JP4926987B2 - Sheet conveying apparatus, image forming apparatus, document reading apparatus, sheet thickness detection method, program, and computer-readable recording medium - Google Patents

Description

  The present invention relates to, for example, an image forming apparatus that performs printing on a sheet and a sheet conveying apparatus that is included in an original reading apparatus that reads an original on a sheet, an original reading apparatus including the same, an image forming apparatus, a sheet thickness detection method, and a program And a computer-readable recording medium.

  In an apparatus that performs processing using a sheet (paper), various suitable controls are possible if the thickness of the sheet can be detected and various parameters can be set according to the thickness. For example, in the case of an image forming apparatus, the print quality can be improved by adjusting the image forming parameters according to the thickness of the sheet.

  On the other hand, when a sensor is provided to detect the thickness of the sheet, there is a problem that the number of parts increases and the cost of the apparatus increases.

Therefore, as a method of detecting the thickness without providing a thickness sensor, the load torque applied to the pickup roller drive unit when forming a deflection when taking out one sheet from the stacked sheets is determined by driving the pickup roller. There has been proposed a method for detecting the thickness of a sheet by detecting the driving current based on the driving current (for example, Patent Document 1).
JP 2001-106386 A (published April 17, 2001)

  However, the load torque at the time of forming a bend when taking out one sheet from the stacked sheets changes every moment from the start to the end of the bend formation and is not stable. Also, even for the same sheet, the load torque at the time of forming a bend when taking out one sheet from the stacked sheets may vary depending on the sheet stacking position and the like, and is not always constant. Therefore, it is difficult for the conventional method to accurately detect the thickness of the sheet. In addition, it is possible to increase the accuracy by measuring the load torque during deflection formation and obtaining the average value, but if you try to secure sufficient deflection time in order to increase the accuracy, high-speed conveyance of the paper It becomes an obstacle.

  SUMMARY An advantage of some aspects of the invention is that a sheet conveying device, a document reading device, an image forming device, a sheet thickness detecting method, a program, and a program that can accurately and quickly detect the thickness of a sheet without providing a sensor. It is to provide a computer-readable recording medium.

  In order to solve the above problems, a sheet conveying apparatus according to the present invention detects a load torque of an abutting member, a sheet conveying member that abuts the sheet against the abutting member, and a driving unit of the sheet conveying member. Torque detection means, load torque fluctuation detection means for detecting a collision timing at which the sheet collides with the abutting member, and a load torque fluctuation at the collision timing. And a collision timing load torque detecting means for outputting a load torque corresponding to the load torque.

  According to the above configuration, the load torque of the drive unit of the sheet conveying member that abuts the sheet against the abutment member at the collision timing when the sheet collides with the abutment member is output as the load torque according to the thickness of the sheet. The load torque at the collision timing is a stable value corresponding to the thickness of the sheet, and the collision does not require time. That is, it is possible to detect the load torque according to the thickness of the sheet with high accuracy and without requiring time. Here, the load torque at the collision timing depends on the thickness of the sheet. Therefore, according to the above configuration, the thickness of the sheet can be detected accurately and quickly without providing a sensor. .

  The output value from the collision timing load torque detecting means (load torque at the collision timing) may be used as it is as the sheet thickness, or a table or calculation formula in which the load torque and the sheet thickness are associated with each other. , The thickness of the sheet may be obtained from the output value.

  In addition to the above-described configuration, the sheet conveying apparatus according to the present invention further includes a sheet thickness detecting unit that detects the thickness of the sheet based on the load torque at the collision timing output from the collision timing load torque detecting unit. Also good. In this case, for example, the sheet thickness detecting unit can detect the thickness of the sheet from the load torque at the collision timing by referring to the correspondence relationship between the magnitude of the load torque and the sheet thickness. Therefore, according to the said structure, the thickness of a sheet | seat can be detected correctly and rapidly, without providing a sensor.

  In the sheet conveying apparatus according to the present invention, in addition to the above configuration, the abutting member may be a registration roller that temporarily stops conveyance of the sheet, and the driving unit may abut the sheet against the registration roller. .

  According to the above configuration, since the sheet is caused to collide with the registration roller in order to align the sheet in the sheet conveyance, the registration roller can be used as an abutting member to detect the torque at the time of collision, thereby preventing an increase in cost. be able to.

  In order to solve the above problems, an image forming apparatus according to the present invention includes any one of the above sheet conveying apparatuses. According to this configuration, it is possible to accurately and quickly detect the load torque according to the sheet thickness without providing a sensor, and according to the detected load torque according to the sheet thickness, that is, the sheet thickness. Accordingly, various settings in the image forming apparatus can be changed.

  Here, the image forming apparatus according to the present invention includes a fixing temperature control for adjusting a fixing temperature for fixing the developer on the sheet based on the load torque at the collision timing detected by the collision timing load torque detecting unit. Means may be provided. According to this configuration, the fixing temperature can be adjusted according to the thickness of the sheet.

  In addition, a document reading apparatus according to the present invention includes any one of the above sheet conveying apparatuses in order to solve the above problems. According to this configuration, it is possible to accurately and quickly detect the load torque according to the sheet thickness without providing a sensor, and according to the detected load torque according to the sheet thickness, that is, the sheet thickness. Accordingly, various settings in the document reading apparatus can be changed.

  Here, the document reading device according to the present invention is configured such that the lamp light amount applied to the sheet when the document image on the sheet is read based on the load torque at the collision timing detected by the collision timing load torque detecting unit. A light amount control means for adjusting According to this configuration, it is possible to adjust the lamp light amount applied to the sheet according to the thickness of the sheet.

  In order to solve the above problems, a sheet thickness detection method according to the present invention is a sheet thickness detection method in a sheet conveyance device provided with a sheet conveyance member that abuts a sheet against an abutment member. A load torque detecting step for detecting a load torque of the drive unit; a load torque fluctuation detecting step for detecting a collision timing at which the seat collides with the abutting member; A collision timing load torque detecting step of outputting the load torque as a load torque corresponding to the thickness of the seat.

  According to the above method, similarly to the sheet conveying apparatus, it is possible to detect the load torque corresponding to the thickness of the sheet without providing a sensor, and it is possible to detect the thickness of the sheet based on the load torque.

  In addition, the sheet conveying apparatus according to the present invention may be realized by a computer. In this case, the sheet conveying apparatus is operated by the computer by operating the computer as each of the above-described units in any of the sheet conveying apparatuses. A sheet thickness detection program to be realized and a computer-readable recording medium on which the sheet thickness detection program is recorded also fall within the scope of the present invention.

  According to these configurations, it is possible to realize the same operational effects as those of the sheet conveying apparatus by causing the computer to read and execute the program.

  As described above, the sheet conveying apparatus according to the present invention includes a butting member, a sheet conveying member that abuts the sheet against the abutting member, and a load torque detecting unit that detects the load torque of the driving unit of the sheet conveying member. Load torque fluctuation detecting means for detecting a collision timing at which the sheet collides against the abutting member, and detecting the load torque at the collision timing according to the thickness of the sheet. And a collision timing load torque detecting means for outputting as a load torque.

  According to the above configuration, the load torque of the drive unit of the sheet conveying member that abuts the sheet against the abutment member at the collision timing when the sheet collides with the abutment member is output as the load torque according to the thickness of the sheet. The load torque at the collision timing is a stable value corresponding to the thickness of the sheet, and the collision does not require time. That is, it is possible to detect the load torque according to the thickness of the sheet with high accuracy and without requiring time. Here, the load torque at the collision timing depends on the thickness of the sheet. Therefore, according to the above configuration, the thickness of the sheet can be detected accurately and quickly without providing a sensor. .

  The output value from the collision timing load torque detecting means (load torque at the collision timing) may be used as it is as the sheet thickness, or a table or calculation formula in which the load torque and the sheet thickness are associated with each other. , The thickness of the sheet may be obtained from the output value.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is an explanatory diagram showing a configuration of an image forming apparatus 11 according to the present embodiment. The image forming apparatus 11 forms a single color image on a predetermined sheet (recording paper) according to image data received from the outside via a network or image data read by the document reading apparatus 12 included in the image forming apparatus 11, for example. It is. In the present embodiment, for the sake of simplicity of explanation, an apparatus that forms a single-color image is used. However, an apparatus that forms a multi-color or single-color image may of course be used. In that case, the developing unit, the photoconductor, the charger, and the cleaner unit are formed so as to form four types of latent images corresponding to the colors of black (K), cyan (C), magenta (M), and yellow (Y). Each of the four colors is provided in accordance with each color. In this case, an intermediate transfer mechanism may be provided.

  As shown in FIG. 1, the image forming apparatus 11 includes an apparatus main body 1 and a document reading device 12. In the present embodiment, the image forming apparatus 11 is described as including the document reading device 12, but the image forming apparatus according to the present invention may not include the document reading device.

  The apparatus body 1 includes an exposure unit 13, a developing device 15, a photoconductor 17, a charger 19, a cleaner unit 21, a fixing unit 23, a paper feed tray 25, a paper feed transport path 27 extending upward from the paper feed tray 25, and paper feed. A sheet conveyance path 31 extending from the end of the conveyance path 27 to the sheet discharge roller 95 through the registration roller 29, the transfer belt 45, and the fixing unit 23, a sheet discharge tray 33, and the like. An upper part of the apparatus main body 1 is provided with an original placing table made of transparent glass on which an original is placed, and an original reading device 12 is attached to the upper side of the original placing stage. The document reading device 12 conveys the document on the document table. The document reading device 12 is configured so that the user can manually place the document by opening the document table.

  The charger 19 is a charging means for uniformly charging the surface of the photoconductor 17 to a predetermined potential. In this embodiment, a non-contact type charger is used as the charger 19. However, a contact type roller type or brush type charger may be used.

  The exposure unit 13 exposes the photoconductor 17 uniformly charged by the charger 19 according to the input image data, thereby forming an electrostatic latent image according to the image data on the surface of the photoconductor 17. It has the function to do. Here, the exposure unit 13 is configured as a laser scanning unit (LSU) including a laser emitting unit 35 and a reflection mirror 37. The reflection mirror 37 includes an optical element such as a polygon mirror that scans the laser beam and a lens or a mirror that guides the laser beam reflected by the polygon mirror to the photosensitive member 17. The exposure unit 13 may not have such a configuration, and may use, for example, an EL or LED writing head in which light emitting elements are arranged in an array.

  The developing unit 15 visualizes the electrostatic latent image formed on the photoreceptor 17 with toner.

  The cleaner unit 21 removes and collects toner remaining on the surface of the photoconductor 17 after development and image transfer.

  The toner visualized on the photoconductor 17 as described above is transferred onto a sheet conveyed through the paper conveyance path 31. The transfer mechanism 39 (transfer belt unit in the image forming apparatus 11 of the present embodiment) is a mechanism that applies an electric field having a polarity opposite to the charge of toner and transfers the toner onto the paper. For example, when the electrostatic image has a negative polarity charge, the polarity applied to the transfer mechanism 39 is a positive polarity.

The transfer mechanism 39 includes a transfer belt 45 that is bridged by a driving roller 41, a driven roller 43, and other rollers and has a predetermined resistance value (for example, a range of 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm). A contact portion 47 between the photoconductor 17 and the transfer belt 45 is provided with an elastic conductive roller 49 that is a roller different from the driving roller 41 and the driven roller 43 and can apply a transfer electric field. The elastic conductive roller 49 has elasticity. As a result, the photoconductor 17 and the transfer belt 45 are not in line contact but in surface contact with each other with a predetermined width (transfer nip width). As a result, the transfer efficiency to the conveyed paper is improved.

  Further, on the downstream side of the transfer area of the transfer belt 45, a charge removing roller 51 is disposed for discharging the sheet charged by the voltage applied when passing through the contact portion 47 and smoothly transporting it to the next process. Has been. The neutralizing roller 51 is disposed on the back surface of the transfer belt 45.

  Further, the transfer mechanism 39 is provided with a cleaning unit 53 that removes toner from the transfer belt 45 and neutralizes the transfer belt 45, and a neutralization mechanism 55 that neutralizes the transfer belt 45. The static elimination mechanism 55 includes a method of grounding through an apparatus or a method of positively applying a polarity opposite to the polarity of the transfer electric field.

  The sheet on which the toner is transferred by the transfer mechanism 39 is conveyed to the fixing unit 23. The fixing unit 23 includes a heating roller 57 and a pressure roller 59. A sheet peeling claw 61, a roller surface temperature detection member 63 (thermistor), and a roller surface cleaning member 65 are disposed on the outer peripheral portion of the heating roller 57. A heat source 67 for heating the surface of the roller to a predetermined temperature (fixing set temperature: approximately 160 to 200 ° C.) is disposed on the inner peripheral portion of the heating roller 57. On the other hand, pressure members are arranged at both ends of the pressure roller 59 so that the pressure roller 59 can be pressed against the heating roller 57 with a predetermined amount of pressure. Similar to the outer periphery of the heating roller 57, a sheet peeling claw and a roller surface cleaning member are arranged. The fixing unit 23 heats and melts unfixed toner on the conveyed paper at the pressure contact portion (fixing nip portion) between the heating roller 57 and the pressure roller 59 at the temperature of the surface of the heating roller 57 and pressurizes. The sheet is fixed on the paper by a throwing action by the pressure contact force of the roller 59.

  The paper feed tray 25 is a tray for accumulating sheets (recording paper) used for image formation. In the present embodiment, the paper feed tray 25 is provided on the lower side and the side wall surface of the apparatus main body 1. For the purpose of high-speed printing processing, the image forming apparatus 11 has a plurality of paper feed trays 25 that can store 500 to 1500 standard sizes in each tray as paper feed trays disposed below the apparatus body 1. Has been placed. On the other hand, a large-capacity paper feed cassette (LCC) 73 capable of storing a large amount of a plurality of paper types and a manual feed tray 75 mainly used for printing of an irregular size are disposed on the side surface of the apparatus main body 1.

  The paper discharge tray 33 is disposed on the side surface opposite to the manual feed tray 75 of the apparatus. However, instead of the paper discharge tray 33, a post-processing device (stapling, punching, etc.) of discharged paper has a plurality of stages. The paper discharge tray 33 can be arranged as an option.

  Sheets picked up one by one from the paper feed tray 25, large-capacity paper feed cassette (LCC) 73, or manual feed tray 75 by the pick-up roller pass through the paper feed transport path 27 having a plurality of transport rollers 93, and are then registered. It is conveyed to the roller 29.

  The registration roller (abutting member) 29 temporarily holds a sheet conveyed through the sheet conveyance path 31. Then, the sheet is conveyed to the transfer mechanism 39 at the timing when the leading edge of the toner image on the photosensitive member 17 is aligned with the leading edge of the sheet.

  The paper conveyance path 31 is also provided with a plurality of rollers for promoting and assisting the conveyance of the sheet.

  In addition, a re-feed conveyance path 137 is provided in the upper part of the paper feed tray 25.

  Further, the image forming apparatus 11 includes a control unit not shown in FIG. This control unit controls the operation of the image forming apparatus 11, and includes, for example, a microcomputer and a ROM that stores a control program that is a procedure of processing executed by the microcomputer, and a RAM that provides a work area for work. , Non-volatile memory that backs up and holds data necessary for control, input signals from sensors and switches, connected to input circuits including input buffers and A / D conversion circuits, and loads such as motors, solenoids, and lamps For example, an output circuit including a driver.

  Next, a paper conveyance process corresponding to the processing mode of the image forming apparatus 11 will be described in detail. The control unit microcomputer conveys the sheet P suitable for the printing request to the registration roller 29 by the conveyance roller 93 in the sheet feeding conveyance path 27. Under the control of the microcomputer, it reaches the registration roller 29 and temporarily stops. The microcomputer re-rotates the registration roller 29 at the timing when the leading edge of the sheet and the image information on the photoconductor 17 are matched, and thereby the sheet is conveyed to the transfer mechanism 39. The toner corresponding to the image information is transferred onto the sheet by the transfer mechanism 39, and then the sheet P is guided to the fixing unit 23 and the transferred toner is fixed onto the sheet. Thereafter, the sheet is discharged to the discharge tray 33. The microcomputer uses a conveyance method from the fixing unit 23 to the discharge tray 33 according to a printing mode (such as a copier mode, a printer mode, or a FAX mode) and a printing processing method (such as single-sided printing / double-sided printing). Control. In the normal copier mode, since the user performs an operation in the vicinity of the apparatus, the sheet conveyance control is often performed so that the printing surface is discharged upward. This is called “face-up discharge”. On the other hand, in each mode of the printer and FAX, a “face-down discharge” method is used in which the user is not in the vicinity of the apparatus and the page order of discharged sheets is aligned.

  Therefore, the image forming apparatus 11 has a mechanism capable of switching between face-up discharge and face-down discharge according to the printing mode. This switching mechanism arranges a plurality of conveyance paths and a plurality of branching claws until the sheet that has passed through the fixing unit 23 is discharged to the sheet discharge tray 33, thereby discharging the sheet according to the print mode. It is configured to be

  FIG. 2 is an enlarged view around the registration roller 29 in the paper feeding unit of the image forming apparatus 11 shown in FIG. Here, the pre-registration roller drive motor (DC motor) 102a that drives the pre-registration roller (sheet conveyance member) 93a is a drive unit that applies the sheet P to the registration roller (butting member) 29.

  FIG. 3 is an enlarged view of the periphery of the registration roller 120 in the document conveying portion of the document reading device 12 provided in the image forming apparatus 11 shown in FIG. Here, the pre-registration roller drive motor (DC motor) 102b that drives the pre-registration roller (sheet conveying member) 121 is a drive unit that applies the sheet to the registration roller (butting member) 120.

  A configuration relating to the control unit of the image forming apparatus 11, particularly the sheet conveying apparatus 99 according to the present embodiment will be described with reference to a block diagram shown in FIG. The image forming apparatus 11 includes a sheet conveying device 99 and a main control unit 100. The sheet conveying device 99 will be described in detail later, but when it is provided in the image forming apparatus 11, a registration roller (abutting member) 29, a pre-registration roller (sheet conveying member) 93a, a pre-registration roller drive motor ( The drive unit 102a includes a load torque calculation unit (load torque detection unit) 111, a load torque variation detection unit (load torque variation detection unit) 112, and a thickness detection unit (collision timing load torque detection unit) 101. The main control unit 100 changes various settings in the image forming apparatus 11 according to the load torque detected by the thickness detection unit 101 and corresponding to the thickness of the sheet.

  The main control unit 100 performs overall control of the image forming apparatus 11. In FIG. 4, for example, the fixing unit 23 and the document reading apparatus 12 are controlled.

  The pre-registration roller drive motor (DC motor) 102a is a motor that drives the pre-registration roller 93a.

  The rotational speed detector 103 detects the angular speed ω of the DC motor 102a using a rotary encoder or the like. The current sensor 104 is a sensor that detects the drive current ia of the DC motor 102a using a Hall element or the like.

The speed control unit 105 performs feedback control based on the angular velocity command value ω ^* transmitted from the main control unit 100 and the angular velocity ω detected by the rotational speed detector 103, and a drive current command is obtained by the following equation (1). The value ia ^* is calculated.

i _a ^* = Ki (ω ^* −ω) (1)
Here, Ki is a constant.

The current control unit 106 performs feedback control based on the drive current command value i _a ^* output from the speed control unit 105 and the actual drive current i _a output from the current sensor 104, and is expressed by the following equation (2). The drive voltage command value v ^* is calculated.

^{_{v * = Kv (i a *}} -i a) (2)
Here, Kv is a constant.

The PWM circuit 107 generates a PWM signal for driving the driver 110 based on the drive voltage command value v ^* output from the current control unit 106. A triangular wave generator 108 and a comparator 109 are connected to the PWM circuit 107, and a PWM signal is generated according to the drive voltage command value v ^* .

The speed control unit 105 and the current control unit 106 are ASIC or 1 chip CPU, and calculate the output values (i _a ^* , v ^* ) in synchronization with the clock cycle.

Driver (drive control unit) 110 controls the driving current _{i a} of the DC motor 102a.

The load torque calculating section 111 calculates the angular velocity ω of the DC motor 102a output by the rotational speed detector 103, and the drive current _{i a} of the DC motor 102a which is output by the current sensor 104, the load torque TL based on the .

  The load torque fluctuation detection unit 112 monitors the load torque TL output from the load torque calculation unit 111 and detects the fluctuation of the load torque TL every predetermined time.

  The thickness detection unit 101 outputs the load torque TLx at the timing when the sheet collides with the registration roller 29 as a load torque corresponding to the thickness of the sheet. The output value (load torque TLx at the collision timing) at the thickness detection unit 101 may be used as it is as the sheet thickness as described below, or the load torque and the sheet thickness are associated with each other. The thickness of the sheet may be acquired from the output value using a table or a calculation formula.

  The clock pulse generator 113 performs operations of the speed control unit 105, the current control unit 106, and the PWM circuit 107, a load torque calculation operation of the load torque calculation unit 111, and a load torque fluctuation detection operation of the load torque fluctuation detection unit 112. The execution timing is controlled to be executed every clock cycle.

FIG. 5 shows temporal changes in the angular velocity ω of the DC motor 102a, the generated torque Te in the DC motor 102a, and the load torque TL of the DC motor 102a. In FIG. 5, the angular velocity ω is a command value (ω ^* ) output from the main control unit 100 to the speed control unit 105. Here, the generated torque Te is obtained by Equation (3) below from the current value _{i a.}

Te = p × φ × i _a (3)
Here, p is the number of pole pairs, and φ is the armature flux linkage.

  When the DC motor 102a is formed using a permanent magnet, the armature linkage magnetic flux φ changes depending on the temperature characteristics of the magnetic material. Therefore, a temperature sensor is provided in the DC motor 102a, and the value of the magnetic flux φ is set according to the temperature. By correcting, the calculation accuracy is increased. Alternatively, when a motor that forms a magnetic field by winding is used as the DC motor 102a, the magnetic flux φ is determined by the current to the winding, so that the influence of temperature can be eliminated.

  The load torque TL is obtained by a mathematical formula (4) described later. It is experimentally required that the load torque TLx at the time of collision increases as the mass of the seat increases.

  In the sheet conveying apparatus 99 of the present embodiment, the thickness detection unit 101 will be described later with reference to FIG. 8, but according to the value of the load torque TLx when the sheet collides with the registration roller 29 (collision timing). Then, a signal is sent to the main control unit 100 to change various settings in the image forming apparatus 11. However, the correspondence relationship between the magnitude of the load torque TLx and the sheet thickness is experimentally obtained in advance and stored in a memory (not shown) as a table, for example, and the thickness detection unit (sheet thickness detection means) 101 uses this table. , The sheet thickness may be acquired from the load torque TLx, and a signal may be sent to the main controller 100 to change various settings according to the sheet thickness.

  The dω necessary for the calculation of the equation of motion shown in Equation (4), which will be described later, is specified as the change in ω at that time based on the timing at which the load torque TL changes suddenly. Also, dt is set according to the control interval. Since each control in the sheet conveying apparatus 99 shown in FIG. 4 is executed in synchronization with the supplied clock pulse, dt corresponds to the clock pulse period (reciprocal of the clock frequency). The area of the resist region in the figure is proportional to the bending length.

  Next, a method for calculating the load torque TL will be described with reference to FIG. The load torque can be obtained by the equation of motion shown in the following formula (4).

  Here, J is the total moment of inertia of the mechanical system, Te is the torque generated by the motor, TL is the load torque, and ω is the angular velocity. Further, the load torque TL includes a damping component (ωD). D is an attenuation coefficient.

  Parameters necessary for the calculation are J, dω, dt, and Te, and the load torque TL can be obtained by substituting these numerical values into the above equation (4). J is a constant and is obtained in advance. Te is obtained from the current value ia using the above-described equation (3).

  As described above, dt corresponds to the clock pulse period. dω corresponds to the amount of change in the angular velocity ω in the clock pulse period.

  Next, a method for calculating the load torque TLx when the sheet collides with the registration roller 29 will be described with reference to FIG. The load torque fluctuation detecting unit 112 detects the fluctuation of the load torque at clock pulse cycle intervals, and the timing (t0, t1, t2) at which the load torque suddenly increases (fluctuates) and thereafter the fluctuation becomes small. To detect. Then, t1 and t2 which are timings of TLx are determined. The load torque fluctuation detection unit 112 instructs the thickness detection unit 101 to acquire the thickness by TLx.

  As described above, the sheet conveying device 99 outputs the load torque TLx of the DC motor 102a at the collision timing when the sheet collides with the registration roller 29 as the load torque corresponding to the thickness of the sheet. The load torque TLx at the collision timing is a stable value corresponding to the thickness of the sheet, and the collision does not require time. That is, when the sheet conveying device 99 is used, it is possible to detect the load torque according to the thickness of the sheet with high accuracy and without requiring time. Here, since the load torque TLx at the collision timing depends on the thickness of the sheet, the sheet conveying apparatus 99 can detect the thickness of the sheet accurately and quickly without providing a sensor.

  The same applies to the case where the sheet conveying device 99 is used for the document reading device 12. Instead of the DC motor 102 a driving the pre-registration roller 93 a, the DC motor 102 b of the document reading device 12 is connected to the document reading device 12. The pre-registration roller 121 is driven. The load torque TL of the DC motor 102b is calculated based on the drive current and angular velocity of the DC motor 102b.

  Next, a processing flow for setting the fixing temperature according to the paper thickness in the sheet conveying apparatus 99 will be described based on the flowchart shown in FIG.

  It is determined whether the paper thickness acquired by the thickness detection unit 101 using TLx is larger than a predetermined value (S1). If the thickness of the paper is larger than the predetermined value (Yes in S1), the main controller 100 sets the fixing temperature in the fixing unit 23 to a second temperature higher than the first temperature, which is the fixing temperature of the standard thickness paper. A signal is transmitted to (S2). If TLx is equal to or less than a predetermined value (No in S1), a signal is transmitted to the main controller 100 so that the fixing temperature is set to a first temperature that is a fixing temperature of a standard thickness sheet (S3).

  When the document reading device 12 includes the sheet conveying device 99, the amount of light emitted from the light source lamp may be adjusted according to the detected thickness of the sheet in the same flow as described above. By adjusting in this way, it is possible to prevent show-through from occurring in the read data. Specifically, instead of S1, it is determined whether or not the sheet thickness of the document is greater than or equal to a predetermined value. When it is determined that the sheet thickness of the document is smaller (thin) than the predetermined value, a signal is transmitted to the main control unit 100 so as to reduce the lamp light amount in the document reading device 12 instead of S3. If it is determined that the value is equal to or greater than the predetermined value, a signal is transmitted to the main control unit 100 so that the lamp light amount is set to the normal light amount instead of S2.

  Finally, the sheet conveying apparatus 99 may be configured by hardware logic, or may be realized by software using a CPU as follows. Specifically, the sheet conveying apparatus 99 is realized by a storage device such as a memory or a hard disk, and the sheet conveying apparatus 99 is realized by a central processing unit (CPU) of a computer and software executed by the CPU. This software is also stored in the storage device, read into the memory, and executed by the CPU.

  That is, the sheet conveying apparatus 99 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is a recording medium on which a program code (execution format program, intermediate code program, source program) of a control program for the sheet conveying apparatus 99, which is software for realizing the functions described above, is recorded so as to be readable by a computer. This can also be achieved by supplying the character conversion apparatus 10 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the sheet conveying apparatus 99 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Further, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range shown to the claim. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be suitably used for an apparatus that conveys and processes a sheet, for example, an image forming apparatus or a document reading apparatus.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view around a registration roller in a paper feeding unit of the image forming apparatus of FIG. 1. FIG. 2 is an enlarged view around a registration roller in a document transport unit of the document reading apparatus in FIG. 1. The block diagram which shows the structure of the control part of the image forming apparatus 11. It is a figure which shows the time change of angular velocity (omega) of DC motor, generated torque Te in DC motor 1, and load torque TL of DC motor. It is a figure explaining load torque TL. It is a figure which shows the load torque and angular velocity (omega) in time t0, t1, t2. It is a figure which shows the processing flow of a sheet conveying apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Image forming apparatus 12 Document reading apparatus 99 Sheet conveying apparatus 29,120 Registration roller (butting member) 29,
93a, 121 Pre-registration roller (sheet conveying member)
100 Main Control Unit 101 Thickness Detection Unit (Collision Timing Load Torque Detection Unit, Sheet Thickness Detection Unit)
102a, 102b Pre-registration roller drive motor (drive unit)
111 load torque calculation unit (load torque detection means),
112 Load torque fluctuation detecting unit (load torque fluctuation detecting means)

Claims (10)

In the sheet conveying device,
An abutting member;
A sheet conveying member that abuts the sheet against the abutting member;
Load torque detecting means for detecting the load torque of the drive section of the sheet conveying member;
Load torque fluctuation detecting means for detecting a fluctuation of the load torque and detecting a collision timing at which the seat collides with the abutting member;
A collision timing load torque detecting means for outputting the load torque at the collision timing as a load torque according to the thickness of the seat;
A sheet conveying apparatus comprising:   2. The sheet conveying apparatus according to claim 1, further comprising a sheet thickness detecting unit configured to detect the thickness of the sheet based on the load torque at the collision timing output from the collision timing load torque detecting unit. . The abutting member is a registration roller that temporarily stops the conveyance of the sheet,
The sheet conveying device according to claim 1, wherein the driving unit abuts the sheet against the registration roller.   An image forming apparatus comprising the sheet conveying device according to claim 1.   5. A fixing temperature control means for adjusting a fixing temperature for fixing the developer on the sheet based on the load torque at the collision timing detected by the collision timing load torque detecting means. The image forming apparatus described.   An original reading apparatus comprising the sheet conveying apparatus according to claim 1.   And a light amount control unit for adjusting a lamp light amount applied to the sheet when reading an original image on the sheet based on the load torque at the collision timing detected by the collision timing load torque detecting unit. The document reading device according to claim 6. A sheet thickness detection method in a sheet conveying apparatus provided with a sheet conveying member for abutting a sheet against an abutting member,
A load torque detecting step for detecting a load torque of the driving portion of the sheet conveying member;
A load torque fluctuation detecting step for detecting a fluctuation of the load torque and detecting a collision timing at which the seat collides with the abutting member;
A collision timing load torque detection step of outputting the load torque at the collision timing as a load torque according to the thickness of the seat;
A sheet thickness detection method comprising:   The program for functioning a computer as said each means of the sheet conveying apparatus of any one of Claim 1 to 3.   A computer-readable recording medium on which the program according to claim 9 is recorded.

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