotation timing of the transfer paper holder (the time when the transfer paper holder and the reference position signal are generated). The operation timing has been determined. This is because, in any image forming mode, the transfer paper is clamped and fixed at a fixed position, so the charging timing, exposure timing, development timing and transfer timing are calculated based on the leading end of the transfer paper fixed at this fixed position. Because it is the easiest and most accurate to do. In each of the above-described steps of charging, exposure, development, and transfer, each image forming condition such as a charging condition, an exposure condition, a development condition, and a transfer condition is kept constant so that a constant image forming operation is always performed. The control and adjustment are performed as described above.

On the other hand, in a copying machine having an automatic density detecting means, for example, as shown in FIG. 4 (a), a front end side of a contact glass 1 as a document placing table on which a document to be copied is placed ( A reference density pattern 2 made of a gray scale plate having a reference density is set so as to be surrounded by a black portion 3 so as to be adjacent to the left end portion in FIG. Then, as shown in FIG. 4 (b),
First, reference image density information data A obtained by irradiating the reference density pattern 2 with scanning light and original image density information data B obtained by irradiating the original 4 placed on the contact glass 1 with scanning light are obtained. These are detected and read at a predetermined timing. These two concentration information data A,
When reading B is performed, the ratio B of both density information data
/ A is calculated. An image forming condition such as a developing bias is set at a predetermined timing based on the value of the calculation result B / A, whereby a toner visible image having a constant density is always formed on the photoconductor. .

[Problem to be Solved by the Invention] As described above, in a copying machine in which each image forming operation timing of charging, exposure, development, and transfer is determined based on the rotation timing of the transfer paper holder, the transfer paper holding If the scanner timing is changed based on the rotation timing of the body, the image is shifted and transferred by an amount corresponding to the amount of change in the scanner timing, and a binding table margin is formed on the transfer paper. . Therefore, by setting a mode for changing the scanner timing by an arbitrary set amount, the mode can be set as a binding margin mode.

However, if such a binding margin changing mode for changing the scanner timing is installed in the copying machine and the automatic density detecting means described above is further provided, the following problem occurs. First, assuming that the scanner timing is delayed, for example, by a certain time in the binding margin mode, the detection of the reference image density information data and the original image density information data by the automatic density detection means is delayed by the delay time of the scanner timing. .
For this reason, the reading operation of the reference image density information data and the original image density information data or the setting operation of the image forming condition based on the above data is not performed well, and the image forming condition becomes inappropriate, resulting in a poor image density. It is possible.

Therefore, the present invention can appropriately execute the control operation of the automatic density detection means provided for a copying machine having a binding margin mode for changing the scanner timing, and can always perform good image formation. It is an object of the present invention to provide an image forming control device for a copying machine.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a reference position signal generation point of a transfer paper holding member that conveys a transfer paper while holding it at a fixed position is used as a reference for various image forming operation timings. In the image forming control device of the copying machine, the reference image density information data obtained from the reference density pattern and the original image density information data obtained from the original to be copied are read at a predetermined timing, and the ratio of the two data is read. Automatic density detecting means for setting image forming conditions at a predetermined timing based on the image forming conditions, and an operation start timing of the scanner by an arbitrary set amount with reference to a reference position signal generation time of the transfer paper holder. A binding mode in which the image is shifted and transferred so as to form a binding margin on the transfer paper by changing In the binding margin mode, the data reading timing and the image forming condition setting timing in the automatic density detection unit are different from the normal mode in which the position of the scanner at the data reading timing and the image forming condition setting timing does not form a binding margin on transfer paper. The configuration is changed in accordance with the variation of the operation start timing of the scanner so as to be the same.

[Operation] In the present invention having such a configuration, since the data reading timing and the image forming condition setting timing in the automatic density detecting means can be changed in accordance with the scanner timing, the reference image density information data and the original image density information data can be changed. The reading operation or the operation of setting the image forming conditions based on the above data is always performed appropriately in the same state regardless of the fluctuation of the scanner timing.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 5 shows a full-color copying machine as an example of an image forming apparatus to which the present invention is applied. As shown in the figure, a photoconductor drum 11 as an electrostatic latent image carrier rotatably driven in the direction of the arrow is provided at a substantially central portion of the copying machine main body.
Is arranged. Around the photoreceptor drum 11, a charger 12 for uniformly charging the surface of the photoreceptor drum 11 along the rotation direction, and supplies toner to an electrostatic latent image formed on the photoreceptor drum 11. Developing unit 13Bk and a color developing unit 13YMC for obtaining a toner visible image by performing development, a transfer drum 14 as a transfer paper holder for transferring the toner visible image obtained by the development onto a transfer paper, and a photosensitive drum after transfer Devices such as a cleaning device 15 and a static eliminator 16 that remove the toner and unnecessary charges remaining on the surface of the device 11 by scraping them off are arranged in order.

At a position 17 between the charger 12 and the developing unit 13, an optical path from an exposure optical system 18 for writing image information on the photosensitive drum 11 to form an electrostatic latent image is provided. The exposure optical system 18 scans and illuminates the original placed on the original placing table 18a, and the reflected light from the original when scanned and illuminated by the lamp 18b is reflected on the photosensitive drum 11. It is composed of a mirror group 18c for condensing light, a lens group 18d, and a color separation filter 18e.

On the other hand, the transfer paper sent out from the paper supply cassette 19 provided as a storage unit of the automatic paper supply unit is wound around the outer peripheral portion of the transfer drum 14, and is conveyed after the leading end is clamped and fixed by the clamper mechanism. ing.
The photosensitive drum is provided inside the transfer drum 14.
A transfer charger 14a is arranged so as to face the photoconductor 11, and the photoconductor drum 11 is
The visible image of each color toner is transferred so as to be superimposed on the transfer paper in order. At this time, the toner visible image is transferred from the leading edge of the transfer paper so that the leading edge of the transfer paper clamped and fixed matches the leading edge of the document.

The transfer paper on which the toner image of each color has been transferred is transferred to the transfer drum 14 by a separation charger 14b and a separation claw 14c.
From the fixing unit 22
After the toner visible image is fixed here, the toner image is discharged to the discharge tray 23.

In this embodiment, the photosensitive drum is used as the latent image carrier, but it goes without saying that a belt-shaped photosensitive member can also be used.

This color copier also has automatic density detection (AD
A control unit 31 constituting S detection) means is provided. The circuit block configuration of the control unit 31 is shown in FIG. That is, the control unit 31 controls the ROM 3 around the CPU 32.
3, RAM 34 and I / O interfaces 35, 36, etc.
Operation unit 37 having display unit and input keys for binding margin mode
The other I / O interface 36 outputs an ADS detection (automatic density detection) start signal, a scanner start signal of the exposure optical system 18, and a developing bias output signal for adjusting image density. And an ADS detection (automatic density detection) signal is input through the I / O interface 36.

On the other hand, the detecting section of the automatic density detecting means is shown in FIG. That is, a reference density formed of a gray scale plate having a reference density so as to be adjacent to the front end side (left end portion in FIG. 4A) of the contact glass 1 serving as an original placing table on which an original to be copied is placed. The pattern 2 is set so as to be surrounded by the black portion 3. Then, as shown in FIG. 4 (b), first, the reference image density information data A obtained by irradiating the reference density pattern 2 with the scanning light and the original 4 placed on the contact glass 1 Document image density information data B obtained by irradiating scanning light is detected, and these are read at a predetermined timing. When reading of both the density information data A and B is performed, the ratio B / A of the density information data is calculated. Image forming conditions such as a developing bias are set at a predetermined timing based on the value of the calculation result B / A, whereby a toner visible image of a constant density is always formed on the photoconductor. .

Further, in the automatic density detecting means in this embodiment, charging and charging are performed based on the rotation timing of the transfer drum 14 (specifically, when a reference position signal of the transfer drum 14 is generated as described later).
Each image forming operation timing of exposure / development and transfer is determined. This is because the transfer paper clamp position of the transfer drum 14 is fixed in any mode,
This is because it is easiest and most accurate to calculate the charging timing, the exposure timing, the development timing, and the transfer timing based on the leading end of the transfer paper in the constant state.

Further, a binding mode in which the scanner timing is changed by an arbitrary set amount based on the rotation timing of the transfer drum 14 is provided. That is, if the scanner timing is changed with reference to the rotation timing of the transfer drum 14, the image is transferred with a shift corresponding to the amount of change in the scanner timing, and a binding margin is formed on the transfer paper. It is formed. Therefore, by setting a mode for changing the scanner timing by an arbitrary set amount, this mode can be set as a binding mode.

Further, as shown in FIG. 1, in the binding margin mode, the data reading timing and the image forming condition setting timing in the automatic density detecting means can be changed in accordance with the variation of the scanner timing. I have.

In this embodiment, first, as shown in the upper part of FIG.
In the case of the normal mode other than the binding mode, the transfer drum home signal H / P is issued, that is, the reference position signal generation time O ₀ at which the transfer drum home signal is generated at the reference position of the transfer drum 14, and T (T). sec) when O has elapsed
_The scanner start timing is set to ₁ and the reading timing of the reference image density information data and the original image density information data by the automatic density detection means is matched with the scanner start timing O1. Further, the setting timing of the switching of the developing bias as the image forming condition determined by the automatic density detecting means
O ₂ is from the data read timing O ₁ to t (se
c) It is set at the time when only elapses. Here, assuming that the linear velocity of the photosensitive drum 11 is V 'and the circumferential distance between the exposure position 17 (see FIG. 5) and the contact point of the developing unit 13 with the drum is l, t = l / V' (sec) Becomes The time t is obtained by adding the data reading time in the automatic density detecting means, the calculation time of the developing bias value as an image forming condition, and the time from when the developing bias signal is sent to when the developing bias is actually applied. .

On the other hand, when the binding mode is selected as shown in the lower part of FIG. 2, the scanner start timing in the binding mode is determined by the transfer drum home signal H / P.
O is issued for T '(sec) from O ₀ when O is issued
It has been changed to ₁ '. That is, the scanner speed according to the current magnification is V (m / sec), and the binding margin is x.
In the case of (m), T ′ = T + x / V (sec).

Also, in this binding mode, since the respective image forming operation timings of charging, exposure, development, and transfer are not changed, the time t as the developing bias setting timing as the above-described image forming condition is similarly required. Therefore, the switching setting timing O ₂ ′ of the developing bias as the image forming condition determined by the automatic density detecting means is changed and set to a point in time when t (sec) has elapsed from the data reading timing O ₁ ′. Therefore, even if the data reading timing and the image forming condition setting timing in the automatic density detecting means are changed in accordance with the variation of the operation start timing of the scanner, the scanner position (physical position) at the data reading timing and the image forming condition setting timing is changed. ) Is the same as the normal mode in which no binding margin is formed on the transfer paper.

At this time, if the scanner start timing in the binding margin mode is not changed at all, the data is read by the automatic density detecting means, the developing bias value is calculated as an image forming condition, and the developing bias signal is sent. Indeed the time until the developing bias is applied from the 'time t from to time O _2' when O ₁ described above i.e., t '= t- (T'- T) only becomes no. As a result, for example, a problem such as the reading of the data of the black portion 3 shown in FIG. 4A occurs, and the image forming conditions become inappropriate, resulting in an image density defect.

In such an embodiment, since the data reading timing and the image forming condition setting timing in the automatic density detecting means are changed corresponding to the scanner timing, the reading operation of the reference image density information data and the document image density information data or The time required for the operation of setting the image forming conditions based on both data is always ensured irrespective of the fluctuation of the scanner timing, so that the read setting operation is always appropriately performed.

[Effects of the Invention] As described above, according to the present invention, a copying machine in which a reference position signal generation point of a transfer sheet holding member that conveys a transfer sheet while holding it at a fixed position is used as a reference for various image forming operation timings. In the image forming control device, the reference image density information data obtained from the reference density pattern and the original image density information data obtained from the original to be copied are read at a predetermined timing, and the image forming conditions are set based on the ratio of the two data. Is set at a predetermined timing, and the operation start timing of the scanner is changed by an arbitrary set amount with reference to the point in time when the reference position signal of the transfer paper holder is generated. A binding mode in which images are shifted and transferred so as to form binding margins on paper; The data reading timing and the image forming condition setting timing in the automatic density detecting means are set so that the scanner position at the data reading timing and the image forming condition setting timing is the same as in the normal mode in which no binding margin is formed on the transfer paper. Since the configuration is changed in accordance with the variation in the operation start timing of the scanner, the control operation in the automatic density detection means can be appropriately executed, and good image formation can always be performed. Moreover, even if the data reading timing and the image forming condition setting timing in the automatic density detecting means are changed in accordance with the variation of the scanner operation start timing, the position of the scanner at the data reading timing and the image forming condition setting timing is the same as in the normal mode. By doing so, the relationship between the physical position of the scanner and the data reading timing and the image forming condition setting timing in the automatic density detection means does not change depending on the binding margin, and the size of the reference density pattern is not affected by the binding margin. The minimum size is required. For this reason, the problems that the first copy speed is reduced and the charging time is longer as the binding margin is increased and ozone is generated and the photoconductor and the band electrode are deteriorated, which occur in the conventional apparatus, do not occur. .

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are a control flow chart and a timing chart showing an image forming condition control procedure in an embodiment of the present invention, and FIG. 3 is a diagram showing an automatic density detection (ADS detection) mechanism. 4 (a) and 4 (b) are explanatory diagrams of a plane configuration and a detection signal diagram of a detection unit of the automatic density detection means, and FIG. 5 is a copying machine to which the present invention is applied. FIG. 1 is an explanatory side view illustrating an entire configuration of a full-color copying machine as one example. 1 ... contact glass, 2 ... reference density pattern, 4
… Original, 11… Photoconductor drum, 14… Transfer drum, 31
... Control unit.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/00 303 G03G 15/36 G03G 21/14 G03G 21/00 370-502 G03G 15/04-15/04 120

Claims (1)

(57) [Claims] An image forming control apparatus for a copying machine in which a reference position signal generation point of a transfer sheet holding member for transporting a transfer sheet while holding it at a fixed position is used as a reference for various image forming operation timings. The reference image density information data obtained from the pattern and the original image density information data obtained from the original to be copied are read at a predetermined timing, and the image forming conditions are set at a predetermined timing based on the ratio of the two data. The automatic density detecting means is provided, and a binding margin is formed on the transfer paper by changing the operation start timing of the scanner by an arbitrary set amount based on the reference position signal generation time of the transfer paper holder. In the binding mode, the automatic density detecting means is provided with The data reading timing and the image forming condition setting timing are adjusted so that the scanner position at the data reading timing and the image forming condition setting timing is the same as the normal mode in which no binding margin is formed on the transfer paper. An image forming control device for a copying machine, wherein the image forming control device is configured to change in accordance with a variation.