# US 5,349,421 A · Electrophotographing apparatus

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- Number: US 5,349,421 A
- Document ID: US5349421A
- Status: Granted
- Kind: A
- Application number: 08/126,500
- Filed: 1993-09-24
- Granted: 1994-09-20
- Earliest claimed: 1992-09-25
- Assignees: Sanyo Electric Co., Ltd.
- Inventors: Yasuhiro Kishimoto; Kunio Tsuboi
- Web page: https://patentgrep.com/patent/US5349421A

## CPC

- G03G 15/5025: {by measuring the original characteristics, e.g. contrast, density}
- G03G 15/065: {Arrangements for controlling the potential of the developing electrode}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An electrophotographing apparatus includes a photosensor for sensing or detecting a reflectance of an original, and an output voltage of the photosensor is sent to a microcomputer. In response to the output voltage of the photosensor, the microcomputer controls a bias voltage which is applied to an electric conductive substrate of a photoreceptor from a bias voltage source. The bias voltage is adjusted such that a change of an exposed voltage according to the reflectance of the original can be canceled, and resultingly, the exposed voltage is kept constant. On the other hand, a developer is connected to the ground, and therefore, a voltage difference between the exposed voltage and a developing voltage becomes constant.

## Claims

### Claim 1

An electrophotographing apparatus, comprising:
a photoreceptor including an electric conductive substrate;
charging means for charging said photoreceptor at a predetermined voltage;
exposing means for exposing said photoreceptor to form an electrostatic latent image according to an original on said photoreceptor;
developing means for toner-developing said electrostatic latent image on said photoreceptor with a predetermined developing voltage;
reflectance sensing means for sensing a reflectance of said original; and
bias voltage applying means for applying a bias voltage that is changed in response to an output of said reflectance sensing means to said electric conductive substrate.

### Claim 2 (depends on 1)

An electrophotographing apparatus according to claim 1, further comprising means for keeping said developing voltage of said developing means constant.

### Claim 3 (depends on 2)

An electrophotographing apparatus according to claim 2, wherein said means includes means for connecting said developing means to the ground.

### Claim 4 (depends on 2)

An electrophotographing apparatus according to claim 2, further comprising exposure light amount controlling means for controlling a light amount of an exposure light from said exposing means in response to the output of said reflectance sensing means.

### Claim 5 (depends on 4)

An electrophotographing apparatus according to claim 4, wherein said exposing means includes a light source for irradiating a light onto said original and driving means for driving said light source, and said exposure light amount controlling means controls a driving voltage applied to said light source from said driving means.

### Claim 6 (depends on 2)

An electrophotographing apparatus according to claim 2, wherein said bias voltage applying means includes a microcomputer for receiving the output of said reflectance sensing means and for outputting a value of the bias voltage according to the output, and a bias voltage source for applying the bias voltage according to an output value of said microcomputer to said electric conductive substrate.

### Claim 7 (depends on 6)

An electrophotographing apparatus according to claim 6, wherein said microcomputer includes a first memory for storing a first table representative of relationship between the output of said reflectance sensing means and said bias voltage, and determines said output value with referring to said first table.

### Claim 8 (depends on 4)

An electrophotographing apparatus according to claim 4, wherein said exposure light amount controlling means includes a microcomputer for receiving the output of said reflectance sensing means and for outputting a value of said driving voltage according to the output, and means for applying a control voltage according to the output value of said microcomputer to said driving means.

### Claim 9 (depends on 8)

An electrophotographing apparatus according to claim 8, wherein said microcomputer includes a second memory for storing a second table representative of relationship between the output of said reflectance sensing means and said driving voltage, and determines said output value with referring to said second table.

### Claim 10

An electrophotographing apparatus, comprising:
a photoreceptor including an electric conductive substrate;
bias voltage applying means for applying a bias voltage to said electric conductive substrate;
charging means for charging said photoreceptor at a predetermined voltage;
exposing means for exposing said photoreceptor to form an electrostatic latent image according to an original on said photoreceptor;
developing means for toner-developing said electrostatic latent image on said photoreceptor with a predetermined developing voltage;
reflectance sensing means for sensing a reflectance of said original; and
bias voltage changing means for changing said bias voltage in response to an output of said reflectance sensing means.