JPH0772702A - Transfer position correcting device for scanning color image forming device - Google Patents

Abstract

PURPOSE:To always hold a recording paper and an image position in a fixed position and to record a color image on the recording paper, while keeping a constant positional relation without a skew, without requiring a complex and expensive mechanism. CONSTITUTION:When the recording paper 12 is carried toward a scanning color image forming device and the carrying state is made constant, the quantity of inclination of the recording paper 12 and recording start timing are detected by two inclination detecting means 10 and simultaneously, the deviation of the recording paper 12 in a direction (right and left directions) perpendicular to the carrying direction is detected by a deviation detecting means 11. The detection signals obtained by these detecting means 10 and 11 are transmitted to a central processing unit 9 and arithmetically processed to correct the quantity of inclination, the recording start timing and the deviation. Thus, the obtained correction signals are transmitted to respective optical system recorders 7a-7b, to operate them and the bits of information of each color are superimposed on the recording paper 12, to record the color image thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer position correcting device for a scanning type color image forming apparatus which superimposes a plurality of color image information and transfers it onto a recording sheet.

[0002]

2. Description of the Related Art A conventional example of a color electrophotographic apparatus for recording a color image by superposing a plurality of pieces of color image information is shown in FIG.
Referring to FIG. 5, reference numeral 1 in FIG. 4 is a recording paper carrying belt (recording paper carrying device), 2 is a photosensitive drum, 3 is a developing device, and 4 is a developing device.
Is a transfer device, 5 is a charger, 6 is a horizontal synchronization sensor, and 7
Reference numerals a to 7d are laser optical system recording devices for respective colors, 8 is a raster image processor (RIP), 9 is a CPU, and 12 in FIGS. 4 and 5 is recording paper.

In the color electrophotographic apparatus shown in FIG.
By inputting the color-separated image data to the raster image processor 8 and developing it into dot data, and converting this into ON and OFF of laser light, a laser optical system recording device 7a for laser scanning in the direction of the arrow An electrostatic latent image is created on the photosensitive drum 2 that has been uniformly charged in advance, while this electrostatic latent image is made into a visible image by the developing device 3, and this visible image is electrostatically applied to the recording paper 12 by the transfer device 4. Transfer to. This step is followed by the laser optical system recording device 7
Repeat steps b to 7d to record image information for each color on recording paper 1.
The color image is recorded on the recording paper 12 so as to be superposed on the recording paper 12.

[0004]

In the conventional color electrophotographic apparatus shown in FIG. 4, a color electrophotographic apparatus for recording a color image by superposing a plurality of color image information,
It is necessary to accurately superpose a plurality of color image information on the recording paper 12. Further, it is necessary to always record at a fixed position without making the image position oblique to the recording paper 12.

However, even though this color electrophotographic apparatus has means for correcting image information on the apparatus, the recording paper 12
Since there is no means for correcting the image position and the image position, and the relative position between the image position where the plurality of color image information are superposed and the recording paper 12 is determined depending on the conveyance accuracy of the recording paper 12, it is usually 1 It was tilted by about 2 mm or was displaced vertically or horizontally.

[0006] For example, in a recording apparatus having an intermediate transfer member used in a color electrophotographic apparatus, since there is one laser optical system recording apparatus, a plurality of color image information is stored horizontally,
By setting the timing in the vertical direction, it is possible to superimpose them on the photosensitive drum or the intermediate transfer member with high precision within the range of the assembly precision. However, the image position on the recording paper 12 is corrected by the correction means for correcting the image position. Without, recording paper 12
It was deviated by about 1 to 2 mm. Further, since each color is recorded every cycle, there is a drawback that the recording speed is slow.

As another conventional example, there is an apparatus for producing a color image by sequentially transferring the images recorded by four sets of image forming sections onto a recording paper 12, but in this color image producing apparatus, recording is performed. Although it has an advantage that the speed can be increased, the adjustment for registering each color becomes complicated, and the recording paper 12 and the image position are tilted in the same manner as described above, and are displaced from each other by 1 to 2 mm in the horizontal and vertical directions. become.

Since the relationship between the recording paper 12 and the image position is determined depending on the accuracy of the recording paper conveying device including the paper feeding device, it is attempted to improve the conveying speed to an accuracy of about 0.1 mm. However, there has been a problem that the recording paper conveying device is very complicated and expensive. The present invention has been made in view of the above problems, and the object thereof is to always hold the recording paper and the image position at a constant position without requiring a complicated and expensive adjusting mechanism. Another object of the present invention is to provide a transfer position correction device of a scanning color image forming apparatus capable of recording a color image on a recording paper while keeping a constant positional relationship without skew.

[0009]

In order to achieve the above-mentioned object, the present invention provides a scanning type color image forming apparatus for superimposing a plurality of color image information and transferring it onto a recording paper, upstream of the recording paper conveying device. Side inclination detecting means for detecting the inclination of the recording paper in the conveying direction, and deviation detection for detecting the deviation in the direction orthogonal to the conveying direction of the recording paper provided on the upstream side of the recording paper conveying device. Means and the detection signals obtained by these detecting means are subjected to arithmetic processing to correct the amount of inclination of the recording paper, the recording start tamming and the deviation, and the resulting correction signals are sent to each optical system recording device. And a central processing unit for operating the optical recording device.

[0010]

The transfer position correcting device of the scanning type color image forming apparatus of the present invention is constructed as described above, and when the recording paper is conveyed toward the scanning type color image forming device and the conveying state becomes constant. The inclination amount of the recording paper and the recording start tamming are detected by the two inclination detecting means, and the deviation in the direction orthogonal to the conveying direction of the recording paper is detected by the deviation detecting means, and the detections obtained by these detecting means are detected. The signal is sent to the central processing unit and is subjected to arithmetic processing to correct the amount of inclination of the recording paper and the recording start tamming and deviation, and the correction signals obtained as a result are sent to each optical system recording device, and each optical system The recording apparatus is operated to superimpose the image information of each color on the recording paper, and the color image is recorded on the recording paper.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the transfer position correcting apparatus for a scanning color image forming apparatus of the present invention will be explained with reference to one embodiment shown in FIGS. 1 and 2. 1 in FIG. 1 is a recording paper carrying belt (recording paper carrying device). Reference numeral 2 is a photosensitive drum, 3 is a developing device, 4 is a transfer device, 5 is a charging device, 6 is a horizontal synchronization sensor, 7a to 7d are laser optical system recording devices for respective colors, and 8 is a raster image processor (RIP). , 9 is a central processing unit (CPU),
Reference numeral 12 in FIGS. 1 and 2 is a recording sheet.

In FIG. 1, reference numerals 10 and 10 denote an inclination detection sensor (photosensor) for detecting the inclination of the recording sheet 12 in the conveying direction, and 11 denotes a deviation in a direction (horizontal direction) orthogonal to the conveying direction of the recording sheet 12. Deviation detection sensor (P
In SD), the inclination detection sensors 10 and 10 and the deviation detection sensor 11 are installed on the upstream side of the recording paper conveyance belt 1.

Next, the operation of the transfer position correction device of the scanning color image forming apparatus shown in FIGS. 1 and 2 will be described. Raster image processor 8 for color-separated image data
To a dot data, which is converted into ON / OFF of the laser beam, and the laser optical system 7a for laser scanning in the direction of the arrow converts the electrostatic latent image on the photosensitive drum 2 which is uniformly charged in advance. Meanwhile, the electrostatic latent image is made into a visible image by the developing device 3, and by the transfer device 4,
This visible image is electrostatically transferred to the recording paper 12. This process is repeated for the subsequent laser optical system recordings 7b to 7d to record a color image on the recording paper 12.

What has the greatest effect on the conveying speed of the recording paper 12 is the operation of feeding the recording paper 12 with the timing for each sheet, and if this operation is not successful, the recording paper 1
2 is tilted or left and right (direction orthogonal to the transport direction)
Or a timing error occurs. Therefore, when the recording paper 12 is conveyed toward the scanning color image forming apparatus and the conveyance state becomes constant (before the recording of the optical system is started), the inclination amount of the recording paper and the recording start tanning are set to two values. The tilt detection sensor 10 detects the deviation, and the deviation detection sensor 11 detects the deviation in the direction (horizontal direction) orthogonal to the conveyance direction of the recording paper 12,
The detection signals obtained by these detection sensors 10, 10 and 11 are sent to the central processing unit 9 and subjected to arithmetic processing to correct the amount of inclination of the recording paper and the recording start tamming and deviation,
The correction signals obtained as a result are sent to the laser optical system recording devices 7a to 7d for the respective colors, and the laser optical system recording devices 7a to 7d are transmitted.
A voltage is applied to an actuator such as a piezo attached to 7d to correct the inclination of the scanning line, and the recording start timing and the horizontal scanning timing of the laser optical system recording devices 7a to 7d are corrected so that the recording paper 12 and the image are recorded. Hold the line position and constant.

The operation of each of the detection sensors 10 and 11 and the central processing unit 9 will be described more specifically. In front of the recording paper 12 which is directed on the recording paper conveyance belt 1 toward the optical system 7a by the two inclination detection sensors 10. Detects two edges,
The inclination of the recording paper 12 in the conveying direction and the recording timing of the recording paper 12 in the conveying direction are detected. Further, the deviation detection sensor 11 detects one side edge of the recording paper 12 on the recording paper conveyance belt 1 toward the optical system 7a, and detects the deviation in the direction (horizontal direction) orthogonal to the conveyance direction of the recording paper 12. To detect.

Of the detected values 1 to 3, the recording paper 1
The inclination amount of 2 appears as a time difference when the leading edge of the recording paper 12 passes through the two inclination detection sensors 10, and thus the time difference amount is sent to the central processing unit (CPU) 9.
Here, the tilt amount is calculated as a tilt angle, the correction signal obtained as a result is sent to the optical system recording devices 7a to 7d, and a voltage corresponding to the correction signal is applied to an actuator such as a piezo provided in the optical system recording device. Then, the scanning device is operated, and the skew of the recording image of each color in the scanning direction is tilted in accordance with the recording paper 12 (the scanning line is tilted with respect to the photosensitive drum 2) to correct the tilt amount of the recording paper 12.

The recording timing of the recording paper 12 in the conveyance direction is determined from the detection signals of the two inclination detection sensors 10.
The recording start position of each color is obtained based on the time obtained by adding the inclination correction amount to one of the detection signals, and the recording timing of each color in the transport direction is corrected based on this reference signal. Recording paper 1
The deviation amount of 2 is a direction orthogonal to the conveyance direction (left-right direction) while adding a tilt correction amount based on the detection signal from the deviation detection sensor 11 and sequentially changing the recording start position of the horizontal scanning for each scanning. ) Make the recording position constant.

FIG. 3 is a flow chart of the transfer position correcting device of the scanning color image forming apparatus.

[0019]

As described above, the transfer position correction device of the scanning type color image forming apparatus of the present invention sends the time difference amount when the leading edge of the recording paper passes the two inclination detecting means to the central processing unit, Here, the tilt amount is calculated as a tilt angle, the correction signal obtained as a result is sent to the optical system recording device, and a voltage corresponding to the correction signal is applied to an actuator such as a piezo provided in the optical system recording device to perform scanning. By operating the device and tilting the skew of the recording image of each color in the scanning direction to the recording paper,
The recording paper and the image position can always be held at a fixed position without requiring a complicated and expensive adjusting mechanism.

Since the skew correction amount is added on the basis of the detection signals of the two inclination detecting means and the deviation detecting means, the writing timing in the carrying direction of scanning and recording and the direction orthogonal to the carrying direction is adjusted. The color image can be recorded on the recording paper while maintaining a constant positional relationship without skew.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a transfer position correction device of a scanning color image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram showing an image output example of the transfer position correction apparatus.

FIG. 3 is a flowchart of the transfer position correction apparatus.

FIG. 4 is a system diagram showing a conventional color electrophotographic apparatus.

FIG. 5 is an explanatory diagram showing an image output example of the color electrophotographic apparatus.

[Explanation of symbols]

1 Recording Paper Conveying Device (Recording Paper Conveying Belt) 2 Photosensitive Drum 3 Developing Device 4 Transfer Device 5 Charging Device 6 Horizontal Sync Sensor 7a to 7d Laser Optical Recording Device for Each Color 8 Raster Image Processor (RI
P) 9 central processing unit (CPU) 10, 10 tilt detecting means (tilt detecting sensor) 11 deviation detecting means (deviation detecting sensor (PS
D)) 12 Recording paper

Claims (1)

[Claims] 1. A scanning type color image forming apparatus which superimposes a plurality of color image information and transfers it onto a recording sheet, and two inclinations for detecting an inclination in a conveying direction of a recording sheet provided on an upstream side of the recording sheet conveying apparatus. Detecting means, deviation detecting means provided on the upstream side of the recording paper conveying device for detecting a deviation in a direction orthogonal to the conveying direction of the recording paper, and processing detection signals obtained by these detecting means. A central processing unit for correcting the tilt amount of the recording paper, the recording start timing and the deviation, and sending the correction signal obtained as a result to each optical system recording device to operate each optical system recording device. A transfer position correction device for a scanning type color image forming apparatus.