JPH03110587A - Recorder - Google Patents

Abstract

PURPOSE:To speed up the conveyance of a recording medium from a white picture area to a black one by varying the carrying speed of the recording medium according to the number of lines of black or white picture elements. CONSTITUTION:When a line number detecting means 20b counts black or white picture element lines exposed by a photosensitive drum 1 after an electrophotographic process is executed, a potential switching means switches the polarity of a transfer potential applied to a transfer means according to the number of detected black or white picture lines and individually controls transfer to the white picture element area and transfer to the black picture element area. In this case, a carrying system varying means 20c varies the carrying speed of the recording medium according to the number of detected black or white picture element lines. Consequently, the conveyance of the recording medium from the white picture element area to the black one is sped up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording device that records an image by scanning a photoreceptor with a light beam modulated based on a manually inputted image signal.

(Prior Art) Conventionally, an apparatus has been proposed that records an image by scanning a photoreceptor with a light beam, as disclosed in, for example, Japanese Patent Publication No. 60-20748.

This type of recording apparatus rotates a photoreceptor at a constant speed, and this process speed is usually fixed during image recording.

[Problem to be solved by the invention]

However, since the photoreceptor is rotated at a constant speed as described above, there is a restriction that the time required for the recording operation for one page must be constant. That is, at the time of starting the recording operation, the contents of the recording page must already be stored in the image memory, or the image signal must be input at a constant speed.

Configuring the system so that image signals are input manually at a constant speed requires a large capacity buffer memory in front of the recording device, which results in expensive memory that is driven at high speed. I had to depend on it.

Therefore, when recording the above image without relying on memory, it is necessary to rotate the photoreceptor in accordance with the timing when the image signal is input, or in some cases slightly adjust the rotation speed of the polygon mirror that is rotating at high speed. It may be necessary to change the system to a new one or repeatedly start and stop it suddenly.

As a result, the electrophotographic process speed fluctuates, and the synchronization timing between the drive of the photoreceptor and the laser scan shifts, resulting in image defects.

In this way, in a light beam scanning type recording device, an image memory for at least one page (approximately 2 MB for an A4 size image with a linear density of 400 DPI) is always required.
'There was a problem in that the overall cost of the device could not be reduced as expected, which became a bottleneck to the widespread use of the device.

This invention was made to solve the above problems, and by switching the polarity of the transfer potential applied in the transfer process according to the number of black and white pixel lines in the input image information, the white image area is An object of the present invention is to obtain a recording device that can perform high-speed recording processing while skipping.

(Means for Solving the Problems) A recording device according to the present invention includes a transfer means for transferring an image developed on a photoconductor to a recording medium, and a line for detecting the number of white or black pixel lines exposed to the photoconductor. a number detection means;
A potential switching means is provided for switching the polarity of the transfer potential applied to the transfer means in accordance with the number of white or black pixel lines detected by the line number detection means.

Further, a conveyance system variable means is provided for varying the conveyance speed of the recording medium according to the number of white or black pixel lines detected by the line number detection means.

[Effect]

In this invention, when the electrophotographic process is executed, when the line number detection means counts the number of white or black pixel lines exposed to the photoreceptor, the potential switching means is activated in accordance with the number of white or black pixel lines detected. By switching the polarity of the transfer potential applied to the transfer means, it is possible to separately control transfer to a white image area and transfer to a black image area.

Further, the conveyance system variable means varies the conveyance speed of the recording medium according to the number of white or black pixel lines detected by the line number detection means, thereby increasing the recording medium conveyance speed from the white pixel area to the black pixel area. make it possible.

(Embodiment) FIG. 1 is an external perspective view illustrating the configuration of a recording apparatus showing an embodiment of the present invention. Reference numeral 1 denotes a photosensitive drum, and a stepping motor, for example, constituting the photosensitive drum driving means according to the present invention. 14 via a deceleration means 15 so as to be self-sustainable. A primary charging unit 2 charges the photosensitive drum 1 uniformly. 3 is a laser unit which is modulated and driven based on an image signal inputted by a laser driver provided in the controller unit C0NT. 4 is a polygon mirror that directs the laser beam emitted from the laser unit 3 to an fθ lens 5. Photosensitive drum 1 via folding mirror 6
Scan horizontally.

A developing unit 7 visualizes the electrostatic latent image formed on the photosensitive drum 1.

Reference numeral 8 denotes a registration roller, which feeds the paper 9 when the writing timing between the fed paper 9 and the leading edge of the image is established. 10 is a transfer unit, 11 is a separation unit, and 13 is a drum cleaning unit, which collects toner remaining on the photosensitive drum 1. Note that the fixing unit 12. The registration rollers 8 and the like are driven by a stepping motor (drive motor) 14 via a power transmission means and an electromagnetic clutch (not shown). A scanner motor 16 rotates the polygon mirror 4 at a constant speed, for example, 6000 revolutions per minute. Reference numeral 17 denotes a beam detection mirror, which guides the laser beam emitted from the laser unit 3 to a beam detector to be described later, in order to create a trigger signal for a laser scanning operation.

Specifically, when the electrophotographic process is executed, when the line number detection means 20b (described later) counts the number of white or black pixel lines exposed on the photosensitive drum 1, the potential switching means (switch 101 described later) The polarity of the transfer potential applied to the transfer means is switched according to the number of detected white or black pixel lines, and transfer to the white image area and transfer to the black image area are individually controlled.

FIG. 2 is a schematic diagram illustrating the image recording process of the photosensitive drum 1 shown in FIG. It is.

Further, the conveyance system variable means 20c also changes according to the number of white or black pixel lines detected by the line number detection means 20b.
makes it possible to vary the conveyance speed of the recording medium (paper 105) and increase the recording medium conveyance speed from the white pixel area to the black pixel area.

When the original image "B" is reproduced as an electrostatic latent image on the surface of the photosensitive drum 1, a video signal is obtained based on the scanning line in the original image "B" and is transmitted to a laser unit via an amplifier (not shown). 3, a laser beam is emitted according to the video signal.

The polygon mirror 4 is rotated by the scanner motor 16.
A laser beam emitted from a laser unit 3 scans the surface of the photosensitive drum 1 while rotating at a rotational speed of 0 RPM. The surface of the photosensitive drum 1 is charged to a negative potential by the negative voltage unit 2, and is rotated by a stepping motor 14 at a predetermined rotational speed. When the rotational angular velocity of the stepping motor 14 is ω8 and the reduction ratio of the reduction means 15 is 1/, the circumferential velocity Vo of the surface of the photosensitive drum 1 is defined by the following equation (1).

Vo = (D/2) (ωM/ζ)...
(1) Note that D in the above formula (1) indicates the diameter of the photosensitive drum 1.

On the other hand, when the rotational speed of the polygon mirror 4 is N (RPM) and the number of reflective surfaces of the polygon mirror 4 is p, the number of times of laser beam scanning per second is PN/60.

This is equivalent to exposing for PN760 scanning lines per second, and during this period it is necessary to drive the peripheral surface of the photosensitive drum 1 by PN/60F a number of sub-scanning times. Here, F is the sub-scanning line density.

Therefore, the circumferential velocity VD of the surface of the photosensitive drum 1 satisfies the following equation (2).

Note that ωM/ζ in the above equation (2) represents the rotational angular velocity of the photosensitive drum 1. As an example, P=6 (hexagonal polygon) N=600ORPM, D=40mm, F=
15, 74842/mm (400DPI), we get (LIM/ζ=1, 905 rad/sec).

Since the scanning speed at this time is 600 times per second, the driving frequency of the stepping motor 14 is set to 600 PP.
Just set it to S. If the step angle of the stepping motor 14 is 1.8DEG/5TEP, ω, = 1.8
X (π/180)X600 = 18.85rad/
sec, so ζ is 18.85/1.905, which is 9.
It becomes 895. If this relationship is maintained, the original image "B" will be reproduced on the surface of the photosensitive drum 1.

FIG. 3 is a circuit block diagram illustrating the configuration of the controller unit C0NT shown in FIG. 1, and the configuration and operation will be described below.

A video signal that is transmitted after being decomposed into each scanning line from the original image is reproduced by the receiving section 19 of the facsimile machine and sent to the video interface 2 of the laser beam recording device.
Sent to 0. At this time, as shown in the figure, the first line and the second line are input consecutively, but the second line and the third line are
It is assumed that there is a no-signal period between the lines. The control section 21 adds a laser ON signal to the beginning of the video signal for each scanning line and sends it to the laser unit 3 . At this time, a laser ON signal is added at a constant cycle even during the no-signal period. That is, since the laser scanning speed is 600 times per second as mentioned above, the period is 1.67
It is m5ec.

The laser drive signal to which the laser ON signal has been added activates the laser unit 3 to emit a laser beam, which is scanned onto the circumferential surface of the photosensitive drum 1 by the polygon mirror 4 rotated by the scanner motor 16 and electrostatic latent. form an image.

Here, the action of laser 0N (i) will be explained.

The timing is set so that the laser beam emitted by the laser ON signal added to the laser drive signal is reflected by the beam detection mirror 17 and sent to the optical fiber 18. When the control unit 21 detects the beam of the laser drive signal, it outputs a beam detection signal (BD scratch signal). When the BD scratch signal is received, if the video signal to be output is input to the video interface 20, Immediately outputs the video signal as a laser drive signal.At the same time, it outputs a command to rotate the photosensitive drum 1 by one scanning line to the driver 22 that drives the stepping motor 14, and the photosensitive drum 1 rotates.The control unit 21 After outputting one line of video signal, the laser ON signal (second
(laser ON signal) is output. This second laser ON
When the BD scratch signal is obtained, since the second line video signal has been input, the third laser ON signal is immediately output following the second line video signal. However, when the third BD scratch signal was obtained, it was a no-signal period,
The video signal of the third line is still connected to video interface 2.
It has not reached 0. At this time, turn the laser drive a signal to
The driver 22 that drives the stepping motor 14 is caused to maintain its current excitation state. One cycle (1,67m5e) after outputting the third laser ON signal
c) Later, a fourth laser ON signal is output, and a fourth BD scratch signal is obtained as the reflected light.

At that time, if the video signal of the third line is not obtained, the holding state continues. In the case of Fig. 3, the third line video signal is obtained after obtaining the fifth BD scratch signal, and in this case, the third line video signal is obtained immediately after obtaining the sixth BD signal. The video signal is output as a laser drive signal, and further, the driver 22 of the stepping motor 14 is instructed to drive one scanning line.

As described above, the control unit 21 turns on the video signal in units of integral multiples of the rotation period of the polygon mirror 4.
If this method is adopted, a laser beam type recording device that reproduces manually input video signals at irregular intervals can be obtained. In addition, 20c
is a conveyance system variable means.

FIG. 4 is a timing chart illustrating the operation of FIG. 3.

Next, a case will be described in which the controller unit C0NT shown in FIG. 3 is applied as a printer for a receiver of a facsimile machine.

A transmitter (not shown) decomposes the original image into pixels and encodes the video signal for each scanning line using the MH encoding method or the like. The number of bits of coded image information differs depending on the density of black/white transition points of pixels. That is, the transmission time of the image signal sent onto the telephone line differs for each scanning line. In the receiver, such a signal is received by a receiving section 19 and demodulated to obtain coded image information. After receiving one line of image information, it is demodulated to obtain coded image information. Since one line of image information is received and then decoded to reproduce pixel information, the time required to obtain pixel information differs for each scanning line. CCITT's G
The III standard sets a minimum transmission time of 0m5e.
c, 5m5ec, 10m5ec.

20 m5ec. However, in order to explain this together with the description of the recording device described above, the minimum transmission time is set to 1.67 m5ec. This is possible with a transmission method that uses an image buffer memory for several tens of lines, and the description based on this assumption also requires a minimum transmission time of 5m5ec, 10m5
This is essentially no different from setting the value to a standard value such as ec.

As shown in FIG. 3, the video signal of each scanning line decoded by the receiving section 19 is input to the video interface 2o of the recording device. Here, it is assumed that the first line and the second line can be received at 1.67 m5ec. Control part 2
1 sends a laser ON signal to the laser unit 3, the laser emits light, and a BD scratch signal is fed back to the control unit 21 from the beam detection mirror 17 through the optical fiber 18. Immediately after the BD signal is detected, the laser unit 3 is driven by the video signal of the first line, and the electrostatic latent image of the first line is formed on the photosensitive drum 1. at the same time,
The stepping motor 14 of the photosensitive drum 1 is driven for one line. After the end of the first line, that is, after sending out the first laser drive signal, the second laser ON signal is sent out 1°67 m5ec, and the BD scratch signal is obtained again. Since more than 1.67 m5ec has passed since the first line was sent out from the control unit 21, the second line has already been decoded and reached the control unit 21. Therefore, when the laser unit 3 is immediately driven with the video signal of the second line, an electrostatic latent image of the second line is formed. At the same time, the drive motor 1 of the photosensitive drum 1
4 for one line. After sending out the second line,
The control unit 21 sends out the third laser drive signal and obtains the BD scratch signal again as described above. Here, the encoded third
Assume that the number of bits in the line is large and it takes 6 m5ec for reception. Therefore, at the time when the BD scratch signal is obtained, the third line has not been completely received, so the laser is not driven.

Further, the drive motor 14 of the photosensitive drum 1 is also not driven, and the photosensitive drum 1 is held at the current position. After sending out the third laser ON signal, the fourth laser ON signal is sent every 1.67m5ec. The fifth laser ON signal is sent out, but even if the BD scratch signal is detected by each laser ON signal, the third line has not yet been received, so the laser is not driven and the drive motor 14 is also maintained. Up to this point, it has taken 5m5ec.

Thereafter, reception and decoding of the third line is completed after 1 m5 ec, that is, when 6 m5 ec has elapsed since the transmission of the third laser drive signal. When a BD scratch signal is detected based on the sixth laser ON signal at the bottom, the control section 2 (light source driving means) drives the laser unit 3 with the video signal of the third line, and also controls the photosensitive drum 1. Drive motor 14
is driven for one line. Thereafter, these operations are repeated to obtain an electrostatic latent image for one page.

[Second Embodiment] FIG. 5 is a schematic perspective view illustrating the configuration of a recording apparatus showing a second embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

In the figure, 23 is a photo encoder, and the photosensitive drum 1
It is integrated with.

A sensor 24 reads the angle of the photo encoder 23. Reference numeral 25 denotes a synchronous motor (scanner motor), which is configured to be able to detect the rotation angle of the polygon mirror 4.

Next, the operation of each part will be explained.

Although the photosensitive drum 1 is made of aluminum or plastic material to reduce its weight, the inertial load of the stepping motor 14 is relatively large.

The reduction ratio of the reduction means 15 is as large as approximately 1/10, and the moment of inertia of the photosensitive drum 1 converted to the output shaft of the stepping motor 14 can be reduced. adversely affect characteristics. Therefore, in the second embodiment, the sensor 2 of the encoder 23 is provided integrally with the photosensitive drum 1.
By controlling the laser beam using the output of No. 4 as a trigger, more accurate scanning of the laser beam can be obtained.

Furthermore, instead of detecting the rotation angle of the polygon mirror 4 with the beam detection mirror 17 (see Fig. 1), if a synchronous motor with an encoder is used as the synchronous motor 25 that rotationally drives the polygon mirror 4, the BD scratch signal can be detected. The control unit 20 can directly synchronize the output of the laser drive signal without any intervention.

FIG. 6 is a schematic diagram illustrating the electrophotographic process of the recording apparatus shown in FIG. 1, and the configuration and operation will be described below.

Photosensitive drum 101 rotates clockwise.

In the next charging step 102, corona discharge is generated so that the surface of the photosensitive drum 101 is negatively charged. In an exposure step 103, a laser beam is irradiated onto the surface of the photosensitive drum 101, which is negatively charged as shown in FIG.

Since the electrical resistance of the portion irradiated with the laser beam decreases, negative charges flow and the potential decreases. Therefore, an electrostatic latent image is formed along the pattern of the laser beam hitting the surface of the photosensitive drum 101. Next development step 104
Then, negatively charged toner from a developing device biased more negatively than the photosensitive drum 101 adheres to the area hit by the laser beam, thereby making the electrostatic latent image visible. Transfer step 10 onto paper 105 aligned by registration rollers 8
6, the toner is transferred and a hard copy is obtained via the next separation step 107. Toner remaining on the surface of the photosensitive drum 101 without being cut onto the recording paper 105 in the transfer step 106 is scraped off in a drum cleaning step 109. Further, in a pre-exposure step 110, all residual charges on the surface of the photosensitive drum 101 are erased, and one cycle is completed.

In the above description, the charge charged on the photosensitive drum 101 in the second charging step 102 is a basic element of the subsequent process. When the photosensitive drum 101 is irradiated with light,
Since the electrical resistance decreases, it is necessary to prevent the irradiation of light other than the laser beam after the -order charging step 102. However, since the dark resistance is not completely zero,
Discharge progresses gradually. Therefore, in a method in which the photosensitive drum 101 does not rotate at a constant speed, the −th charging step 10
The density of the visualized image may change depending on the time required from step 2 to development step 104.

FIG. 7 is a schematic diagram illustrating the driving operation of the developing step 104 shown in FIG. 6, and the same parts as in FIG. 6 are given the same reference numerals. Note that the developing method is a jumping developing method in which an alternating current voltage with a direct current bias is applied to the developing sleeve. The configuration and operation will be explained below.

Sleeve 112 rotating around fixed magnet 111
There is a magnetic action of the fixed magnet 111 and the blade 1
13, a toner layer of uniform thickness is formed around the sleeve 112. Further, an AC voltage 114 and a negative bias 115 are applied to the sleeve 112 .

FIG. 8 is a characteristic diagram illustrating the characteristics of the developing bias applied to the developing sleeve shown in FIG. 7, where the vertical axis indicates voltage, VB indicates negative DC bias, and VO indicates AC voltage.

As can be seen from this figure, the potential of the sleeve 112 is −(
It changes from Va +Vo ) to +(va +VO). Since the potential of the electrostatic latent image on the photosensitive drum 1o1 is about "0" V, toner corresponding to the shaded area in FIG. 8 jumps toward the latent image. That is, the larger the negative DC bias -18 is on the negative side, the greater the amount of toner used for development, and the higher the density of the developed image.

FIG. 9 is a circuit block diagram illustrating the variable application processing operation of the DC bias VB applied to the sleeve 112 shown in FIG. 7, and the same components as in FIGS. It is attached. The configuration and operation will be explained below.

A video signal input from the video input terminal is temporarily stored in a video buffer 119. Video buffer 119
If there is a video signal, the BD scratch signal is output from the video signal detector 120 to the motor driver 121.
A drive signal is output to rotate the photosensitive drum 101.

At the same time, from the video buffer 119, the laser unit 11
6, a laser drive signal is output and scanned onto the photosensitive drum 101 via the polygon mirror 117. Using the motor drive signal output from the video signal detector 120 as a trigger, the time of the clock 122 is held by the latch 123 and stored in the memory 124. The calculator 125 calculates the difference between the current time t and the time to (stored in the memory 124) when the portion at the developing step 104 is at the temporary charging step 102 at this point. Then, the required time Δt=t−to is determined. The value of time Δt is converted by a D/A converter 126 and then applied as a bias voltage to the sleeve 112 via an amplifier 127.

In other words, when the time Δt is long, the negative potential on the negative-order charged photosensitive drum 101 is decreasing.
The ground part of the recorded latent image is easily fogged. Therefore,
The negative bias voltage is weakened to control excess 1-ner from adhering to the photosensitive drum 101. In addition,
118 is a stepping motor.

As shown in FIG. 10, a surface potential detector 12B is disposed near the end of the photosensitive drum 101, which is encountered immediately before the developing step 104 and where no image is reproduced, and the surface potential detector 12B is arranged near the end of the photosensitive drum 101 where the image is not reproduced. The bias voltage applied to the sleeve 112 may be variably controlled.

Generally, both ends of the photosensitive drum 101 are provided with areas that are not used for image reproduction, so these areas are utilized. Further, the same area can also be used in a device using a separation belt method.

FIG. 11 is a schematic diagram illustrating the surface potential control operation in the recording apparatus according to the present invention, and the same parts as in FIG. 6 are given the same reference numerals. The configuration and operation will be explained below.

Reference numeral 129 denotes a bias exposure device, which is arranged so as to act uniformly over the entire width in the axial direction of the photosensitive drum 101, similarly to the secondary charging step 102 and the developing step 104. -20 to 50% more than normal in the next charging step 102
The photosensitive drum 101 is charged so that the potential becomes high. In the exposure step 103, a laser scanning operation is performed as described above to form an electrostatic latent image. However,
As described above, in the present invention, the time required from the -order charging step 102 to the development step 704 is not constant, so the longer the time, the lower the charging potential is due to dark discharge. Therefore, by the method explained in FIG. 9 or 10, the photosensitive drum 101
The surface potential of the upper ground portion is detected, and the exposure amount of the bias exposure device 129 is changed according to the detected value. In other words, when the time required is short, the exposure amount is increased and the potential is lowered.
On the other hand, when the time required is long, the exposure amount is reduced to maintain the contrast of D, W, and. Here, it is preferable to use a light emitting body such as an LED or a rare gas discharge tube for the bias exposure device 129, which has a wide dynamic range even if its brightness is low.

FIG. 12 is a sectional view illustrating the configuration of the transfer unit 10 shown in FIG. 1, and the configuration and operation will be described below.

In the transfer unit 10, the operation of transferring the toner on the photosensitive drum 101 onto the paper (recording paper) 105 is executed.
By setting the toner to a positive potential, toner having a negative charge is more likely to transfer to the recording paper 105, thereby facilitating the transfer process.

On the other hand, the switch 131 is switched to the b side and the transfer device 130
When the voltage is set to a negative potential, the toner having a negative charge repels the paper 105 and is not transferred. The first laser beam type operation that uses this principle allows for efficient non-constant speed recording operation.
This will be explained with reference to FIG.

FIG. 13 is a flowchart illustrating the recording processing procedure in the recording apparatus according to the present invention. In addition, (1) to (
9) shows each step.

Recording processing for one page is started, one line of image is manually input (1), pixels are detected from one line of manually input video signal (2), and the change point of the detected pixels is from a white pixel to a black pixel. 3)
If No, the line number detection means 20b counts the number of consecutive black lines (9), returns to step (1), and Y
If ES, determine whether the pixel change point was a change point from a black pixel to a white pixel 4), if YES, stop the motor 5) Code the number of lines 7), determine the end of the page 8) ), if YES, end the process,
N.

If so, return to step (1).

On the other hand, if the determination in step (4) is No, the motor is started (6) and the process proceeds to step (7).

In this way, it is checked whether or not black pixels are included in the input video signal for one line, and it is assumed that the first line of the page to be recorded is a line that includes black pixels. in general,
The first few lines are often all white, so
The first line is considered to have been converted from a black line to a white line. Therefore, initially, the number of lines is coded assuming that zero black lines have been read. Next, the number of frontage lines following the white line is counted, and the encoding is completed when the black line appears. The encoding method used here is MH, which is well known as a facsimile band compression method.
Using codes allows for efficient encoding. In this encoding process, when a change point from a black line to a white line is detected, the drive motor for the photosensitive drum 1 is stopped, and the laser output is also stopped in conjunction. In other words, the recording operation is stopped while the white line continues. When the point of change from the white line to the black line is detected, the recording operation is restarted.

Next, the transfer potential switching processing operation according to the present invention will be explained with reference to FIG.

FIG. 14 is a flowchart illustrating an example of the transfer potential switching processing procedure according to the present invention.

Note that (1) to (7) indicate each step.

The black line is decoded (1), the number of black lines is detected, and the potential of the transfer device is set to the transfer side (in this embodiment, the switch 131 shown in FIG. 12 is switched to the b side) for that number. 2) The paper feed roller is also the photosensitive drum 10.
(3) Next, when the number of white lines is decoded (4), a positive potential is applied to the transfer device (in this embodiment, the switch 131 shown in FIG. 12 is switched to the a side). 5), paper feed rollers (for example, registration rollers 10), conveyance system variable means 20c
is driven at high speed 6), and the recording of the areas where the white line continues is omitted. Next, it is determined whether the page is finished (7) If NO, the process returns to step (1), and if YES, the process ends.

In addition, in the above embodiment, a case was explained in which a stepping motor was used as a driving means for the photosensitive drum 1.
A similar effect can be achieved by augmenting the servo motor and feedback control circuit.

〔Effect of the invention〕

As explained above, the present invention includes a transfer means for transferring an image developed on a photoreceptor to a recording medium, a line number detection means for detecting the number of white or black pixel lines exposed on the photoreceptor, and a line number detection means for detecting the number of white or black pixel lines exposed on the photoreceptor. Since a potential switching means is provided for switching the polarity of the transfer potential applied to the transfer means according to the number of white or black pixel lines detected by the detection means, the white or black pixel line detected by the line number detection means is also provided. Since the conveyance system variable means for varying the conveyance speed of the recording medium according to the number of pixels is provided, it is possible to increase the speed of conveyance of the recording medium to the white pixel line area, and the recording processing time can be significantly shortened.

Therefore, excellent effects such as being able to record only black pixels clearly and at high speed on a recording medium while skipping recording white pixel lines are achieved.

[Brief explanation of drawings]

FIG. 1 is an external perspective view illustrating the configuration of a recording apparatus showing an embodiment of the present invention, FIG. 2 is a schematic diagram illustrating image recording processing of the photosensitive drum shown in FIG. 1, and FIG. , a circuit block diagram explaining the configuration of the controller section shown in FIG. 1, FIG. 4 is a timing chart explaining the operation of FIG. 3, and FIG. 6 is a schematic diagram illustrating the electrophotographic process of the recording apparatus in the recording apparatus shown in FIG. 1; FIG. 7 is a schematic perspective view illustrating the structure of the recording apparatus; FIG. 7 is a driving operation of the developing step shown in FIG. 6. FIG. 8 is a characteristic diagram explaining the characteristics of the developing bias applied to the developing sleeve shown in FIG. 7, and FIG. 9 is a schematic diagram explaining the characteristics of the developing bias applied to the developing sleeve shown in FIG. 10 is a perspective view showing the arrangement position of the potential sensor provided on the photosensitive drum shown in FIG. 9, and FIG. 11 is a circuit block diagram illustrating the variable application processing operation of FIG. FIG. 12 is a schematic diagram illustrating the potential control operation; FIG. 12 is a sectional view illustrating the configuration of the transfer unit shown in FIG. 1; FIG. 13 is a flowchart illustrating the recording processing procedure in the recording apparatus according to the present invention;
FIG. 14 is a flowchart illustrating an example of a transfer potential switching IA processing procedure according to the present invention. In the figure, 1 is a photosensitive drum, 2 is a primary charging unit, 3 is a laser unit, 4 is a polygon mirror 5 is an fθ lens, 6
1 is a folding mirror, 7 is a developing unit, 8 is a registration roller, 9 is paper, 10 is a transfer unit, 11 is a separation unit, 13 is a drum cleaning unit, 16 is a scanner motor, 20b is a line number detection means, 20. c is a conveyance system variable means, and C0NT is a controller section. fig.

Claims (2)

[Claims] (1) A recording device that records an image by scanning a photoreceptor with a light beam emitted from a light source, including a transfer means that transfers the image developed on the photoreceptor to a recording medium, and a transfer means that transfers the image developed on the photoreceptor to a recording medium; A line number detection means for detecting the number of white or black pixel lines, and a potential switching means for switching the polarity of the transfer potential applied to the transfer means according to the number of white or black pixel lines detected by the line number detection means. A recording device characterized by comprising: (2) A printing apparatus characterized by comprising a conveyance system variable means for varying the conveyance speed of the recording medium according to the number of white or black pixel lines detected by the line number detection means.