JP2522267B2 - Recording device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a recording apparatus adopting an electrophotographic system.

“Prior Art” FIG. 3 shows a schematic configuration of a laser printer that employs an electrophotographic method called a so-called xerographic method.

This device has a cleaning device 2 on the outer periphery of the photoconductor 1.
An erase lamp 3, a charge corotron 4, an exposure device 5, a developing device 6, a transfer device 7 and a peeling corotron 8 are provided. A paper feed tray 11, a paper feed roller 12, a sensor 13, a registration roller 14, a guide plate 15, a fixing roller 16 and a discharge tray 17 are provided on a recording paper conveyance path 10 passing through the transfer device 7. The exposure device 5 also includes a laser beam output unit 51 that modulates a laser beam according to an image signal, a lens 52 that matches the laser beam diameter, and a laser beam that reflects the laser beam and scans it parallel to the rotation axis of the photoconductor 1. And a f-θ lens 54 that corrects the optical path difference of the laser beam.

To start the recording operation by this device, first, the outer peripheral surface of the photoconductor 1 is cleaned by the cleaning device 2,
After removing the residual charges by the erase lamp 3, the photoconductor 1 is uniformly charged by using the charge corotron 4. Next, an electrostatic latent image is formed on the photoconductor 1 by the exposure device 5. This electrostatic latent image is developed by the developing device 6, and a toner image corresponding to the electrostatic latent image is formed on the photoconductor 1. This is transferred by the transfer device 7 to a recording sheet (not shown) on the transport path 10. Here, the recording paper is sent from the paper feed tray 11 by the paper feed roller 12, skew-corrected by the registration roller 14, and sent to the transfer device 7 through the guide plate 15. After the transfer, the recording paper is separated from the photoconductor 1 by the action of the peeling corotron 8, passes through the fixing device 16, and is discharged to the discharge tray.
It is discharged to 17.

“Problems to be Solved by the Invention” In the recording apparatus as described above, the transfer unit 21 for recording paper is used.
It is necessary to match the timing with the exposure and the rotation of the photoconductor 1 when feeding the photoconductor. In the apparatus shown in FIG. 3, this was carried out by the method shown in FIG.

In FIG. 4, first, the ready lamp is turned on on the illustrated console panel, and the operator is informed that the copying start preparation is completed (FIG. 4a). When the operator presses the print start button here, the conveyance of the recording paper is started (b in the figure). When the recording paper exits the paper feed tray 11 and the leading edge of the paper reaches the sensor 13, first the sensor is t1
13 is turned on (Fig. 6c). When the leading edge of the recording sheet hits the registration roller 14, the conveyance is temporarily stopped at the timing of t2 for skew correction and waiting for the conveyance restart (b in the figure). On the other hand, the exposure device 5 starts the exposure at a timing t3, which is a fixed time after the timing t1 at which the leading edge of the recording sheet is detected by the sensor 13 (d in the figure).

Here, as shown in FIG.
Is defined as l1 and the distance from the registration roller 14 to the transfer portion 21 is defined as l2. In this case, when the image initially exposed by the exposure unit 22 advances in the direction of the transfer unit 21 by the distance (l1-l2), the registration roller 14 starts to convey the recording paper, so that the toner image is formed. The timings at which the leading edge of the sheet and the leading edge of the recording sheet reach the transfer unit 21 coincide. Fourth
In the figure, the interval from the exposure start timing t3 to the transport start timing t4 is thus determined.

For this reason, conventionally, it is necessary for the recording paper to wait at the registration roller 14 for a certain period of time from the timing t2 to the timing t4 shown in FIG.

This waiting time is also required in the so-called multi-print mode in which a plurality of sheets are continuously printed at high speed. For this reason, it is impossible to further reduce the conveyance interval of the recording paper conveyed from the paper feed tray. Therefore, in the conventional recording apparatus, there is a limit to increase the recording speed in the multi-print mode.

The present invention has been made in view of the above points, and an object of the present invention is to provide a recording apparatus that enables a high-speed recording by reducing the conveyance interval of recording sheets.

"Means for Solving Problems" In the present invention, (a) a photoconductor that moves its surface at a constant speed, and (b) an electrostatic latent image forming unit that forms an electrostatic latent image on its outer peripheral surface. And (c) a developing device for developing the electrostatic latent image to form a toner image, (d) a transfer section for transferring the toner image onto a recording sheet, and (e) a conveying path for conveying the recording sheet. (F) between the registration roller arranged in the conveyance path and starting the conveyance at a predetermined timing at a predetermined timing when the recording sheet arrives; and (g) between the registration roller and the transfer section in the conveyance path. A sensor for detecting the passage of the leading edge of the recording sheet, and (h) at the time when the sensor has detected the passage of the leading edge of the recording sheet and the time for which the recording sheet is further conveyed by a predetermined amount has elapsed. Start formation of an electrostatic latent image by the electrostatic latent image forming unit The recording apparatus is provided with an exposure start timing adjusting means.

[Operation] As described above, in the case of the present invention, the sensor that detects the leading edge of the recording sheet is arranged between the registration roller and the transfer section. Since the distance between the sensor and the transfer portion is set longer than the distance between the electrostatic latent image forming portion and the transfer portion, the electrostatic latent image is not formed after the start of feeding the recording paper in the transfer portion direction. Will be started.

As a result, it is not necessary to wait the recording sheet for a long time with the registration rollers, and the recording sheet can be sent to the transfer portion at the minimum interval required for skew correction and the like, and high-speed continuous copying can be performed.

[Embodiment] FIG. 1 is a schematic configuration diagram showing an embodiment of a recording apparatus of the present invention.

This device is similar to that shown in FIG.
Cleaning device 2 and erase lamp 3
, Charge corotron 4, exposure device 5, and developing device 6
And a transfer device 7 and a peeling corotron 8. In addition, a paper feed tray 11, a paper feed roller 12, a registration roller 14, a sensor 13, a guide plate 15, a fixing device 16 and a discharge tray 17 are provided in this order on the recording paper conveyance path 10.

The structure of the exposure device 5 and the operations from cleaning to transfer of the photoconductor 1 are the same as those described with reference to FIG.

In this device, when the recording paper is sent from the paper feed tray 11 by the paper feed roller 12, the recording paper is temporarily stopped by the registration roller 14 for a very short time to perform skew correction and the like, and then is conveyed onto the guide plate 15. On the guide plate 15, the sensor 13 detects the passage of the leading edge of the recording paper, and then the electrostatic latent image forming unit 25
The exposure starts at. The toner image corresponding to the electrostatic latent image is transferred onto the recording sheet by the transfer device 7, fixed by the fixing device 16 and discharged to the discharge tray 17.

Here, in the recording apparatus of the present invention, the distance l2 between the sensor 13 and the transfer portion 21 is selected longer than the distance l1 between the electrostatic latent image forming portion 25 and the transfer portion 21. In this apparatus, the timing of conveying and exposing the recording paper is adjusted in the manner shown in FIG.

In FIG. 2, first, a ready lamp (not shown) on the console panel is turned on (FIG. 2a), and the print start button is pressed by the operator to start conveyance of the recording sheet (b). When the recording paper reaches the registration roller 14 at timing t2, skew correction is performed,
Immediately, the conveyance is restarted at timing t4. The recording paper, which has been restarted to be conveyed from the registration rollers 14, traverses just before the sensor 13, and the sensor 13 detects this at timing t5 (FIG. 11C).

When the sensor 13 detects the leading edge of the recording sheet, the recording sheet is conveyed by a distance corresponding to the difference between l2 and l1, and then exposure in the electrostatic latent image forming unit 25 is started (FIG. 4d). . Since the transport speed and the rotation speed of the photoconductor are synchronized, the leading edge of the toner image after development and the leading edge of the recording paper reach the transfer section 21 at the same time.

As described above, in the case of the recording apparatus of the present invention, the conveyance stop time of the recording sheet (between the timings t2 and t4) is only a very short time necessary for skew correction, and therefore the timing t5,
High-speed recording can be performed by successively conveying recording paper at minute intervals, such as t8 and t9.

"Modification" The recording apparatus of the present invention is not limited to the above embodiments.

The electrostatic latent image forming unit is not limited to one using a laser printer, but may be replaced with an optical system that irradiates a document and guides the reflected light to a photoconductor, or an optical writing head using a light emitting element array. .

[Advantages of the Invention] As described above, according to the present invention, a sensor for detecting the passage of the leading edge of the recording sheet is arranged between the registration roller and the transfer portion in the conveyance path, and the conveyance speed of the registration roller is detected. The electrostatic latent image forming unit sets the speed at the same time as the moving speed of the body surface, and at the time when the sensor detects the passage of the leading edge of the recording sheet and the recording sheet is further conveyed by a predetermined amount, Since it was decided to start forming the latent image, unlike the conventional case where the distance between the resist roller and the transfer position of the photoconductor was made equal from the exposure position of the photoconductor to the transfer position, the The stop time of the recording paper can be set to the minimum. Therefore, when recording continuously, it is possible to feed them onto the conveying path with the minimum distance between recording sheets,
It is possible to improve the number of recording processing sheets per unit time.

Further, in the present invention, after the posture of the recording sheet is corrected by the registration roller, the passage of the leading edge of the recording sheet is detected by the sensor, and the electrostatic latent image forming section starts the formation of the electrostatic latent image at a predetermined timing calculated from this. Therefore, unlike the case where the sensor is placed in front of the registration roller to detect the leading edge of the recording paper without correcting the attitude of the recording paper and set the timing of electrostatic latent image formation from now on, the paper The position of the electrostatic latent image can always be accurately adjusted.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a recording apparatus of the present invention,
FIG. 2 is a timing chart for explaining the operation, and FIG.
FIG. 4 is a schematic configuration diagram showing an example of a conventional recording apparatus, and FIG. 4 is a timing chart explaining its operation. 1 ... Photoconductor, 6 ... Developing device, 10 ... Conveyance path, 13 ... Sensor, 14 ... Registration roller, 21 ... Transfer section, 25 ... Electrostatic latent image forming section.

Continuation of front page (56) Reference JP-A-57-58166 (JP, A) JP-A-57-58164 (JP, A) JP-A-62-174776 (JP, A) JP-A-57-23967 (JP , A) JP 62-208065 (JP, A) JP 62-180378 (JP, A) JP 59-39647 (JP, A) JP 59-188677 (JP, A) JP 61-43758 (JP, A)

Claims (1)

(57) [Claims] 1. A photosensitive member, the surface of which moves at a constant speed, an electrostatic latent image forming portion for forming an electrostatic latent image on the outer peripheral surface thereof, and a toner image formed by developing the electrostatic latent image. Developing device, a transfer unit for transferring the toner image onto a recording sheet, a conveying path for conveying the recording sheet, and a recording sheet arranged in the conveying path and when the recording sheet arrives at a predetermined timing at the constant speed. A registration roller that starts this conveyance, a sensor that is disposed between the registration roller and the transfer unit in the conveyance path and detects the passage of the leading edge of the recording sheet, and this sensor detects the passage of the leading edge of the recording sheet. Exposure start timing adjusting means for starting the formation of the electrostatic latent image by the electrostatic latent image forming section at a time point when a predetermined amount of recording paper is further conveyed from the detection time point. Characteristic Recording apparatus for.