JPH0974467A - Image forming device and identification method for its recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain automatic identification of a recording medium depending on a level difference by providing a function of adjustment of a detection level and calibration to an optical sensor section sensing the recording medium so as to attain stable sensing. SOLUTION: A photo transistor PT 102 receives a light emitted from an LED 101 and generates a current 115 is response to the luminous quantity. A detection level Vs of the PT 102 is converted into digital data by an A/D converter 106 via a buffer amplifier 105. A storage circuit 111 stores digital data of a detection level of the PT 102 for a prescribed recording medium in the initial adjustment of the sensor. A comparator circuit 112 compares an output of an A/D converter 106 with data of the storage circuit 111 to output the comparison result. A luminous quantity control circuit 113 receives the comparison result and provides an output of luminous quantity data in response to the comparison result. Then a D/A converter 109 converts the digital luminous quantity data into an analog voltage to decide a reference voltage of an operational amplifier 108 thereby adjusting and calibrating a luminous quantity of the photo transistor PT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and a recording medium detecting method therefor, and more particularly to an image forming apparatus for detecting a recording medium by using a transmissive or reflective detection sensor which is a combination of an LED and a phototransistor. And a method for identifying the recording medium.

[0002]

2. Description of the Related Art Recently, the number of types of recording media used in copying machines has increased, and functions and performances have been required so that uniform image quality can be obtained even if the recording media are different. for that purpose,
It is necessary to detect the recording medium and change the process condition control according to the detection result. However, since the conventional recording medium is identified by the user through the operation panel or the like, inconvenience may occur when different recording media are mixed when performing continuous copying.

As a solution to such a case, there is a method of examining the difference in the transmittance of the medium using an optical sensor and identifying the medium by this transmittance.

[0004]

However, since a stable detection level cannot be obtained due to electrical variations of LEDs and phototransistors used for optical sensors and changes with time and aging, a sensor suitable for the type of recording medium is used. I had to equip some of them, and there was a problem of mounting space and high cost.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides an optical sensor section for detecting a recording medium with a detection level adjusting and calibrating function, thereby stably recording with a detection level difference. An image forming apparatus capable of automatically identifying a medium and a method of identifying a recording medium thereof are provided.

That is, the image forming apparatus of the present invention identifies the recording medium by using the optical medium detecting sensor including the light emitting means and the light receiving means, and the image forming is capable of changing the image formation corresponding to the recording medium. In the device, when there is a change with time with a determining means for determining a change with time of the light emitting means,
Calibration means for calibrating the optical medium detection sensor so that the detection level of the recording medium falls within a predetermined range.

Here, the image forming apparatus has an adjustment mode and a calibration mode, and the judging means detects the optical medium so that a detection level of a predetermined recording medium falls within a predetermined range in the adjustment mode. A storage unit that adjusts the sensor and stores it as a calibration reference value, and a comparison unit that compares a detection level of a predetermined medium with the stored calibration reference value in a calibration mode, the calibration unit, Based on the comparison output of the comparison means, the optical medium detection sensor is calibrated so that the detection level of a predetermined recording medium falls within a predetermined range. Further, the operation is simplified by controlling the optical medium detection sensor so that the detection level in the absence of the storage medium falls within a predetermined range. Further, the optical medium detection sensor further includes display means for displaying an error message when the detection level of a predetermined recording medium exceeds a predetermined range, thereby enabling quick calibration.

Further, a means for setting the light emission amount of the light emitting means by a current value, a means for storing the light reception amount received by the light receiving means as a detection level, and a detection level of a predetermined recording medium are always within a predetermined range. And a means for controlling the current value so that the adjustment and the calibration of the optical medium detection sensor are performed by the light emission amount of the light emitting means.
Further, a means for detecting the amount of light received by the light receiving means by a current value, a means for storing the amount of light received by the light receiving means as a detection level, and a detection level of a predetermined recording medium are always within a predetermined range. Further, means for controlling the current value is further provided, and the adjustment and calibration of the optical medium detection sensor are performed by the light receiving sensitivity of the light receiving means. Further, a resistor for generating a voltage according to the amount of light received by the light receiving means,
The light receiving means further comprises means for storing a voltage corresponding to the amount of light received by the light receiving means as a detection level, and means for changing the resistance value of the resistor, and the adjustment and calibration of the optical medium detection sensor are performed by the light receiving means. It is performed according to the light receiving sensitivity of.

Further, in the recording medium identifying method of the present invention, the recording medium can be identified by using the optical medium detecting sensor including the light emitting means and the light receiving means, and the image formation can be changed corresponding to the recording medium. A method of identifying a recording medium in an image forming apparatus, wherein, during adjustment, the optical medium detection sensor is adjusted so that a detection level of a predetermined recording medium falls within a predetermined range, and the detection level is calibrated. It is stored as a reference value, the recording medium is identified based on the detection level, and at the time of calibration, the detection level of a predetermined recording medium is compared with the stored reference value of the calibration, and the detection level is within the predetermined range. Calibrating the optical medium detection sensor to be inside.

Here, the operation is simplified by controlling the optical medium detection sensor so that the detection level in the absence of the recording medium falls within a predetermined range. Also,
Further, by displaying an error message when the detection level of a predetermined recording medium exceeds a predetermined range, quick calibration is possible.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. <Structural Example of Color Image Forming Apparatus> FIG. 1 shows a schematic external view of the color image forming apparatus of the present embodiment. The color image forming apparatus according to the present embodiment is a copying machine including an upper digital color image reader unit 500 and a lower digital color image printer unit 600, but the present invention is not limited to the copying machine and image forming is performed. It is also applied to other devices such as a dedicated printer and a facsimile having an image forming unit.

In the operation of the present embodiment, in the upper digital color image reader unit 500, the original image 30 is placed on the original platen glass 31 and started, whereby the reader unit 500 reads a color image and a predetermined image is read. Signal processing is performed, and the digital color image printer unit 60 at the bottom is processed.
Sent to 0. In the lower digital color image printer unit 600, the type of the recording medium is identified, and by a predetermined process corresponding to the type, it is transferred to the recording material stored in the recording material cassette 7 and post-processed, and the tray 10 To discharge.

Next, details of the upper digital color image reader unit 500 and the lower digital color image printer unit 600 of the color image forming apparatus of the present embodiment will be described with reference to FIG. (Structural Example of Digital Color Image Reader Unit) In the upper digital color image reader unit 500, as described above, the original document 30 is placed on the original platen glass 31 and is exposed and scanned by the exposure lamp 32 to reflect from the original document 30. The light image is condensed on the full-color sensor 34 by the lens 33,
A color separation image signal is obtained. The color-separated image signal is processed by a video processing unit (not shown) through an amplifier circuit (not shown) and sent to the digital color image printer section 600.

(Structural Example of Digital Color Image Printer Unit) In the lower digital color image printer unit 600, the photosensitive drum 1 as an image carrier is rotatably supported in the direction of the arrow, and pre-exposure is performed around the photosensitive drum 1. Lamp 1
1, corona charger 2, laser exposure optical system 3, potential sensor 12, four developing devices 4y, 4c, 4m, 4B of different colors
k, the on-drum light amount detection means 13, the transfer device 5, and the cleaning device 6 are arranged.

In the laser exposure optical system 3, the image signal from the upper digital color image reader unit 500 is converted into an optical signal by a laser output unit (not shown), and the converted laser light is reflected by the polygon mirror 3a. And the lens 3b
Then, the light is projected on the surface of the photosensitive drum 1 through the mirror 3c. At the time of image formation in the digital color image printer unit 600, the photosensitive drum 1 is rotated in the direction of the arrow,
The photosensitive drum 1 after the charge is removed by the pre-exposure lamp 11 is uniformly charged by the charger 2, and the light image E is emitted for each separated color to form a latent image.

Next, a predetermined developing device is operated to develop the latent image on the photosensitive drum 1 to form a resin-based toner image on the photosensitive drum 1. The developing device is an eccentric cam 24.
By the operations of y, 24c, 24m, and 24Bk, the photosensitive drum 1 is selectively approached according to each separated color. Further, the recording material stored in the recording material cassette 7 is supplied to a position corresponding to the photosensitive drum 1 via the transport system and the transfer device 5. The toner image on the photosensitive drum 1 is transferred to the recording material.

In this embodiment, the transfer device 5 includes a transfer drum 5a, a transfer charger 5b, an adsorption charger 5c for electrostatically adsorbing a recording material, and an adsorption roller 5g facing the adsorption roller 5g.
A recording material carrying sheet 5f made of a dielectric material is integrally formed in a cylindrical shape in a peripheral opening area of a transfer drum 5a which is provided with an inner charging device 5d and an outer charging device 5e and is rotatably supported. It is stretched. The recording material carrying sheet 5f uses a dielectric sheet such as a polycarbonate film.

As the drum-shaped transfer device, that is, the transfer drum 5a is rotated, the toner image on the photosensitive drum 1 is transferred onto the recording material carried on the recording material carrying sheet 5f by the transfer charger 5b. As described above, a desired number of color images are transferred to the recording material that is adsorbed and conveyed to the recording material carrying sheet 5f to form a full-color image.

In the case of forming a full-color image, when the transfer of the four color toner images is completed in this way, the recording material is separated from the transfer drum 5a by the action of the separating claw 8a, the separating push-up roller 8b and the separating charger 5h. The sheet is discharged to the tray 10 via the heat roller fixing device 9. On the other hand, the post-transfer photosensitive drum 1 is subjected to the image forming process again after cleaning the residual toner on the surface with the cleaning device 6.

When images are formed on both sides of the recording material,
Immediately after being discharged from the heat roller fixing device 9, the conveyance path switching guide 19 is driven, guided through the conveyance vertical path 20 to the reversing path 21a once, and then is reversed by the reversing roller 21b. With the rear end as the leading end, it is retracted in the fixed direction opposite to the fed direction, and is stored in the intermediate tray 22. After that, an image is formed on the other surface by the above-described image forming step.

The transfer drum 5a is the transfer drum 5a.
In order to prevent the powder from being scattered on the recording material carrying sheet 5f and the oil on the recording material, the fur brush 1 is used.
4 through the recording material carrying sheet 5f
The cleaning is carried out by the action of the backup brush 15 facing the oil removing roller 4 and the backup brush 17 facing the oil removing roller 16 via the oil removing roller 16 and the recording material carrying sheet 5f. Such cleaning is performed before or after image formation, and at any time when a jam (paper jam) occurs.

Further, in the present embodiment, the eccentric cam 25 is operated at a desired timing, and the cam follower 5i integrated with the transfer drum 5f is operated, whereby the recording material carrying sheet 5a and the photosensitive drum 1 are separated. The gap can be set arbitrarily. For example, during standby or when the power is off, the interval between the transfer drum and the photosensitive drum is increased.

(Configuration Example of Control Unit of Color Image Forming Apparatus)
FIG. 3 is a diagram showing the configuration of the control unit of the color image forming apparatus of this embodiment. In the figure, 50 is C which controls the entire control.
PU. A RAM 51 is a digital color image storage unit 52 that stores the image read by the digital color image reader unit 500, and data corresponding to the storage medium detected by the optical sensor is read from the storage medium detection unit 59 and a predetermined process is performed. And a cassette selection parameter 53 for storing the type of recording material selected. 54
Is a ROM that stores the processing of the CPU 50, and includes a reader control program 55 and a printer control program 5.
6 and a cassette selection program 57. Reference numeral 58 is the digital color image reader unit, and 60 is the digital color image printer unit. Reference numeral 61 is an operation panel, and 62 is a bus for exchanging data and control between the CPU 50 and each unit. The programs stored in the ROM 54 are floppy disks, CDs, ICs,
From the control program storage unit 65 of the external storage medium 64 such as CARD to the control program loading unit 6 of the RAM 51.
3 may be configured to be loaded and executed.

(Structural Example 1 of Storage Medium Detecting Section) FIG. 4 is a basic structural diagram showing a storage medium detecting section having the transmissive optical sensor of the first structural example. In FIG. 4, the LED 101 emits a light amount corresponding to the resistor 103 and the current 114 determined by the emitter potential of the transistor 107. On the other hand, the phototransistor (PT) 102 is the LED
The light emitted by 101 is received, and the current 115 corresponding to the amount of light is received.
Occurs. The detection level Vs of PT converted into a voltage by the current 115 and the resistor 104 is the buffer amplifier 10
After passing 5, the AD converter 106 converts the data into digital data.

The memory circuit 111 stores digital data of the detection level of the PT 102 of a predetermined recording medium at the time of initial adjustment of the sensor, and the switch 1 at the time of adjustment.
10 is closed and the digital data output from the AD converter 106 is input. The comparison circuit 112 includes the AD converter 106.
And the data in the memory circuit 111 are compared, and the comparison result is output. The light amount control circuit 113 inputs the comparison result,
The digital light amount data corresponding to the comparison result is output. DA
The converter 109 converts the digital light quantity data into an analog voltage and determines the reference voltage of the operational amplifier 108. Switches 116 and 117 are closed only during sensor adjustment and calibration, and are normally open.

(Optical Sensor Adjustment Example 1) Next, with respect to the method of adjusting the transmission type optical sensor (setting of the reference value), the control of the control unit will be described with reference to the flowchart of FIG.
First, in step S1, the switches 116 and 117 are closed. In step S2, predetermined light amount data is set in the DA converter 109. In step S3, a recording medium for adjustment is inserted between the LED 101 and the PT 102.
Here, in the transmissive sensor, when the object to be detected is transmissive, the variation in the detection level is very large, so the recording medium for adjustment is selected from the recording media used in the copying machine and has a high transmissivity. And good.

Next, in step S4, it is determined whether the detection level output from the PT 102 is within a predetermined range. If it is within the range, the process proceeds to step S5. Go to S6. Step S5
Then, since it is within the range, the switch 110 is closed and the detection level is stored in the memory circuit 111 as the reference value, and the process proceeds to step S9 to finish the adjustment of the sensor unit. The reference value stored here is set as a reference value used for calibration described later. The detection level may be stored in the RAM 51 shown in FIG.

On the other hand, in step S6, since it is outside the range, if the light amount data is within the settable range, step S6 is executed.
Go to 7. If it is outside the light amount setting range, that is, if it does not fall within the predetermined range, the process proceeds to step S8. In step S7, the set value of the light amount data is changed, and the process returns to step S4 again. In step S8, when the set value of the light amount data exceeds the possible range, an error message is displayed on the operation panel 20, and the process proceeds to step S9.

In step S9, the switches 116 and 11
7 is opened, and if the switch 110 is closed, the switch 110 is also opened and the processing is ended. (Calibration Example 1) In an optical sensor, an LED element, which is often used as a light emitting source, has a large change in the amount of emitted light with respect to a constant current value due to aging. Therefore, in order to detect the transmittance and determine the material of the recording medium as in the present embodiment, the detection must be performed stably, and for that purpose, the LED serving as the light source is regularly used.
It is necessary to calibrate the light amount of the above and set a constant light amount as the light source of the LED. The procedure of the calibration performed by the control unit will be described below with reference to FIG.

First, in step S10, the switches 116,
117 is closed. In step S11, the LED 101
A recording medium for calibration adjustment is inserted between the PT 102 and the PT 102. In step S12, the comparison circuit 112 compares the detection level output from the PT 102 with the reference value set by the adjustment method stored in the storage circuit 111, that is, the calibration data.

In step S13, if the comparison result is within the predetermined allowable range, the process proceeds to step S14. If not, that is, if the comparison result is outside the allowable range, the process proceeds to step S15. In step S15, it is determined whether or not the light amount data is within the settable range. If it is within the settable range, the process proceeds to step S16, and if it is outside the allowable range, the process proceeds to step S17. In step S16, the light amount data of the light amount control circuit 113 is changed and the value is changed to DA.
The converter 109 is set and the process returns to step S13.

When the processing comes to step S17, it means that the comparison result is not within the predetermined range and the light amount data exceeds the settable range, an error message is displayed on the operation panel, and the process goes to step S14. move on. Step S
At 14, the switches 116 and 117 are opened to end the calibration. (Structural Example 2 of Storage Medium Detecting Unit) In the above structural example 1, the sensor sensitivity is controlled to be constant by controlling the light emission amount of the LED, which is the light emitting side of the transmissive optical sensor.
On the other hand, the same effect can be obtained by controlling the light receiving sensitivity of the phototransistor on the light receiving side. This configuration example 2
Is an example of controlling the light receiving sensitivity of the phototransistor on the light receiving side. Hereinafter, with reference to the drawings, the adjustment of the storage medium detection unit and the sensor of Configuration Example 2, and the calibration thereof will be described in detail.

FIG. 7 is a diagram showing a basic configuration of a storage medium detecting section having the transmission type optical sensor of the second configuration example. L
The ED 401 has a current value 4 determined by the resistor 403.
A light amount corresponding to 16 is emitted. The PT 402 is a light receiving element of a phototransistor, and generates a current 417 according to the amount of light emitted from the LED 401. This current 417
Is converted into a detection level (sense voltage) Vs by the variable resistor 404 and the resistor 405. The detection level Vs is
After passing through the buffer amplifier 407, it is given to the AD converter 408 and converted into digital data. Here, the variable resistor 404 is a variable resistor whose resistance value can be externally controlled.
It is common to use the on-resistance of ET.

The memory circuit 410 stores the detection data for calibration, and the switch 409 is closed during the adjustment of this sensor to input the calibration data. The comparison circuit 411 compares the input data with a predetermined standard value or calibration data, and outputs the comparison result. The sensitivity control circuit 412 generates digital data according to the comparison result of the comparison circuit 411, and the DA converter 41 via the switch 15.
Set sensitivity data to 3. Switches 414 and 415
Should be closed during adjustment and calibration of this sensor, and should normally be open.

(Example 2 of Adjustment of Optical Sensor) Next, with respect to the method of adjusting the transmission type optical sensor (setting of the reference value), the control of the control unit will be described with reference to the flowchart of FIG.
First, in step S20, the switches 414 and 415 are closed. In step S21, sensitivity data as a predetermined initial value is set in the DA converter 413. In step S22, the LEDs 401 and PT4 are used as recording media for adjustment.
Insert between 02 and. Here, in the transmissive sensor, when the object to be detected is transmissive, the detection level varies greatly, so the recording medium for adjustment should be a recording medium used in a copying machine with a high transmissivity. Good to choose.

Next, in step S23, the detection level output from the PT 402 (actually, the buffer amplifier 4
It is determined whether or not the value converted to a digital signal by the AD converter 408 and sent to the main body control circuit) is within a predetermined range, and if it is within the range, go to step S24. Go to step S2 if out of range
Go to 5. In step S24, since the detection level is within the range, the switch 409 is closed to store the detection level in the memory circuit 410 as the reference value, and the process proceeds to step S28. The reference value stored here is set as a reference value used for calibration described later. The detection level may be stored in the RAM 51 shown in FIG.

On the other hand, in step S25, since the detection level is out of the range, if the sensitivity data is within the settable range, the process proceeds to step S7. If it is outside the sensitivity setting range, that is, if the sensitivity does not fall within the predetermined range, the process proceeds to step S27. In step S26, the setting value of the sensitivity data is changed, and the process returns to step S23. In step S27, when the setting value of the sensitivity data exceeds the possible range, an error message is displayed on the operation panel 20, and the process proceeds to step S28.

In step S28, the switches 414, 4
15 is opened, and if the switch 409 is closed, the switch 409 is also opened, and the process ends. (Calibration Example 2) In an optical sensor, an LED element that is often used as a light emission source has a large change in the amount of light emission with respect to a constant current value due to aging. Therefore,
In order to detect the transmittance and determine the material of the recording medium as in the second configuration example, the detection must be performed stably. For that purpose, the sensitivity is regularly calibrated, The amplification factor of the differential amplifier 406 must be set and set so that the output voltage (sense voltage Vs) becomes a predetermined value. The calibration procedure will be described below with reference to FIG.

First, in step S30, the switches 414,
415 is closed. In step S31, the LED 401
And a recording medium for calibration adjustment is inserted between PT402 and PT402. In step S32, the comparison circuit 411 compares the detection level output from the PT 402 with the reference value set by the adjustment method stored in the storage circuit 410, that is, the calibration data.

In step S33, if the comparison result is within the predetermined allowable range, the process proceeds to step S34. If not, that is, if the comparison result is outside the allowable range, the process proceeds to step S35. In step S35, it is determined whether or not the sensitivity data is within the settable range. If it is within the settable range, the process proceeds to step S36, and if it is outside the allowable range, the process proceeds to step S37. In step S36, the sensitivity data of the sensitivity control circuit 412 is changed and the value is changed to DA.
The converter 413 is set and the process returns to step S33.

When the processing comes to step S37, it means that the comparison result is not within the predetermined range and the sensitivity data exceeds the settable range, an error message is displayed on the operation panel, and the process goes to step S34. move on. Step S
At 34, the switches 414 and 415 are opened to end the calibration. In addition, although the example of the transmission type optical sensor is shown in the present embodiment, the present invention can be similarly applied to the reflection type optical sensor. Further, although the adjustment and calibration on the light emitting side and the adjustment and calibration on the light receiving side have been described independently, more appropriate and wide-range adjustment can be performed by combining these. Further, in the present embodiment, the optical medium detection sensor is adjusted and calibrated with a predetermined recording medium, but the adjustment and the calibration may be performed without the recording medium in order to simplify the operation. .

The present invention may be applied to a system composed of a plurality of devices such as a host computer, an interface and a printer, or to an apparatus composed of a single device such as a copying machine. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus. in this case,
The storage medium storing the program according to the present invention constitutes the present invention. Then, by reading the program into the system or device from the storage or other means, the system or device operates in a predetermined manner.

[0043]

As described above, according to the present invention, the optical sensor section for detecting the recording medium is provided with the detection level adjusting and calibrating function, so that the automatic identification of the recording medium can be stably performed by the detection level difference. Became.

[Brief description of drawings]

FIG. 1 is an external view of a color image forming apparatus according to this embodiment.

FIG. 2 is a sectional view for explaining the structure of the color image forming apparatus according to the present embodiment.

FIG. 3 is a diagram showing a configuration of a control unit according to the present embodiment.

FIG. 4 is a basic configuration diagram showing a configuration example of a storage medium detection unit of the present embodiment.

5 is a flowchart showing an adjustment procedure in the configuration example of FIG.

6 is a flowchart showing a calibration procedure in the configuration example of FIG.

FIG. 7 is a basic configuration diagram showing another configuration example of the storage medium detection unit of the present embodiment.

8 is a flowchart showing an adjustment procedure in the configuration example of FIG.

9 is a flowchart showing a calibration procedure in the configuration example of FIG.

Claims (10)

[Claims] 1. An image forming apparatus capable of discriminating a recording medium by using an optical medium detection sensor comprising a light emitting means and a light receiving means and changing image formation corresponding to the recording medium. It is characterized by further comprising: determination means for determining a change; and calibration means for calibrating the optical medium detection sensor so that the detection level of the recording medium falls within a predetermined range when there is a change over time. Image forming apparatus. 2. The image forming apparatus has an adjustment mode and a calibration mode, and the determination means is configured to detect the optical medium detection sensor so that a detection level of a predetermined recording medium falls within a predetermined range in the adjustment mode. A storage means for adjusting and storing as a calibration reference value, and a comparison means for comparing a detection level of a predetermined medium and the stored calibration reference value in a calibration mode, the calibration means, Based on the comparison output of the comparison means,
The image forming apparatus according to claim 1, wherein the optical medium detection sensor is calibrated so that a detection level of a predetermined recording medium falls within a predetermined range. 3. The image forming apparatus according to claim 1, wherein the optical medium detection sensor is controlled so that the detection level in the absence of the storage medium falls within a predetermined range. 4. The image forming apparatus according to claim 1, further comprising display means for displaying an error message when a detection level of a predetermined recording medium in the optical medium detection sensor exceeds a predetermined range. apparatus. 5. A means for setting a light emission amount of the light emitting means by a current value, a means for storing a light reception amount received by the light receiving means as a detection level, and a detection level of a predetermined recording medium is always within a predetermined range. And a means for controlling the current value so that the adjustment and the calibration of the optical medium detection sensor are performed by the light emission amount of the light emitting means.
Or the image forming apparatus according to 2. 6. A means for detecting the amount of light received by the light receiving means by a current value, a means for storing the amount of light received by the light receiving means as a detection level, and a detection level of a predetermined recording medium is always within a predetermined range. 3. The image forming method according to claim 1, further comprising: a unit that controls the current value so that the adjustment and the calibration of the optical medium detection sensor are performed by the light receiving sensitivity of the light receiving unit. apparatus. 7. A resistor for generating a voltage according to the amount of light received by the light receiving means, a means for storing a voltage corresponding to the amount of light received by the light receiving means as a detection level, and a resistance value of the resistor. 3. The image forming apparatus according to claim 1, further comprising a changing unit, wherein the adjustment and the calibration of the optical medium detection sensor are performed by the light receiving sensitivity of the light receiving unit. 8. A method for identifying a recording medium in an image forming apparatus, which is capable of identifying a recording medium by using an optical medium detection sensor including a light emitting means and a light receiving means and changing image formation corresponding to the recording medium. Therefore, at the time of adjustment, the optical medium detection sensor is adjusted so that the detection level of a predetermined recording medium falls within a predetermined range, and the detection level is stored as a reference value for calibration. The recording medium is identified on the basis of the detection result, and at the time of calibration, the detection level of a predetermined recording medium is compared with the stored reference value of the calibration, and the optical medium detection is performed so that the detection level falls within the predetermined range. A method for identifying a recording medium, which comprises calibrating a sensor. 9. The method for identifying a recording medium according to claim 8, wherein the optical medium detection sensor is controlled so that the detection level in the absence of the recording medium falls within a predetermined range. 10. The method for identifying a recording medium according to claim 8, further comprising displaying an error message when the detection level of the predetermined recording medium exceeds a predetermined range.