JP4669351B2 - Image forming apparatus and transfer material detection method - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine and a laser printer, and a transfer material detection method.

  Hereinafter, as an example of a conventional image forming apparatus, an overall configuration of a color laser printer which is a multicolor image forming apparatus will be described.

  FIG. 18 is a cross-sectional view showing the overall configuration of the image forming apparatus. FIG. 19 is an explanatory diagram showing an engine control unit for image formation, a controller unit of the main unit, and interface signals between them. This will be described with reference to the timing charts of FIGS.

  In FIG. 19, reference numeral 201 denotes an engine control unit, and 202 denotes a controller unit. A serial command transmission signal line 203 transmits a command from the controller unit 202 to the engine control unit 201 by serial communication. A serial status transmission signal line 204 transmits status data by serial communication from the engine control unit 201 to the controller unit 202 in response to a command. A reference vertical synchronization signal line 205 transmits a reference vertical synchronization signal (hereinafter referred to as a TOP signal) from the engine control unit 201 to the controller unit 202. A Y horizontal synchronization signal line 206 transmits a yellow horizontal synchronization signal from the engine control unit 201 to the controller unit 202. Reference numeral 207 denotes an M horizontal synchronizing signal line for transmitting a magenta horizontal synchronizing signal from the engine control unit 201 to the controller unit 202. Reference numeral 208 denotes a C horizontal synchronizing signal line for transmitting a cyan horizontal synchronizing signal from the engine control unit 201 to the controller unit 202. Reference numeral 209 denotes a K horizontal synchronizing signal line for transmitting a black horizontal synchronizing signal from the engine control unit 201 to the controller unit 202. A Y image data signal line 210 transmits a yellow image data signal from the controller unit 202 to the engine control unit 201. Reference numeral 211 denotes an M image data signal line for transmitting a magenta image data signal from the controller unit 202 to the engine control unit 201. A C image data signal line 212 transmits a cyan image data signal from the controller unit 202 to the engine control unit 201. Reference numeral 213 denotes a K image data signal line for transmitting a black image data signal from the controller unit 202 to the engine control unit 201.

  FIG. 20 is a timing chart showing signal timings of the TOP signal, the vertical synchronization signal, and the image data when the full color mode is selected.

  When receiving a print operation start command from a host computer (not shown), the controller unit 202 issues a print operation start command to the engine control unit 201 via the serial communication signal line 203. When the engine control unit 201 receives the print operation start command, the engine control unit 201 starts the print operation and transmits a status indicating that the print operation is started via the serial communication signal line 204.

  Referring also to FIG. 18, when the printing operation is started, the engine control unit 201 activates the photosensitive drums 5Y, 5M, 5C, and 5K, the intermediate transfer member (belt) 12, and the scanner units 10Y, 10M, 10C, and 10K. Then, preparation for image formation with each color is performed. When preparation is complete, the engine control unit 201 outputs a TOP signal 301 for vertical synchronization of the first color to the controller unit 202 via the TOP signal line 205. Here, it is assumed that images are formed in the order of Yellow, Magenta, Cyan, and Black. The controller unit 202 outputs yellow image data 303 via the image signal line 210 in synchronization with the TOP signal 301 and Y horizontal synchronization signal 302 output from the engine control unit 201.

  The engine control unit 201 primarily transfers the visible image formed on the photosensitive drum 5Y to the intermediate transfer body 12 based on the image data 303 from the controller unit 202. The yellow toner image transferred to the intermediate transfer body 12 passes through the lowest point of the Magenta photosensitive drum 5M. In accordance with this timing, the engine control unit 201 outputs the Magenta image data 305 with a predetermined time interval T1 (304) so that the Magenta toner image comes to the lowest point of the Magenta photoreceptor 5M. Then, the intermediate transfer body 12 is accurately transferred to the yellow toner image at the primary transfer portion at the lowest point of the photosensitive drum 5M and is primarily transferred. The engine control unit 201 performs the same operation as that of Magenta for Cyan and Black toner images. That is, the engine control unit 201 forms Cyan and Black images with a predetermined time interval T2 (306) and T3 (308) from the TOP signal so that the four color images are accurately overlapped, and performs intermediate transfer. An image is formed on the body 12.

  As described above, the color laser printer forms an electrostatic latent image with image light formed based on the image signal transmitted from the controller in the image forming unit. The color laser printer develops the electrostatic latent image and superimposes and transfers the visible image to form a color visible image. The color visible image is transferred to a transfer material (medium) 2 and fixed.

  The image forming unit includes photoconductors 5Y, 5M, 5C, and 5K for each station arranged in parallel for development colors, injection charging units 7Y, 7M, 7C, and 7K as primary charging units, and developing units 8Y, 8M, 8C, and 8K. . Further, the image forming unit includes toner cartridges 11Y, 11M, 11C, and 11K, an intermediate transfer body 12, a paper feeding unit, a transfer unit, and a fixing unit 13.

  The photosensitive drums (photoconductors) 5Y, 5M, 5C, and 5K are configured by applying an organic optical transmission layer to the outer periphery of an aluminum cylinder, and are rotated by the driving force of a driving motor (not shown) being transmitted. The drive motor rotates the photosensitive drums 5Y, 5M, 5C, and 5K in the counterclockwise direction according to the image forming operation. The exposure light beams to the photosensitive drums 5Y, 5M, 5C, and 5K are sent from the scanner units 10Y, 10M, 10C, and 10K, and are selectively exposed on the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. An image is formed.

  As primary charging means, four injection chargers 7Y, 7M, 7C, and 7K for charging yellow (Y), magenta (M), cyan (C), and black (K) photoconductors are provided for each station. Prepare. Each injection charger 7Y, 7M, 7C, 7K is provided with a sleeve 7YS, 7MS, 7CS, 7KS.

  The image forming unit, as developing means, develops yellow (Y), magenta (M), cyan (C), and black (K) for each station in order to visualize the electrostatic latent image. Developing devices 8Y, 8M, 8C, and 8K are provided. Each developing device is provided with sleeves 8YS, 8MS, 8CS, and 8CK. Each developing device is detachably attached.

  The intermediate transfer body 12 is in contact with the photosensitive drums 5Y, 5M, 5C, and 5K, rotates clockwise when forming a color image, and is driven to rotate as the photosensitive drums 5Y, 5M, 5C, and 5K rotate. Receives transfer of visible image. Further, the intermediate transfer body 12 simultaneously superimposes and transfers the color visible image on the intermediate transfer body 12 onto the transfer material 2 by nipping and conveying the transfer material 2 by contact with a transfer roller 9a described later at the time of image formation.

  The transfer roller 9a is in contact with the intermediate transfer body 12 while the color visible image is superimposed and transferred onto the intermediate transfer body 12, but is separated to a position 9b at the end of the printing process.

  The fixing unit 13 fixes the transferred color visible image while conveying the transfer material 2. The fixing unit 14 heats the transfer material 2 and pressurization for pressing the transfer material 2 against the fixing roller 14. And a roller 15. The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and heaters 16 and 17 are incorporated therein. That is, the transfer material 2 holding the color visible image is conveyed by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the surface by applying heat and pressure.

  The cleaning unit 21 cleans the toner remaining on the photosensitive drums 5Y, 5M, 5C, and 5K and the intermediate transfer body 12. Waste toner after the visible image formed by the toner formed on the photosensitive drums 5Y, 5M, 5C, and 5K is transferred to the intermediate transfer member 12 is stored in a cleaner container of the cleaning unit 21. Alternatively, the waste toner after transferring the four color visible images formed on the intermediate transfer body 12 to the transfer material 2 is stored in a cleaner container of the cleaning means 21.

  After the visible image is fixed, the transfer material 2 is switched to be discharged to the FU tray 24 by the flapper solenoid 23 or to the FD tray 25 having a longer conveying path, and then discharged to one of the trays. This completes the image forming operation.

  When the printer having the above-described configuration is normally conveyed, the conveyance of the transfer material 2 is temporarily stopped after a lapse of a predetermined time from the timing when the leading edge of the transfer material 2 is detected by the pre-registration sensor 19 (FIG. 21A). To do. At this time, the transfer material 2 forms a loop with the registration roller 28 (FIG. 21B). At this time, the printer determines the type of the transfer material 2 based on the amount of light from the LED (light emitting unit) 104 to the media sensor (transfer material determination sensor) 100. Thereafter, the printer starts driving the registration roller 28 in accordance with the image on the intermediate transfer body 12, restarts the conveyance of the transfer material 2, and performs optimum fixing control according to the type of the medium.

  FIG. 22 is a flowchart of a transfer material size detection sequence in the pre-registration sensor 19.

  In FIG. 22, the engine control unit 201 determines whether or not the transfer material 2 has turned on the sensor 19 (S501), and starts the timer count when the transfer material 2 has turned on the pre-registration sensor 19. (S502). The engine control unit 201 determines whether or not the timer count is the registration arrival timing (S503), and if it is the registration arrival timing, stops the sheet conveyance and the timer count (S504). Next, the engine control unit 201 determines the type of media by the media sensor 100 (S505). The process of S505 will be described later with reference to FIGS.

  Next, the engine control unit 201 confirms the timing at which the transfer of the transfer material 2 is resumed (S506), and starts the timer count if the timing is good (S507). The engine control unit 201 stops the counting operation at the timing (S508) when the transfer material 2 is conveyed and the trailing edge of the transfer material 2 is detected by the pre-registration sensor 19 (S508). The engine control unit 201 calculates the size of the transferred transfer material 2 from the loop amount, the distance between the pre-registration sensor 19 and the registration roller 28, and the timer count value (S509). If the difference between the calculated transfer material size and the specified size is within a predetermined range, the engine control unit 201 ends the transfer material size detection sequence. If it is not within the predetermined range, the engine control unit 201 proceeds to step S511, separates the transfer roller, and discharges the transfer material 2 to the designated discharge port. At that time, the engine control unit 201 notifies the controller of the mismatch of the transfer material size, so that the misprint is determined, and the transfer material 2 is discharged as it is to the designated discharge tray.

  FIG. 23 shows an image forming apparatus having a means for detecting the actual size of the transferred transfer material and a plurality of paper discharge ports, when the size of the designated transfer material is different from the actual paper size. It is a flowchart explaining the control which discharges | emits a transfer material.

  The engine control unit 201 calculates the size of the transfer material 2 actually conveyed by the pre-registration sensor 19 (S601, processing in FIG. 22). If the calculated transfer material size matches the specified size, it is determined that the paper discharge port can be discharged at the time of specifying the paper discharge port, so that it can be discharged to the specified paper discharge port. .

  When the calculated transfer material size is different from the designated size, the engine control unit 201 performs the following control (S602). The engine control unit 201 first determines whether the designated discharge port is FD tray discharge or FU tray discharge (S603). When the FU tray discharge is selected, the flapper solenoid 23 is switched to the FU side (S607), and the transfer material 2 is discharged to the FU tray (S608).

  When the designated paper discharge port is the FD tray 25, the engine control unit 201 compares the detected transfer material size with the maximum distance between the rollers on the conveyance path to the FD tray 25. When the transfer material size is larger, it can be discharged to the FD tray 25. If the maximum distance between the rollers is larger than the transfer material size, the transfer material 2 remains in the machine without being conveyed, so it can be determined that it cannot be discharged to the FD tray 25. If it is determined that the FD tray can be discharged (S604), the engine control unit 201 discharges the transfer material 2 to the FD tray 25 (S605, S606). If the engine control unit 201 determines that the size of the transfer material 2 is small and cannot be conveyed to the FD tray 25, the flapper solenoid 23 is switched to the FU side to forcibly transfer the transfer material 2 to the FU tray 24. It discharges (S607, S608).

  As described above, when the size of the designated transfer material 2 is different from the actually detected size, or when the size of the paper is so small that the FD tray cannot be discharged, the printer automatically It is discharged to the tray 24. As a result, the misprinted paper can be discharged out of the apparatus without the transfer material 2 remaining in the printer engine, thereby improving usability.

  With reference to FIGS. 24 to 28, the medium identifying method (S505, S405 described later) of the transfer material 2 will be described.

  FIG. 24 shows the configuration of the transfer material discrimination sensor 100. As shown in FIG. 24, the transfer material discrimination sensor 100 includes an LED (light-emitting diode) 101 that is a first irradiation unit, a phototransistor 103 that is a first reading unit, and a phototransistor that is a second reading unit. 102. Further, the transfer material determination sensor 100 faces the LED 104 as the second irradiation means.

  Light using the LED 101 as a light source is applied to the surface of the transfer material 2 on the transfer material conveyance guide 105 through the slit 111. In this example, the transfer material conveyance guide 105 is provided with a window for irradiating light from the back surface side of the transfer material. The reflected light from the transfer material 2 is collected through the slits 112 and 113 and received by the phototransistors 102 and 103. Thereby, the glossiness of the transfer material 2 is detected.

  Light having the LED 104 as a light source is irradiated to the back surface of the transfer material 2 through a light collecting guide 114 for collecting the light. The transmitted light from the transfer material 2 is received by the phototransistors 102 and 103 through the slits 112 and 113. As a result, the amount of light transmitted from the transfer material 2 is detected. The LED 101 is arranged so that LED light is irradiated obliquely at a predetermined angle with respect to the surface of the transfer material 2 as shown in FIG. Further, the LED 104 is arranged so that the LED light is irradiated on the back surface of the transfer material 2 from a position directly below the phototransistor 102 as shown in FIG.

  Next, the internal configuration of the control unit of the sensor 100 will be described with reference to a block diagram with reference to FIG. In the figure, reference numerals 101 and 104 denote light emitting elements (LEDs), and 102 and 103 denote light receiving elements (phototransistors). A light emitting element driving unit 125 drives the light emitting elements 101 and 104, and a main control unit 200 controls the light emitting element driving unit. A signal processing unit 126 performs A / D (analog to digital) conversion on output values from the light receiving elements 102 and 103 with a resolution of 16 bits and calculates the output values. For example, in the calculation of the output value, a value indicating the glossiness of the recording paper (regular reflection output / diffuse reflection output) and a value indicating the light transmittance of the recording paper (regular transmission output / diffuse transmission output) are obtained. Reference numeral 127 denotes a comparison operation unit that performs a comparison operation with a set value stored in advance in the memory 128 based on a result obtained by the signal processing unit. The memory 128 represents a nonvolatile memory such as an EEPROM (Electronically Erasable and Programmable Read Only Memory), and stores setting values for recording sheet discrimination. Also, the memory 128 stores two or more different light emission quantity values for each of the light emitting elements 101 and 104. For example, two or more different emission light quantity values obtained by detecting the regular reflection light quantity and irregular reflection light quantity from the reference paper using the reference paper at the time of shipment from the factory, and obtaining the result by calculation using the result are obtained. Stored in the memory 128. Similarly, at the time of shipment from the factory, the same reference paper as described above is used to detect the normal transmitted light amount and diffuse transmitted light amount from the reference paper, and the result and two or more types obtained by calculation using the result are different. The emitted light quantity value is stored in the memory 128.

FIG. 26 is a control flowchart of the media sensor. First, the control unit 200 causes the LED 101 to emit light with the light amount A1 (S701). At that time, the LED 104 is turned off. The control unit 200 receives the regular reflection light amount and the irregular reflection light amount by the phototransistors 102 and 103 (S702), performs signal processing on the obtained output value (S703), and outputs a value Pa1 (regular reflection light amount) indicating the glossiness of the recording paper. / Diffuse reflected light amount). Then, the control unit 200 performs a comparison operation with the glossiness determination threshold value Ta1 stored in advance in the memory (S704). The control unit 200 determines OHT (overhead transparencies) if Ta1 ≦ Pa1 (S705). When Ta1> Pa1, the controller 200 causes the LED 101 to emit light with the light amount A2 (> A1) (S706). Similarly to the above, the control unit 200 receives the regular reflection light amount and the irregular reflection light amount by the phototransistors 102 and 103 (S707), and the result Pa2 (regular reflection light amount / diffuse reflection light amount) obtained by signal processing the output value (S708). ) Is compared with the glossiness discrimination threshold Ta2 (S709). The control unit 200 determines plain paper (S710) if Ta2 ≧ Pa2, and performs plain paper discrimination processing (paper thickness detection processing) (S711). Otherwise, the control unit 200 determines that the paper is glossy paper or glossy film (S712), and performs glossy paper discrimination processing (gloss paper detection processing). (S713)
FIG. 27 is a flowchart showing a control flow for discriminating the paper type discriminated as plain paper according to the paper thickness. The control unit 200 causes the LED 104 to emit light with the light amount B1 with the LED 101 turned off (S721), and the phototransistors 102 and 103 respectively receive the regular transmitted light amount and the diffuse transmitted light amount (S722). The control unit 200 performs signal processing on the obtained output value (S723), and obtains a value Pb1 (regular transmission output / diffuse transmission output) indicating the light transmittance of the recording paper. Then, the control unit 200 performs a comparison operation with the light transmission determination threshold value Tb1 stored in advance in the memory (S724). The control unit 200 determines that the paper is thin (˜64 g / m2) when Tb1 ≧ Pb1 (S725), and performs the same sequence (F1: S726 to S729) as above again when Tb1 <Pb1. Therefore, the description of F1 is omitted. Here, the light quantity has a relationship of light quantity B1 <light quantity B2. If the value indicating the light transmittance of the recording paper obtained in F1 is Pb2, when Tb2 ≧ Pb2, it is determined as plain paper 1 (65 to 90 g / m 2) (S730). In the case of Tb2 <Pb2, the control unit 200 emits the light amount B3 (> light amount B2) (S731), and again performs the same sequence (F2: S731 to S734) as described above. Therefore, the description of F2 is also omitted. If the value indicating the light transmittance of the recording paper obtained in F2 is Pb3 (regular transmission output / diffuse transmission output), it is determined that plain paper 2 (91 to 120 g / m2) is satisfied when Tb3 ≧ Pb3 (S735). If Tb3 <Pb3, it is determined that the paper is thick (121 g / m2˜) (S736).

  Next, with reference to FIG. 28, a sequence for discriminating gloss paper and gloss film will be described. When it is determined that the paper is glossy paper or glossy in S710 of FIG. 26, the control unit 200 causes the LED 104 to emit light with the light amount B2 in order to classify them (S751). Then, the phototransistors 102 and 103 respectively receive the normal transmitted light amount and the diffuse transmitted light amount (S752), and signal processing is performed on the obtained output values (S753). The control unit 200 obtains a value Pc1 (regular transmission output / diffuse transmission output) indicating the light transmittance of the recording paper, and compares it with a threshold value Tc for discriminating gloss paper and gloss film (S754). If Tc1 ≦ Pc1, the paper is determined to be glossy paper (S755), and if Tc1> Pc1, the paper is determined to be glossy film (S756). The transfer material is determined by the method described above.

  Further, a configuration in which the conventional configuration is developed and the front and rear ends of the transfer material are detected by the media sensor 100 without arranging the pre-registration sensor 19 is considered. This is because the sensor is difficult to arrange and the cost is reduced. This configuration will be described below.

  FIG. 29 is a block diagram illustrating an internal configuration of the sensor control unit. Description of the same parts as those in FIG. 25 is omitted. Reference numeral 129 in the figure is a conversion circuit that converts the signal of the light receiving unit 102, and sends information of the light receiving unit 102 to the control unit 200. As shown in FIG. 30, when the amount of received light (voltage) of the light receiving unit 102 exceeds a predetermined value, the conversion circuit 129 is turned on. Further, when the amount of received light (voltage) of the light receiving unit 102 becomes less than a predetermined value, the conversion circuit 129 is turned off.

  When the printer having the above-described configuration is normally conveyed, the conveyance of the transfer material 2 is temporarily stopped after a lapse of a specified time from the timing when the leading edge of the transfer material 2 is detected by the media sensor 100 (FIG. 31A). . At this time, the transfer material 2 forms a loop with the registration roller 28 (FIG. 31B). At this time, the printer determines the type of the transfer material 2 by the media sensor 100 and the LED light emitting unit 104. Thereafter, the driving of the registration roller 28 is started in accordance with the image on the intermediate transfer body 12, the conveyance of the transfer material 2 is resumed, and optimal fixing control according to the type of media is performed.

  The processing of the printer to which FIGS. 29 to 31 are applied will be described below with reference to the flowchart of FIG.

  In FIG. 32, the control unit 200 emits the LED 101 (S400), determines whether the tip of the transfer material 2 has passed the media sensor 100 (S401), and when the tip of the transfer material 2 has passed the media sensor 100, Timer count is started (S402). The control unit 200 determines whether the timer count is the registration arrival timing (S403), and if it is the registration arrival timing, stops the paper conveyance and the timer count (S404). Next, the control unit 200 determines the type of media using the media sensor 100 (S405). The process of S405 is as described above with reference to FIGS.

  Next, the control unit 200 confirms the timing for resuming the conveyance of the transfer material 2 (S406), and starts the timer count if the timing is good (S407). The control unit 200 stops the counting operation at the timing (S408) when the transfer material 2 is conveyed and the rear end of the transfer material 2 is detected by the media sensor 100 (S408). Then, the control unit 200 calculates the size of the transferred transfer material 2 from the loop amount, the distance between the media sensor 100 and the registration roller 28, and the timer count value (S409). If the difference between the calculated size of the transfer material and the designated size is within a predetermined range, the control unit 200 ends the transfer material size detection sequence. If not within the predetermined range, the control unit 200 proceeds to step S411, separates the transfer roller, and discharges the transfer material 2 to the designated paper discharge port. At that time, the control unit 200 informs the controller that the transfer material size does not match, so that misprinting is determined, and the transfer material 2 is discharged as it is to the designated discharge tray. After all the processes are completed, the control unit 200 turns off the LED 101 (S412).

  Several documents disclose the technical contents related to the conventional technique as described above (see, for example, Patent Documents 1 and 2).

JP 2004-182361 A JP 2005-114866 A

  However, the conventional image forming apparatus has the following problems. FIG. 33 is a timing chart when the registration sensor 19 is used, and shows ON / OFF of the registration sensor 19, the roller 28, the LED 101, and the LED 104 from the top. In the printer to which FIGS. 29 to 32 are applied, FIG. 34 is a timing chart when the leading edge and the trailing edge of the sheet are detected by the media sensor 100 without using the registration sensor 19. FIG. 34 shows ON / OFF of the media sensor 100, the roller 28, the LED 101, and the LED 104 from the top. As can be seen from FIG. 34, when the media sensor 100 performs an operation of detecting the leading and trailing edges of the transfer material, the LED 101 is kept on.

  FIG. 35 shows the relationship between LED light quantity deterioration and time. As can be seen from FIG. 35, the light amount of the LED deteriorates as time elapses. However, in the printer to which FIGS. 29 to 32 are applied, if the light amount of the LED greatly deteriorates, the light amount of the light receiving element is affected, and the media cannot be detected accurately.

  The present invention has been made in view of such problems, and the object of the present invention is to suppress the deterioration of the light emitting element used in the transfer material discriminating means for discriminating the type of the transfer material, and to detect the transfer material. An object of the present invention is to provide an image forming apparatus and a transfer material detection method which are accurately performed.

  In order to achieve such an object, the image forming apparatus of the present invention is based on transfer material conveying means for conveying a transfer material for recording an image, and reflected light reflected on the surface of the transfer material by causing a light emitting element to emit light. In the image forming apparatus, the transfer material discriminating means for discriminating the type of the transfer material, the transfer material discriminating means for detecting the transfer material end in the transport direction based on the reflected light. The light emission operation of the light emitting element is controlled so that the light emission amount from the light emitting element when detecting the end in the transport direction is smaller than the light emission amount from the light emitting element when determining the type of transfer material. To do.

  In order to achieve the above object, a transfer material detection method of the present invention is a transfer material detection method for detecting an end in a conveyance direction of a transfer material to be image-formed. The transfer material detection method emits light from a light emitting element on the surface of the transfer material. A determination step for discriminating the type of recording material based on the reflected reflected light, a detection step for detecting the conveyance direction end of the transfer material based on the reflected light, and a light emission amount from the light emitting element in the detection step for light emission in the determination step And a control step of controlling the light emitting operation of the light emitting element so as to be smaller than the amount of light emitted from the element.

  With the above configuration, the image forming apparatus can accurately detect the media even when the image forming apparatus main body is near the end of its life by suppressing the deterioration of the LEDs used in the media sensor that determines the type of the media. Can do.

  According to the present invention, it is possible to accurately detect the transfer material while suppressing the deterioration of the light emitting element used in the transfer material determining means for determining the type of the transfer material.

  Embodiments to which the present invention can be applied will be described below in detail with reference to the drawings. In the drawings referred to in this specification, portions having the same function are denoted by the same reference numerals. The image forming apparatus and the apparatus unit of this embodiment will be described in detail with reference to the drawings.

[Embodiment 1]
In the first embodiment, the deterioration of the LED is suppressed by reducing the absolute light emission amount of the LED.

(Device configuration)
Since the configuration of the apparatus is substantially the same as that of the above-described prior art, an outline thereof will be described. Hereinafter, as an example of the image forming apparatus of the present embodiment, the overall configuration of a color laser printer that is a multicolor image forming apparatus will be described.

  FIG. 1 is a cross-sectional view showing the overall configuration of the image forming apparatus. FIG. 2 is an explanatory diagram showing an engine control unit for image formation, a controller unit of the main unit, and interface signals between them. This will be described with reference to FIGS. 1 and 2 and the timing chart of FIG.

  In FIG. 2, reference numeral 201 denotes an engine control unit, and 202 denotes a controller unit. A serial command transmission signal line 203 transmits a command from the controller unit 202 to the engine control unit 201 by serial communication. A serial status transmission signal line 204 transmits status data by serial communication from the engine control unit 201 to the controller unit 202 in response to a command. A reference vertical synchronization signal line 205 transmits a reference vertical synchronization signal (hereinafter referred to as a TOP signal) from the engine control unit 201 to the controller unit 202. A Y horizontal synchronization signal line 206 transmits a yellow horizontal synchronization signal from the engine control unit 201 to the controller unit 202. Reference numeral 207 denotes an M horizontal synchronizing signal line for transmitting a magenta horizontal synchronizing signal from the engine control unit 201 to the controller unit 202. Reference numeral 208 denotes a C horizontal synchronizing signal line for transmitting a cyan horizontal synchronizing signal from the engine control unit 201 to the controller unit 202. Reference numeral 209 denotes a K horizontal synchronizing signal line for transmitting a black horizontal synchronizing signal from the engine control unit 201 to the controller unit 202. A Y image data signal line 210 transmits a yellow image data signal from the controller unit 202 to the engine control unit 201. Reference numeral 211 denotes an M image data signal line for transmitting a magenta image data signal from the controller unit 202 to the engine control unit 201. A C image data signal line 212 transmits a cyan image data signal from the controller unit 202 to the engine control unit 201. Reference numeral 213 denotes a K image data signal line for transmitting a black image data signal from the controller unit 202 to the engine control unit 201.

  FIG. 3 is a timing chart showing signal timings of the TOP signal, the vertical synchronization signal, and the image data when the full color mode is selected.

  When receiving a print operation start command from a host computer (not shown), the controller unit 202 issues a print operation start command to the engine control unit 201 via the serial communication signal line 203. When the engine control unit 201 receives the print operation start command, the engine control unit 201 starts the print operation and transmits a status indicating that the print operation is started via the serial communication signal line 204.

  Referring also to FIG. 1, when the printing operation is started, the engine control unit 201 activates the photosensitive drums 5Y, 5M, 5C, and 5K, the intermediate transfer member (belt) 12, and the scanner units 10Y, 10M, 10C, and 10K. Then, preparation for image formation with each color is performed. When preparation is complete, the engine control unit 201 outputs a TOP signal 301 for vertical synchronization of the first color to the controller unit 202 via the TOP signal line 205. Here, it is assumed that images are formed in the order of Yellow, Magenta, Cyan, and Black. The controller unit 202 outputs yellow image data 303 via the image signal line 210 in synchronization with the TOP signal 301 and Y horizontal synchronization signal 302 output from the engine control unit 201.

  The engine control unit 201 primarily transfers the visible image formed on the photosensitive drum 5Y to the intermediate transfer body 12 based on the image data 303 from the controller unit 202. The yellow toner image transferred to the intermediate transfer body 12 passes through the lowest point of the Magenta photosensitive drum 5M. In accordance with this timing, the engine control unit 201 outputs the Magenta image data 305 with a predetermined time interval T1 (304) so that the Magenta toner image comes to the lowest point of the Magenta photoreceptor 5M. Then, the intermediate transfer body 12 is accurately transferred to the yellow toner image at the primary transfer portion at the lowest point of the photosensitive drum 5M and is primarily transferred. The engine control unit 201 performs the same operation as that of Magenta for Cyan and Black toner images. That is, the engine control unit 201 forms Cyan and Black images with a predetermined time interval T2 (306) and T3 (308) from the TOP signal so that the four color images are accurately overlapped, and performs intermediate transfer. An image is formed on the body 12.

  As described above, the color laser printer forms an electrostatic latent image with image light formed based on the image signal transmitted from the controller in the image forming unit. The color laser printer develops the electrostatic latent image and superimposes and transfers the visible image to form a color visible image. The color visible image is transferred to the transfer material 2 and fixed.

  The image forming unit includes photoconductors 5Y, 5M, 5C, and 5K for each station arranged in parallel for development colors, injection charging units 7Y, 7M, 7C, and 7K as primary charging units, and developing units 8Y, 8M, 8C, and 8K. . Further, the image forming unit includes toner cartridges 11Y, 11M, 11C, and 11K, an intermediate transfer body 12, a paper feeding unit, a transfer unit, and a fixing unit 13.

  The photosensitive drums (photoconductors) 5Y, 5M, 5C, and 5K are configured by applying an organic optical transmission layer to the outer periphery of an aluminum cylinder, and are rotated by the driving force of a driving motor (not shown) being transmitted. The drive motor rotates the photosensitive drums 5Y, 5M, 5C, and 5K in the counterclockwise direction according to the image forming operation. The exposure light beams to the photosensitive drums 5Y, 5M, 5C, and 5K are sent from the scanner units 10Y, 10M, 10C, and 10K, and are selectively exposed on the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. An image is formed.

  As primary charging means, four injection chargers 7Y, 7M, 7C, and 7K for charging yellow (Y), magenta (M), cyan (C), and black (K) photoconductors are provided for each station. Prepare. Each injection charger 7Y, 7M, 7C, 7K is provided with a sleeve 7YS, 7MS, 7CS, 7KS.

  The image forming unit, as developing means, develops yellow (Y), magenta (M), cyan (C), and black (K) for each station in order to visualize the electrostatic latent image. Developing devices 8Y, 8M, 8C, and 8K are provided. Each developing device is provided with sleeves 8YS, 8MS, 8CS, and 8CK. Each developing device is detachably attached.

  The intermediate transfer body 12 is in contact with the photosensitive drums 5Y, 5M, 5C, and 5K, rotates clockwise when forming a color image, and is driven to rotate as the photosensitive drums 5Y, 5M, 5C, and 5K rotate. Receives transfer of visible image. Further, the intermediate transfer body 12 simultaneously superimposes and transfers the color visible image on the intermediate transfer body 12 onto the transfer material 2 by nipping and conveying the transfer material 2 by contact with a transfer roller 9a described later at the time of image formation.

  The transfer roller 9a is in contact with the intermediate transfer body 12 while the color visible image is superimposed and transferred onto the intermediate transfer body 12, but is separated to a position 9b at the end of the printing process.

  The fixing unit 13 fixes the transferred color visible image while conveying the transfer material 2. The fixing unit 14 heats the transfer material 2 and pressurization for pressing the transfer material 2 against the fixing roller 14. And a roller 15. The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and heaters 16 and 17 are incorporated therein. That is, the transfer material 2 holding the color visible image is conveyed by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the surface by applying heat and pressure.

  The cleaning unit 21 cleans the toner remaining on the photosensitive drums 5Y, 5M, 5C, and 5K and the intermediate transfer body 12. Waste toner after the visible image formed by the toner formed on the photosensitive drums 5Y, 5M, 5C, and 5K is transferred to the intermediate transfer member 12 is stored in a cleaner container of the cleaning unit 21. Alternatively, the waste toner after transferring the four color visible images formed on the intermediate transfer body 12 to the transfer material 2 is stored in a cleaner container of the cleaning means 21.

  After the visible image is fixed, the transfer material 2 is switched to be discharged to the FU tray 24 by the flapper solenoid 23 or to the FD tray 25 having a longer conveying path, and then discharged to one of the trays. This completes the image forming operation.

  FIG. 4 shows the configuration of the transfer material discrimination sensor 100. As shown in FIG. 4, the transfer material discrimination sensor 100 includes an LED (light-emitting diode) 101 that is a first irradiation unit, a phototransistor 103 that is a first reading unit, and a phototransistor that is a second reading unit. 102. Further, the transfer material determination sensor 100 faces the LED 104 as the second irradiation means.

  Light using the LED 101 as a light source is applied to the surface of the transfer material 2 on the transfer material conveyance guide 105 through the slit 111. In this example, the transfer material conveyance guide 105 is provided with a window for irradiating light from the back surface side of the transfer material. The reflected light from the transfer material 2 is collected through the slits 112 and 113 and received by the phototransistors 102 and 103. Thereby, the glossiness of the transfer material 2 is detected.

  Light having the LED 104 as a light source is irradiated to the back surface of the transfer material 2 through a light collecting guide 114 for collecting the light. The transmitted light from the transfer material 2 is received by the phototransistors 102 and 103 through the slits 112 and 113. As a result, the amount of light transmitted from the transfer material 2 is detected. The LED 101 is arranged so that LED light is irradiated obliquely at a predetermined angle with respect to the surface of the transfer material 2 as shown in FIG. Further, the LED 104 is arranged so that the LED light is irradiated to the back surface of the transfer material 2 from a position directly below the phototransistor 102 as shown in FIG.

  Next, the internal configuration of the control unit of the sensor 100 will be described with reference to a block diagram with reference to FIG. In the figure, reference numerals 101 and 104 denote light emitting elements (LEDs), and 102 and 103 denote light receiving elements (phototransistors). A light emitting element driving unit 125 drives the light emitting elements 101 and 104, and a main control unit 200 controls the light emitting element driving unit. A signal processing unit 126 performs A / D (analog to digital) conversion on output values from the light receiving elements 102 and 103 with a resolution of 16 bits and calculates the output values. For example, in the calculation of the output value, a value indicating the glossiness of the recording paper (regular reflection output / diffuse reflection output) and a value indicating the light transmittance of the recording paper (regular transmission output / diffuse transmission output) are obtained. Reference numeral 127 denotes a comparison operation unit that performs a comparison operation with a set value stored in advance in the memory 128 based on a result obtained by the signal processing unit. The memory 128 represents a nonvolatile memory such as an EEPROM (Electronically Erasable and Programmable Read Only Memory), and stores setting values for recording sheet discrimination. Also, the memory 128 stores two or more different light emission quantity values for each of the light emitting elements 101 and 104. For example, two or more different emission light quantity values obtained by detecting the regular reflection light quantity and irregular reflection light quantity from the reference paper using the reference paper at the time of shipment from the factory, and obtaining the result by calculation using the result are obtained. Stored in the memory 128. Similarly, at the time of shipment from the factory, the same reference paper as described above is used to detect the normal transmitted light amount and diffuse transmitted light amount from the reference paper, and the result and two or more types obtained by calculation using the result are different. The emitted light quantity value is stored in the memory 128.

  Reference numeral 129 in the figure is a conversion circuit that converts the signal of the light receiving unit 102, and sends information of the light receiving unit 102 to the control unit 200. As shown in FIG. 6, when the amount of received light (voltage) of the light receiving unit 102 exceeds a predetermined value, the conversion circuit 129 is turned on. Further, when the amount of received light (voltage) of the light receiving unit 102 becomes less than a predetermined value, the conversion circuit 129 is turned off.

  When the printer having the above-described configuration is normally conveyed, the conveyance of the transfer material 2 is temporarily stopped after a lapse of a specified time from the timing when the leading edge of the transfer material 2 is detected by the media sensor 100 (FIG. 7A). . At this time, the transfer material 2 forms a loop with the registration roller 28 (FIG. 7B). At this time, the printer determines the type of the transfer material 2 by the media sensor 100 and the LED light emitting unit 104. Thereafter, the driving of the registration roller 28 is started in accordance with the image on the intermediate transfer body 12, the conveyance of the transfer material 2 is resumed, and optimal fixing control according to the type of media is performed.

(Description of operation)
FIG. 8 is a flowchart of the process of the engine control unit that detects the transfer material leading edge detection, the media detection, and the transfer material size. The difference from the conventional printers shown in FIGS. 29 to 32 is that the amount of light emitted from the LED 101 is suppressed when the leading edge and the trailing edge of the LED 101 are detected.

  In FIG. 8, the control unit 200 emits the LED 101 with the light amount A0 (S100), and determines whether the leading edge of the transfer material 2 has passed through the media sensor 100 based on the output of the media sensor 100 (S101). When the leading edge of the transfer material 2 passes the media sensor 100, the control unit 200 starts a timer count (S102). The control unit 200 determines whether or not the timer count is the registration arrival timing (S103), and if it is the registration arrival timing, stops the paper conveyance and the timer count (S104). Next, the control unit 200 causes the LED 101 to emit light with the maximum light amount A3, and the media sensor 100 determines the type of media (S105). The process of S105 will be described later with reference to FIGS.

  After the determination, the control unit 200 turns off the LED 101 (S106). Next, the control unit 200 confirms the timing for resuming the conveyance of the transfer material 2 (S107), emits the LED 101 with the light amount A0 (S108), and starts the timer count (S109). The transfer material 2 is conveyed. The control unit 200 stops the counting operation at the timing (S110) when the media sensor 100 detects the trailing edge of the transfer material 2. Then, the control unit 200 calculates the size of the transferred transfer material 2 from the loop amount, the distance between the media sensor 100 and the registration roller 28, and the timer count value (S111). If the difference between the calculated size of the transfer material and the designated size is within a predetermined range, the control unit 200 ends the transfer material size detection sequence. If not within the predetermined range, the control unit 200 proceeds to step S113, separates the transfer roller, and discharges the transfer material 2 to the designated paper discharge port. At that time, the control unit 200 informs the controller that the transfer material size does not match, so that misprinting is determined, and the transfer material 2 is discharged as it is to the designated discharge tray. Thereafter, the control unit 200 waits until a predetermined transfer material passage timing (S114), and turns off the LED 101 (S115).

  FIG. 9 is a timing chart of this embodiment. From the top, the media sensor 100, the ON / OFF of the roller 28, the light emission amount of the LED 101, and the ON / OFF of the LED 104 are shown. As shown in FIG. 9, when the operation of detecting the leading and trailing ends of the transfer material is performed by the media sensor 100, the LED 101 emits 100% of A3 only when the media is detected, and in other cases , A0 emits 30%.

  FIG. 10 is a diagram illustrating a relationship between the LED light emission amount setting and the LED light emission amount according to the present embodiment.

  The medium identifying method (S105) of the transfer material 2 will be described with reference to FIGS.

  FIG. 11 is a control flowchart of the media sensor. First, the control unit 200 causes the LED 101 to emit light with the light amount A1 (S701). At that time, the LED 104 is turned off. The control unit 200 receives the regular reflection light amount and the irregular reflection light amount by the phototransistors 102 and 103 (S702), performs signal processing on the obtained output value (S703), and outputs a value Pa1 (regular reflection light amount) indicating the glossiness of the recording paper. / Diffuse reflected light amount). Then, the control unit 200 performs a comparison operation with the glossiness determination threshold value Ta1 stored in advance in the memory (S704). The control unit 200 determines OHT (overhead transparencies) if Ta1 ≦ Pa1 (S705). When Ta1> Pa1, the controller 200 causes the LED 101 to emit light with the light amount A2 (> A1) (S706). Similarly to the above, the control unit 200 receives the specular reflection light amount and the irregular reflection light amount by the phototransistors 102 and 103 (S707), and the result Pa2 (regular reflection light amount / diffuse reflection light amount) obtained by performing signal processing on the output value (S708). ) Is compared with the glossiness discrimination threshold Ta2 (S709). The control unit 200 determines plain paper (S710) if Ta2 ≧ Pa2, and performs plain paper discrimination processing (paper thickness detection processing) (S711). Otherwise, the control unit 200 determines that the paper is glossy paper or glossy film (S712), and performs glossy paper discrimination processing (gloss paper detection processing). (S713)

  FIG. 12 is a flowchart showing a control flow for discriminating the paper type discriminated as plain paper according to the paper thickness. The control unit 200 causes the LED 104 to emit light with the light amount B1 with the LED 101 turned off (S721), and the phototransistors 102 and 103 respectively receive the regular transmitted light amount and the diffuse transmitted light amount (S722). The control unit 200 performs signal processing on the obtained output value (S723), and obtains a value Pb1 (regular transmission output / diffuse transmission output) indicating the light transmittance of the recording paper. Then, the control unit 200 performs a comparison operation with the light transmission determination threshold value Tb1 stored in advance in the memory (S724). The control unit 200 determines that the paper is thin (˜64 g / m2) when Tb1 ≧ Pb1 (S725), and performs the same sequence (F1: S726 to S729) as described above again when Tb1 <Pb1. Therefore, the description of F1 is omitted. Here, the light quantity has a relationship of light quantity B1 <light quantity B2. If the value indicating the light transmittance of the recording paper obtained in F1 is Pb2, when Tb2 ≧ Pb2, it is determined as plain paper 1 (65 to 90 g / m 2) (S730). In the case of Tb2 <Pb2, the control unit 200 emits the light amount B3 (> light amount B2) (S731), and again performs the same sequence (F2: S731 to S734) as described above. Therefore, the description of F2 is also omitted. If the value indicating the light transmittance of the recording paper obtained in F2 is Pb3 (regular transmission output / diffuse transmission output), it is determined that plain paper 2 (91 to 120 g / m2) is satisfied when Tb3 ≧ Pb3 (S735). If Tb3 <Pb3, it is determined that the paper is thick (121 g / m2˜) (S736).

  Next, a sequence for discriminating gloss paper and gloss film will be described with reference to FIG. When it is determined that the paper is glossy paper or glossy in S710 of FIG. 11, in order to classify these, the control unit 200 causes the LED 104 to emit light with the light amount B2 (S751). Then, the phototransistors 102 and 103 respectively receive the normal transmitted light amount and the diffuse transmitted light amount (S752), and signal processing is performed on the obtained output values (S753). The control unit 200 obtains a value Pc1 (regular transmission output / diffuse transmission output) indicating the light transmittance of the recording paper, and compares it with a threshold value Tc for discriminating gloss paper and gloss film (S754). If Tc1 ≦ Pc1, the paper is determined to be glossy paper (S755), and if Tc1> Pc1, the paper is determined to be glossy film (S756). The transfer material is determined by the method described above.

  As described above, by reducing the absolute LED light emission amount, it is possible to suppress the deterioration of the LED and perform accurate transfer material type detection.

[Embodiment 2]
In the second embodiment, light emission of the LED is performed in a time-sharing manner, and deterioration of the LED is suppressed by reducing the entire light emission amount.

(Device configuration)
Since the configuration of the apparatus is the same as that of the first embodiment, description thereof is omitted.

(Description of operation)
Hereinafter, only differences from the first embodiment will be described.

  FIG. 14 is a flowchart of the process of the engine control unit that detects the transfer material tip detection, the media detection, and the transfer material size. The difference from the conventional printers shown in FIGS. 29 to 32 is that the LED 101 emits light in a time-sharing manner when the trailing edge of the paper is detected, thereby suppressing the entire light emission amount. The reason why the time division processing is not performed at the leading edge of the sheet is to maintain the accuracy of stopping the transfer material by the registration roller 28, to accurately match the timing of the transfer material and the image, and to make the writing position constant. On the other hand, at the rear end of the transfer material, the length of the rear end of the transfer material is detected and notified to the controller, but the accuracy as high as the detection of the front end of the transfer material is not necessary.

  In FIG. 14, the control unit 200 emits the LED 101 with the light amount A3 (S150), and determines whether the leading edge of the transfer material 2 has passed through the media sensor 100 based on the output of the media sensor 100 (S151). When the leading edge of the transfer material 2 passes the media sensor 100, the control unit 200 starts a timer count (S152). The control unit 200 determines whether or not the timer count is the registration arrival timing (S153), and if it is the registration arrival timing, stops the paper conveyance and the timer count (S154). Next, the control unit 200 determines the type of media by the media sensor 100 (S155). The process of S155 is the same as the process described with reference to FIGS.

  After completion of the determination, the control unit 200 turns off the LED 101 (S156). Next, the timing for resuming the conveyance of the transfer material 2 is confirmed (S157), and the timer count is started (S158). Next, the control unit 200 repeats the operation of emitting the LED 101 with the light amount A3 (S159) and turning off the LED 101 (S160) at predetermined intervals (S161 → S159). The control unit 200 stops the counting operation at the timing (S161) when the transfer material 2 is conveyed and the media sensor 100 detects the trailing edge of the transfer material 2. Then, the control unit 200 calculates the size of the transferred transfer material 2 from the loop amount, the distance between the media sensor 100 and the registration roller 28, and the timer count value (S162). If the difference between the calculated size of the transfer material and the designated size is within a predetermined range, the control unit 200 ends the transfer material size detection sequence. If not within the predetermined range, the control unit 200 proceeds to step S164, separates the transfer roller, and discharges the transfer material 2 to the designated discharge port. At that time, the control unit 200 informs the controller that the transfer material size does not match, so that misprinting is determined, and the transfer material 2 is discharged as it is to the designated discharge tray. Thereafter, the control unit 200 emits the LED 101 (S165), turns off the LED 101 (S166), repeats the operation (S167 → S165), waits for a predetermined transfer material passing timing (S167), and ends the process.

  FIG. 15 is a timing chart of the present embodiment. From the top, the media sensor 100, the ON / OFF of the roller 28, the light emission amount of the LED 101, and the ON / OFF of the LED 104 are shown. As shown in FIG. 15, when the operation of detecting the leading and trailing edges of the transfer material is performed by the media sensor 100, the LED 101 emits 100% of A3 only when the leading edge of the transfer material and the media are detected. In other cases, light is emitted in a time-sharing manner.

  As described above, by repeating ON / OFF of the LED in time division, it is possible to suppress the deterioration of the LED and perform accurate transfer material type detection.

[Embodiment 3]
The third embodiment suppresses the deterioration of the LED by performing the light emission of the LED in a time-sharing manner and suppressing the absolute value of the LED light emission amount.

(Device configuration)
Hereinafter, only differences from the first embodiment will be described.

  Since the configuration of the apparatus is the same as that of the first embodiment, description thereof is omitted.

(Description of operation)
FIG. 16 is a flowchart of processing of the engine control unit that detects the transfer material leading edge detection, the media detection, and the transfer material size. The difference from the conventional printers shown in FIGS. 29 to 32 is that when detecting the trailing edge of the paper, the LED 101 emits light in a time-sharing manner, suppressing the absolute value of the LED light emission amount, and emitting light at the timing of detecting the trailing edge of the transfer material. It is a point to suppress the amount of light.

  In FIG. 16, the control unit 200 emits the LED 101 with the light amount A3 (S200), and determines whether the leading edge of the transfer material 2 has passed through the media sensor 100 based on the output of the media sensor 100 (S201). When the leading edge of the transfer material 2 passes the media sensor 100, the control unit 200 starts a timer count (S202). The control unit 200 determines whether or not the timer count is the registration arrival timing (S203), and if it is the registration arrival timing, stops the paper conveyance and the timer count (S204). Next, the control unit 200 determines the type of media using the media sensor 100 (S205). The process of S205 is the same as the process described with reference to FIGS.

  After the determination, the control unit 200 turns off the LED 101 (S206). Next, the control unit 200 confirms the timing for resuming the conveyance of the transfer material 2 (S207), and starts a timer count (S208). Next, the controller 200 emits the LED 101 with the light amount A0 (S209) and turns off the LED 101 (S210), and repeats the operation at predetermined intervals (S211 → S209). The control unit 200 stops the counting operation at a timing (S211) when the transfer material 2 is conveyed and the media sensor 100 detects the rear end of the transfer material 2. Then, the control unit 200 calculates the size of the transferred transfer material 2 from the loop amount, the distance between the media sensor 100 and the registration roller 28, and the timer count value (S212). If the difference between the calculated size of the transfer material and the designated size is within a predetermined range, the control unit 200 ends the transfer material size detection sequence. If not within the predetermined range, the control unit 200 proceeds to step S214, separates the transfer roller, and discharges the transfer material 2 to the designated paper discharge port. At that time, the control unit 200 informs the controller that the transfer material size does not match, so that misprinting is determined, and the transfer material 2 is discharged as it is to the designated discharge tray. Thereafter, the control unit 200 waits for a predetermined transfer material passage timing (S215) and ends the process.

  FIG. 7 is a timing chart of this embodiment. From the top, the media sensor 100, the ON / OFF of the roller 28, the light emission amount of the LED 101, and the ON / OFF of the LED 104 are shown. As shown in FIG. 17, when the operation of detecting the leading and trailing edges of the transfer material is performed by the media sensor 100, the LED 101 emits 100% of A3 only when the leading edge of the transfer material and the media are detected. Do. In other cases, the LED 101 emits 30% of A0 with the amount of light suppressed in a time-sharing manner.

  As described above, it is possible to suppress the deterioration of the LED and accurately detect the transfer material type by repeating ON / OFF of the LED in time division and reducing the absolute LED light emission amount. It becomes.

[Other Embodiments]
In addition to the embodiments described above, the following embodiments can be implemented.
(1) The above-described embodiment can also be realized by software that sequentially executes each data processing. That is, a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded is supplied to the system or apparatus. Needless to say, an embodiment to which the present invention can be applied is also achieved by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment. The program code can be written in various storage media such as a CD (compact disc), an MD (magnetic disk), a memory card, and an MO (magneto-optic disc).

  The functions of the above-described embodiments are not only realized by executing the program code read by the computer. For example, an operating system (OS) running on the computer performs part or all of the actual processing based on the instruction of the program code. Further, it goes without saying that the case where the functions of the above-described embodiment are realized by the processing is also included in the embodiment to which the present invention can be applied.

Further, consider a case where the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. In this case, based on the instruction of the program code, the CPU or the like provided in the function expansion card or function expansion unit performs part or all of the actual processing. It goes without saying that the case where the functions of the above-described embodiment are realized by the processing is also included in the embodiment to which the present invention can be applied.
(2) In the above-described embodiment, an image forming apparatus that is a color laser printer has been shown. The present invention can be applied to an image reading apparatus having only a function.

[Effect of the embodiment]
As described above, according to the present embodiment, as a first aspect, the image forming apparatus (FIG. 1) of the present invention has the following.
Transfer material conveying means (105, 12, 9a, 28) for conveying a transfer material (2) for recording an image
Transfer material determining means for determining the type of the transfer material based on the reflected light reflected from the surface of the transfer material by causing the first light emitting element (101) to emit light (FIGS. 4, 5, and 11 to 13)
In the image forming apparatus, the transfer material determining unit detects the transfer direction end of the transfer material based on the reflected light (FIGS. 8, 14, and 16). The transfer material determining means adjusts the light emission amount of the first light emitting element (101) when detecting the end of the transfer material in the conveyance direction (FIGS. 8, 14, and 16). (Embodiments 1, 2, and 3).

  Accordingly, it is possible to suppress the deterioration of the LED used in the media sensor that determines the type of the media and accurately detect the media.

  Here, as a second aspect, in the image forming apparatus according to the first aspect, the adjustment of the light emission amount may be an adjustment of an absolute value of the light amount (Embodiments 1 and 3).

  Thereby, by reducing the absolute LED light emission amount, it is possible to suppress the deterioration of the LED and perform accurate transfer material type detection.

  Further, as a third aspect, in the image forming apparatus according to the first aspect, the adjustment of the light emission amount may be adjustment of the light amount in time division (Embodiments 2 and 3).

  Thus, by repeating ON / OFF of the LED in a time-sharing manner, it is possible to suppress the deterioration of the LED and perform accurate transfer material type detection.

  Further, as a fourth aspect, in the image forming apparatus according to the first aspect, the adjustment of the light emission amount may be adjustment of an absolute value of the light amount and adjustment of the light amount in a time division manner (implementation). Form 3).

  Accordingly, it is possible to suppress the deterioration of the LED and accurately detect the transfer material type by repeating ON / OFF of the LED in a time division manner and reducing the absolute LED light emission amount.

  As a fifth aspect, in the image forming apparatus according to the first, second, or fourth aspect, the adjustment of the light emission amount can reduce the absolute value of the light amount (Embodiments 1 and 3). .

  Thereby, by reducing the absolute LED light emission amount, it is possible to suppress the deterioration of the LED and perform accurate transfer material type detection.

  As a sixth aspect, in the image forming apparatus according to any one of the first to fifth aspects, the adjustment of the light emission amount includes a timing for detecting the leading edge of the transfer material and a timing for detecting the trailing edge of the transfer material. The amount of emitted light can be changed with (Embodiments 1, 2, and 3).

  According to a seventh aspect, in the image forming apparatus according to any one of the first to sixth aspects, the light emission amount is adjusted by causing the first light emitting element to emit light at a timing when the rear end of the transfer material is detected. It can be characterized by stopping (Embodiments 1, 2, and 3).

  According to an eighth aspect, in the image forming apparatus according to any one of the first to seventh aspects, the transfer material determining unit further emits the second light emitting element and transmits the second light emitting element based on the transmitted light transmitted through the transfer material. It is possible to determine the thickness of the transfer material (Embodiments 1, 2, and 3).

  As a ninth aspect, in the image forming apparatus according to the eighth aspect, the first light emitting element and the second light emitting element may be LEDs (Embodiments 1, 2, and 3). ).

  With the above configuration, the image forming apparatus can accurately detect the media even when the image forming apparatus main body is near the end of its life by suppressing the deterioration of the LEDs used in the media sensor that determines the type of the media. Can do.

1 is a cross-sectional view illustrating an overall configuration of a laser printer as an example of an image forming apparatus according to a first embodiment to which the present invention can be applied. It is a figure showing the signal between the engine control part of Embodiment 1 which can apply this invention, and a controller part. It is a figure showing the signal for the image synchronization of the engine control part and controller part of Embodiment 1 which can apply this invention. It is a figure showing the structure of the media sensor of Embodiment 1 which can apply this invention. It is a block diagram of the media sensor of Embodiment 1 which can apply this invention. It is a figure showing the output signal of the media sensor of Embodiment 1 which can apply this invention. It is a figure showing operation | movement of the media sensor of Embodiment 1 which can apply this invention. It is a flowchart of the engine control part of Embodiment 1 which can apply this invention. It is a timing chart at the time of conveyance of Embodiment 1 which can apply the present invention. It is a figure showing the LED light quantity setting of Embodiment 1 which can apply this invention. It is a detection flowchart of the media sensor of Embodiment 1 which can apply this invention. It is a detection flowchart of the media sensor of Embodiment 1 which can apply this invention. It is a detection flowchart of the media sensor of Embodiment 1 which can apply this invention. It is a flowchart of the engine control part of Embodiment 2 which can apply this invention. It is a timing chart at the time of conveyance of Embodiment 2 which can apply the present invention. It is a flowchart of the engine control part of Embodiment 3 which can apply this invention. It is a timing chart at the time of conveyance of Embodiment 3 which can apply the present invention. It is sectional drawing which shows the whole structure of the laser printer as an example of the conventional image forming apparatus. It is a figure showing the signal between the conventional engine control part and a controller part. It is a figure showing the signal for the image synchronization of the conventional engine control part and a controller part. It is a figure showing operation | movement of the conventional registration sensor. It is a flowchart of the conventional engine control part. It is a flowchart of the conventional engine control part. It is a figure showing the structure of the conventional media detection sensor. It is a block diagram of the conventional media detection sensor. It is a detection flowchart of the conventional media detection sensor. It is a detection flowchart of the conventional media detection sensor. It is a detection flowchart of the conventional media detection sensor. It is a block diagram of the conventional media detection sensor. It is a figure showing the output signal of the conventional media detection sensor. It is a figure showing operation | movement of the conventional media sensor. It is a flowchart of the conventional engine control part. It is a timing chart at the time of the conventional conveyance. It is a timing chart at the time of the conventional conveyance. It is a figure showing conventional LED degradation.

Explanation of symbols

2 transfer material 3 multi-tray 5Y, 5M, 5C, 5K photosensitive drum 9a transfer roller 12 intermediate transfer member 13 fixing unit 14 fixing roller 15 pressure roller 16, 17 heater 19 pre-registration sensor 21 cleaning means 23 flapper solenoid 24 FU tray / FU1 discharge port 25 FD tray 28 Registration roller 29 Paper discharge port switching flapper 30 in the paper discharge option Paper discharge option device 100 Media sensor 101 LED
102, 103 Phototransistor 104 LED
105 Transfer material conveyance guides 111, 112, 113 Slit 114 Condensing guide 200 Main control unit 201 for controlling light emitting element driving unit Engine control unit 202 Controller unit

Claims (8)

Transfer material conveying means for conveying a transfer material for recording an image; and transfer material determining means for determining the type of the transfer material based on reflected light reflected from the surface of the transfer material by emitting a light emitting element; In an image forming apparatus having transfer material discrimination means for detecting a transfer direction end of the transfer material based on the reflected light,
The transfer material discriminating unit makes the light emission amount from the light emitting element when detecting the conveyance direction end of the transfer material smaller than the light emission amount from the light emitting element when discriminating the type of the transfer material. And an image forming apparatus for controlling a light emitting operation of the light emitting element.   The transfer material discriminating unit discriminates the type of the transfer material by adjusting the intensity of the light emission amount from the light emitting element and detecting the light emission amount from the light emitting element when detecting the conveyance direction end of the transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled so as to be smaller than a light emission amount from the light emitting element.   The transfer material determining means repeatedly executes light emission and stop of the light emitting element, and determines the amount of light emitted from the light emitting element when detecting the conveyance direction end of the transfer material, and the type of the transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled so as to be smaller than a light emission amount from the light emitting element at the time. Timing for detect the conveying direction end of the transfer material includes the timing for detecting the conveying direction of the distal end of the transfer material, and the timing of detecting the trailing edge of the transfer material,
4. The image forming apparatus according to claim 1, wherein the transfer material determining unit detects a front end and a rear end of the transfer material and detects a size of the transfer material in a conveyance direction. 5. . A transfer material detection method for detecting a conveyance direction end of a transfer material to be imaged,
A determination step of discriminating the type of the transfer material based on the reflected light emitted from the light emitting element and reflected by the surface of the transfer material;
A detection step of detecting a conveyance direction end of the transfer material based on the reflected light;
A control step of controlling a light emitting operation of the light emitting element so that a light emission amount from the light emitting element in the detection step is smaller than a light emission amount from the light emitting element in the determination step;
A transfer material detection method comprising:   The control step adjusts the intensity of the light emission amount from the light emitting element, and controls the light emission amount from the light emitting element in the detection step to be smaller than the light emission amount from the light emitting element in the determination step. The transfer material detection method according to claim 5, further comprising a step of:   The control step repeatedly executes light emission and stop of the light emitting element, and controls the light emission amount from the light emitting element in the detection step to be smaller than the light emission amount from the light emitting element in the determination step. The transfer material detection method according to claim 5 or 6, wherein: Detecting the transfer material conveyance direction end includes the timing of detecting the transfer material conveyance direction leading edge, and the timing of detecting the transfer material trailing edge,
The transfer material according to claim 5, wherein the detecting step includes a step of detecting a front end and a rear end of the transfer material to detect a size of the transfer material in a conveyance direction. Detection method.

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