JP2004021093A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can highly accurately detect a variety of recording media and form images of high image quality. <P>SOLUTION: The image forming apparatus is equipped with an image carrier forming a toner image, a light emission/reception unit 13 outputting a light reception signal by emitting measurement light from a light emitting element and receiving it by a light receiving element, and a recording medium kind discriminating device 20 having a recording medium kind determination part 14 determining the kind of an object recording medium to be decided on the basis of the light reception signal. The image forming apparatus forms a toner image corresponding to the kind of the form judged by the recording medium kind descriminating device 20 on an image carrier to form an image and is equipped with a rotation part 22 which rotates the light emission/reception unit 13 so as to change the irradiation direction of the measurement light with which the object recording medium to be judged is irradiated; and the recording medium kind determination part 14 determines the kind of the object recording medium to be judged on the basis of the light reception signal outputted by the light emission/reception part 13 when the light emission/reception unit 13 is rotated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus such as a copying machine and a printer, and more particularly to an image forming apparatus provided with a recording medium type discriminating apparatus for discriminating a type of a sheet on which an image is formed.
[0002]
[Prior art]
Conventionally, when an image is formed on a sheet using an image forming apparatus, the image quality of the formed image may be different depending on the type of sheet used. 2. Description of the Related Art A high-quality image is widely formed by selecting a medium type and adjusting image forming conditions according to the selected recording medium type.
[0003]
However, when the selected recording medium type is OHP paper, the material is different between OHP paper for black-and-white copying and OHP paper for color copying. Therefore, in order to form a high-quality image on OHP paper, It is necessary to determine the type more finely and adjust the image forming conditions according to the result of the determination. In addition, if an inappropriate sheet is set to form an image, the image forming apparatus may be damaged. Therefore, the type of the recording medium is detected, and when the inappropriate sheet is detected, the apparatus is stopped. It is necessary to warn the user that the loaded paper is inappropriate.
[0004]
Generally, in order to detect the type or surface state of an object to be detected, such as paper, an optical method is known in which light is emitted from a light emitting element and the reflected light is received by a light receiving element. A method of determining a difference in (gloss), a method of determining a difference in diffuse reflection intensity, a method of determining the presence or absence of light transmission, and the like are used.
[0005]
For example, Japanese Patent No. 2722859 discloses a technique for detecting the intensity of reflected light reflected from the surface of an object to be detected and the intensity of transmitted light.
[0006]
Japanese Patent Application Laid-Open No. Hei 10-221902 discloses a technique for calculating the ratio between a specific amount of polarized light and the amount of specular reflection, reducing the influence of fluctuations in light reflectance on the surface and fluctuations in the amount of irradiation, and performing highly accurate measurement. It has been disclosed.
[0007]
On the other hand, Japanese Patent Application Laid-Open No. 2000-314658 discloses that among reflected light reflected by a detection object, reflected light (S wave) passing through a phase difference film and a polarizing plate and reflected light (P wave) passing through a polarizing plate. A technique of detecting the glossiness of an object to be detected based on the level of each received light signal is detected by a sensor separately.
[0008]
[Problems to be solved by the invention]
However, the techniques disclosed in Japanese Patent No. 2722859, Japanese Patent Application Laid-Open No. 10-221902, and Japanese Patent Application Laid-Open No. 2000-314658 compare the surface state (reflection of light) or the light transmission state of an object. In consideration of the resolution of the sensor, the size of the spot irradiated on the object at the time of measurement, and the like, there are limits to the types that can be identified.
[0009]
On the other hand, in an electrophotographic image forming apparatus, various kinds of toners such as a polymerized toner capable of forming a high-quality color image have been developed in recent years. There is a strong demand for an image forming apparatus that can handle various recording media.
[0010]
In view of the above circumstances, an object of the present invention is to provide an image forming apparatus capable of detecting various recording media with high accuracy and forming a high-quality image.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: an image carrier for forming a toner image; and a measuring light beam emitted from a light emitting element toward a recording medium to be discriminated and reflected by the recording medium to be discriminated. A light emitting / receiving unit that outputs a light receiving signal by receiving light with a light receiving element, and a recording medium type having a recording medium type determining unit that determines the type of a target recording medium based on the light receiving signal output from the light emitting / receiving unit An image forming apparatus comprising: a discriminating device, and forming an image on the recording medium according to the type of the recording medium determined by the recording medium type discriminating device on the image carrier.
A rotation unit that rotates the light emitting and receiving unit so that the irradiation direction of the measurement light irradiated toward the determination target recording medium changes,
The recording medium type determination unit is configured to determine the type of the determination target recording medium based on a light receiving signal output from the light emitting and receiving unit when the light emitting and receiving unit rotates.
[0012]
In this way, by rotating the light emitting and receiving unit and changing the irradiation direction of the measurement light irradiated toward the recording medium to be determined, a plurality of data having different irradiation directions are obtained based on the light receiving signal received by the light receiving element, and Since the profile of the recording medium to be discriminated is specified from the data, even if the sheet on which the image is formed is a stretched film or the like, it can be discriminated with high accuracy and the image forming conditions can be adjusted.
[0013]
According to a second aspect of the present invention, there is provided an image forming apparatus, comprising: an image carrier for forming a toner image; and a measuring light reflected from the discrimination target recording medium by irradiating measurement light from a light emitting element toward the discrimination target recording medium. A light emitting / receiving unit that outputs a light receiving signal by receiving light with a light receiving element, and a recording medium type having a recording medium type determining unit that determines the type of a target recording medium based on the light receiving signal output from the light emitting / receiving unit An image forming apparatus comprising: a discriminating device, and forming an image on the recording medium in accordance with the type of paper determined by the recording medium type discriminating device on the image carrier.
The light emitting and receiving unit includes a polarizing element that polarizes the measurement light reflected by the recording medium to be determined, which is received by the light receiving element, in a predetermined polarization direction, and a rotating member that rotates a polarization plane of the polarizing element, The recording medium type determination unit determines the type of the recording medium to be determined based on a light receiving signal output from the light receiving element before and after the rotation of the polarization plane.
[0014]
As described above, the polarization plane of the polarization element provided on the front surface of the light receiving element of the light emitting and receiving unit is rotated, and each polarization component can be obtained from the light reception signal before and after the rotation. By comparing the respective polarized components, it is possible to determine a difference from a black-and-white OHP sheet or the like and adjust image forming conditions.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the image forming apparatus of the present invention will be described.
[0016]
FIG. 1 is a schematic configuration diagram illustrating the image forming apparatus according to the first embodiment.
[0017]
The first embodiment corresponds to an embodiment of the first invention.
[0018]
The image forming apparatus shown in FIG. 1 includes an image processing unit (not shown) that performs color conversion processing and gradation processing on an input image signal or an image signal read from a document image, and an image signal processed by the image processing unit. An image forming unit that forms an image formed of a toner image based on the image processing unit, and an image processing unit and a control unit that controls the image forming unit are provided, but the image processing unit is omitted for convenience.
[0019]
The image forming unit is stretched around four photoconductors 1Y, 1M, 1C, and 1K rotating in the direction of arrow A and a roll 10, and circulates in the direction of arrow B while contacting each of the four photoconductors 1 to move each photoconductor. And an intermediate transfer belt 6 that receives the transfer of the toner image from the body 1.
[0020]
Each of the four photoconductors 1 has a scorotron charger 2Y, 2M, 2C, 2K for charging the surface of the photoconductor 1 and an image signal obtained by color-separating the charged surface of each photoconductor 1 for each color. A laser output unit (ROS) 3Y, 3M, 3C, 3K for exposing the photosensitive latent image on the photosensitive member 1 by exposing with the exposure light modulated on the basis of the electrostatic latent image on the photosensitive member 1; Developing units 4Y, 4M, 4C, and 4K for developing toner images on each photoconductor 1 by developing with each color developer, and primary transfer for transferring each color toner image on each photoconductor 1 to the intermediate transfer belt 6 The devices 5Y, 5M, 5C, and 5K are provided, and a cleaner (not shown) for cleaning the surface of each photoconductor 1 and a negative device (not shown) for removing residual charges on the surface of the photoconductor 1 are also provided.
[0021]
Further, the toner images of the respective colors, which are sequentially superimposed and transferred on the intermediate transfer belt 6 facing the roll 10 with the intermediate transfer belt 6 interposed therebetween, are sent from the paper tray 11 for storing the paper P by the feed roll 12. And a fixing device 9 for fixing the toner images transferred to the paper P to the paper P by heating and pressurizing the toner images. A belt cleaner 8 that cleans the surface of the intermediate transfer belt 6 is provided upstream of the photoconductor 1Y in the circulating movement direction B.
[0022]
Further, the paper tray 11 is provided with a recording medium type discriminating device 20 having a light emitting / receiving unit and a recording medium type deciding unit for discriminating the type of the stored recording medium. The medium type information is sent to the control unit 15.
[0023]
The control unit 15 adjusts the image processing performed on the image signal by the image processing unit (not shown) or adjusts the fixing temperature of the fixing unit 9 based on the received recording medium type information. In addition, an image forming condition optimal for a sheet on which an image is formed is set.
[0024]
Signals separated for each color and pulse width modulated by an image processing unit (not shown) are input to laser output units 3Y, 3M, 3C, and 3K, and each laser output unit 3 is provided with a scorotron charger 2Y, 2M, The surfaces of the photoconductors 1Y, 1M, 1C, and 1K uniformly charged by 2C and 2K are irradiated with a laser beam R. By the irradiation of the laser beam R, an electrostatic latent image corresponding to the color-separated image signal is formed on each photoconductor 1, and the electrostatic latent image is transferred from the developing units 4Y, 4M, 4C, and 4K of each color to the toner. Is applied and developed, and a toner image is formed on each photoconductor 1. The toner images formed on the respective photoconductors 1 are sequentially superimposed and transferred onto the intermediate transfer belt 6 by the primary transfer units 5Y, 5M, 5C and 5K. After the transfer of the toner image to the intermediate transfer belt 6 is completed, the photoreceptor 1 having the toner image transferred thereon is cleaned by a cleaner (not shown) to remove the residual toner and the like, and the residual electric charge is removed by a negative electric device (not shown).
[0025]
The toner image superimposed and transferred on the intermediate transfer belt 6 is transferred onto the sheet P sent from the sheet tray 11 by the secondary transfer device 7, and the toner image transferred onto the sheet P is fixed. Heating and pressurizing are performed by the container 9, and the image is fixed on the sheet P to form an image. On the intermediate transfer belt 6 on which the transfer of the toner image onto the paper P has been completed, the belt cleaner 8 removes the adhered matter such as residual toner, and one image forming operation is completed.
[0026]
Although the image forming apparatus of the present embodiment has been described based on a tandem type image forming apparatus using an intermediate transfer body, the image forming apparatus is not necessarily limited to the one using the intermediate transfer body, A belt may be used. Further, the image forming apparatus does not necessarily have to be of a tandem type, and may be, for example, an image forming apparatus of four cycles or an apparatus for forming a single mode image.
[0027]
Further, in the present embodiment, the recording medium type discriminating apparatus 20 is provided on the paper tray 11, but the place where the recording medium type is provided is not limited to the paper tray 11.
[0028]
Next, determination of the type of recording medium on which an image is formed in the image forming apparatus of the present embodiment will be described.
[0029]
FIG. 2 is a schematic plan view showing a main part for determining a type of a recording medium on which an image is formed in the image forming apparatus of the present embodiment. A paper tray 11 for storing paper, which is attached to and detached from a paper storage chamber (not shown) of the forming apparatus, is shown. At one end of the drawer opening 11a of the paper tray 11, there is provided an operating member 21 for transmitting a force acting on the paper tray 11 to the rotating member 22 when the paper tray 11 is attached to and detached from the paper storage chamber. A semicircular rotating part 22 is rotatably mounted on the upper wall of the storage room. Near the circumference of the rotating part 22, a column member 23 is provided as an action point for rotating the rotating part 22 in the direction of arrow D and in the opposite direction. A support member 24 is provided for changing the force acting in the direction of arrow C and the direction opposite thereto when the paper tray 11 is attached and detached, to the rotational force of the rotating portion 22. Further, the light emitting element 13a irradiates the surface of the rotating unit 22 on the paper tray 11 side with the measuring light from the light emitting element 13a toward the recording medium to be discriminated, and receives the measuring light reflected by the recording medium to be discriminated stored in the paper tray 11. The light emitting and receiving unit 13 that outputs a light receiving signal by receiving light with the element 11 b is attached so that the center position thereof matches the center position of the rotating unit 22.
[0030]
The drawing further shows an enlarged view of the light emitting and receiving unit 13 and a recording medium type determining unit 14 connected to the light emitting element 13a and the light receiving element 13b of the light emitting and receiving unit 13.
[0031]
Although not shown, the rotation unit 22 is provided with an angle sensor that detects the rotation angle of the rotation unit, and the output of the angle sensor is configured to be sent to the recording medium type determination unit 14.
[0032]
The light emitting and receiving unit 13 includes a light emitting element 13a that emits measurement light toward the recording medium to be determined, and one of a P-polarized component and an S-polarized component disposed on the front surface of the light-emitting element 13a and transmits the other. A polarizing element 13c for absorbing light. Also, the measurement light applied to the discrimination target recording medium via the polarization element 13c transmits a P-polarization component of the measurement light that is regularly reflected by the discrimination target recording medium, and the polarization element 13d reflects the S-polarization component. A light-receiving element 13b for receiving a P-polarized component and a light-receiving element 13b for receiving an S-polarized component are provided via the polarizing element 13d. It is sent to the decision unit 14. The recording medium type determination unit 14 has a look-up table for storing data of light reception signals obtained from various types of paper in advance, and refers to the look-up table to generate data of light reception signals sent from the light emitting / receiving unit 13. The recording medium type is determined based on the recording medium type.
[0033]
When the paper tray 11 is pulled out from the paper storage chamber in the direction of arrow C, the operating member 21 of the paper tray 11 moves in the direction of arrow C, and the rotating part 22 rotates in the direction of arrow D. Move to position. At this time, the light emitting / receiving unit is also arranged in the direction of (1).
[0034]
Therefore, after the sheets are stored in the sheet tray 11, the discrimination of the recording medium type by the light emitting / receiving unit 13 is detected by irradiating the measuring light in the width direction of the sheet, which crosses the direction of the arrow C.
[0035]
Next, in order to store the paper tray 11 in the paper storage chamber, when the paper tray 11 is pushed in the direction opposite to the arrow C direction, the operating member 21 of the paper tray 11 moves in the direction opposite to the arrow C direction, and the rotating unit 22 The rotation in the direction opposite to the arrow D direction causes the cylindrical member 23 and the light emitting / receiving unit 13 to move accordingly. When the paper tray 11 is completely stored in the paper storage chamber, the columnar member 23 moves to the position (2). At this time, the light emitting / receiving unit 13 is also rotated in the direction opposite to the direction of the arrow D and arranged in the direction of (2).
[0036]
Therefore, the measurement light whose irradiation direction gradually changes from the width direction to the longitudinal direction is irradiated from the light emitting and receiving unit 13 to the sheet stored in the paper tray 11, and the irradiation direction is changed from the light receiving element 13 b of the light emitting and receiving unit 13. A light receiving signal based on the measurement light whose gradual change is output.
[0037]
Here, the rotating section 22 of the present embodiment is driven to rotate by the action member 21, the support member 24, and the columnar member 23, but is not necessarily limited to this configuration, and rotates in accordance with attachment and detachment of the paper tray 11. What is necessary is just to be the thing comprised so that it may perform.
[0038]
FIG. 3 is a diagram schematically showing a waveform of a light receiving signal obtained by receiving the measuring light reflected by the recording medium to be determined by a specific light receiving element.
[0039]
In FIG. 3, the vertical axis represents the output of the light receiving element that has received the P-polarized component or the S-polarized component, and the horizontal axis represents the irradiation direction of the measurement light.
[0040]
When the recording medium to be discriminated is, for example, OHP paper, a stretching process is added during the manufacturing process of the PET film as a base material, and the molecular arrangement is often oriented in a predetermined direction. Is not constant in the width direction and the longitudinal direction. Therefore, even in the case of OHP sheets of the same lot, the phase of the light receiving signal output from the light receiving element often differs. Therefore, the profile of the recording medium to be determined is known from the received light signal received while changing the irradiation direction of the measurement light by rotating the light emitting / receiving unit, and the recording medium type is determined from the profile.
[0041]
FIG. 4 is a flowchart illustrating the operation of the paper tray and the operation of the recording medium type determination unit.
[0042]
In FIG. 4, (S-1) to (S-4) indicate the operation of the paper tray, and (S-21) to (S-24) indicate the operation of the recording medium type determination unit.
[0043]
First, when the user pulls out the paper tray to supply the paper to the paper tray (S-1), the output of the light receiving element in the state immediately before replacing the paper is held (S-21).
[0044]
Next, when the user replaces the paper or performs jam processing (S-2), and tries to push in again to store the paper tray in the storage chamber (S-3), the recording medium type determination unit determines Then, sampling of data obtained from the light receiving signal output from the light receiving element of the light emitting and receiving unit is started (S-22). The data sampled at intervals of 200 ms after the paper tray is first pushed in and the rotation angle data sent from the angle sensor provided in the rotation unit are stored (S-23).
[0045]
Then, three angles including zero degrees or three angles including 90 degrees are extracted from the sampling data, and from the outputs Y1, Y2, and Y3 at that time and the times t1, t2, and t3, Y1 = The simultaneous equations α × sin (ωt1 + φ), Y2 = α × sin (ωt2 + φ), and Y3 = α × sin (ωt3 + φ) are solved to find the peak value α, period ω, and phase φ, respectively. The recording medium type can be determined by comparing the data with the LUT data as a parameter.
[0046]
Alternatively, by extracting two of the sampled data in which the difference between the adjacent data is minimized, setting the output at the midpoint between the two as the peak value α, and comparing the output with the LUT data using α as a parameter. The type may be determined.
When the paper tray is completely stored in the storage chamber (S-4), the sampling of the output of the light receiving element ends (S-24).
[0047]
Here, in the present embodiment, the light receiving signal output from the light receiving element is sampled at intervals of 20 ms. However, the sampling is not necessarily performed at intervals of 20 ms, and the data of the light receiving signals at three points are synchronized with the rotation angle. Is not necessary if sampling is obtained.
[0048]
In this way, by rotating the light emitting and receiving unit, a plurality of data having different irradiation directions of the measurement light are obtained, and the profile of the recording medium to be determined is specified from the data. Even if the amount of reflected light differs depending on the irradiation direction, the type of recording medium can be determined with high accuracy.
[0049]
Next, a second embodiment will be described.
[0050]
The image forming apparatus according to the second embodiment is an embodiment in which the second invention is combined with the first invention, and is different from the first embodiment in that the light emitting / receiving of the recording medium type discriminating apparatus is different from that of the first embodiment. The units are different, but the others are common. Therefore, the description will focus on the differences.
[0051]
FIG. 5 is a schematic diagram illustrating a light emitting and receiving unit in the image forming apparatus according to the second embodiment.
[0052]
The light emitting and receiving unit 13 of the present embodiment is different from the light emitting and receiving unit 13 of the first embodiment in that the polarizing element 13e provided on the front surface of the light receiving element 13b rotates the polarization plane by 90 degrees. Since the other components are common, the same components are denoted by the same reference numerals, and differences will be described.
[0053]
FIG. 5A is a diagram illustrating a semicircular rotating unit 22 to which the light emitting and receiving unit 13 is attached, and an action member 21 provided at the drawer opening 11a of the paper tray 11, and FIG. FIG. 5C is a diagram illustrating a plan view of the light emitting and receiving unit 13 attached to the surface of the rotating unit 22 on the sheet tray 11 side, and FIG.
[0054]
In FIG. 5A, an operating member 21 that transmits a force acting on the paper tray 11 to the rotating unit 22 when the paper tray is attached to or detached from the paper storage chamber is provided at one end of a drawer opening 11 a of the paper tray 11 (not shown). Have. A semicircular rotating part 22 is rotatably provided on the upper wall of the paper storage chamber (not shown), and a cylindrical member 23 serving as an action point for rotating the rotating part 22 is provided near the circumference of the rotating part 22. ing. Further, a support member for changing the force acting in the direction of arrow C and the opposite direction when the paper tray is attached / detached to the rotation force for rotating the rotation unit 22 is provided near the rotation unit 22 on the upper wall of the paper storage chamber (not shown). 24 are provided. The light-emitting element 13a irradiates measurement light from the light-emitting element 13a toward the discrimination target recording medium on the paper tray side surface of the rotating unit 22, and receives the measurement light reflected by the discrimination target recording medium by the light-receiving element 13b, thereby receiving a light reception signal. The light emitting and receiving unit 13 for outputting is mounted such that the center position matches the center position of the rotating unit 22.
[0055]
As described in the first embodiment, the rotating member 22 and the light emitting / receiving unit 13 move the operating member 21 in the direction indicated by the arrow C and the opposite direction by the attachment / detachment of the paper tray 11, and rotate the rotating member 22. Rotates in the direction of arrow D and in the opposite direction, so that the columnar member 23 and the light emitting / receiving unit 13 rotate accordingly.
[0056]
5 (b) and 5 (c), the light emitting / receiving unit 13 is provided with a light emitting element 13a for irradiating measurement light toward the recording medium to be determined, and is disposed on the front surface of the light emitting element 13a, and the light emitting element 13a emits light. A polarizing element 13c that transmits either the P-polarized component or the S-polarized component of the measuring light to be absorbed and absorbs the other, and a light receiving element 13b that receives specularly reflected light of the measuring light applied to the recording medium to be discriminated. And a polarizing element 13e that is disposed in front of the light receiving element 13b and that transmits either the P-polarized component or the S-polarized component by rotating the polarization plane and absorbs the other. Further, a shaft 25 is provided which is perpendicular to the recording medium to be discriminated and has an umbrella-shaped gear 25a attached to the end. The umbrella-shaped gear 25a meshes with the polarizing element 13e, and when the shaft 25 rotates in the direction of arrow E, the umbrella-shaped gear 25a rotates to rotate the polarizing element 13e in the direction of arrow F. The shaft 25 is connected to a rotation drive unit (not shown) such as a motor.
[0057]
Here, the polarizing element 13e is rotated by an umbrella-shaped gear 25a attached to the shaft 25, but is not necessarily limited to this configuration.
[0058]
In the image forming apparatus according to the present embodiment, since the light emitting / receiving unit 13 is attached to the rotating unit 22, for example, recording is performed while the rotating unit 22 is rotating or moved to the position (1) or (2). A timing signal is sent from the medium type determination unit to a rotation drive unit such as a motor, and the polarization element 13e is rotated to obtain light reception signals before and after rotation. Further, even if the paper tray 11 is not attached and detached, and the rotating unit 22 remains stopped, the polarizing element 13e is rotated by rotating the polarizing element 13e depending on the type of the paper selection mode selected by the paper selection button, for example. A light receiving signal can be obtained.
[0059]
After the paper is stored in the paper tray 11, the measuring light is emitted from the light emitting and receiving unit 13 in the width direction of the paper, and the measurement is gradually performed from the width direction of the paper to the longitudinal direction of the paper according to the rotation of the light emitting and receiving unit 13. The recording medium type is determined based on data obtained by sampling a light reception signal that has received the regular reflection light of the paper, the rotation angle data, and the data before and after the rotation of the polarizing element 13e. You.
[0060]
In the present embodiment, each polarization component in the reflected light is obtained by obtaining a light reception signal before and after the rotation of the polarization plane of the polarization element 13c. Therefore, for example, the image receiving layer is thick and includes the image receiving layer like color OHP paper. Even when the reflectance and the refractive index inside the paper are different, the type of the recording medium can be determined by comparing the obtained polarization components.
[0061]
The recording medium type discriminating apparatus 20 of the present embodiment is provided in the paper tray 11 and is used in combination with the rotating unit 22 and the like described in the first embodiment. The recording medium type discrimination device 20 having the light receiving unit 13 does not necessarily need to be combined with the rotating unit 22 or the like, and can be used alone, and the position where it is provided is not limited to the paper tray 11. Further, if the data of the LUT provided in the recording medium type determination unit 14 is rewritten or added, it can be used for measuring the density of the toner image.
[0062]
【The invention's effect】
As described above, according to the image forming apparatus of the first invention, the profile is grasped by obtaining the light receiving signal while changing the irradiation direction of the measuring light irradiating the sheet for discriminating the recording medium type. A high-quality image can be formed by detecting a high-quality recording medium with high accuracy. Further, according to the image forming apparatus of the second aspect, it is possible to obtain a light receiving signal of each polarization component before and after the rotation of the polarization plane of the polarizing element in front of the light receiving element. By determining the recording medium based on the difference between the two, a high-quality image can be formed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment.
FIG. 2 is a schematic plan view showing a main part for determining a type of a recording medium on which an image is formed in the image forming apparatus according to the embodiment; FIG. FIG. 4 is a diagram schematically showing a waveform of a light receiving signal received by the light emitting device.
FIG. 4 is a flowchart illustrating an operation of a paper tray and an operation of a recording medium type determination unit.
FIG. 5 is a schematic diagram illustrating a light emitting and receiving unit in an image forming apparatus according to a second embodiment.
[Explanation of symbols]
1, 1Y, 1M, 1C, 1K Photoconductor 2, 2Y, 2M, 2C, 2K Scorotron charger 3, 3Y, 3M, 3C, 3K Laser output unit 4, 4Y, 4M, 4C, 4K Developing unit 5, 5Y, 5M, 5C, 5K Primary transfer unit 6 Intermediate transfer belt 7 Secondary transfer unit 8 Belt cleaner 9 Fixing unit 11 Paper tray 11a Paper tray draw-out port 12 Feed roll 13 Light emitting and receiving units 13a and 13d Light emitting element 13b Light receiving element 13c Polarizing element 14 Recording medium type determining unit 15 Control unit 20 Recording medium type discriminating device 21 Working member 22 Rotating unit 23 Column member 24 Support member 25 Shaft 25a Umbrella-shaped gear

Claims (4)

An image carrier that forms a toner image, and a light emitting and receiving device that irradiates a measuring light from a light emitting element toward a recording medium to be discriminated and outputs a light receiving signal by receiving the measuring light reflected by the recording medium to be discriminated by a light receiving element. Unit, and a recording medium type determination device having a recording medium type determination unit that determines a type of a determination target recording medium based on a light receiving signal output from the light emitting and receiving unit, wherein the recording medium is provided on the image carrier. In an image forming apparatus that forms an image on the recording medium according to the type of the recording medium determined by the type determination device,
A rotation unit that rotates the light emitting and receiving unit so that the irradiation direction of the measurement light irradiated toward the determination target recording medium changes,
The image forming apparatus, wherein the recording medium type determining unit determines the type of the recording medium to be determined based on a light receiving signal output from the light emitting and receiving unit when the light emitting and receiving unit rotates. apparatus. A removable paper tray for storing paper for forming the image is provided,
2. The image forming apparatus according to claim 1, wherein the rotating unit rotates in accordance with the detachment of the paper tray, and rotates the light emitting and receiving unit. The light emitting and receiving unit includes a polarizing element that polarizes measurement light reflected by the discrimination target recording medium received by the light receiving element in a predetermined polarization direction, and the recording medium type determination unit is output from the light receiving element. 2. The image forming apparatus according to claim 1, wherein the type of the recording medium to be determined is determined based on a light receiving signal. An image carrier that forms a toner image, and a light emitting and receiving device that irradiates a measuring light from a light emitting element toward a recording medium to be discriminated and outputs a light receiving signal by receiving the measuring light reflected by the recording medium to be discriminated by a light receiving element. Unit, and a recording medium type determination device having a recording medium type determination unit that determines a type of a determination target recording medium based on a light receiving signal output from the light emitting and receiving unit, wherein the recording medium is provided on the image carrier. An image forming apparatus that forms an image on the recording medium according to the type of paper determined by the type determination device,
The light emitting and receiving unit includes a polarizing element that polarizes the measurement light reflected by the recording medium to be determined, which is received by the light receiving element, in a predetermined polarization direction, and a rotating member that rotates a polarization plane of the polarizing element, The image forming apparatus, wherein the recording medium type determining unit determines the type of the recording medium to be determined based on a light receiving signal output from the light receiving element before and after the rotation of the polarization plane.

Images