JP2001022201A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of obtaining satisfactory image quality irrespective of the thickness of recording paper. SOLUTION: Sheets of recording paper 71 stacked on a manual insertion tray 70 is separated one by one from the uppermost sheet of recording paper 71 by cooperating action of a paper feed roller 72 and separation pad 73. The separation pad 73 is pressed to the paper feed roller 72 by pressing force of a spring 75 via a support member 74. In a spring 75, a strain gage 76 for detecting an amount of strain of the spring 75 is disposed. Therefore, an amount of strain of the spring 75 when each of the stacked sheets of recording paper 71 is separated is detected by the strain gage 76. Based on the amount of the strain, the transfer voltage of a transfer unit 90 is adjusted. Namely, based on the thickness of the recording paper 71, the transfer voltage of the transfer unit 90 is adjusted. Therefore, irrespective of the thickness of the recording paper 71, satisfactory image quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art In recent years, image forming apparatuses typified by facsimile apparatuses having a copy function are configured to be capable of copying on various types of recording paper. In other words, when copying on a postcard as recording paper, if the mode of the recording paper is set to “postcard mode” by a user's operation, the image forming apparatus recognizes that the recording paper is a postcard, and changes the transfer voltage. Adjust to the transfer voltage corresponding to the postcard thickness. As a result, it is possible to copy a postcard with good image quality.

Further, there are recording papers of the same size but different thicknesses. Therefore, when the recording paper is thicker than the standard recording paper thickness, the transfer voltage is increased by setting the recording paper mode to the “thick paper mode” by the user's operation, thereby improving the image quality. Some image forming devices can be obtained.

[0004]

However, in an image forming apparatus simply provided with a "postcard mode" or a "thick paper mode", the recording paper mode must be set in advance according to the recording paper. In addition, since the thickness of the recording paper varies, good image quality may not be obtained only in the “thick paper mode”. In other words, when the recording paper is thicker than the standard recording paper, the transfer voltage is insufficient.
The image on the recording paper has a blurred image quality. On the other hand, when the recording paper is thinner than the standard recording paper, the transfer voltage is high, so that the once-transferred toner image may return to the photosensitive drum, that is, reverse transfer may occur.

The present invention has been made in view of such a problem, and has as its object to provide an image forming apparatus capable of obtaining good image quality regardless of the thickness of recording paper. Is to do.

[0006]

In order to achieve the above object, according to the present invention, in an electrophotographic image forming apparatus, a separating means for separating stacked recording papers one by one. And a control means for adjusting the transfer voltage of the transfer device based on the amount of displacement accompanying the separating operation of the separating means.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the separating unit includes an urging unit that is displaced in accordance with the thickness of the recording paper. According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, when the recording paper is thicker than a predetermined recording paper, the control means increases the transfer voltage, and If the recording paper is thinner than the thickness of the recording paper, the transfer voltage is reduced.

In the embodiments of the invention described below, “separating means” described in claims or means for solving the problems corresponds to the paper feed roller 72 and the separating pad 73, Means ”is MPU11, RO
M12 and RAM13, and “biasing means” also corresponds to the spring 75.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a facsimile machine 1 as an image forming apparatus includes an MPU 1
1, ROM 12, RAM 13, reading unit 14, recording unit 1
5, an operation unit 16, a display unit 17, an image memory 18, a codec 19, a modem 20, and an NCU 21. Each of the units 11 to 21 is connected via a bus 22.

The MPU 11 controls each unit constituting the facsimile machine 1. The ROM 12 stores a program for controlling the facsimile machine 1. RAM 13
Temporarily stores various information on the facsimile machine 1.

The reading section 14 reads image data on a document and outputs black and white binary image data. The recording unit 15 is composed of an electrophotographic printer, and records received image data and image data of a document read by the reading unit 14 on recording paper in a copy operation. The recording unit 1
Details of 5 will be described later.

The operation unit 16 includes ten keys (including * and # keys) 16a for inputting a telephone number, a FAX number and the like.
Registering the abbreviated number, abbreviated key 16b for inputting a telephone number, a facsimile number, etc. from the abbreviated number, a start key 16c for starting a document reading operation, "
X) Communication for setting "operation" or "copy" operation /
Various operation keys such as a copy key 16d are provided.

A display unit 17 such as an LCD displays various information such as an operation state of the facsimile machine 1. The image memory 18 temporarily stores received image data and image data read by the reading unit 14. The codec 19 transmits the image data read by the reading unit 14 to M
Encoding is performed by the H, MR, MMR method or the like. The codec 19 decodes the received image data.

The modem 20 conforms to ITU-T Recommendation T.30. 30 based on a facsimile transmission control procedure according to V.30. 1
7, V. 27ter, V.A. Modulation and demodulation of transmission / reception data according to 29 or the like are performed. The NCU 21 has a function of controlling connection with the telephone line L and detecting transmission and reception of a dial signal corresponding to a fax number of the other party.

Next, a specific configuration of the recording section 15 will be described in detail according to a recording process. As shown in FIG. 2, a photoconductor drum 30 as a photoconductor is rotatably supported on a shaft, and a photoconductive film 31 is formed on an outer peripheral surface thereof.

The charger 40 is constituted by a brush roller on which a conductive brush is implanted.
1 is uniformly charged to a predetermined potential. Exposure unit 50 is an LED
The photoconductive film 3 of the photosensitive drum 30 which is constituted by an array 51
1 is irradiated with light to form an electrostatic latent image.

The developing unit 60 includes a toner case 61 for storing toner, a supply roller 62 disposed below the toner case 61 and supplied with a predetermined voltage, a supply roller 62 and the photosensitive drum 30. And a developing roller 63 that is disposed at the lower end opening of the toner case 61 and is supplied with a predetermined voltage. The toner conveyed from the toner case 61 by the supply roller 62 and the developing roller 63 and charged to a predetermined polarity changes the applied polarity and the potential of the electrostatic latent image formed on the photosensitive drum 30. Is selectively attached to the same electrostatic latent image. A toner image is formed on the photosensitive drum 30 by the toner attached to the electrostatic latent image.

A stirring body 64 is rotatably supported in the toner case 61. By the rotation of the stirring body 64, the toner in the toner case 61 is constantly stirred, and the toner is maintained at a uniform density.

On the manual feed tray 70, recording paper 71 of a predetermined size is stacked. In the lower part of the paper feed roller 72,
A separation pad 73 is provided. This separation pad 73
Are disposed on the support member 74. Separation pad 73
Are urged to the paper feed roller 72 by the urging force of a spring 75 via a support member 74. Spring 7
5 is provided with a strain gauge 76 for detecting a strain amount of the spring 75. This strain gauge 76
It is connected to the MPU 11 via a bridge circuit 77. Then, the paper feed roller 72 and the separation pad 73 cooperate to feed out the uppermost recording paper 71 stacked on the manual feed tray 70 one by one. At this time, the strain gauge 76
Detects the amount of distortion of the spring 75 according to the thickness of the recording paper 71. Then, the sent recording paper 71 is transported toward the photosensitive drum 30. Note that a dashed line P indicates a transfer path of the recording paper 71.

The transfer unit 90 is provided below the photosensitive drum 30, and is controlled to a predetermined potential. Then, the transfer device 90
Transfers the toner image on the photosensitive drum 30 onto the recording paper 71 based on the difference between the predetermined potential and the potential of the toner image.

The memory removing brush 91 is made of a conductive brush, and disturbs the toner remaining on the photosensitive drum 30 after the transfer and uniformly distributes the toner on the photosensitive drum 30.
The heat fixing device 100 includes a heating roller 101 and a pressure roller 102, and is disposed on the recording paper sending side of the photosensitive drum 30. Inside the heating roller 101,
Lamp 1 for maintaining heat fixing unit 100 at a predetermined temperature
01a (for example, a halogen lamp) is built in. The heat fixing device 100 is configured such that the recording paper 71
The toner image on the recording paper 71 is heated and fixed based on the toner image being sent between the pressure roller 01 and the pressure roller 102.

Next, the operation of the facsimile machine 1 during recording will be described with reference to the flowchart shown in FIG. This operation is executed under the control of the MPU 11 based on a program stored in the ROM 12.

When the user sets a document on a document table (not shown), selects a recording sheet on the manual feed tray 70, and inputs the number of copies from the ten keys 16a of the operation unit 16, the process proceeds to step S1. , Start key 1
6c is waited for to be pressed.

In step S2, the reading section 14 reads an image on the document. At step S3, the read image data is
The image is encoded according to a method or the like and is temporarily stored in the image memory 18.

In step S4, the image memory 18
Are decoded by the codec 19 into binary data. In step S5, the feed roller 7
2 and the separation pad 73, the manual feed tray 7
The topmost recording paper 7 of the recording papers 71 stacked on 0
1 are separated one by one. Then, the sheet is transported toward the photosensitive drum 30.

In step S6, the strain gauge 76
, The amount of distortion of the spring 75 is detected. Step S7
In, the transfer voltage of the transfer unit 90 is adjusted based on the amount of distortion. Specifically, when the recording paper 71 is thicker than the standard recording paper 71, that is, when the distortion amount is large, the transfer voltage is increased. On the other hand, the standard recording paper 71
When the recording paper 71 is thinner than the thickness of the recording paper 71, that is, when the amount of distortion is small, the transfer voltage is reduced.

In step S8, based on the decoded binary data, light from the LED array 51 of the exposure device 50 is irradiated on the photoconductive film 31 of the photosensitive drum 30 to form an electrostatic latent image. You.

In step S9, the developing roller 63
Thus, a toner image is formed on the photosensitive drum 30. In step S10, based on the adjusted transfer voltage, the toner image on the photosensitive drum 30 is
1 is transferred.

In step S11, the toner image on the recording paper 71 is heat-fixed by the heat fixing device 100.
As described above, according to the present embodiment, the following operations and effects can be obtained.

(1) The recording paper 71 stacked on the manual feed tray 70 is separated one by one from the uppermost recording paper 71 by the cooperation of the paper feed roller 72 and the separation pad 73. The separation pad 73 is urged by the paper feed roller 72 by the urging force of a spring 75 via a support member 74. The spring 75 is provided with a strain gauge 76 for detecting the amount of strain of the spring 75. Thus, the strain gauge 76 detects the amount of distortion of the spring 75 when the stacked recording papers 71 are separated one by one. Then, the transfer voltage of the transfer device 90 is adjusted based on the distortion amount. In other words, the transfer voltage of the transfer device 90 is adjusted based on the thickness of the recording paper 71. Therefore, excellent image quality can be obtained regardless of the thickness of the recording paper 71.

(2) When the recording paper 71 is thicker than the standard recording paper 71, that is, when the amount of distortion is large, the transfer voltage is increased. On the other hand, when the recording paper 71 is thinner than the standard recording paper 71, that is, when the amount of distortion is small, the transfer voltage is reduced. Therefore, good image quality can be obtained according to the thickness of the recording paper 71.

(3) The transfer voltage of the transfer unit 90 is adjusted according to the thickness of the recording paper 71. Therefore, the recording paper 71
Does not need to be set by the user in advance.
Therefore, good image quality can be easily obtained regardless of the thickness of the recording paper 71.

The above embodiment can be modified and embodied as follows. In the above-described embodiment, the configuration is such that the amount of distortion of the spring 75 is detected. However, a pressure-sensitive element is disposed between the separation pad 73 and the support member 74, and based on a detection signal from the pressure-sensitive element. Alternatively, the transfer voltage may be adjusted.

Instead of the spring 75, a configuration may be adopted in which the separation pad 73 is urged against the paper feed roller 72 by a leaf spring, and the amount of distortion of the leaf spring is detected. In the above embodiment, a thick recording paper 71 such as a postcard is used.
Has been described in the case of the manual feed tray 70 in consideration of the fact that paper is often fed from the manual feed tray 70,
The above-described embodiment may be applied to a paper feed cassette (not shown) that separates the stacked recording papers 71 in cooperation with the paper feed roller 72 and the separation pad 73.

Further, technical ideas other than the claims grasped from the embodiment and the like will be described below together with their effects. [1] charging means for forming an electrostatic latent image on a photosensitive member, developing means for forming a toner image by attaching toner to the electrostatic latent image, transfer means for transferring the toner image to recording paper, In an image forming apparatus provided with a fixing unit for fixing the transferred image to recording paper, a separation pad and a separation rotating body for separating the stacked recording papers one by one, and the separation pad is separated into a separation rotating body. An image forming apparatus comprising: urging means for urging; detecting means for detecting a displacement amount of the urging means; and control means for controlling a transfer voltage of a transfer means based on a displacement amount from the detecting means.

According to this structure, good image quality can be obtained regardless of the thickness of the recording paper. [2] The image forming apparatus according to [1], wherein the control unit controls a potential difference between the photoconductor and the transfer unit based on a displacement amount from the detection unit.

According to this structure, good image quality can be obtained regardless of the thickness of the recording paper. [3] The image forming apparatus according to claim 2, further comprising a detecting unit for detecting a displacement amount of the urging unit, wherein the control unit adjusts a transfer voltage of the transfer unit based on a detection signal from the detecting unit. Image forming device.

With this configuration, it is possible to obtain good image quality regardless of the thickness of the recording paper.

[0039]

Since the present invention is configured as described above, it has the following effects. According to the invention described in any one of claims 1 to 3, good image quality can be obtained regardless of the thickness of the recording paper.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a facsimile apparatus.

FIG. 2 is a partial cross-sectional view schematically illustrating a configuration of a recording unit.

FIG. 3 is a flowchart showing an operation at the time of recording.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Facsimile machine as an image forming apparatus, 11 ... MPU which comprises a control means, 12 ... R which comprises a control means
OM, 13 RAM constituting control means, 71 recording paper, 72 paper feed roller constituting separation means, 73 separation pad constituting separation means, 75 spring acting as urging means, 90 transfer device .

Claims (3)

[Claims] 1. An electrophotographic image forming apparatus, comprising:
An image forming apparatus comprising: a separating unit that separates stacked recording papers one by one; and a control unit that adjusts a transfer voltage of a transfer unit based on a displacement amount accompanying the separating operation of the separating unit. 2. The image forming apparatus according to claim 1, wherein the separating unit includes an urging unit that is displaced in accordance with a thickness of the recording sheet. 3. The image forming apparatus according to claim 1, wherein the control unit increases the transfer voltage when the recording paper is thicker than a predetermined recording paper, and controls the predetermined recording paper. An image forming apparatus that reduces the transfer voltage when the recording paper is thinner than the thickness.