JP2017170859A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the usability even if the set type of sheets does not accord with the type of sheets stored in storage means.SOLUTION: An image forming apparatus includes a storage unit 15 that stores information on the types of sheets that were detected by a medium sensor 14 in the past. At the start of a printing operation in an instruction mode, if the type of sheets set by an operation unit 13 does not accord with the result of determination based on the information on the types of sheets stored in the storage unit 15 (S303: N), and if a plurality of candidate types of sheets are extracted by the determination based on the information stored in the storage unit 15, a CPU 10 causes a sheet-feeding pickup roller 151 not to start sheet feeding (S400: N).SELECTED DRAWING: Figure 11

Description

  The present invention relates to an image forming apparatus such as an electrophotographic system or an electrostatic recording system.

  In an image forming apparatus that develops an electrostatic latent image formed on a photosensitive member with a laser beam light with toner to form a toner image, transfers the formed toner image onto a sheet, and thermally fixes the image, Characteristic information such as thickness and surface properties is important as a control parameter. By using the characteristic information of the media, it is possible to realize the optimum fixing temperature and conveyance speed for the paper. It is generally known that sheet characteristic information is set by a user operation from an operation unit provided in the image forming apparatus or a driver screen. However, in recent years, a configuration has been proposed in which a sensor for detecting the characteristics of media is provided inside the image forming apparatus, which improves convenience by eliminating the need for user operation.

  When an image forming apparatus equipped with a sensor that detects media characteristics (hereinafter referred to as a media sensor) detects a different media while an image forming operation is being performed with control parameters suitable for a given media. The control of is disclosed. For example, a media sensor that detects the characteristics of a sheet is disposed on the conveyance path, and the medium is detected for a plurality of sheets that are continuously fed (see, for example, Patent Document 1). If the characteristics of the already output paper and the newly detected paper are different, the print job is stopped.

JP 2010-211062 A

  However, in order to detect the media with the media sensor arranged on the conveyance path, it is necessary to feed the sheet and convey the sheet to a position where the media sensor is arranged on the conveyance path. If a mismatch between the detection result by the media sensor and the currently operating control parameter is determined, it is necessary to stop the sheet transport operation and the image forming operation at the determination timing. Therefore, in order for the user to resume the subsequent print job, it is necessary to check the paper type of the paper cassette, change the paper type setting, and remove the paper stopped on the transport path. is there.

  The present invention has been made under such circumstances, and an object of the present invention is to improve usability even when the set paper type does not match the paper type stored in the storage means.

  In order to solve the above-described problems, the present invention has the following configuration.

  (1) A sheet feeding unit that feeds the recording medium loaded on the sheet feeding unit, a detection unit that detects the type of the recording medium fed by the sheet feeding unit, and a type of the recording medium are manually set. Printing is performed in any one of a setting unit, a first mode for controlling the printing operation based on the type of the recording medium set by the setting unit, and a second mode for controlling the printing operation based on the detection result by the detection unit. Control means for controlling the operation; and storage means for storing information relating to the type of the recording medium detected in the past by the detection means, wherein the control means starts the printing operation in the first mode. In addition, the type of the recording medium set by the setting unit does not match the result determined based on the information about the type of the recording medium stored in the storage unit, and is based on the information stored in the storage unit Another consequence, when the type of recording medium has a plurality of candidates, the image forming apparatus and controls so as not to start the feeding of the recording medium by the feeding means.

  According to the present invention, usability can be improved even when the set paper type does not match the paper type stored in the storage means.

Sectional view of the image forming apparatus of the embodiment Block diagram of an image forming apparatus according to an embodiment Sectional view of the fixing device of the embodiment Explanatory drawing of the media sensor of an embodiment Explanatory drawing of the media sensor of an embodiment Explanatory drawing of the amount of reflected light by the paper type of the embodiment The figure explaining discrimination | determination of the paper type of embodiment Explanatory drawing of automatic detection mode and instruction mode of embodiment Flowchart showing print control according to the embodiment The figure which shows the operation part of embodiment Flowchart showing print control according to the embodiment

[Embodiment]
<Image forming apparatus>
FIG. 1 is a cross-sectional view of an image forming apparatus 100 according to the embodiment, and FIG. 2 is a block diagram illustrating the configuration of the present embodiment. The basic configuration will be described with reference to FIGS. In FIG. 2, the CPU 10, the ROM 11, the RAM 12, and the storage unit 15 that is a storage unit constitute a control unit. A print operation start instruction (hereinafter referred to as an operation start instruction) is input to the CPU 10 from the operation unit 13 as setting means. The CPU 10 can drive and control the paper feed motor 150 in accordance with an operation start instruction input from the operation unit 13 and can feed and transport paper. The CPU 10 detects the position of the paper in the image forming apparatus 100 by monitoring the paper feed pickup sensor 152 and the like.

  Further, the CPU 10 controls the image forming unit 17. The image forming unit 17 controls high voltage application and driving of the cartridges 120a, 120b, 120c, and 120d in FIG. Here, the subscripts a, b, c, and d denote colors, for example, a is yellow (Y), b is magenta (M), c is cyan (C), and d is black ( K). Hereinafter, subscripts a to d are omitted unless a specific color is described. The image forming unit 17 can control the high voltage and driving of the intermediate transfer belt 130, the primary transfer unit 123, the secondary transfer unit 140, and the laser scanner 122. The ROM 11 stores a procedure for image formation and a flowchart described later. The media sensor 14 constituting the detection means can detect the material (for example, thickness) of the paper being conveyed on the conveyance path, and can output information on the type of the paper to the CPU 10 described later. Details of the media sensor 14 will be described later.

  Next, a basic image forming operation will be described with reference to FIGS. When an operation start instruction is received from the operation unit 13 or the like, the CPU 10 starts a sheet feeding operation from a sheet feeding cassette 220 that is a sheet feeding unit on which sheets as recording media are stacked. The paper feed motor 150 serving as a drive source of the paper feed pickup roller 151 serving as a paper feed unit is driven to rotate the paper feed pickup roller 151 so that the paper in the paper feed cassette 220 is fed and conveyed one by one. . At this time, the CPU 10 monitors whether or not the paper feeding operation has been normally performed by using the paper feed pickup sensor 152.

  When the paper picked up by the paper feed pickup roller 151 and transported by the transport roller 154 is transported to the position of the media sensor 14, the CPU 10 detects the material (thickness etc.) of the paper by the media sensor 14. At this time, depending on the configuration of the media sensor 14, the paper may be temporarily stopped at the position of the media sensor 14 or the conveyance speed may be decreased in order to improve the reading accuracy. In this embodiment, it is assumed that there is no need to temporarily stop the conveyance of the sheet or decrease the conveyance speed when the detection by the media sensor 14 is performed. The CPU 10 reflects the sheet information detected by the media sensor 14 on the image forming conditions in the image forming process, for example, the fixing temperature in the fixing process by the fixing device 170. As another image forming condition, for example, it is conceivable to change the conveyance speed of the paper to a conveyance speed corresponding to the information detected by the media sensor 14 and continue the conveyance of the paper. For example, when it is determined from the detection result of the media sensor 14 that the paper being transported is thick paper, the transport speed (1/2) of the transport speed of the thick paper is larger than the transport speed of the plain paper or the thin paper ( The conveyance speed is changed, such as changing to 1/2 speed). In this embodiment, as an example, the sheet conveyance speed is not changed to be constant, and the detection result by the media sensor 14 is reflected in the fixing temperature of the fixing device 170.

  The CPU 10 starts an image forming operation with the cartridge 120 so as to be in time for the arrival of the sheet at the secondary transfer unit 140. The cartridge 120 is attached to the main body of the image forming apparatus 100 and is configured to be removable. After the surface of the photosensitive drum 121 is charged by the charging roller 124, a latent image is formed on the photosensitive drum 121 by the laser light emitted from the laser scanner 122. The latent image formed on the photosensitive drum 121 is developed with toner in the developing device 125, and a toner image is formed on the photosensitive drum 121. The toner image formed on the photosensitive drum 121 is transferred to the intermediate transfer belt 130 by the primary transfer unit 123 to which a transfer voltage is applied. The toner image transferred onto the intermediate transfer belt 130 is moved to the secondary transfer unit 140 along with the movement of the intermediate transfer belt 130.

  The CPU 10 detects the position of the sheet transported by the transport roller 155 by monitoring the pre-registration transport sensor 160. The CPU 10 considers the timing when the leading edge of the sheet reaches the pre-registration conveyance sensor 160, so that the leading edge of the sheet and the leading edge of the toner image on the intermediate transfer belt 130 coincide with each other at the secondary transfer unit 140. Control the transport of For example, if the CPU 10 determines that the paper has arrived earlier than the specified timing based on the detection result of the pre-registration conveyance sensor 160, the CPU 10 stops the paper at the position of the pre-registration conveyance roller 161 for a predetermined time. The conveyance is resumed again.

  By applying a transfer voltage to the secondary transfer unit 140, the toner image is transferred to the paper that has reached the secondary transfer unit 140. The sheet on which the toner image is transferred is conveyed to the fixing device 170. The CPU 10 controls the temperature of the fixing unit 170 to the optimum temperature for the sheet according to the detection result of the media sensor 14. Details of the fixing device 170 will be described later. The CPU 10 fixes the toner image on the sheet to the sheet by the fixing unit 170 and then conveys the sheet to the downstream side of the fixing unit 170 in the sheet conveying direction. When the leading edge of the sheet after fixing reaches the conveyance sensor 171, the CPU 10 determines whether the sheet is conveyed to the conveyance path 230 or the conveyance path 231 in accordance with an instruction specified in advance from the operation unit 13. The CPU 10 switches the paper transport destination by switching the flapper 172 according to the determination. Specifically, the CPU 10 conveys the sheet to the conveyance path 230 in the case of a double-sided print instruction, and conveys the sheet to the conveyance path 231 in the case of single-sided printing or the back side (second side) of double-sided printing.

  Hereinafter, a case where a sheet is conveyed to the conveyance path 231 will be described. The sheet conveyed to the conveyance path 231 is further conveyed downstream in the conveyance direction by the conveyance roller 232. In this case as well, whether the paper is transported to the transport path 180 side or the transport path 181 side by switching the flapper 190 in accordance with an instruction designated in advance from the operation unit 13 as in the previous switching. Can be switched. The sheet is transported to the transport path 180 when the user's discharge designation destination is the discharge tray 200, and is transported to the transport path 181 side when the discharge designation destination is the discharge tray 196. The basic image forming operation described above is an example, and the present invention is not limited to the configuration described above.

<Description of Fixing Unit 170>
FIG. 3 is a diagram illustrating the configuration of the fixing device 170, and shows a state in which the sheet S carrying the toner T is conveyed to the fixing device 170 from the direction of the arrow in the drawing. The fixing device 170 includes a heater holder 207, a fixing heater 204, and a fixing film 203. The fixing heater 204 is fixedly disposed on the lower surface of the heater holder 207 along the longitudinal direction of the heater holder (the direction orthogonal to the drawing and also the direction orthogonal to the paper transport direction). The fixing film 203 has an elastic layer. The pressure roller 205 is disposed such that both ends of the core metal are rotatably supported between the side plates of the fixing device 170. The fixing device 170 is arranged in parallel with the pressure roller 205 so that the fixing heater 204 is in contact with the pressure roller 205, and both ends of the heater holder 207 are pressed with a predetermined pressing force by an urging means (not shown). It is in a state.

  Accordingly, the surface of the fixing heater 204 is pressed against the elasticity of the pressure roller 205 with the fixing film 203 interposed therebetween, thereby forming a fixing nip portion 206 having a predetermined width. The pressure roller 205 is rotationally driven at a predetermined peripheral speed in an arrow direction (counterclockwise direction) by a drive mechanism (not shown). The fixing heater 204 is formed by forming a resistance heating element on a ceramic substrate. A thermistor 208 is in contact with the fixing heater 204. The CPU 10 detects the temperature of the fixing heater 204 with the thermistor 208 and controls the power supplied to the fixing heater 204 so that the temperature of the fixing heater 204 becomes a predetermined temperature.

  The target temperature of the fixing heater 204 is determined by the paper type and the environmental temperature. The CPU 10 determines the target temperature of the fixing heater 204 according to the media type set from the operation unit 13 or the media type detected by the media sensor 14. At this time, when the environmental temperature or the like is further known, the CPU 10 generally corrects the target temperature of the fixing heater 204 in consideration of the environmental temperature.

<Description of Media Sensor 14>
Next, an example of the media sensor 14 will be described with reference to FIG. Inside the media sensor 14, there is a sensor unit 470 in which an LED 481 as a light emitting element and a photodiode 480 as a light receiving element are arranged. The photodiode 480 can detect the amount of light (the amount of reflected light) that is emitted from the LED 481 to the object (paper S) and reflected from the object. Further, the guide portion 483 into which the sheet S enters is pressed toward the sheet side by a spring 482 serving as a pressing unit. The pressing force of the spring 482 is changed by a cam 484 rotated by a driving unit (not shown). When the cam 484 rotates in the direction in which the effective length of the spring 482 is shortened, the pressing force by which the spring 482 presses the guide portion 483 is strong, and the cam 484 rotates in the direction in which the effective length of the spring 482 is increased. When the spring 482 is present, the pressing force with which the spring 482 presses the guide portion 483 is weak. While the material of the sheet S is detected by the media sensor 14, the cam 484 is driven to rotate, and the pressing force of the spring 482 changes.

  FIG. 4B to FIG. 4E are schematic diagrams illustrating a state where thin paper and thick paper are conveyed as an example. FIG. 4B shows a state when the pressing force of the spring 482 is weak during thin paper conveyance, and FIG. 4C shows a state when the pressing force of the spring 482 is strong during thin paper conveyance. When thin paper is being transported, the thin paper is transported in a stable state with respect to the guide portion 483 regardless of the pressing force of the spring 482. On the other hand, FIG. 4D shows a state when the pressing force of the spring 482 is weak during transport of thick paper, and FIG. 4E shows a state when the pressing force of the spring 482 is strong during transport of thick paper. In a state in which the pressing force of the spring 482 is weak, a thick thick paper has pushed the guide portion 483. On the other hand, in a state where the pressing force of the spring 482 is strong, the sheet S, which is a thick sheet, is pressed against the sensor unit 470 by the pressing force of the spring 482 and the guide portion 483, and is in a stable state.

  Next, a plot 250 of the amount of reflected light obtained by the photodiode 480 when the paper S is thin paper is shown in FIG. 5A, and a plot of the amount of reflected light obtained by the photodiode 480 when the paper S is thick paper. 255 is shown in FIG. FIG. 5 shows time on the horizontal axis and the amount of reflected light obtained by the photodiode 480 on the vertical axis, from a state where the pressing force of the spring 482 is weak at timings t11 and t12 (FIGS. 4B and 4D). It is changed to a strong state (FIG. 4C, FIG. 4E). The amount of reflected light obtained when the sheet S is thin is stably conveyed along the guide portion 483 regardless of the pressing force of the spring 482 (251, 252). For this reason, both the average value of the reflected light amount and the difference between the maximum value and the minimum value (hereinafter referred to as amplitude) of the reflected light amount do not change before and after the timing t11 (250).

  On the other hand, the amount of reflected light obtained when the paper S is a thick paper is the average when the pressing force of the spring 482 changes from the weak state (256) to the strong state (257) at timing t12, compared to the state where the pressing force of the spring 482 is weak. The value increases and the amplitude of the amount of reflected light decreases (255). The average value here does not indicate the average value in each range, such as the average value in the state where the pressing force is weak and the average value in the state where the pressing force is strong. It is an average value in the entire range shown in the drawings including the same, and the same applies to FIG. The amount of reflected light obtained when the paper is thick varies depending on the pressing force of the spring 482 and the average value and amplitude of the reflected light amount change. This is because, when the pressing force of the spring 482 is weak (256), the sheet S is not stably conveyed along the guide portion 483, whereas when the pressing force of the spring 482 is strong (257), the sheet S This is because the toner is stably conveyed along the guide portion 483.

  The CPU 10 receives an input signal of the photodiode 480 as an output value of the media sensor 14. The CPU 10 detects the reflected light amount detected by the media sensor 14 when the paper S is pressed with a predetermined force by the spring 482 and the media sensor 14 when pressing the paper S with a force stronger than the predetermined force. The type of paper S is determined based on the amount of reflected light. In this way, the CPU 10 can determine the type of paper being conveyed (material, thickness, etc. of the paper S) based on the output value of the media sensor 14 for each paper S.

  This will be described in more detail with reference to FIGS. The CPU 10 detects the input signal of the photodiode 480, and calculates the average value of the reflected light amount and the size of the variation based on the detected input signal. The horizontal and vertical axes in FIG. 6 are the same as those in FIG. In the example of the thin paper in FIG. 6A, the average value is a value indicated by 260 in the figure. The variation in the amount of reflected light is detected by detecting the difference (hereinafter referred to as amplitude) between the maximum value and the minimum value of the input signal of the photodiode 480, and the maximum amplitude and the minimum among the amplitudes of each cycle of the input signal. The difference from the amplitude is the size of the variation. In the example of the thin paper shown in FIG. 6A, since the amplitude of the reflected light amount is uniform, for example, the variation that is the difference between the amplitude 261 and the amplitude 262 is 0 or a very small value.

  In the example of thick paper shown in FIG. 6B, the average value of the reflected light amount is a value indicated by 270 in the drawing, which is a little higher than the average value 260 of the reflected light amount of the thin paper. Further, the magnitude of the variation is the difference between the amplitude 271 and the amplitude 272 in the case of the thick paper shown in FIG. As described above, in the case of thick paper, the variation in the amount of reflected light is larger than that in the case of thin paper.

<Amount of reflected light and paper type>
Next, the relationship between the input signal value of the photodiode 480, that is, the amount of reflected light and the type of paper will be described. FIG. 7A is a diagram showing the relationship between the amount of reflected light and the type of paper. The horizontal axis represents the average value of the reflected light amount, and the vertical axis represents the variation in the amount of reflected light. As shown in FIG. 7A, the paper defined as thick paper 1 has an average value of the reflected light amount in the range indicated by B in the figure, and the variation in the reflected light quantity is indicated by A in the figure. The paper is in the range to be printed. On the other hand, a sheet defined as thin paper is a sheet in which the average value of the reflected light amount is in the range indicated by D in the figure and the variation in the reflected light amount is in the range indicated by C in the figure. When the CPU 10 determines the type of paper based on the amount of reflected light detected by the media sensor 14, the CPU 10 previously determines values such as A, B, C, and D that indicate the average value of the amount of reflected light and the range of variation. It is stored in the ROM 11. Therefore, the CPU 10 detects the input signal of the photodiode 480 when the sheet passes through the media sensor 14, and determines the average value of the reflected light amount and the size of the variation, thereby determining the type of the sheet being conveyed. It is possible. The CPU 10 optimally controls the temperature of the fixing device 170 according to the type of paper determined based on the detection result of the media sensor 14. Further, the CPU 10 stores the determined paper type in the storage unit 15. When there are a plurality of paper feeding units, the CPU 10 may be configured to store information on the paper type for each paper feeding unit in the storage unit 15.

  As described above, the media sensor 14 described in the present embodiment is arranged on the conveyance path, and has a configuration in which the type of the sheet is detected when the sheet S passes through a position facing the media sensor 14. is there. Therefore, the CPU 10 stops the conveyance of the paper S when the paper type detected by the media sensor 14 is different from the paper type set from the operation unit 13. In this case, the user needs to remove the stopped paper S. Further, after the sheet is removed by the user, the CPU 10 needs to restart the image forming operation.

  The example of the configuration of the media sensor 14 used in the present embodiment has been described above. The configuration of the media sensor 14 described here is an example, and the present invention is not limited to this configuration. For example, a method of combining an ultrasonic sensor such as a piezoelectric element in addition to the light emitting element and the light receiving element described in this embodiment is also effective. In such a configuration, it is possible to detect the basis weight of the sheet by using the reception signal of the ultrasonic sensor, and it is possible to determine the type of the sheet with higher accuracy. The present invention is an effective configuration even if the media sensor 14 has other configurations.

<Automatic detection mode and instruction mode>
(Automatic detection mode)
Next, the automatic detection mode that is the second mode of the present embodiment and the instruction mode that is the first mode will be described with reference to FIG. In FIG. 8, the horizontal axis indicates time, and indicates an event that occurs in the image forming apparatus 100 such as the start of a printing operation, the timing at which the paper reaches the media sensor 14, and the like. In addition, the vertical axis in FIG. 8 indicates control targets such as fixing control and paper transport control.

  The operation when the automatic detection mode is set by the operation unit 13 will be described with reference to FIG. When an operation start instruction is input from the operation unit 13 at timing t1, the CPU 10 starts paper conveyance control. At this time, since the actual type of the sheet is unknown, the control for the fixing device 170 is not started. Thereafter, the CPU 10 monitors the paper feed pickup sensor 152 and waits for the paper to reach the media sensor 14. Then, after the leading edge of the paper reaches the media sensor 14 at the timing t2, the CPU 10 determines the paper type of the conveyed paper based on the detection result of the media sensor 14 by the control described above. When the determination of the paper type using the media sensor 14 is completed, the CPU 10 determines a target temperature for the fixing device 170 according to the determined paper type and starts fixing start-up control.

  When it is determined that when the fixing start-up control is started, the temperature of the fixing device 170 is lower than the target temperature, and the temperature does not reach the target temperature until the paper reaches the fixing nip portion 206 of the fixing device 170. The CPU 10 temporarily stops the conveyance of the paper. The CPU 10 waits for the temperature of the fixing device 170 to reach the target temperature ((X) in FIG. 8). Then, at the timing t3 when the temperature of the fixing device 170 reaches the target temperature, the CPU 10 performs paper conveyance control for driving the motor to resume conveyance of the paper. Further, the CPU 10 performs fixing temperature control for controlling the temperature of the fixing device 170 to be maintained at the target temperature. When the sheet reaches the fixing device 170 at timing t4, the fixing processing is performed.

  As described above, the automatic detection mode does not require the user to be aware of or select the paper type when manually setting, but the fixing start-up operation cannot be started until the paper type is determined. The formation end timing is delayed. There is also a method of speeding up the fixing start-up control in the automatic detection mode based on the detection result of the media sensor 14 performed in the past. However, in a state where the paper type is indeterminate, such as immediately after the paper feed cassette 220 is opened or closed, or immediately after the image forming apparatus 100 is turned on, the fixing unit is used until the paper type is determined. 170 startup operation cannot be started. Also in this case, there is a possibility that the end of image formation is delayed.

(Instruction mode)
Next, an operation when the instruction mode is set from the operation unit 13 will be described with reference to FIG. When a paper type is selected from the operation unit 13 at timing t5 and an operation start instruction is input, the CPU 10 starts a paper transport operation. Further, since the paper type is selected at the timing t5, the target temperature for the fixing device 170 is determined at this time. Therefore, the CPU 10 starts a start-up operation for the fixing device 170 at the timing t5 as well as the sheet transport operation. The CPU 10 monitors a thermistor 208 as well as a conveyance sensor such as a paper feed pickup sensor 152.

  The CPU 10 detects that the temperature detected by the thermistor 208 has reached the target temperature at timing t6, and shows an example in which the leading edge of the paper reaches the media sensor 14 at timing t7. As described above, when the sheet reaches the media sensor 14 after the temperature of the fixing device 170 reaches the target temperature, the CPU 10 stops the sheet at the timing when the determination of the sheet type using the media sensor 14 is completed. The operation can be continued without any problems. This is because the temperature of the fixing unit 170 has already reached the target temperature at the timing t8 when the sheet reaches the fixing unit 170. Therefore, in the instruction mode, the waiting time as in (X) of the automatic detection mode (FIG. 8A) does not occur, and therefore the time from the start of the printing operation (timing t5) until the paper is discharged is shortened. Is possible.

  As described above, in the instruction mode, the user needs to be aware of or select the type of paper, and the fixing start-up operation can be performed at the fastest speed. Thereby, it is possible to perform the image formation end timing at the fastest speed.

  The image forming apparatus 100 according to the present embodiment includes both the automatic detection mode and the instruction mode, so that it is possible to cope with a user who does not want to perform an operation for setting the paper type. Is possible. Moreover, even if it is necessary to set the paper type in consideration, it is possible to cope with the user who needs the product at the fastest speed.

  In addition, embodiment mentioned above is an example and this invention is not limited to this. For example, the automatic detection mode and the instruction mode can be set from a personal computer having a printer driver other than the operation unit 13. In the above-described embodiment, the fixing start-up control has been described as an example of the cause of the problem that the image formation end timing is delayed in the automatic detection mode. However, the present invention is not limited to this. If the control requires time as a preparation operation for the image forming operation, the same problem occurs. For example, the same problem exists in an image forming apparatus that requires an operation for determining a voltage value to be applied to the secondary transfer unit 140 according to the type of paper.

<Explanation of Flowchart for Determining Mistakes in Paper Type>
Next, the characteristic of the present embodiment is that the set paper type does not match the paper type detected by the media sensor 14 before the paper feeding operation is started (hereinafter referred to as paper type mismatch). A method for determining the above will be described with reference to the flowchart of FIG. When the user selects the instruction mode from the operation unit 13 and selects the type of paper to be conveyed, when the operation start instruction is input, the CPU 10 starts the operation after step (hereinafter referred to as S) 300. To do. In S300, the CPU 10 starts a print job in the instruction mode. In S301, the CPU 10 acquires the paper type set by the user.

(When the detection result of the media sensor is stored in the storage unit)
In step S <b> 302, the CPU 10 determines whether the sheet detection result by the media sensor 14 is stored in the storage unit 15. If the CPU 10 determines in S302 that the storage unit 15 has a sheet detection result, the process proceeds to S303. In S303, the CPU 10 determines whether or not the paper type acquired in S301 matches the detection result of the paper stored in the storage unit 15, in other words, the past detection result. If the CPU 10 determines in step S303 that the paper type set from the operation unit 13 does not match the paper detection result stored in the storage unit 15, the process advances to step S312.

  In this case, there is a possibility that the paper type set by the user and the paper type detected in the past by the media sensor 14, in other words, the paper type in the paper feed cassette 220 do not match. In S <b> 312, the CPU 10 displays a message indicating that there is a possibility that there is an error in the user setting on the operation unit 13, etc., notifies the user, and ends the process. As described above, the operation unit 13 also functions as a notification unit. FIG. 10A is a diagram illustrating an example of a screen displayed on the operation unit 13. Displaying a screen as shown in FIG. 10A on the operation unit 13 prompts the user to confirm the setting of the paper type and the paper in the paper cassette 220. In this case, the CPU 10 does not start the operation (printing operation) of the paper feed motor 150, the image forming unit 17, and the like.

  By performing the above operation, in the instruction mode and when the detection result by the media sensor 14 is stored in the storage unit 15, the paper types do not match before the paper feeding operation by the paper feeding motor 150 is performed. It becomes possible to judge. As a result, the operation of removing the paper stopped on the conveyance path, which is necessary when it is determined that the paper types do not match after the start of paper feeding, is eliminated, and usability is improved.

  If the CPU 10 determines in S303 that the detection result stored in the storage unit 15 matches the paper type set by the user, the process proceeds to S305. In step S <b> 305, the CPU 10 starts a printing operation such as a sheet feeding operation and an image forming operation. In step S <b> 306, the CPU 10 performs a sheet detection operation by the media sensor 14 for each page of the sheet, and determines the type of the sheet being conveyed. This is performed in order to cope with the case where different types of paper are mixed by mistake in the paper in the paper feed cassette 220. Further, the CPU 10 stores information on the amount of reflected light detected by the media sensor 14 in the storage unit 15. Note that the CPU 10 may be configured to store, in the storage unit 15, information regarding the paper type determined based on the amount of reflected light detected by the media sensor 14. In the present embodiment, it is assumed that the amount of reflected light detected by the media sensor 14 is stored in the storage unit 15.

  In S308, the CPU 10 determines whether or not the paper type set by the user matches the paper type determined based on the detection result of the media sensor 14 in S306. If the CPU 10 determines in step S308 that the paper type set by the user does not match the paper type discrimination result by the media sensor 14, the process advances to step S309. In S309, the CPU 10 stops the printing operation. In S313, the CPU 10 causes the operation unit 13 or the like to display a message notifying that different types of paper are mixed in the paper feed cassette 220, and ends the process. An example of the screen displayed on the operation unit 13 in S313 is shown in FIG. For example, the CPU 10 displays on the operation unit that printing has been interrupted, the paper type has changed, and the like, and prompts the user to confirm the paper type setting or the paper in the paper cassette 220.

  If the CPU 10 determines in S308 that the sheet type set by the user matches the determination result of the sheet type by the media sensor 14, the operation is continued, and it is determined in S310 whether the page is the last page. If the CPU 10 determines in S310 that the page is the last page, the printing ends in S311 and the process ends. If the CPU 10 determines in S310 that the page is not the last page, the process returns to S306.

(When the detection result of the media sensor is not stored in the storage unit)
The operation when the instruction mode is selected and the detection result of the media sensor 14 is not stored in the storage unit 15 will be described using the flowchart of FIG. If the CPU 10 determines in S302 that the detection result by the media sensor 14 is not stored in the storage unit 15, the process proceeds to S304. In S304, the CPU 10 starts a paper feeding operation and an image forming operation, and changes from a standby state such as the above-described fixing control and high voltage control to a printing state according to the type of paper set by the user. Processing (referred to as pre-rotation processing) is started, and the process proceeds to S305. In step S <b> 305, the CPU 10 starts printing and waits for the paper conveyed by the paper feed pickup roller 151 to reach the media sensor 14. In step S <b> 306, when the paper reaches the media sensor 14, the CPU 10 performs a paper type determination process using the media sensor 14. Since the processing after S308 has been described above, a description thereof will be omitted.

  If the detection result of the paper type is not stored in the storage unit 15, and if the paper type set by the user in the process of S <b> 308 does not match the paper type determined by the media sensor 14. In step S309, the CPU 10 stops the printing operation. In this case, when the media sensor 14 determines the type of paper and stops the printing operation, it is necessary to remove the paper that has stopped on the conveyance path as described above.

<If the paper type is not uniquely determined>
There are many types of paper in the market. In addition, depending on the environment in which the image forming apparatus is installed, the state of the paper such as the moisture absorption amount of the paper varies. Therefore, there is a case where the paper type cannot be uniquely specified by the detection result by the media sensor 14. In the following, a method for determining a paper type mismatch that considers the case where the paper type cannot be uniquely specified will be described.

  FIG. 7B illustrates a relationship between the amount of reflected light and the type of paper. The horizontal and vertical axes in FIG. 7B are the same as those in FIG. As an example, a case where paper of the types of thick paper 2 and thick paper 3 is used as paper having a larger basis weight than that of the thick paper 1 will be described. The range of the average amount of reflected light when discriminating the thick paper 2 is the range indicated by F in the figure. On the other hand, the range of the average value of the reflected light quantity when discriminating the thick paper 3 is the range indicated by G in the figure. In this case, the region indicated by H in the figure belongs to both the range F when discriminating the thick paper 2 and the range G when discriminating the thick paper 3. For this reason, when the average value of the amount of reflected light is a value in the range H based on the detection result of the media sensor 14, there is a possibility that it is determined as either the thick paper 2 or the thick paper 3. It cannot be uniquely identified. In other words, as a result of determining the paper type based on the detection result of the media sensor 14, there may be a plurality of candidates for the paper type. As described above, since there are a large number of types of paper and the state of the paper can be various, the areas for discriminating the type of paper overlap in this way for a specific paper. May end up. 7B, for example, an average value of the target fixing temperature of the thick paper 2 and the target fixing temperature of the thick paper 3 is obtained as a target value. It is also possible to make the configuration.

  Hereinafter, as in the case of thick paper 2 and thick paper 3 in FIG. 7B, there is a case where an area for discriminating the paper type overlaps and the paper type cannot be uniquely specified based on the detection result by the media sensor 14. A method for determining the mismatch of paper types in consideration will be described. FIG. 11 is a flowchart illustrating a process for determining a paper type mismatch when a paper type cannot be uniquely identified. In addition, the same step number is attached | subjected to the same process as the flowchart demonstrated in FIG. 9, description is abbreviate | omitted.

  In S303, if the paper type set by the user does not match the paper type stored in the storage unit 15, the CPU 10 advances the process to S400. In S <b> 400, the CPU 10 includes the sheet detection result stored in the storage unit 15 in the area (H) where the sheet type is not uniquely determined in FIG. 7B and the sheet type set by the user. Is a type similar to the sheet detection result stored in the storage unit 15. Here, the types of paper being similar means that the characteristic information of the paper (for example, the average value of the reflected light amount) is approximated as in the thick paper 2 and the thick paper 3 in FIG. Note that the thick paper 1 and the thick paper 3 in FIG. 7B are not similar types because the paper characteristic information is not approximate. For example, based on the detection result of the paper stored in the storage unit 15, it is determined that the paper is thick paper based on the variation in the amount of reflected light, but the average value of the reflected light is an area shown in FIG. If it is included in H, it cannot be specified whether the paper is thick paper 2 or thick paper 3. In this case, when the set paper is the thick paper 2 or the thick paper 3, it can be said that the set paper type is similar to the paper detection result stored in the storage unit 15. On the other hand, when the set paper is the thick paper 1, the set paper type cannot be said to be similar to the paper detection result stored in the storage unit 15.

  In S400, the CPU 10 cannot determine that the past detection result is in an area where the paper type is not uniquely determined and the paper type set by the user is similar to the past detection result. The process proceeds to S312. In S <b> 312, the CPU 10 displays and notifies the operation unit 13 and the like that there is a possibility that there is an error in the user settings, and ends the processing.

  On the other hand, in S400, the CPU 10 determines that the past detection result is in an area where the paper type is not uniquely determined, and the paper type set by the user is similar to the past detection result. If so, the process proceeds to S401. In this case, the detection result by the media sensor 14 is included in the region H described above, and there are a plurality of candidates, and the type of paper cannot be uniquely determined, and the accuracy of the detection result is low. If the CPU 10 cannot determine which of the plurality of candidates is the set paper type, it starts printing and paper feeding operations in S401. In this case, the CPU 10 determines the image forming conditions based on the paper type set by the user. In this case, detection of the paper during the printing operation as in the process of S306 is not performed. In S402, the CPU 10 determines whether or not the page is the last page. If it is determined that the page is not the last page, the process returns to S402, and if it is determined that the page is the last page, the process ends. In the process of S306, if the detection result by the media sensor 14 is an area in which the paper type cannot be uniquely determined, this is stored in the storage unit 15.

  As described above, the method for determining the mismatch of the paper types before starting the paper feeding operation, considering the case where the paper type cannot be uniquely specified, has been described. By performing the above operation, if the type of paper is not uniquely determined by the detection result by the media sensor 14, the printing operation can be continued without stopping. On the other hand, if the paper type is uniquely determined by the detection result by the media sensor 14, it is possible to accurately discriminate the paper type before the paper feeding operation by the paper feeding motor 150 is performed.

  In addition, the example mentioned above is an example and this invention is not limited to this. In this embodiment, the case where overlap occurs in the area of the average value of the reflected light amount has been described as an example. However, the same control can be performed when overlap occurs in the area where the amount of reflected light varies. is there. Further, even when other paper type detection methods are used, if there is a case where the paper type is not uniquely determined, the configuration can be controlled similarly.

  As described above, according to the present embodiment, usability can be improved even when the set paper type does not match the paper type stored in the storage unit.

10 CPU
13 Operation unit 14 Media sensor 15 Storage unit 151 Paper feed pickup roller

Claims (10)

Paper feeding means for feeding the recording medium loaded in the paper feeding unit;
Detecting means for detecting the type of recording medium fed by the paper feeding means;
A setting means for manually setting the type of recording medium;
The printing operation is controlled in either the first mode for controlling the printing operation based on the type of the recording medium set by the setting unit or the second mode for controlling the printing operation based on the detection result by the detecting unit. Control means;
Storage means for storing information on the type of recording medium detected in the past by the detection means;
With
The control means, when starting the printing operation in the first mode, the result of determination based on the information about the type of the recording medium set by the setting means and the type of the recording medium stored in the storage means If there is a plurality of candidates for the type of recording medium as a result of determination based on the information stored in the storage means, control is performed so as not to start feeding the recording medium by the paper feeding means. An image forming apparatus. A notification means for reporting information;
The image forming apparatus according to claim 1, wherein the control unit causes the notification unit to notify whether there is an error in setting the type of the recording medium by the setting unit.   The control unit starts a printing operation when the type of the recording medium set by the setting unit is included in the plurality of candidates even when the plurality of candidates exist. The image forming apparatus according to claim 1.   When the set type of the recording medium matches the determined type of the recording medium, the control unit starts a printing operation and feeds the recording medium from the paper feeding unit by the paper feeding unit. The image forming apparatus according to claim 1, wherein the image forming apparatus starts, detects a recording medium fed from the paper feeding unit by the detection unit, and stores a detection result in the storage unit.   5. The image according to claim 4, wherein the control unit stops the printing operation when the set type of the recording medium and the type of the recording medium detected by the detecting unit do not match. Forming equipment. A notification means for reporting information;
The image forming apparatus according to claim 5, wherein the control unit causes the notification unit to notify that there is a possibility that different types of recording media are mixed in the sheet feeding unit.   2. The detection unit includes: a light emitting element that irradiates a recording medium with light; and a light receiving element that detects an amount of light irradiated from the light emitting element to the recording medium and reflected from the recording medium. The image forming apparatus according to claim 6.   The detection means has a pressing means for pressing the recording medium in the direction in which the light emitting element and the light receiving element are arranged, and the amount of reflected light detected when the recording medium is pressed with a predetermined force by the pressing means. The type of the recording medium is discriminated based on the amount of reflected light detected when the pressing means presses with a force stronger than the predetermined force. Image forming apparatus.   The image forming apparatus according to claim 8, wherein the detection unit determines the type of the recording medium based on an average value of the reflected light amount and a magnitude of variation in the reflected light amount.   The control unit starts a printing operation according to the type of the recording medium set by the setting unit when the storage unit does not store information on the type of the recording medium detected by the detection unit. The image forming apparatus according to claim 1.

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