JP2011080831A - Recorded medium detecting device, apparatus and method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recorded medium detecting device, an image forming apparatus, and an image forming method obtaining good transferability even when a recorded medium has a nonuniform width perpendicular to a moving direction of the recorded medium and a nonuniform thickness along the width direction. <P>SOLUTION: The recorded medium detecting device includes a light source, an optical scanning means deflection-scanning light from the light source onto a recorded medium in a direction perpendicular to a conveying direction, a conversion means receiving light transmitting through the recorded medium and converting it into an electric signal, and a detection means detecting a thickness and a width of the recorded medium based on the electric signal from the conversion means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a recording medium detection apparatus, an image forming apparatus, and an image forming method.

The background technology of the image forming apparatus and the recording medium detection apparatus used therefor will be described.
First, an image forming apparatus having a recording medium detection unit will be described (see Patent Documents 1 to 5).
In Patent Document 1, a member for detecting the thickness of a recording medium is displaced according to the thickness of the recording medium while the recording medium to be conveyed is sandwiched between opposing fixing members. Accordingly, a configuration is disclosed in which a transfer bias variable member mechanically coupled to a member for detecting a recording medium is mechanically displaced to change the transfer bias.

  The invention described in Patent Document 2 selectively controls an optimum transfer bias based on information including a change in the thickness of a recording medium detected by a recording medium thickness detection mechanism.

  The invention described in Patent Document 3 detects the thickness from the amount of displacement of two rollers sandwiching the recording medium and controls the transfer bias.

  The invention described in Patent Document 4 includes means for detecting the thickness of the recording medium, and transfer bias setting means for setting a transfer bias for the recording medium based on detection information of the detection means. That's it.

  The invention described in Patent Document 5 measures the electrical resistance of a recording medium and controls the transfer bias. In this method, it can be detected as including changes in both the thickness and width of the recording medium.

Next, a known example relating to an image forming apparatus having a transfer portion divided into a plurality of regions electrically independent from each other along a width direction perpendicular to the moving direction of the recording medium (see, for example, Patent Documents 6 and 7). ).
The invention described in Patent Document 6 is such that the transfer bias roller extending in the width direction of the recording medium conveyance belt is divided into a plurality of parts in the longitudinal direction so that a voltage can be applied independently to each of them. is there. For this reason, the width of the recording medium conveyed by the recording medium conveyance belt can be detected to determine the area to which the transfer bias is applied.

  In the invention described in Patent Document 6, a normal image forming apparatus that applies a transfer bias to the same region on the transfer bias changes the transfer bias amount according to the width of the recording medium, regardless of the width of the recording medium. In a recording medium having a small width, it is necessary to apply a high transfer bias. On the other hand, in the invention described in Patent Document 6, a high transfer bias is applied even when transferring a toner image to a recording medium having a small width. Since it is not necessary to apply voltage, a power supply device having a small capacity can be used, its cost can be reduced, and malfunction of the control device due to noise can be prevented.

  In Patent Document 7, a transfer bias applied to a transfer member divided into a plurality of parts in the width direction is changed at the boundary between an image portion and an image portion or between an image portion and a non-image portion. It is disclosed that the transfer bias applied to the transfer member divided into a plurality of parts in the width direction corresponding to the image portion is changed according to the rate.

  However, in the invention described in Patent Document 1, a change in the thickness of the recording medium is detected, but a change in the width of the recording medium cannot be detected. Therefore, in the case of a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform, the thickness of the recording medium and the thickness along the width direction are continuously set. There is a drawback that it cannot be detected accurately. Further, in application to an image forming apparatus, there is a drawback that an optimum transfer bias cannot be applied.

  Further, Patent Document 2 does not specifically describe the means for detecting the thickness of the recording medium and responds to the change in the width of the recording medium from the control contents although the thickness of the recording medium is detected. Such control is not disclosed, and it is assumed that the thickness of the recording medium changes uniformly in the width direction. Therefore, in the case of a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform, the thickness of the recording medium and the thickness along the width direction are continuously set. There is a drawback that it cannot be detected accurately. Further, in application to an image forming apparatus, there is a drawback that an optimum transfer bias cannot be applied.

  In the invention described in Patent Document 3, a change in the thickness of the recording medium is detected, but a change in the width of the recording medium cannot be detected. Therefore, in the case of a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform, the thickness of the recording medium and the thickness along the width direction are There was a drawback that it could not be detected continuously and accurately. Further, in application to an image forming apparatus, there is a drawback that an optimum transfer bias cannot be applied.

  The invention described in Patent Document 4 can detect a change in the thickness of the recording medium, but cannot detect a change in the width of the recording medium. Therefore, in the case of a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform, the thickness of the recording medium and the thickness along the width direction, Has a drawback that it cannot be detected continuously with high accuracy. Further, in application to an image forming apparatus, there is a drawback that an optimum transfer bias cannot be applied.

  The invention described in Patent Document 5 cannot accurately detect a recording medium whose thickness is not uniform in the width direction. Therefore, in the case of a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform, the thickness of the recording medium and the thickness along the width direction are continuously set. There is a drawback that it cannot be detected accurately. Further, in application to an image forming apparatus, there is a drawback that an optimum transfer bias cannot be applied.

  Patent Document 6 discloses a means for detecting the width of the recording medium, and there is no specific description, and although the width of the recording medium is detected, the change in the thickness of the recording medium is determined from the control content. Is not detected and is assumed to change uniformly in the width direction of the recording medium. Therefore, in the case of a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform, the thickness of the recording medium and the thickness along the width direction are continuously set. Therefore, there is a drawback that an optimum transfer bias cannot be applied because it cannot be accurately detected.

  Further, the invention described in Patent Document 7 does not disclose the control of the transfer bias according to the change in the thickness or width of the recording medium. For this reason, in the case of a recording medium in which the width of the recording medium that is perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform, the thickness of the recording medium and the thickness along the width direction Therefore, there is a drawback that an optimum transfer bias cannot be applied.

  Therefore, an object of the present invention is to obtain a good transfer property even in a recording medium in which the recording medium moving direction and the width of the recording medium perpendicular to the recording medium and the thickness along the width direction are not uniform. It is an object of the present invention to provide a recording medium detection apparatus, an image forming apparatus, and an image forming method.

  In order to solve the above problems, the invention described in claim 1 is directed to a light source, a scanning optical stage that deflects and scans light from the light source on the recording medium in a direction perpendicular to the transport direction, and the recording medium. And a detecting means for detecting the thickness and width of the recording medium based on the electric signal from the converting means.

  According to a second aspect of the present invention, in the first aspect of the invention, the scanning optical unit includes a collimator lens that converts the light from the light source into parallel rays, a movable mirror that deflects and scans the light from the light source, and And an imaging lens system for imaging the light beam deflected and scanned by the movable mirror on the conversion means.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the light source is an array light source integrated in a line shape, the conversion means is a line sensor, and the light from the light source is converted into the line. It has a lens array for forming an image on a sensor.

  According to a fourth aspect of the present invention, the recording medium detection apparatus according to any one of the first to third aspects and the photosensitive drum on which the latent image is formed are developed with a developer, and the obtained visible image is converted into the visible image. And transfer means for transferring to a recording medium.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the transfer bias application amount and the transfer bias application position are determined based on a table in which the output value of the detecting means is associated with the transfer bias. It is characterized by.

  According to a sixth aspect of the present invention, in the fifth aspect of the invention, the resolution along the width direction perpendicular to the recording medium conveyance direction of the detection means is perpendicular to the recording medium conveyance direction of the transfer means. The number is equal to the number of transfer bias application regions that are electrically independent from each other along the width direction.

  According to the seventh aspect of the invention, the light from the light source is deflected and scanned on the recording medium in a direction perpendicular to the conveyance direction, and the light transmitted through the recording medium is received and converted into an electrical signal. The thickness and width of the recording medium are detected based on an electric signal, the photosensitive drum on which the latent image is formed is developed with a developer, and the obtained visible image is transferred to the recording medium. And

  According to the present invention, the light deflected by the rotary polygon mirror continuously scans the recording medium, and further, the light transmitted through the recording medium is detected by the line sensor. The width of the perpendicular recording medium and the thickness along the width direction can be continuously detected with high accuracy.

1 is an overall view showing a configuration of an embodiment of an image forming apparatus according to the present invention. 3 is an example of a configuration diagram of a detection unit 401 of a recording medium 4. FIG. FIG. 6 is a diagram showing a result of detecting an envelope as a recording medium 4 by a detector 407 of the recording medium 4. 3 is an example of an output level of a secondary transfer bias corresponding to an output value level X of the line sensor 47. FIG. FIG. 2 is a conceptual diagram of the vicinity of the secondary transfer device 301 shown in FIG. FIG. 4 is a diagram illustrating secondary transfer bias output patterns corresponding to detection positions 481, 482, 483, and 484 in FIG. 3 at 481B, 482B, 483B, and 484B. The detector 407 of the recording medium 4 is an example of a configuration different from that in FIG.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall view showing a configuration of an embodiment of an image forming apparatus according to the present invention.
The image forming apparatus includes an image carrier 54, a charger 55 for charging the image carrier 54, and an electrostatic latent image corresponding to image information to be recorded by light beam scanning using a semiconductor laser (not shown) as a light source. For an optical writer 56 formed on the body 54, a developer 57 for attaching toner to the electrostatic latent image to form a toner image on the image carrier 54, and a toner image on the image carrier 54, A primary transfer device 58 that transfers a toner image on the image carrier 54 onto the intermediate transfer member 20 by applying a bias having a polarity opposite to that of the toner image on the image carrier 54 and the image carrier 54 after the transfer are neutralized. And an image forming mechanism unit 501 including the static eliminator 53 to be cleaned.

  Image forming mechanisms 502, 503, and 504, which have the same configuration as the image forming mechanism 501 and have different toner colors, are arranged along the traveling direction of the intermediate transfer body 20.

The toner images transferred on the intermediate transfer body 20 in the order of the image forming mechanisms 501, 502, 503, and 504 reach the secondary transfer device 301 by the rotation of the driving rollers 21, 22, and 23.
The recording medium 4 is conveyed by the pickup roller 9 and the conveying roller 11 and reaches the detection unit 401 of the recording medium 4, which includes the scanning optical unit 40 and the line sensor 47.
The configuration of the detection unit 401 of the recording medium 4 is shown in FIG.
A light beam 48 emitted from a light source 43 such as a semiconductor laser driven by a power source 42 is converted into a substantially parallel light beam by a collimator lens 44 and then reaches a rotating polygon mirror 45 by a condenser lens 49. The light beam 48 deflected and scanned by the rotary polygon mirror 45 scans the recording medium 4 through the scanning lens 46.

  The scanning optical unit 40 is configured as described above. Further, the light beam 48 transmitted through the recording medium 4 forms an image on the line sensor 47 and scans the line sensor 47. A light receiving element such as a CCD (not shown) is disposed on the line sensor 47, and converts the intensity of the light beam 48 into a voltage.

  The light source 43 may be a gas laser or the like (required is that the light receiving element of the line sensor 47 has a sensitive wavelength band and light intensity, and is not particularly limited. Helium neon laser, argon laser, etc.). Of course, instead of the rotating polygon mirror 45, for example, a galvano mirror may be used.

Further, FIG. 7 shows a configuration of the detector 407 of the recording medium 4 which is different from FIG.
A plurality of light beams 408 emitted from a light source 401 such as an LED array driven by a power source 402 are transmitted through the recording medium 4 via a lens array (not shown) and imaged on the line sensor 407. A light receiving element such as a CCD (not shown) is disposed on the line sensor 407, and converts the intensity of the light beam 408 into a voltage.

The result of detecting the envelope as the recording medium 4 by the detector 407 of the recording medium 4 is shown in FIG.
In general, an envelope is made by folding and stacking a single sheet of paper. Therefore, the number of overlapping sheets varies depending on the part of the envelope. In the case of the envelope shown in FIG. 3, the part 60 is 3PLY (PLY “ply”: layer), the part 61 is 2PLY, and the part 62 is 1PLY.

  Here, the part 60 is 3PLY, and the part 61 is 2PLY ”. This is because the part 60 is 3PLY because the band-shaped margin is bent.

When this envelope is detected by the detection unit 401 of the recording medium 4, the detection result, that is, the output pattern of the line sensor 47 differs for each detection position in the transport direction.
Output patterns of the line sensor 47 corresponding to the detection positions 481, 482, 483, and 484 in FIG. 3 are shown in 481A, 482A, 483A, and 484A in FIG.

  At the detection position 481, the envelope has not yet reached the light beam 48, and the light beam 48 is not attenuated by the recording medium 4, and the recording medium 4 is not yet aligned along the width direction perpendicular to the moving direction of the recording medium 4. The level changes at level X, which is the detection level.

  At the detection position 482, the output of the line sensor 47 is level X until the light beam 48 reaches the envelope. When the light beam 48 reaches the envelope part 60, the output of the line sensor 47 attenuates to level E-3. Further, when the light beam 48 reaches the envelope portion 61, the output of the line sensor 47 rises to the level E-2. This is because the portion 60 is 3PLY, whereas the portion 61 is 2PLY, so the attenuation of the light ray 48 is small. Further, when the light beam 48 reaches the part 63, the output of the line sensor 47 is attenuated to the level E-3. This is because the part 60 and the part 63 are both the same 3PLY, and the attenuation of the light ray 48 is the same. Further, when the light beam 48 comes off the envelope, the output of the line sensor 47 rises to level X.

  At the detection position 483, the output of the line sensor 47 is level X until the light beam 48 reaches the envelope as in the case of 482. When the light beam 48 reaches the envelope part 62, the output of the line sensor 47 attenuates to level E-1. Since the part 62 is a flap part of the envelope and is 1PLY, the output of the line sensor 47 is larger than the level E-2 of the part 61 of 2PLY and the level E-3 of the part 60 and part 63 of 3PLY.

  At the detection position 484, since the envelope has already passed through the light beam 48, the light beam 48 is not attenuated in the recording medium 4, and the recording medium is not aligned along the width direction perpendicular to the moving direction of the recording medium 4. The level changes at level X, which is the detection level.

  The level Y shown in FIG. 4 indicates the output level of the line sensor 47 when the intensity of the light beam 48 is attenuated to a level that the line sensor 47 cannot detect. In designing the detection unit 401 of the recording medium 4, it is necessary to pay attention so that the output level of the line sensor 47 is equal to or higher than the level Y even when the thickest recording medium 4 handled by the mounted image forming apparatus is detected. There is.

  In FIG. 4, as representative examples, output patterns 481A, 482A, 483A, and 484A of the line sensor 47 corresponding to the four detection positions 481, 482, 483, and 484 are shown. Accordingly, it goes without saying that the output pattern of the line sensor 47 can be obtained continuously.

  The recording medium 4 that has passed the detection unit 401 of the recording medium reaches the secondary transfer unit 301, and here, based on the output pattern of the line sensor 47 that is the output result of the detection unit 401 of the recording medium 4, A secondary transfer bias having a reverse polarity to the toner image on the intermediate transfer member 20 is applied, and the toner image on the intermediate transfer member 20 is transferred onto the recording medium 4.

  Here, how to apply the secondary transfer bias having the opposite polarity to the toner image on the intermediate transfer body 20 based on the output pattern of the line sensor 47 is described in the explanation of FIG. As described above, in the CPU (Central Processing Unit) unit 32, the table information of the secondary transfer bias value stored in the ROM unit 34 in synchronization with the output value of the line sensor 47 input to the RAM (Random Access Memory) unit 33. The secondary transfer bias applied to the plurality of conductive portions 311 of the transfer roller A31 is determined, and the plurality of power supply units 351 and the switch unit 361 are controlled.

FIG. 5 is a conceptual diagram of the vicinity of the secondary transfer unit 301 shown in FIG. 1 as viewed from the conveyance direction of the recording medium 4.
The transfer roller A31 has a plurality of conductive portions 311, and the conductive portions 311 are electrically divided by insulating portions 312. A power supply unit 351 and a switch unit 361 are connected to each conductive unit 311, and electricity for applying a secondary transfer bias between the transfer roller A 31 and the transfer roller B 30 facing each other with the recording medium 4 interposed therebetween. The circuit is configured.

  Here, the switch unit 361 in FIG. 5 is not particularly limited with respect to a specific ON / OFF mechanism for applying the secondary transfer bias. However, an FET (field effect transistor) switch is easy to control. And semiconductor switches such as SSR (Solid State Relay). Further, since the present invention is not related to the control of the primary transfer bias, the primary transfer bias is omitted.

  On the other hand, the output pattern information of the line sensor 47, which is the output result of the detection unit 401 of the recording medium 4, is input to the RAM unit 33 via a communication mechanism (not shown). The ROM (Read Only Memory) unit 34 stores the output value of the line sensor 47 and the table information of the secondary transfer bias value corresponding to the output value of the line sensor 47. The CPU (Central Processing Unit) unit In 32, in synchronization with the output value of the line sensor 47 input to the RAM unit 33, the secondary transfer bias value table information stored in the ROM unit 34 is referred to and applied to the plurality of conductive units 311 of the transfer roller A31. The secondary transfer bias to be determined is determined, and the plurality of power supply units 351 and the switch unit 361 are controlled.

FIG. 6 is a diagram showing secondary transfer bias output patterns corresponding to the detection positions 481, 482, 483, and 484 in FIG. 3 at 481B, 482B, 483B, and 484B.
The output level of the secondary transfer bias corresponding to the output value level X of the line sensor 47 shown in FIG. 4 is level BX, and the output level of the secondary transfer bias corresponding to level E-1 is level BE-1 and level E. The output level of the secondary transfer bias corresponding to -2 is level BE-2, and the output level of the secondary transfer bias corresponding to level E-3 is level BE-3. As described above, although the thickness and width of the envelope vary depending on the location, the toner image on the inter-sheet transfer member 20 is transferred onto the recording medium 4 at an optimum secondary transfer level.

  In FIG. 6, as representative examples, output patterns 481B, 482B, 483B, and 484B of secondary transfer bias corresponding to the four detection positions 481, 482, 483, and 484 are shown, but the envelope of the recording medium 4 is shown. Needless to say, since the output pattern of the line sensor 47 is continuously obtained with the movement, the output pattern of the secondary transfer bias corresponding to this is also obtained.

  Further, the recording medium 4 to which the toner image is transferred reaches the fixing device 60 by the conveying belt 8. The fixing device 60 includes a fixing belt 61, a driving roll 62, a heating roll 63, and a backup roll 64. The heating roll 63 is provided with a heater (not shown), where the toner image on the recording medium 4 is heated and melted and fixed, and image formation by the image forming apparatus is completed.

  As described above, the case where the recording medium 4 is an envelope has been described as an example, but the width and width of the recording medium perpendicular to the moving direction of the recording medium are not limited to the envelope and in any form of recording medium. It goes without saying that the detection of the thickness along the direction and the output pattern of the secondary transfer bias corresponding to this can be obtained.

  If the number of divisions of the line sensor 47 of the detection unit 401 of the four recording media and the number of divisions of the plurality of conductive portions 311 of the transfer roller A31 of the secondary transfer unit 301 are large, the output pattern of the line sensor 47 is increased. Needless to say, since the resolution increases, the resolution of the output pattern of the secondary transfer bias corresponding to the resolution also increases.

  In FIG. 5, a large number of power supply units 351 are provided between the switch unit 361 and the transfer roller 351 of the secondary transfer device, but the switch unit 361 and the transfer roller A31 are directly connected without using the power supply unit 351. In addition, a common power supply unit may be inserted between 30 and the ground. Further, if the voltage of the power supply unit 351 is different, a resistor may be used instead of the power supply unit 351.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

  As described above, according to the image forming apparatus of the present invention, the recording medium that is perpendicular to the moving direction of the recording medium and the width of the recording medium perpendicular to the width direction and the thickness along the width direction are good. Therefore, it is possible to provide an image forming apparatus capable of obtaining a high transferability.

  According to the recording medium detection unit of the image recording apparatus according to the present invention, the light deflected by the rotary polygon mirror continuously scans the recording medium, and the light transmitted through the recording medium is detected by the line sensor. By detecting, the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction can be detected continuously and accurately.

  According to the recording medium detection unit of the image recording apparatus according to the present invention, the recording medium detection unit detects the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction, Since a transfer bias can be applied, good transferability can be obtained even for a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform. Can do.

  According to the recording medium detection unit of the image recording apparatus according to the present invention, the recording medium detection unit detects the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction, Since a transfer bias can be applied, good transferability can be obtained even for a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform. Can do.

  According to the recording medium detection unit of the image recording apparatus according to the present invention, the recording medium detection unit detects the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction, Since a transfer bias can be applied, good transferability can be obtained even with a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform. be able to.

  According to the recording medium detection unit of the image recording apparatus according to the present invention, the recording medium detection unit detects the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction, Since a transfer bias can be applied, good transferability can be obtained even for a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform. Can do.

  According to the recording medium detection unit of the image recording apparatus according to the present invention, the recording medium detection unit detects the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction, Since a transfer bias can be applied, good transferability can be obtained even for a recording medium in which the width of the recording medium perpendicular to the moving direction of the recording medium and the thickness along the width direction are not uniform. Can do. Further, the resolution along the width direction orthogonal to the moving direction of the recording medium of the detection unit of the recording medium is electrically independent from each other along the width direction orthogonal to the moving direction of the recording medium of the transfer roller A. Since the resolution of the plurality of conductive portions is equal, the plurality of conductive properties of the transfer roller can be determined from the information about the width of the recording medium that is perpendicular to the moving direction of the recording medium and the thickness along the width direction obtained by the detecting portion of the recording medium. It is easy to determine the secondary transfer bias applied to the portion.

  The present invention can be used in laser printers, digital PPCs, electrophotographic multifunction printers, and the like.

4 Recording medium 20 Intermediate transfer member 21, 22, 23 Drive roller 40 Scanning optical unit 43, 48 Light beam 44 Collimator lens 45 Rotating polygon mirror 47 Line sensor 49 Condensing lens 53 Static eliminator 54 Image carrier 55 Charger 56 Light Writing device 57 Developing device 58 Primary transfer device 301 Secondary transfer device 401 Light source 407 Detector 501, 502, 503, 504 Image forming mechanism

Japanese Patent Laid-Open No. 10-288897 Japanese Patent No. 3357969 JP 09-034316 A Japanese Patent Application Laid-Open No. 07-104590 Japanese Patent No. 30603329 Japanese Patent Laid-Open No. 10-104969 JP 2005-352050 A

Claims (7)

  A light source, a scanning optical stage that deflects and scans light from the light source on the recording medium in a direction perpendicular to the conveyance direction, and conversion means that receives the light transmitted through the recording medium and converts it into an electrical signal; A recording medium detection apparatus comprising: detection means for detecting the thickness and width of the recording medium based on an electrical signal from the conversion means.   The scanning optical means forms a collimator lens for collimating the light from the light source, a movable mirror for deflecting and scanning the light from the light source, and forming an image of the light deflected and scanned by the movable mirror on the conversion means. 2. A recording medium detection apparatus according to claim 1, further comprising: an imaging lens system to be operated. The light source is an array light source integrated in a line, and the conversion means is a line sensor,
3. The recording medium detection apparatus according to claim 1, further comprising a lens array for forming an image of light from the light source on the line sensor. A recording medium detection device according to any one of claims 1 to 3,
An image forming apparatus comprising: a transfer unit that develops a photosensitive drum on which a latent image is formed with a developer, and transfers the obtained visible image to the recording medium.   The image forming apparatus according to claim 4, wherein an application amount of the transfer bias and an application position of the transfer bias are determined based on a table in which the output value of the detection unit is associated with the transfer bias.   A plurality of transfer biases whose resolutions along the width direction perpendicular to the recording medium conveyance direction of the detection means are electrically independent from each other along the width direction perpendicular to the conveyance direction of the recording medium of the transfer means. The image forming apparatus according to claim 5, wherein the number is equal to the number of application areas.   The light from the light source is deflected and scanned on the recording medium in a direction perpendicular to the conveyance direction, the light transmitted through the recording medium is received and converted into an electric signal, and the recording target is based on the obtained electric signal. An image forming method comprising: detecting a thickness and width of a medium; developing a photosensitive drum on which a latent image is formed with a developer; and transferring the obtained visible image onto the recording medium.

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