JPS63192073A - Image output device - Google Patents

Abstract

PURPOSE:To reduce the deviation among leading parts of images in case of transfer of plural images on the same form by measuring time characteristics with which a form carrying part is moved by a prescribed extent and controlling the exposure start timing by this measured data. CONSTITUTION:A prescribed position of the form carrying part is detected by a home position sensor 1 to detect a gripper position detecting piece provided with plural grippers by position sensor 6. The time when the form carrying part passes between two position sensors is measured by a speed measuring circuit 2, and this data is averaged and is sent to and stored in a laser timing circuit 5. When an image output device is started thereafter, the laser timing circuit 5 controls the exposure start timing in accordance with respective grippers so that a laser optical system starts exposure after a preliminarily calculated time when the position detecting piece passes the position sensor 6. Thus, the deviation among leading parts of images is reduced in case of transfer of plural images on the same form.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image output device that forms a plurality of images on the same sheet of paper while the sheet is conveyed by a sheet conveying section.

[Conventional technology]

FIG. 5 is a diagram showing the overall configuration of the image output device, and FIG. 6 is a diagram for explaining the mechanism of the paper conveyance section, in which 11 is a laser optical system, 12 is a photoreceptor, 13 is a developing device, and 14 is a diagram for explaining the mechanism of a paper conveyance section. Cleaner, 15 is a fuser, 16 is a paper transport unit, 17 is a cassette tray, 18 is a chain, 19 is a gear, 20 is a motor, 21 is a gripper, 122 is a gripper position detection piece, 23 is a position sensor, 24 is a home A positive sensor is shown.

In the image output device shown in FIG. 5, a photoreceptor 12 is charged in advance, exposed to light by a laser optical system 11 to form an electrostatic latent image, and developed by a developer 13. The paper conveying section 16 includes a gripper 2 as shown in FIG.
1, a chain 18, and a motor 20 that drives it. The sheets are sent one by one from the cassette tray 17 to the sheet conveying section 16 using rubber rollers (not shown) and gripped by a gripper 21. When the gripped paper passes under the photoreceptor 12, the image developed on the photoreceptor 12 is transferred to the paper. Since the motor 20 of the paper transport section 16 rotates at a constant speed, the paper is fed at a roughly constant speed and images are transferred one after another on each photoreceptor 12, and the four images are transferred one after another. When the toner is formed on a sheet of paper, the paper leaves the gripper 21 and the fixing device 15 fixes the toner on the paper. Note that since the surface speed of the photoreceptor 12 and the transport speed of the paper transport section 16 are controlled to be constant, when forming an image at a fixed position on the paper, the position is adjusted as shown in FIG. 6(b). Gripper position attached to gripper 21 by sensor 23! It is necessary to detect the position of the paper by detecting the detection piece 22, and to start exposure of the laser optical system 11 at a fixed timing.

[Problem that the invention seeks to solve]

By the way, in the image output device as shown in FIG. 5, when the gripper 21 grips and conveys the paper and transfers the image on each photoreceptor drum, the chain supporting the gripper 21 18, gear 19, motor 20, etc., a low frequency vibration is generated.
In the case of an image output device as shown in the figure, the motor 20 is
Although it is rotating at a constant speed, the chain 18 has a circumference of 2
m or more, and since the chain 18 has multiple grippers 21 made of metal, the gripper 2
1 vibrates in the movement direction at a low frequency. In this case, the vibration frequency is often below IH2, and with fixed time timing control, the initial position of the developed image on the photoreceptor transferred to paper will shift. .

This frequency and the magnitude of positional deviation are expressed as 2πf, where ΔX represents the amount of positional deviation, f represents the vibration frequency, and Δ■ represents the magnitude of vibration. The frequency and magnitude of this vibration differ depending on the type of paper transport section 16, and also differ depending on the tension and friction of the chain even in the same type of paper transport section 16. Therefore, even if an attempt is made to place an image on the same point on a sheet of paper, there is a problem in that the low-frequency vibrations cause misalignment. In addition, when there are multiple grippers, there is a drawback that variations occur in each sensor, which causes the problem that the image becomes misaligned when controlled for a certain period of time.

The present invention eliminates the above-mentioned drawbacks and provides an image output device that reduces misalignment of images on paper.

[Means for solving problems]

For this purpose, the image output device of the present invention is an image output device that forms a plurality of images on the same sheet of paper while the paper is transported by the paper transport section, and the image output device of the present invention moves a predetermined distance when the paper transport section is operating. The apparatus is characterized in that it includes a measuring means for measuring time characteristics, and uses the moving time characteristics measured by the measuring means to control the timing from paper position detection to the start of image formation.

[Effect]

In the image output device of the present invention, the time characteristic of moving a predetermined distance when the paper transport section is in operation is measured by the measuring means, and the timing from paper position detection to the start of image formation is controlled using the measured data. Therefore, the timing is controlled by measurement data that includes low-frequency vibrations. Therefore,
When a plurality of images are formed on the same sheet while the sheet is being conveyed by the sheet conveying section, the displacement of images is reduced.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining one embodiment of the image output device according to the present invention, FIG. 2 is a diagram for explaining time measurement processing, and FIGS. 3 and 4 are image output according to the present invention. In Figure 0, which is a diagram for explaining another embodiment of the device, 1 is a home position sensor, 2 is a machine controller, 3 is a motor, 4 is a speed measurement circuit, 5 is a laser timing circuit, and 6 is a position sensor. , 7 is a cleaner, 8 is a photoreceptor, 9
indicates a developing device.

In FIG. 1, the machine controller 2 controls the entire image output device, but in the present invention, the home position sensor 1 detects the specified position of the paper transport section, and the motor 3 and the speed measurement circuit 4 and the laser timing circuit 5. The speed measuring circuit 4, as shown in FIG. 2, detects the signals from each position sensor 6, takes the data of the time when the same gripper passes the same position sensor, and averages the data. The laser timing circuit 5 controls the exposure start timing of the laser optical system, and starts after a pre-calculated time has elapsed from the time when the gripper position detection piece passes the position sensor 6 according to each gripper. Control the laser optical system to start exposure. In addition, the position sensor 6,
The cleaner 7, the photoconductor 8, and the developing device 9 are the position sensor 23, the cleaner 14, and the photoconductor 12 shown in FIG. 5, respectively.
, are the same as the developing device 13.

Next, the operation will be explained. First, when the image output device is powered on, the machine controller 2 rotates the motor 3. Then, while the home position sensor 4 detects the specified position of the paper conveyance unit, the speed measuring circuit 2 detects the gripper position detection pieces attached to the plurality of grippers (the gripper position detection pieces shown in FIG. 6 fbl). 22) is detected by the position sensor 6, and the time it takes to pass between the two position sensors is measured. Although this resolution depends on the paper conveyance speed, it is, for example, about 10 μm in terms of distance.

In this way, the paper transport section is rotated several times or more, and the speed measurement circuit 2 collects data on the time when the same gripper passes the same position sensor, averages it, and sends the data to the laser timing circuit 3. After storing the time data in the laser timing circuit 3 in this way, when the image output device is activated, the laser timing circuit 3 detects the position sensor 6 according to the sensor position detection piece according to each gripper. The laser optical system is controlled so that it starts exposure after a pre-calculated time has elapsed from the time the laser passes through.

As described above, in the image output device according to the present invention, the gripper, which is a member that grips and conveys paper, is connected between two position sensors corresponding to a plurality of marking units (laser optical system, photoreceptor, developer, cleaner, etc.). The time it takes for the laser to pass through the paper is measured in advance, and the time data is processed to control the exposure start timing of the laser optical system.This reduces misalignment at the leading edge of the image when multiple images are transferred onto paper. .

Note that the present invention is not limited to the above embodiments, and various modifications are possible. For example, in the above embodiment, the speed of the paper conveyance section is measured by the elapsed time between two points, but in order to obtain more accurate dynamic characteristics, multiple position sensors 6 are installed at each position as shown in FIG. , it is necessary to take time to travel between short distances. For example, if seven position sensors 6 are placed at equal intervals as shown in FIG. 4, the time taken to pass through the position sensors 6 can be measured from tl to tl. In addition, in the example shown in Fig. 3, multiple position sensors shown in Fig. 5 are installed, but optical or magnetic linear position sensors used for positioning in linear motion are also used as position sensors. You may also use

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the measurement means measures the time characteristics of movement of a predetermined distance while the paper transport section is operating, and obtains measurement data including low frequency vibrations. Since the exposure start timing of the laser optical system is controlled based on data, it is possible to reduce misalignment of the leading edge of images when a plurality of images are transferred onto the same sheet of paper. Furthermore, even if there are multiple grippers and there are variations in the position sensors, image deviation can be minimized by using averaged data.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the image output device according to the present invention, FIG. 2 is a diagram for explaining time measurement processing, and FIGS. 3 and 4 are image output according to the present invention. FIG. 5 is a diagram for explaining another embodiment of the apparatus, FIG. 5 is a diagram showing the overall configuration of the image output device, and FIG. 6 is a diagram for explaining the mechanism of the paper conveying section. DESCRIPTION OF SYMBOLS 1... Home position sensor, 2... Machine controller, 3... Motor, 4... Speed measurement circuit, 5... Laser timing circuit, 6... Position sensor, 7... Cleaner, 8... Photoreceptor, 9...
Developing device. Applicant: Fuji Xerox Co., Ltd. Representative Patent Attorney
Ryukichi Abe (2 others) Figure 3 U

Claims (1)

[Claims] (1) In an image output device that forms multiple images on the same sheet of paper while the paper is transported by the paper transport section, a measuring means for measuring the time characteristic of moving a predetermined distance when the paper transport section is operating. 1. An image output device comprising: an image output device that controls the timing from paper position detection to the start of image formation using the moving time characteristics measured by the measuring means.