JP5530910B2 - Detection apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a detection apparatus and an image forming apparatus.

  An image forming apparatus using an electrophotographic process is equipped with an ID sensor that detects a toner density of a toner image on a photosensitive drum or an intermediate transfer belt. The ID sensor detects toner density by irradiating light onto a toner image and detecting the reflected light, and an infrared light emitting diode (hereinafter simply referred to as LED) is used as the light source. Since the light emission amount of this LED changes due to a temperature change due to self-heating, the light emission amount is stabilized by feedback control called APC (Auto Power Control) control. As a result, the light quantity of the LED is stabilized, so that the measurement accuracy of the ID sensor is improved. For example, Patent Documents 1 and 2 listed below disclose inventions that further improve the measurement accuracy of an ID sensor with a stabilized light quantity.

JP 09-267514 A JP 2008-096744 A

  However, the APC control in the above prior art cannot keep up with the temperature change immediately after the start of light emission of the LED, so the light quantity cannot be stabilized unless several seconds to several tens of seconds have elapsed since the start of light emission. Therefore, the measurement of the ID sensor becomes unstable for a few seconds to several tens of seconds from the start of LED emission. The inventions described in Patent Documents 1 and 2 improve the measurement accuracy of the ID sensor using LED light stabilized by APC control, and perform the unstable operation immediately after the start of LED emission as described above. It cannot be excluded.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to eliminate an unstable operation immediately after the start of LED light emission.

  In order to achieve the above object, according to the present invention, as a first solving means related to the detection device, the detection device includes an LED (Light Emitting Diode) and performs detection using light of the LED, The unstable time determination information for determining the unstable time (unstable time) of the light amount immediately after the start of light emission of the LED is stored, and the unstable time of the LED is determined as the unstable time at the start of light emission of the LED. A means is adopted that comprises a detection control means that makes a judgment based on the judgment information and does not use the light of the LED during the unstable period from the start of light emission for detection.

  In the present invention, as a second solving means related to the detecting device, in the first solving means, the detecting device includes a driving means for supplying driving power to the LED, and the detection control means includes the LED. The unstable power time determination is performed based on the voltage value (drive voltage value) of the driving power supplied to make the predetermined light quantity and the unstable time registration table in which the unstable time corresponding to the drive voltage value is registered. The information is stored, and at the start of light emission of the LED, the unstable time of the LED is determined based on the drive voltage value of the LED and the unstable time registration table, and between the unstable time from the start of light emission. A means of not using the light of the LED for detection is adopted.

  In the present invention, as a third solving means relating to the detection apparatus, in the first solving means, the detection control means stores the unstable time of the LED, and starts emission from the start of light emission of the LED. A means is adopted in which the light of the LED during the unstable time is not used for detection.

  In the present invention, as a first solving means relating to the image forming apparatus, a detection device employing any one of the first to third solving means is used as an ID sensor to detect the toner density of the toner image. Adopt the means.

  According to the present invention, the unstable time determination information is stored, the unstable time of the LED is determined based on the unstable time determination information at the start of light emission of the LED, and the interval between the unstable time and the start of light emission is determined. The light from the LED is not used for detection. Thereby, the unstable operation immediately after the start of LED light emission can be eliminated.

It is a functional block diagram which shows the characteristic component of the multifunctional machine A which concerns on embodiment of this invention. It is a functional block diagram which shows the component of ID sensor 5 of the multifunctional machine A which concerns on embodiment of this invention. It is a graph which shows the light quantity fluctuation | variation from the light emission start of the infrared LED51a in the multi-function device A which concerns on embodiment of this invention. It is a functional block diagram which shows infrared LED51a, light emission side phototransistor 51d, and LED drive circuit 52d of the copier A which concerns on embodiment of this invention. It is a schematic diagram which shows the drive voltage value (a) memorize | stored in the memory | storage part 9 of the multifunctional machine A which concerns on embodiment of this invention, and the unstable time registration table (b).

Embodiments of the present invention will be described below with reference to the drawings.
The multifunction peripheral (image forming apparatus) A according to the present embodiment has a copy function, a print function, a scan function, a facsimile transmission / reception function, and an e-mail transmission function. As shown in FIG. 1, the multi-function machine A includes an image forming unit 1, an intermediate transfer belt 2, a primary transfer roller 3, a secondary transfer roller 4, an ID sensor 5, a fixing roller 6, a thermistor 7, an operation display unit 8, A storage unit 9 and a main control unit 10 are provided. The said memory | storage part 9 and the main-control part 10 comprise the detection control means in this embodiment. As for the multi-function device A, only the characteristic components described above will be described, and description of other components will be omitted.

  Each image forming unit 1 forms an image made of toner corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (BK), and is viewed from the front of the multi-function device A. As shown in FIG. 1, the photosensitive drum 11, the charging unit 12, the laser scanning unit 13, the developing unit 14, and the cleaner 15 are provided.

The photosensitive drum 11 is formed of a cylindrical member that supports a toner image formed based on the electrostatic latent image on its peripheral surface, and is disposed extending in the depth direction when viewed from the front of the multi-function device A. The main control unit Under the control of 10, a drive source (not shown) capable of speed adjustment such as a motor rotates in the circumferential direction during image formation.
The charging unit 12 is disposed so as to face the photoconductive drum 11 and makes the peripheral surface of the photoconductive drum 11 in a charged state under the control of the main control unit 10.
The laser scanning unit 13 forms an electrostatic latent image by irradiating the peripheral surface of the charged photosensitive drum 11 with laser light under the control of the main control unit 10.

The developing unit 14 stores therein a two-component developer in which toner and a carrier (magnetic carrier) are mixed, and supplies the toner to the peripheral surface of the photosensitive drum 11 under the control of the main control unit 10. Thus, a toner image based on the electrostatic latent image is formed (developed) on the peripheral surface of the photosensitive drum 11.
The cleaner 15 removes the toner remaining on the photosensitive drum 11 after the toner image is transferred from the photosensitive drum 11 to the recording sheet under the control of the main control unit 10.

The intermediate transfer belt 2 is provided so as to be in contact with the photosensitive drum 11, to which a toner image formed on the photosensitive drum 11 is primarily transferred, and includes a belt member 21, a driving roller 22, a driven roller 23, and a tension. The roller 24 is configured.
The belt member 21 is an endless belt stretched around the driving roller 22, the driven roller 23, and the tension roller 24, and is provided so as to pass between the photosensitive drum 11 and the primary transfer roller 3. Travel according to the rotation. The belt member 21 is primarily transferred with the toner image formed on the peripheral surface of the photosensitive drum 11 by the voltage applied from the primary transfer roller 3.

The driving roller 22 is a roller that supports the belt member 21 together with the driven roller 23 and the tension roller 24 and applies a running force to the belt member 21. A driving source (not shown) such as a motor is connected via a clutch. Yes. That is, the drive roller 22 travels the belt member 21 by being rotationally driven by the drive source under the control of the main control unit 10.
The driven roller 23 is a roller that rotates as the belt member 21 travels.
The tension roller 24 is a kind of driven roller that rotates following the rotation of the drive roller 22, and has a spring mechanism to apply tension to the belt member 21.

  The primary transfer roller 3 is disposed so as to face the photosensitive drum 11 so as to sandwich the belt member 21. The primary transfer roller 3 includes a charger that applies a predetermined voltage to the belt member 21 and a drive source (not shown) such as a motor. It is connected via a clutch. The primary transfer roller 3 applies a voltage from the photosensitive drum 11 to the belt member 21 by applying a voltage to the belt member 21 by a charger while being rotated by a drive source under the control of the main control unit 10. Transfer.

  The secondary transfer roller 4 is disposed so as to face the driving roller 22 so as to sandwich the belt member 21, and the toner image formed on the belt member 21 is recorded on the recording sheet conveyed from the paper feed cassette (not shown). The transfer is performed next, and includes a charger that applies a predetermined voltage to the belt member 21 and a drive source (not shown) such as a motor is connected via a clutch. The secondary transfer roller 4 is conveyed between the belt member 21 and the secondary transfer roller 4 by applying a voltage to the recording paper by a charger while being rotated by a drive source under the control of the main control unit 10. The toner image on the belt member 21 is secondarily transferred to the recording paper.

  The ID sensor 5 is provided between the image forming unit 1 closest to the secondary transfer roller 4 and the secondary transfer roller 4 and on the transfer surface side of the belt member 21 of the intermediate transfer belt 2, and the toner image on the belt member 21. And a detection signal (voltage signal) indicating the toner concentration is output to the main control unit 10. As shown in FIG. 2, the ID sensor 5 includes a sensor head portion 51, a light emitting side circuit (driving means) 52, and a light receiving side circuit 53. The light emission side circuit 52 is a driving unit in the present embodiment.

  The sensor head unit 51 is a light emitting device or a light receiving device exposed on the surface of the ID sensor 5, and as shown in FIG. 2, an infrared LED (Light Emitting Diode) 51a, a polarizing filter 51b, a polarization separating prism 51c, a light emitting device. A side phototransistor 51d, an S-wave side photodiode 51e, and a P-wave side photodiode 51f.

The infrared LED 51a is an LED that emits infrared light, and irradiates infrared light onto the transfer surface of the belt member 21 of the intermediate transfer belt 2 via the polarizing filter 51b. The light quantity of the infrared LED 51a is stabilized by APC (Auto Power Control) control.
The polarizing filter 51b transmits only a predetermined polarization of infrared light incident from the infrared LED 51a, that is, only a P wave. The infrared P wave transmitted through the polarizing filter 51 b is applied to the transfer surface of the belt member 21 of the intermediate transfer belt 2.

The polarization separation prism 51c reflects the S wave of incident light and transmits the P wave, and transmits the S wave of infrared light reflected on the transfer surface of the belt member 21 to the S wave side photodiode 51e. The P wave is reflected and transmitted toward the P wave side photodiode 51f.
The light-emitting side phototransistor 51d is a light receiving device that detects infrared light emitted from the infrared LED 51a in order to perform APC control of the infrared LED 51a, and a detection current indicating the amount of infrared light incident from the infrared LED 51a. Output.

The S-wave side photodiode 51e is a light receiving device that detects incident light, and outputs an S-wave detection current indicating the amount of S-wave light of infrared light incident from the polarization separation prism 51c.
The P-wave side photodiode 51f is a light receiving device that detects incident light, and outputs a P-wave detection current indicating the P-wave light amount of infrared light incident from the polarization separation prism 51c.

The light emission side circuit 52 includes a monitor light detection circuit 52a, an impedance conversion circuit 52b, a differential amplifier circuit 52c, and an LED drive circuit 52d.
When the monitor light detection circuit 52a detects the detection current input from the light-emitting side phototransistor 51d, the monitor light detection circuit 52a converts the detection current into a detection voltage and outputs the detection voltage to the impedance conversion circuit 52b.
The impedance conversion circuit 52b prevents the detection voltage input from the monitor light detection circuit 52a from being lowered by impedance conversion, and outputs the detection voltage to the differential amplifier circuit 52c.

The differential amplifier circuit 52c amplifies the difference between the reference voltage (control voltage) input from the main control unit 10 and the detection voltage input from the impedance conversion circuit 52b with a predetermined gain, and the amplified differential voltage is LED It outputs to the drive circuit 52d.
The LED drive circuit 52d outputs drive power based on the differential voltage input from the differential amplifier circuit 52c to the infrared LED 51a.

The light receiving side circuit 53 includes an S wave side I / V conversion circuit 53a, an S wave side gain adjustment amplification circuit 53b, a P wave side I / V conversion circuit 53c, and a P wave side gain adjustment amplification circuit 53d.
The S-wave side I / V conversion circuit 53a converts the S-wave detection current input from the S-wave side photodiode 51e into an S-wave detection voltage, and outputs the S-wave detection voltage to the S-wave side gain adjustment amplification circuit 53b. To do.
The S-wave side gain adjustment amplification circuit 53b amplifies the S-wave detection voltage input from the S-wave side I / V conversion circuit 53a with a gain appropriately adjusted by the main control unit 10, and outputs it to the main control unit 10 To do.

The P-wave side I / V conversion circuit 53c converts a P-wave detection current indicating the P-wave amount of infrared light input from the P-wave side photodiode 51f into a P-wave detection voltage, and converts the P-wave detection voltage to P It outputs to the wave side gain adjustment amplification circuit 53d.
The P-wave side gain adjustment amplification circuit 53d amplifies the P-wave detection voltage input from the P-wave side I / V conversion circuit 53c with a gain appropriately adjusted by the main control unit 10 and outputs it to the main control unit 10 To do. The main controller 10 detects the toner density based on the ratio between the S wave detection voltage and the P wave detection voltage.

The fixing roller 6 includes a heating roller 61 provided with a heater therein, and a pressure roller 62 that is pressed against the heating roller 61. The fixing roller 6 performs recording by sandwiching and conveying a recording sheet onto which a toner image is transferred by the two rollers. The paper is heated and pressurized to fix the toner image on the recording paper.
The thermistor 7 detects the ambient temperature of the infrared LED 51 a and outputs the detection result to the main control unit 10.

  The operation display unit 8 includes operation keys and a touch panel, and functions as a man-machine interface that associates the user with the multifunction peripheral A. The operation display unit 8 outputs an operation instruction for each pressed operation key to the main control unit 10 and displays various screens on the touch panel under the control of the main control unit 10.

  The storage unit 9 is a non-volatile memory such as a flash memory, for example, and sets the drive power voltage value (drive voltage value) supplied to set each LED of the infrared LED 51a to a desired predetermined light amount, and the drive voltage value. An unstable time registration table in which the corresponding unstable time is registered is stored. The unstable time is an unstable time of light quantity immediately after the start of light emission of the infrared LED 51a.

  The infrared LED 51a exhibits the light amount characteristic shown in FIG. 3 at the start of light emission. That is, in the LED, as shown in FIG. 3, the light amount becomes unstable immediately after the start of light emission, and then the light amount gradually decreases and settles to a certain level. The cause of this light quantity variation is that the APC control cannot keep up with the temperature change due to self-heating immediately after the start of LED light emission. Therefore, the light quantity of the LED is not stabilized unless several seconds to several tens of seconds (unstable time) have elapsed since the start of light emission. Each LED has individual differences in its unstable time.

  In each of such LEDs, even if the same driving power is supplied due to individual differences in characteristics, the same amount of light is not obtained. Therefore, in order to cause each LED to emit light with the same amount of light, an adjustment operation of driving power supplied to each LED is performed in the manufacturing stage. In the adjustment operation, driving power is actually supplied to each LED, and the driving power at which each LED has a desired predetermined light amount is measured. Further, the voltage value of the driving power is also measured.

  Hereinafter, a specific method for measuring the voltage value will be described. As shown in FIG. 4, the LED drive circuit 52d includes a transistor 52d-1, and the supply of drive power is switched by the transistor 52d-1. In the adjustment operation, the driving power output from the emitter terminal of the transistor 52d-1 is measured, and the voltage value of the driving power is also measured. The voltage value of each LED measured in this way is the above-described drive voltage value (see FIG. 5A) and is stored in the storage unit 9.

  Next, the unstable time corresponding to the drive voltage value is measured. The self-heating of each LED of the infrared LED 51a is caused by the drive current of the drive power. That is, the amount of self-heating heat of each LED is determined by the drive current value. The unstable time corresponding to the drive voltage value proportional to the drive current value is measured. In the measurement, driving power that actually becomes a desired predetermined light amount is supplied to the LED, and an unstable time corresponding to the driving voltage value of the driving power is measured. The unstable time measured in this way is registered according to the drive voltage in the above-described unstable time registration table (see FIG. 5B).

  The unstable time is proportional to the self-heat generation amount, and becomes longer as the drive current value is larger, that is, as the drive voltage value is larger. For example, the unstable time registered in the unstable time registration table shown in FIG. 5B has a relationship of “a seconds <b seconds <c seconds <d seconds”. Thus, the unstable time at the start of light emission of each LED can be obtained from the drive voltage value of each LED stored in the storage unit 9 and the unstable time registration table.

  The main control unit 10 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an interface circuit for inputting / outputting signals to / from each of the above units, and the like and stored in the ROM. The overall operation of the multi-function peripheral A is controlled based on the control program, the operation instruction received by the operation display unit 8, the drive voltage value stored in the storage unit 9, and the unstable time registration table. The control program stored in the ROM includes a detection control program. Based on this detection control program, the main control unit 10 transmits light from the infrared LED 51a during the unstable period from the start of light emission. Is not used for toner density detection. The details of the processing executed by the main control unit 10 will be described as the operation of the multifunction device A below.

Next, the operation of the MFP A according to the present embodiment having the above configuration will be described.
When the main control unit 10 detects the toner density of the toner image on the belt member 21 of the intermediate transfer belt 2, the main control unit 10 outputs the reference voltage to the differential amplifier circuit 52c so that the drive power is sent to the LED drive circuit 52d. The infrared LED 51a starts to emit light. At that time, the main control unit 10 determines the unstable time of each LED based on the drive voltage value of each LED of the infrared LED 51a stored in the storage unit 9 and the unstable time registration table. That is, the main control unit 10 determines that the unstable time corresponding to the drive voltage value of the LED is the unstable time of the LED. The main control unit 10 does not use the LED light during the unstable time from the start of light emission to detect the toner density.

  As described above, in the multi-function device A according to the present embodiment, the main control unit 10 makes the unstable drive voltage value of each LED of the infrared LED 51a stored in the storage unit 9 and unstable at the start of light emission of the infrared LED 51a. The unstable time of each LED is determined from the time registration table, and the light of each LED between the start of light emission and the unstable time is not used for toner density detection. Thereby, in the multi-function device A, the unstable operation immediately after the start of LED emission can be eliminated in the ID sensor 5.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, the unstable time of each LED is determined based on the drive voltage value of each LED stored in the storage unit 9 and the unstable time registration table, but the present invention is limited to this. Not.
For example, at the stage of adjustment work, the unstable time of each LED of the infrared LED 51a is measured, and the unstable time corresponding to each LED is stored in the storage unit 9. And the main control part 10 may make it not use for the detection of the light of each LED during the said unstable time from light emission start at the time of the light emission start of infrared LED51a.

  (2) In the multifunction device A according to the above embodiment, the detection device according to the present invention is applied to an ID sensor. However, in addition to the ID sensor, if it is an optical sensor that performs sensing using LED light, The present invention can be applied.

A ... MFP, 1 ... image forming unit, 2 ... intermediate transfer belt, 3 ... primary transfer roller, 4 ... secondary transfer roller, 5 ... ID sensor, 6 ... fixing roller, 7 ... thermistor, 8 ... operation display section , 9 ... Storage section, 10 ... Main control section, 11 ... Photosensitive drum, 12 ... Charging section, 13 ... Laser scanning unit, 14 ... Development unit, 15 ... Cleaner, 21 ... Belt member, 22 ... Drive roller, 23 ... Drive roller, 24 ... tension roller, 51 ... sensor head, 52 ... light emission side circuit, 53 ... light reception side circuit, 51a ... infrared LED, 51b ... polarization filter, 51c ... polarization separation prism, 51d ... light emission side phototransistor, 51e: S-wave side photodiode, 51f: P-wave side photodiode, 52a: Monitor light detection circuit, 52b: Impedance conversion circuit, 52c: Differential amplification 52d ... LED drive circuit, 52d-1 ... transistor, 53a ... S wave side I / V conversion circuit, 53b ... S wave side gain adjustment amplification circuit, 53c ... P wave side I / V conversion circuit, 53d ... P wave Side gain adjustment amplifier circuit

Claims (2)

A detection device that includes an LED (Light Emitting Diode) and a driving unit that supplies driving power to the LED, and performs detection using light of the LED,
A voltage value (driving voltage value) of the driving power supplied to make the LED have a predetermined light amount and an unstable time of the LED according to the driving voltage value (an unstable light amount immediately after the start of light emission of the LED) Is stored as unstable time determination information , and at the start of light emission of the LED, the LED is based on the drive voltage value of the LED and the unstable time registration table. A detection control means for determining the unstable time of the LED and not using the light of the LED during the unstable time from the start of light emission for detection,
The detection apparatus characterized in that the unstable time registered in the unstable time registration table becomes longer as the drive voltage value is larger.   An image forming apparatus for detecting a toner density of a toner image using the detection apparatus according to claim 1 as an ID sensor.

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