JPH037945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording apparatus that aligns images in a direction perpendicular to the conveying direction of a recording member (paper).

In a recording device that uses sheet paper, one or more pairs of registration rollers are installed in the middle of the paper transport path from the paper feed section to the image transfer section, and the image on the photoreceptor is aligned with the leading edge of the paper. Although the paper is aligned in the traveling direction, the alignment in the direction perpendicular to the paper traveling direction is determined by the mechanical position of the paper feeder and the paper loading position.

In the case of a recording device such as copying material, if you move the position of the original document, the image on the photoreceptor will naturally also move, so if the image position after transfer is uneven, it may be necessary to move the document. It can be easily corrected.

However, in the case of a laser beam recording device, the writing position on the photoreceptor is fixed, so if the paper being conveyed is misaligned in the direction perpendicular to the direction of travel, that is, in the horizontal direction, there will be no trace on the paper at the time of conveyance. The positional deviation directly becomes an image positional deviation, and in extreme cases, image loss may occur.

There are two main reasons why paper shifts laterally in the conveyance path.
It can be divided into

1. Misalignment of paper stacking position in the paper feeder. Paper width < paper feed guide width. For example, in the case of A4 paper, the width is 297mm, and the standard is 297 ^±0.7 , so a maximum of 297.7mm of paper can be stored. In order to do this, the guide width must be approximately 298.5 mm, which creates a gap of +1.5 mm between the paper feed guide and the nominal value, so generally when a large number of papers are loaded. , within that gap, the paper is stacked with an offset to the right or left, and this shift in stacking position appears on the printed image.

2 Misalignment of the paper along the diagonal bridge due to the registration rollers.As mentioned above, the paper is stacked with a gap in relation to the guide width. For this reason, when paper is fed using separation claws in a paper feeding device, the left and right separation claws are applied differently, and as a result, there is a difference in the force that overcomes the left and right separation claws, making skew feeding more likely to occur. Although the skewed paper is corrected by the registration rollers, the paper is fed with the lateral deviation caused by the skew remaining at the time of correcting the skew. Here again, the paper will be misaligned during paper transport.

The present invention was made in view of the above points, and it forms an image by irradiating a photoreceptor with light modulated by recorded information and scanning it, and transfers the image onto a conveyed recording member. In a recording apparatus that records information on a recording member using a recording medium and discharges the recording member on which the information has been recorded to a first discharge means 43, the conveyance direction of the recording member that is provided in the conveyance path of the recording member and conveyed is recording member detection means 34, 35 for detecting the position of the side part in the direction perpendicular to the recording member; and a deviation amount detection means 57 for detecting the amount of lateral deviation of the recording member from the reference position based on the output of the recording member detection means.
and controlling the timing in the scanning direction of the light modulated by the recording information in accordance with the amount of lateral shift detected by the shift amount detection means in order to record information from a predetermined position on the recording member. and means 44 for ejecting the recording member to a second ejecting means 45 different from the first ejecting means when the amount of lateral deviation detected by the deviation amount detecting means is larger than a predetermined amount. The purpose is to provide equipment. This improves image position accuracy with respect to paper, making it possible to use preprinted paper that requires image position accuracy, or to use printed paper for OCR.

Furthermore, it goes without saying that when the printer device has two or more paper feeding sections, mechanical conveyance errors of paper fed from each paper feeding section can also be eliminated.

In addition, if the amount of paper misalignment is large and the recording position cannot be corrected, the paper is separated from normally recorded paper, so there is no possibility that poorly recorded paper may be mixed in with normally recorded paper. This makes it easier to remove paper with poor recording.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the basic configuration of a laser beam printer to which the present invention is applied.
A laser beam emitted from a laser oscillator 1 enters an optical modulation system composed of a lens 2, an A/O modulation element 3 that utilizes the known acousto-optic effect, and a lens 4. Here, the lens 2 serves to focus and project the laser beam onto the black reflection surface generated within the A/O modulation element, and the lens 4 converts the laser beam, which is diffracted from the black reflection surface and is diverging, into a parallel beam. It has the function of

When using an E/O modulation element that utilizes a known electro-optic effect, lenses 2 and 4 are unnecessary, and when the laser oscillator is a gas laser or the like capable of current modulation, the above-mentioned optical modulation system can be omitted. Needless to say.

The laser beam emitted from the lens 4 becomes a parallel beam, enters a beam expander 7, and the beam diameter is expanded while remaining a parallel beam.

Furthermore, the laser beam whose beam diameter has been expanded is incident on a polyhedral rotating mirror 8 having one or more mirror surfaces. The polyhedral rotating mirror 8 is mounted on a shaft supported by a high-precision bearing (for example, an air bearing) and is driven by a motor 9 that rotates at a constant speed (for example, a hysteresis synchronous motor, a DC servo motor). The laser beam horizontally swept by the polyhedral rotating mirror 8 is imaged as a spot on the photosensitive drum 14 by an imaging lens 13 having f-θ characteristics. In a general imaging lens, when the incident angle of a light ray is θ, the position r of the image on the image plane has the following relationship: r=f・tanθ−(1) (f: focal length of the imaging lens) As in this embodiment, when the polyhedral rotating mirror 8 is rotated at a constant speed, the angle of incidence of the reflected laser beam 52 on the imaging lens 13 changes linearly with time. Changes to Therefore, the moving speed of the imaged spot position on the photosensitive drum 14, which is the image, changes non-linearly and is not constant. That is, the moving speed increases at the point where the angle of incidence increases. Therefore, the laser beam is emitted at regular intervals.
When a row of spots is drawn on the photosensitive drum 14 with the switch ON, the interval between them is wider at both ends than at the center. To avoid this phenomenon, the imaging lens 13
is designed to have the following characteristic: r=f·θ −(2).

Such an imaging lens 13 is called an f-θ lens. Furthermore, when collimated light is imaged into a spot by an imaging lens, the minimum diameter of the spot dmin is: dmin = fλ/A - (3) where f; focal length λ of the imaging lens; wavelength A of the light used. is given by the entrance aperture of the imaging lens, and if f and λ are constant, a smaller spot diameter dmin can be obtained by increasing A.
The beam expander 7 mentioned above is used to provide this effect. Therefore, the necessary
When dmin is obtained by the beam diameter of the laser oscillator, the beam expander 7 is omitted.

As described above, the deflected and modulated laser beam 52 is irradiated onto the photosensitive drum 14, visualized by an electrophotographic process, transferred and fixed onto plain paper, and output as a hard copy. 1 of the electrophotographic process applied to this example
For example, as described in Japanese Patent Publication No. 42-23910 of the present applicant, the surface of the insulating layer of the photosensitive drum 14 whose basic constituents are a conductive support, a photoconductive layer, and an insulating layer is charged with a first corona charge. The charged layer is uniformly charged positively or negatively in advance by a container 16, and charges with a polarity opposite to the charged polarity are captured at the interface between the photoconductive layer and the insulating layer or inside the photoconductive layer, and then the charged At the same time as the surface of the insulating layer is irradiated with the laser beam, an alternating current corona discharge is applied by an alternating current corona discharger 17 to form a pattern on the surface of the insulating layer due to a difference in surface potential that occurs according to the light and dark pattern of the laser beam. The entire surface of the insulating layer is uniformly exposed to light using a full-surface exposure lamp 18 to form a high-contrast electrostatic latent image on the surface of the insulating layer, and the electrostatic latent image is formed using a developer mainly composed of charged colored particles. After being developed and visualized by the developing device 19, the visible image is transferred by the transfer charger 22 onto a sheet of paper (hereinafter referred to as paper) fixed on the photosensitive drum 14 by the means described later. Then, the transferred image is fixed by a fixing means as described below to obtain an electrophotographic print image, and after the transfer is performed, the surface of the insulating layer is cleaned by a cleaning device 23 to remove remaining charged particles. , the photosensitive plate 14 is used repeatedly. As yet another embodiment, an electrophotographic electrostatic image forming process as described in Japanese Patent Publication No. 19748/1974 by the present applicant is applied. That is, using a photosensitive plate whose basic constituents are a conductive support, a photoconductive layer, and an insulating layer,
The surface of the insulating layer is uniformly charged positively or negatively in advance by the first corona discharge, and charges having a polarity opposite to the charged polarity are captured on the surfaces of the photoconductive layer and the insulating layer or inside the photoconductive layer. Further, an alternating current corona discharge is applied to the charged surface to attenuate the charge on the surface of the insulating layer, and then the laser beam as an information signal is irradiated to form an electrostatic latent image according to the brightness of the laser beam. The process of forming the electrostatic image on the surface of the insulating layer and then developing the electrostatic image is the same as that of the first embodiment.

The pre-static charger 15 is a pre-exposure lamp, which makes the surface unit of the photosensitive drum 14 constant and uniform, and the pre-exposure lamp 16 makes the characteristics of the photosensitive layer constant and uniform. These functions work together to erase various antecedents, such as residual potential, remaining on the photosensitive drum 14 after passing through the cleaning device 23, and are useful for always obtaining stable images.

The applicant has proposed an electrostatic latent image stabilization method as a means of always obtaining stable and good images in the electrophotographic process applied to this embodiment. 21
1 is an electrostatic electrometer for realizing such a means, and it measures the electrostatic potential of a bright part of the photosensitive drum 14, that is, a part scanned and exposed by a laser beam, and a dark part.

A carrier removing device 20 prevents carriers mixed in the developer in the developing device 19 from adhering to the photosensitive drum 14 and from adhering to the paper or entering the cleaning device 23 .

FIG. 2 shows three-dimensionally the arrangement of the optical system in FIG. 1, and in the explanation of FIG. 1, parts having the same functions are given the same numbers. (The same applies hereinafter) In FIG. 2, 51 detects the scanning start position of the swept laser beam 52 with a beam detector consisting of a small entrance slit and a photoelectric conversion element with a fast response time (for example, a PIN diode), A recording signal is applied to the terminal 6 after a certain period of time T after obtaining this detection signal, and recording is started. That is, this T determines the blank area (left margin) formed on the left side of the paper.

In FIG. 2, the scanning direction of the laser beam is indicated by an arrow 53.

Next, paper conveyance will be described. When the paper 31 stacked on the paper feeding stage 30 is sent out by a paper feeding roller 32, a pair of registration rollers 33 corrects the skew during paper feeding and aligns the leading edge of the paper. When the paper leaves the registration roller 33, a detector consisting of a lamp 34 and a photo sensor 35 detects the amount of deviation in the lateral direction of the paper.

If the amount of deviation is greater than a predetermined value, the conveyance switching piece 44 is moved from the state shown by the solid line to the state shown by the dotted line using a solenoid (not shown), and the paper is discharged onto the auxiliary tray 45.

By providing the second tray between the paper feed section and the transfer section in this way, it is possible to quickly remove inappropriate conveyed paper without causing jams or the like.

If the amount of deviation is less than the set value, the solenoid does not work and the conveyance switching piece 44 is in the state shown by the solid line, so the paper 31 passes through the conveyance guide 36, feed roller 37, and conveyance guide 38 and comes into contact with the drum. The image on the drum is then transferred onto paper by a transfer charger 22. After the paper has been transferred, it is separated from the drum by a separating means (not shown), and then transferred to the conveyor belt 39.
is sent to the fixing device 40 by. Here, the toner on the paper is fused under the heat and pressure of a fuser to form a permanent image. After fixing, the paper is conveyed by a conveyor belt 41, discharged from a paper discharge roller 42, and stacked on a tray 43.

To further describe the side detection of the paper, in FIG. 3, when the paper 31 passes through the transport guides 36a and 36b in a direction perpendicular to the plane of the paper, the light from the lamp 34 passes through the hole made in the guide. Blocks the photo sensor 35. At this point, it becomes possible to detect the side edges of the paper. The sensor is preferably one that can output an output in proportion to the position of the paper, such as a CCD. However, a resolution of about 0.25 mm is sufficient, and optical fibers may be lined up and a phototransistor or the like may be provided at one end of the fibers. The length of the sensor may be determined depending on the amount of paper misalignment. In Figure 3, the detection width of the sensor is from A to B.

When a beam detection signal is obtained by the beam detector 51, this beam detection signal is applied to a delay circuit 55, and after being delayed by a time t1, the beam detection signal is further applied to a delay circuit 56.
is applied and delayed by time Tα, and this delay circuit 5
6 is used as a recording start signal to instruct the start of recording. This time t1 is, for example, the time when the beam reaches the position indicated by W--W in FIG. 3.

The delay time in this delay circuit 56 is variably controlled from 0 to tβ by the output of the deviation amount detection circuit 57.

That is, it is assumed that the beam is substantially scanned in the direction from A to B in FIG.
Letting tα be the time for the beam to scan the distance β, the delay circuit 56 may be configured to obtain a delay time tα corresponding to the distance α detected by the deviation amount detection circuit 57.

With this configuration, even if the paper 31 shifts to the left or right in FIG. 3, the recording start position changes according to the amount of shift, so recording can be started from a fixed position. be.

[Brief explanation of the drawing]

1 and 2 show a laser beam printer to which the present invention is applied, with FIG. 1 being a side view and FIG. 2 being a perspective view of the main parts. Figure 3 is a side view of the main parts of Figure 1,
FIG. 4 is a main signal waveform diagram of the laser beam printer, and FIG. 5 is a recording start signal forming circuit diagram. Here, 31 is paper, 35 is a photo sensor, 51 is a beam detector, 55 and 56 are delay circuits, and 57 is a deviation amount detection circuit.

Claims (1)

[Claims] 1. An image is formed by irradiating and scanning light modulated by recorded information onto a photoreceptor, and the image is transferred onto a conveyed recording member to transfer information onto the recording member. In a recording device that records information and discharges the recording member on which information is recorded to a first discharge means, a side portion provided in the conveyance path of the recording member and perpendicular to the conveyance direction of the recording member being conveyed. recording member detection means for detecting the position of the recording member; deviation amount detection means for detecting the amount of lateral displacement of the recording member from a reference position based on the output of the recording member detection means; and recording information from a predetermined position of the recording member. means for controlling the timing in the scanning direction of the light for emitting light modulated by the recorded information according to the amount of lateral deviation detected by the deviation amount detection means; A recording apparatus characterized by comprising: means for ejecting the recording member to a second ejecting means different from the first ejecting means when the amount of lateral deviation is larger than a predetermined amount.