JP2010260689A - Paper-feeding table lift controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain paper feeding performance at low cost in a stable fashion with an existing device structure remained intact without adding any special device. <P>SOLUTION: A paper-feeding table lift controller includes: a drive section for raising and lowering a paper feeding table 121; a measured value storing section 335 storing a measured value on a drive force of a drive motor 351 at timing when an upward position sensor 401 detects an upper surface position; a timing calculating section 333 calculating switch timing of operating speeds of the drive section in response to the measured value in storage; and a transition pattern storing section 332 storing a plurality of transition patterns, determining the transition between operating speeds of the drive section, and driving elapsed times of the drive section in correlation to each other. A drive control section 331 reads out the transition pattern correlated with calculated switch timing for drivably raising a paper feed table 121 in accordance with the transition pattern. Such raising drive causes an upper position detecting section 334 to provide a measured value in detection for storage in the measured value storing section 335 for use in calculating subsequent switch timing. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a sheet feed table raising / lowering control apparatus for an image forming apparatus that supplies a recording medium loaded in a sheet feeding tray to a conveyance path and performs a printing process on the recording medium.

  2. Description of the Related Art Conventionally, image forming apparatuses have been provided with a paper feed tray for storing recording media for printing. In this paper feed tray, a bundle of recording media of a predetermined size is stacked, and a paper feed such as a pickup roller is provided. The mechanism picks up the stacked recording medium on the uppermost surface and sends it out from the paper feed tray to the image forming unit via the transport path.

  In such a paper feed tray, a structure in which a paper feed table arranged at the bottom of the paper feed tray moves up and down according to the remaining amount of the recording medium is common. Specifically, in the paper feed tray, the recording medium is raised up to the height of the supply position of the transport path, and the stacked uppermost recording medium is sent out by the paper feeding means. Then, as the paper feeding operation proceeds, the paper feed table is raised to maintain a position where the pickup operation by the pickup roller can be performed.

  Here, in the paper feeding operation, when the driving force for raising the paper feed table is constant, the ascending speed varies depending on the weight of the recording medium loaded on the paper feed table, and there is a problem that stable driving cannot be performed. .

  In order to solve such a problem, a technology for detecting the load on the rising paper feed tray and controlling the rising speed at the start of the paper feed operation in accordance with the loading amount of the recording medium loaded on the paper feed tray. (For example, Patent Document 1).

JP 2005-138914 A

  However, in the technique disclosed in Patent Document 1, since the driving force is simply controlled according to the load on the paper feed table, the speed is maintained at a high speed to the paper feed position. When the paper table is raised, the target position may be overrun by the inertial force, and the inertial force may cause an excessive impact on the paper feed mechanism. For this reason, in the technique disclosed in Patent Document 1, the paper feed mechanism is robustly designed to withstand the excessive impact that occurs when the paper feed base is raised, or a device such as a weight measuring instrument for the paper feed base is provided. It becomes necessary to add, which causes an increase in manufacturing cost and an increase in size and complexity of the apparatus.

  Accordingly, the present invention has been made in view of the above points, and ascending / descending the sheet feed base of an image forming apparatus that can obtain an inexpensive and stable paper feed performance while maintaining the paper feed base as an existing apparatus configuration. It is an object to provide a control device.

  In order to solve the above-described problems, the present invention provides a paper feed table on which a recording medium is loaded, an upper position detection unit that detects the upper surface position of the recording medium loaded on the paper feed table, and an elevation of the paper feed table. A drive control unit that controls the operation of the drive unit, a measurement value storage unit that stores a measurement value of the drive force of the drive unit when the upper position detection unit detects the upper surface position, and a storage unit Based on the stored measurement value, a timing calculation unit that calculates a switching timing for changing the operation speed of the drive unit, a plurality of transition patterns that set a transition of the operation speed of the drive unit, and an elapsed drive time of the drive unit, And a transition pattern storage unit that stores the information in association with each other, and the drive control unit reads a transition pattern corresponding to the switching timing calculated by the timing calculation unit, and controls the drive unit according to the read transition pattern. The sheet supply table is driven upward, the measurements upper position detection unit detects this ascent movement, characterized in that is stored in the measurement value storage unit for the calculation of the next switching timing.

  According to such an invention, since the operation speed of the drive unit is changed according to a plurality of transition patterns that set the transition of the operation speed of the drive unit, the paper feed stage is moved at a high speed at the beginning of the paper feed operation to perform recording. Immediately before the medium stops at the paper feed position, the ascent of the paper feed table can be decelerated. Since this transition pattern is selected and read out in accordance with the timing calculated based on the measurement value previously detected by the upper position detection unit, the loading weight of the recording medium that changes as the paper feeding operation proceeds Stable paper feeding operation can be performed following the above.

  According to another aspect of the present invention, there is provided a paper feed table on which a recording medium is loaded, an upper position detection unit that detects an upper surface position of the recording medium loaded on the paper feed table, a drive unit that raises and lowers the paper feed table, And a drive control unit that controls the operation of the drive unit, wherein the drive control unit controls the drive unit according to a time function that changes the operation speed of the drive unit, and drives the paper feed table up.

  According to such an invention, the drive control unit controls the operation speed of the drive unit according to a predetermined time function, thereby following the loading weight of the recording medium that changes as the paper feeding operation proceeds, A stable paper feeding operation can be performed.

  As described above, according to these inventions, in an image forming apparatus that supplies a recording medium from a paper feed tray on which the recording medium is loaded, a device that measures the loading amount of the recording medium loaded on the paper feed tray, etc. Without adding a special device, it is possible to obtain an inexpensive and stable paper feeding performance while maintaining the existing device configuration.

It is a figure which shows the outline | summary of the printing paper conveyance path | route in the printing apparatus which concerns on 1st Embodiment. It is a side view which shows schematic structure of the paper feed mechanism which concerns on 1st Embodiment. FIG. 3 is a perspective view showing a paper feed tray provided in the printing apparatus according to the embodiment. It is explanatory drawing which shows the presence or absence of operation | movement of the upper position sensor and drive motor which concern on the paper feed mechanism which concerns on 1st Embodiment. It is a block diagram which shows the relationship between the module which concerns on the paper feed mechanism of the arithmetic processing part which concerns on 1st Embodiment, and a surrounding module. (A) is a graph which shows the transition diagram of the setting pattern of the driving force which concerns on 1st Embodiment, (b) is a graph which shows the time function which concerns on 2nd Embodiment. It is a flowchart figure which shows the outline | summary of the paper feed control which concerns on 1st Embodiment. It is a flowchart figure which shows the front measurement of the paper feed control concerning 1st Embodiment. It is a block diagram which shows the relationship between the module which concerns on the paper feed mechanism of the arithmetic processing part which concerns on 2nd Embodiment, and a surrounding module. (A) is a graph which shows the transition of the control current of the conventional driving force, (b) is a graph which shows the moving speed of the paper feed table in the conventional control, and (c) is the graph in the conventional control. FIG. 6 is a graph showing a deviation amount from a paper feed position of a paper feed tray. (A) is a graph which shows transition of the control current of the driving force in 1st Embodiment, (b) is a graph which shows the moving speed of a paper feed stand, (c) is a paper feed stand. FIG. 12 is a graph showing the amount of misalignment from a sheet feeding position of 121; (A) is a graph which shows transition of the control current of the driving force in 2nd Embodiment, (b) is a graph which shows the moving speed of a paper feed stand, (c) is a paper feed stand. It is a graph which shows the deviation | shift amount from the paper feed position. It is explanatory drawing regarding the setting conditions of the switching timing in 1st Embodiment.

[First Embodiment]
(Overall configuration of printing device)
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an outline of a printing paper conveyance path in the printing apparatus 100 according to the present embodiment. In the present embodiment, the printing apparatus 100 includes a plurality of ink heads on which a large number of nozzles are formed, discharges black or color ink from each of the ink heads, performs printing in units of lines, and records on the conveyance belt 160. An inkjet line color printer that forms a plurality of images on top of each other will be described as an example.

  As shown in FIG. 1, the printing apparatus 100 is an apparatus that forms an image on the surface of a sheet transported on an annular transport path. The transport path includes a paper feed system transport path FR that supplies the paper, and this paper feed. A general path CR from the system transport path FR through the head unit 110 to the paper discharge path DR and a reverse path SR branched and connected to the normal path CR are roughly configured.

  The recording medium 10 fed from one of the side paper feed trays 120 and the paper feed trays 130 (130a, 130b, 130c, 130d) in the paper feed system conveyance path FR is the leading portion of the recording medium 10. To the resist portion R which is the reference position. A head unit 110 having a plurality of print heads is provided on the conveyance direction side of the registration unit R, and the recording medium 10 is determined by printing conditions by a conveyance belt 160 provided on the opposite surface of the head unit 110. While being conveyed at a speed, an image is formed line by line with ink ejected from each print head.

  In the normal path CR, the conveyor belt 160 is wound around a driven roller 161 and a driving roller 162 disposed at the front end and the rear end of the surface facing the head unit 110 and rotates. Further, on the upper surface of the transport belt 160, ink heads of four colors are arranged side by side along the belt moving direction, and a head unit 110 that forms a color image so as to overlap a plurality of images is opposed to the head unit 110. Yes.

  The printed recording medium 10 is further conveyed on the normal route CR by a driving mechanism such as a roller. In the case of single-sided printing in which printing is performed only on one side of the recording medium 10, the paper is directly discharged to the paper discharge port 140 through the paper discharge route DR and discharged, and is provided as a receiving tray for the paper discharge port 140. It is stacked on the paper board 150 with the printing surface facing down.

  On the other hand, in the case of double-sided printing in which printing is performed on both sides of the recording medium 10, it is not guided to the paper discharge path DR when printing is completed, but is further transported in the housing and sent to the reverse path SR. A switching mechanism 170 for switching the transport path for back side printing is provided at a branch point between the paper discharge path DR and the reversal path SR. The recording medium 10 that has not been sent to the discharge path by the switching mechanism 170 is provided. , Is pulled into the reversal path SR.

  In the reversing path SR, a sheet is delivered from the normal path CR, and a so-called switchback is performed in which the sheet is reversed by reciprocating the sheet. Then, it is returned to the normal route CR via the switching mechanism 172 by a driving mechanism such as a roller, and is fed again via the registration portion R, and the back side is printed by the same procedure as the front side.

  Note that the printing apparatus 100 includes an arithmetic processing unit 330. The arithmetic processing unit 330 is configured by a processor such as a CPU or DSP (Digital Signal Processor), memory, hardware such as other electronic circuits, software such as a program having the function, or a combination thereof. Various functional modules are virtually constructed by appropriately reading and executing a program, and various functional modules for processing related to image data, operation control of each unit, and user operations are constructed by each constructed functional module. Process. In addition, an operation panel 340 is connected to the arithmetic processing unit 330, and an instruction and a setting operation by a user can be received through the operation panel 340.

(Paper feed mechanism)
In the present embodiment, a paper feed mechanism according to the present invention is provided in the side paper feed tray 120 of the paper feed system conveyance path FR. FIG. 2 is a side view schematically showing a schematic configuration of the side paper feeding mechanism according to the present embodiment, and FIG. 3 is a perspective view thereof.

  The paper feed mechanism according to the present invention is provided in the side paper feed tray 120 in the paper feed system transport path FR, and the recording medium 10 loaded in the side paper feed tray 120 is placed in the paper feed system transport path FR. It is a sending mechanism. Specifically, the paper feed mechanism includes a side paper feed tray 120, a side paper feed drive unit 220, a drive motor 351, a lower limit position sensor 402, and an upper position sensor 401. The side paper feed tray 120 is a box that stores a large number of recording media 10 in a stacked state. The side paper feed tray 120 is provided with a paper feed table 121 and a driving force transmission unit 125. Yes.

  The side paper feed drive unit 220 is a drive unit that is positioned above the side paper feed tray 120 and that sends the recording medium 10 stacked on the side paper feed tray 120 to the registration unit R. The side paper feed driving unit 220 includes a downstream pickup roller 220a and an upstream pickup roller 220b. The pickup rollers 220a and 220b are supported by a rotating shaft 222 and receive a rotational force from the rotating shaft 222. Is transmitted and driven to rotate. These pickup rollers 220a and 220b pick up and take in the uppermost recording medium 10 one by one from among the stacked recording media 10, and send it to the image forming section through the registration section R.

  The drive motor 351 is a self-propelled drive mechanism that is attached to the paper feed table 121 and moves up and down together with the paper feed table 121 by the driving force. The drive motor 351 is a feed that can pick up the recording medium 10 under the control of the arithmetic processing unit 330. Raise to paper position. The drive motor 351 transmits drive force to the side paper feed tray 120 via the drive force transmission unit 125 (pinion 125a and rack 125b), moves up and down with the paper feed table 121, and is loaded on the paper feed table 121. The medium 10 is moved up and down.

  The paper feed table 121 is a bottom plate member provided on the bottom surface in the side paper feed tray 120 and on which the recording medium 10 is stacked. In the present embodiment, triangular side walls 122 and 122 are provided in front of both sides of the paper feed path. The recording medium 10 loaded by the both side walls 122 and 122 is regulated.

  In addition, a driving force transmission unit 125 is provided on the outer surface of the both side walls 122 of the sheet feeding table 121, and the driving force of the driving motor 351 is transmitted to the sheet feeding table 121 via the driving force transmission unit 125. The The driving force transmission unit 125 is a rack and pinion member that converts the rotational force of the driving motor 351 into the vertical movement of the paper feed table 121.

Specifically, it is a member in which a pinion 125a, which is a circular gear, and a rack 125b are combined. The rotational force generated by the driving force of the driving motor 351 is converted into a linear motion by the pinion 125a and the rack 125b. At the same time, the sheet feeding table 121 is moved up and down. Due to the reduction ratio of the driving force transmission unit 125, as shown in FIG. 3B, the driving force (generated torque) Tm of the driving motor 351 opposes the weight M of the recording medium according to the transmission efficiency η. It is converted into a lifting force Fup that lifts the paper feed table 121. In addition, the rotational motion equation of the motor shaft at this time is expressed by the following equation.

  In the above equation, Tmo [N · m] is a load torque applied to the motor shaft as a static load, and Jm is an armature inertia moment of the motor (an approximate value ignoring the inertia moment viewed from the motor shaft). Further, ωm [rad / Sec] is the rotational angular velocity of the motor. In addition, when the drive torque becomes larger than the load torque (Tmo <Tm), the sheet feeding table starts to rise.

  The upper position sensor 401 is a sensor that is installed above the pickup rollers 220a and 220b and detects whether the upper surface of the recording medium 10 loaded on the paper feed table 121 is within the range of the optimum paper feed position. The upper position sensor 401 is, for example, a reflection type sensor that detects the presence or absence of the recording medium 10 loaded on the paper feed table 121. In the present embodiment, the upper position sensor 401 is turned on when the recording medium 10 is present, and the recording medium 10 is turned on. When there is not, it becomes OFF state. The upper position sensor 401 is a reflective sensor in the present embodiment, but is not limited to this form. For example, a transmissive sensor may be used.

  On the other hand, the lower limit position sensor 402 is a sensor that is installed below the side sheet feed tray 120 and detects whether or not the position of the sheet feed tray 121 is at the lower limit position.

(Configuration of arithmetic processing unit)
In the present embodiment, the control of the vertical movement of the paper feed tray 121 is performed by the arithmetic processing unit 330 described above. In particular, in the present embodiment, the vertical movement is controlled according to the operation state of the printing process by adjusting the moving speed of the ascending of the paper feed tray 121.

  FIG. 5 is a block diagram showing the relationship between the print processing and paper feed mechanism module of the arithmetic processing unit 330 and the surrounding modules, and FIG. 6 is a graph showing the transition diagram of the driving force setting pattern. . The “module” used in the description indicates a functional unit for achieving a predetermined operation, which is configured by hardware such as an apparatus or a device, software having the function, or a combination thereof. .

  As illustrated in FIG. 5, the arithmetic processing unit 330 includes an image processing unit 338 and a print processing operation detection unit 337 as modules relating to print processing. The image processing unit 338 is an arithmetic processing unit that performs digital signal processing specialized for image processing. The image processing unit 338 receives job data that is a printing processing unit, and converts image data necessary for printing included in the job data. Etc., and a module for executing printing.

  The image processing unit 338 controls the operation of a communication interface that receives job data, a color conversion circuit that converts an RGB print image into a CMYK print image, driving of ink heads of each color, and driving means of a conveyance path, and image formation An image forming control function for controlling the entire image forming process through the unit 341 is included. The image forming unit 341 is a module that controls the operation of the head unit 110 and each driving unit in the transport path to execute image formation. When print processing is executed in the image processing unit 338, a control signal indicating the processing operation is sent to the print processing operation detection unit 337. The image processing unit 338 is a module for identifying the type of the recording medium 10 for image processing included in the job data, and notifies the paper type acquisition unit 336 of the information.

  The paper type acquisition unit 336 is a module that acquires, as paper type data such as the size, type, or thickness of the recording medium 10 related to paper feeding, detected by the image processing unit 338. Then, the paper type acquisition unit 336 transmits the acquired paper type data to the transition pattern selection unit 333a during the printing process.

  The print processing operation detection unit 337 is a module that detects execution of print processing in the printing apparatus 100 based on a control signal sent from the image processing unit 338. Then, the print processing operation detection unit 337 notifies the drive control unit 331 of the detected execution state of the print processing.

  The arithmetic processing unit 330 includes a drive control unit 331, a timing calculation unit 333, an upper position detection unit 334, a measured value storage unit 335, and a transition pattern storage unit 332 as modules relating to the paper feed mechanism. ing.

  The upper position detection unit 334 is a module that detects the upper surface position of the recording medium 10 loaded on the paper feed table based on the detection result of the upper position sensor 401 loaded on the paper feed table. The timing calculation unit 333 is notified of the received signal. Further, the upper position detection unit 334 causes the measurement value storage unit 335 to store the measurement value detected by the raising of the paper feed tray 121 for calculation of the next switching timing.

  The measurement value storage unit 335 is a memory device that stores the measurement value of the driving force of the drive motor 351 at the time when the upper position detection unit 334 detects the upper surface position. The measured value storage unit 335 notifies the timing calculation unit 333 of the previous driving force of the driving motor 351 for each printing operation.

  The timing calculation unit 333 is a module that calculates a switching timing for changing the operation speed of the drive motor 351 based on the measurement value stored in the measurement value storage unit 335. Specifically, the timing calculation unit 333 reads the driving force of the driving motor 351 acquired by the upper position detection unit 334 in the previous paper feeding operation from the measurement value storage unit 335, and based on the read previous measurement value. Then, a predetermined coefficient is calculated to calculate the switching timing.

  The timing calculation unit 333 is provided with a transition pattern selection unit 333a. The transition pattern selection unit 333 a selects, from the transition pattern storage unit 332, the optimum transition pattern for the paper feeding operation based on the paper type data from the paper type acquisition unit 336 and the switching timing calculated by the timing calculation unit 333. It is a module that reads out. The read transition pattern is transferred to the drive control unit 331.

  The transition pattern storage unit 332 is a memory device that stores a plurality of transition patterns for setting transitions of the operation speed of the drive motor 351 and the drive elapsed time of the drive motor 351 in association with each other. In this embodiment, as shown in FIG. 6A, this transition pattern is a pattern in which the first inclination data indicating the rate of change of the driving force per time and the second inclination data are connected. These inclination data are functions that define the relationship between the driving force and the time transition, and the first inclination data and the second inclination data are linked with the switching timing as a singular point, and at this switching timing, The rate of increase in driving force is changed.

  Specifically, the transition pattern according to the present embodiment decelerates the sheet feeding table 121 and the first inclination data in which the increase rate of the driving force per unit time is increased in order to move the sheet feeding table 121 at a high speed. In this way, the pattern is formed by connecting the second inclination data in which the increase rate of the driving force is reduced. Further, the switching timing is a time when the control amount is reduced by about 5% to 10% from the previous upper limit detection amount (for example, immediately before the upper limit detection time), and the first inclination data is obtained at that time. To the second slope data.

  Note that a plurality of types of transition patterns are prepared depending on the type of recording medium such as size and paper quality, and are appropriately selected according to the paper type. This transition pattern is stored in the transition pattern storage unit 332 at the time of factory shipment or maintenance.

  The drive control unit 331 is a module that controls the operation of each function in the printing apparatus 100, such as each drive unit that drives each conveyance path and the switching mechanism 170. In particular, in the present embodiment, the drive control unit 331 calculates by the timing calculation unit 333. A transition pattern corresponding to the switched timing is input, and the drive motor 351 is controlled in accordance with the input transition pattern to drive the paper feed table 121 upward.

  Accordingly, as shown in FIG. 6A, the drive control unit 331, when a large amount of the recording medium 10 is loaded on the sheet feed table 121, the sheet feed table 121 is driven with the driving force by the first inclination. Immediately before the uppermost surface of the recording medium 10 loaded on the paper feed tray 121 reaches the paper feed position (switching timing), the operation speed is changed according to the second inclination.

(Up and down movement of the paper feed tray)
The upward movement of the sheet feeding table 121 described above is detected by the upper position sensor 401, and the drive motor is controlled based on the presence or absence of this detection. FIG. 4 is an explanatory diagram showing the presence / absence of operations of the upper position sensor and the drive motor according to the paper feed mechanism.

  Specifically, when the uppermost surface of the recording medium 10 loaded on the paper feed tray 121 is not at a position where it can be picked up (P1), the upper limit position signal from the upper position sensor 401 is turned off. In response to this, the control current for the drive motor 351 is increased, and when the torque of the motor becomes equal to or greater than a predetermined value, the position transition of the paper feed tray is started (P2). That is, when the driving torque (Tm) expressed by the above equation 1 becomes larger than the load torque (Tmo) (Tmo <Tm), the ascent of the paper feed table is started.

  During the ascent of the sheet feed table 121, the drive motor 351 is controlled in accordance with the transition pattern corresponding to the switching timing calculated by the timing calculation unit 333. At the switching timing (P3), the ascending speed of the sheet feed table 121 is in two stages. Can be switched to. That is, with the switching timing (P3) as a boundary, the transition is made from the first inclination in which the increase rate of the driving force per unit time is increased to the second inclination data in which the increase rate of the driving force is reduced, and the paper feed table 121. Reduces the rate of ascent.

  Next, when the sheet feeding table 121 is raised and the uppermost recording medium 10 loaded on the sheet feeding table 121 moves to a position where it can be picked up (P4), the upper position sensor 401 is turned on. In response to this, the control current for the drive motor 351 is interrupted, the ascending speed is decreased, and the transition of the ascending position is stopped (P5). At this time, the greater the load torque (Tmo), the greater the deceleration gradient (deceleration acceleration). Therefore, the greater the load of the recording medium, the sooner it stops.

  After that, when the printing operation is continued, the uppermost surface of the recording medium 10 loaded on the paper feed tray 121 is taken into the pickup rollers 220a and 220b, and the recording medium 10 is conveyed. As a result, a gap corresponding to the thickness (d) of the conveyed recording medium is generated on the uppermost surface of the recording medium 10 loaded on the paper feed tray 121, and the upper position sensor 401 is turned off (P6). -P5 is repeated (P7-P10). In this way, the drive motor 351 is controlled as the printing operation proceeds, and the paper feed position of the recording medium 10 is maintained.

(Paper feed mechanism control method)
By operating the paper feed control mechanism having the above configuration, the paper feed control method according to the present embodiment can be implemented. FIG. 7 is a flowchart showing an outline of paper feed control according to this embodiment, and FIG. 8 is a flowchart showing pre-measurement of paper feed control according to this embodiment.

  First, when a printing instruction is given, the arithmetic processing unit 330 determines whether or not there is a paper feeding operation last time (S101). If no data related to the previous paper feeding operation is stored ("N" in S101), pre-measurement is performed (S112). On the other hand, if there was a paper feeding operation last time and the data at that time is stored (“Y” in S101), the paper feeding operation is started immediately (S102).

  In the paper feeding operation, the drive control unit 331 first determines whether or not the upper position sensor 401 is in an OFF state (S103). When the upper position sensor 401 is not in the OFF state (“N” in S103), the state is maintained by the loop processing, and the paper feeding and printing processing is continued. On the other hand, in step S103, when the upper position sensor 401 is in the OFF state (“Y” in S103), the drive control unit 331 raises the sheet feed table 121 with the first inclination (S104). At this time, the drive control unit 331 reads a transition pattern corresponding to the switching timing calculated by the timing calculation unit 333 based on the previous measurement value of the driving force, and the drive control unit 331 reads the paper feed table 121 until the switching timing. (S105), the drive motor 351 is controlled according to the transition pattern at the switching timing, and the transition pattern is switched from the first inclination to the second inclination (S106).

  Next, in a state where the paper feed stand 121 is driven with the transition pattern to the second inclination, the drive control unit 331 monitors whether or not the upper position sensor 401 is turned on (S107). When the upper position sensor 401 is not in the ON state (“N” in S107), the ascending operation of the sheet feeding table 121 is continued by the loop process. On the other hand, when the upper position sensor 401 is in the ON state (“Y” in S107), the drive control unit 331 acquires the drive force of the drive motor 351 at that time, and stores it in the measured value storage unit 335 at the same time. The ascending operation is stopped (S108 and S109).

  Then, it is determined whether or not the set number of prints is completed (S110). If the set number of prints is not completed ("N" in S110), the next paper feeding operation is started. At this time, the timing calculation unit 333 calculates the switching timing for switching from the first inclination to the second inclination based on the measured value of the driving force acquired in the current paper feeding operation. On the other hand, when the set number of prints has been completed (“Y” in S110), the drive control unit 331 lowers the paper feed table 121, stops when the lower limit position sensor 402 detects it, and ends (S111). ).

  The pre-measurement method in step S112 described above is performed according to the following procedure prior to the paper feeding operation (S102) when the printing operation was not performed last time.

  First, as shown in FIG. 8, the drive control unit 331 determines whether or not the upper position sensor 401 is in an OFF state (S201). If the upper position sensor 401 is not in an OFF state (“N” in S201), the drive control unit 331 drives. The control unit 331 lowers the paper feed table 121 until the upper position sensor 401 is turned off (S202). On the other hand, if the upper position sensor 401 is in the OFF state (“Y” in S201), the drive control unit 331 stops the sheet feeding table 121 and makes it stationary (S203). The ascending operation of the sheet feeding table 121 is started at the first inclination (S204).

  Next, the drive control unit 331 determines whether or not the upper position sensor 401 is in an ON state in a state in which the paper feed stand 121 is performing the ascending operation (S205). When the upper position sensor 401 is not in the ON state (“N” in S205), the drive control unit 331 continues the ascending operation. On the other hand, when the upper position sensor 401 is in the ON state (“Y” in S205), the drive control unit 331 acquires the drive force of the drive motor 351 at that time, and saves it in the measured value storage unit 335 and increases at the same time. The operation is stopped (S206 and S207). Then, the pre-measurement is finished (S209), and the paper feeding operation is started (step S102 in FIG. 7).

  Thereby, in the next paper feeding operation, the timing calculation unit 333 can calculate the switching timing from the first inclination to the second inclination based on the measurement value acquired in the current paper feeding operation. Therefore, the drive control of the paper feed table 121 using the transition pattern can be executed even in the first paper feed operation, and the paper feed control with little variation in the paper feed position can be performed.

(Action / Effect)
According to the present embodiment, the drive control unit 331 reads the transition pattern based on the previous detection result by the upper position sensor 401 in the paper feeding operation, and changes the operation speed according to the transition pattern. At the start of the ascending operation, the sheet feeding table can be moved at a high speed, and the sheet feeding table 121 can be moved at a low speed immediately before the recording medium 10 reaches the sheet feeding position. As a result, as the paper feeding operation proceeds, the top surface position of the stacked recording media can be held within a certain range, and a stable paper feeding operation can be performed.

  10A and 10B show a comparison between the conventional control and the control according to the present embodiment. 10A (a) is a graph showing the transition of the control current of the driving force in the prior art, and FIG. 10A (b) is a graph showing the moving speed of the paper feed table in the conventional control. ) Is a graph showing the amount of deviation from the paper feed position of the paper feed tray in the conventional control. 10B (a) is a graph showing the transition of the control current of the driving force in the present embodiment, and FIG. 10B (b) is a graph showing the moving speed of the paper feed table 121. FIG. FIG. 6C is a graph showing the amount of deviation from the paper feed position of the paper feed tray 121.

  10A and B (a), the vertical axis represents the control current of the drive motor, and the vertical axis in FIGS. 10A and B (b) represents the moving speed of the paper feed table 121. FIGS. The vertical axis of) indicates the deviation distance from the paper feed position, and the horizontal axis indicates the passage of time from the start of control.

  In the control for raising the paper feed tray, for example, when the thickness of the recording medium 10 is 0.1 mm and the paper feed tray is lifted by more than 0.1 mm from the paper feed position, an overrun occurs. As shown in FIG. 10A, in the conventional control in which the motor control current is increased simply in proportion to the passage of time, when the loaded paper weight is light, the arrival time to the upper limit position is short, but the increase speed is light. Results in an overrun amount that is outside the allowable range.

  In the control according to the first embodiment, as shown in FIG. 10B, the rate of increase of the driving force is changed in two steps before and after the switching timing. The vehicle is decelerated just before it reaches, and the overrun amount is within the allowable range.

  More specifically, for example, as shown in FIGS. 11A and 11B, the switching timing is set within a predetermined range according to the load torque associated with the load amount of the recording medium at that time. You can set conditions. FIG. 11A illustrates the case where the load torque at a certain load amount is used as a reference, and shows the setting conditions of the switching timing at that moment.

  Specifically, the switching timing T1 determined by the setting condition 1 is set as the lower limit value, the switching timing T2 determined by the setting condition 2 is set as the upper limit value, and a range in which the switching timing can be set between these T1 and T2 (switching timing setting) Range). The setting conditions 1 and 2 are set before and after the timing at which the torque control amount becomes equal to or greater than the load torque and the paper feed tray starts to move. From the torque control amount at that time, the lower limit value (earliest) and the upper limit value (highest) This is a condition for calculating (late time).

  Setting condition 1 is to obtain the shortest time (the earliest time) from the minimum torque control amount to switching to the second inclination data, and the control amount is smaller than the load torque according to the load amount at that time. The time is increased until the control torque exceeds the load torque. As a result, the sheet feeding tray decelerates according to the above equation 1, and stops at the next sheet feeding before reaching the position where the upper limit is detected.

  Setting condition 2 is to obtain the longest time (latest time) from the maximum torque control amount to switching to the second inclination data, and the control amount is larger than the load torque corresponding to the load amount at that time. The first tilt data includes a torque control amount that is greater than or equal to the load torque. As a result, the sheet feeding tray decelerates according to the above equation 1, but the acceleration increases and the overrun amount increases.

  By setting the switching timing within such a range, as shown in FIG. 11, even if the setting value of each inclination data has a certain width, the pattern moves in parallel with the change in the loading amount. Only, the movement speed, acceleration, overrun amount, and control amount at the time of detecting the upper limit become a constant ratio, and the tray drive operation can be made to follow the cycle of the paper feed operation, and the overrun amount is within the allowable range. be able to.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the paper feed tray control calculates the switching timing based on the measurement value at the time of the previous paper feed, and the feed tray raising / lowering control is performed using the transition pattern corresponding thereto. The gist of the second embodiment is to control the drive motor 351 in accordance with a time function that changes the operation speed. FIG. 9 is a block diagram showing the relationship between the modules related to the paper feed mechanism of the arithmetic processing unit and the surrounding modules according to this modification. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the functions and the like are the same unless otherwise specified, and the description thereof is omitted.

  As shown in FIG. 9, in this embodiment, a time function calculation unit 339 is provided instead of the timing calculation unit 333, the transition pattern selection unit 333a, the measurement value storage unit 335, and the transition pattern storage unit 332 described above. Yes.

  In this embodiment, the time function calculation unit 339 is provided in the drive control unit 331, and controls the drive motor 351 according to the time function that changes the operation speed as shown in FIG. This is a module for driving the paper stand 121 upward. This time function is an exponential function that defines the relationship between the passage of time and the control amount of the driving force, and is a cube function in this embodiment. Specifically, when the upper position sensor 401 is in the OFF state, the sheet feeding table 121 starts to rise, the upper position sensor 401 is in the ON state, and the driving force at time T until the lifting operation is stopped by the brake. Defines the changes. A plurality of time functions are prepared according to the paper type, and the type data of the recording medium 10 from the paper type acquisition unit 336 is input, and the time function is appropriately selected.

  Further, the detection signal from the upper position detection unit 334 is input to the drive control unit 331, and when the upper position sensor 401 is OFF, the ascending operation is started, and when the upper position sensor 401 is ON, the ascending operation is stopped.

(Action / Effect)
According to the present embodiment, since the drive control unit 331 controls the operation speed of the drive motor 351 according to a predetermined time function, the drive control unit 331 supplies at an optimum operation speed according to the recording medium 10 loaded on the sheet feed table 121. The rise of the paper table 121 can be controlled.

  More specifically, since the drive control unit 331 changes the operation speed of the drive unit according to the drive elapsed time T of the drive motor 351, when the loading amount of the recording medium 10 loaded on the sheet feed table 121 is large, The weight increases, torque is required to raise the paper feed table 121, and the elapsed driving time becomes longer. Since the time function is defined to increase in a quadratic curve, the driving force of the driving motor 351 increases as the driving elapsed time T becomes longer. Here, when the loading amount of the recording medium 10 is large, the rising speed does not increase too much due to the weighting, and the sheet can be reached to the feeding position of the stacked sheets at an appropriate speed.

  On the other hand, when the amount of recording medium loaded on the paper feed tray 121 is small, the weight is reduced, and the drive elapsed time Tn when the paper feed stand 121 is raised is shorter than T. Since the time function is defined to increase in a quadratic curve, the driving force of the driving motor 351 can be reduced as the driving elapsed time Tn becomes shorter. Here, when the loading amount of the recording medium 10 is small, since the weight is small, the ascending speed is likely to increase. However, since it reaches the sheet feeding position in a short time, the ascending speed is not increased too much. And can reach the paper feeding position of the loaded paper at an appropriate speed.

  10A and 10C show a comparison between the conventional control and the control according to the present embodiment. 10A (a) is a graph showing the transition of the control current of the driving force in the prior art, and FIG. 10A (b) is a graph showing the moving speed of the paper feed table in the conventional control. ) Is a graph showing the amount of deviation from the paper feed position of the paper feed tray in the conventional control. 10C (a) is a graph showing the transition of the control current of the driving force in the present embodiment, and FIG. 10C (b) is a graph showing the moving speed of the paper feed table 121. FIG. FIG. 6C is a graph showing the amount of deviation from the paper feed position of the paper feed tray 121.

  10A and 10 (a), the vertical axis indicates the control current of the drive motor, and the vertical axis in FIGS. 10A and 10 (b) indicates the moving speed of the paper feed table 121. FIGS. The vertical axis of) indicates the deviation distance from the paper feed position, and the horizontal axis indicates the passage of time from the start of control.

  In the control for raising the paper feed tray, as in the first embodiment described above, for example, the thickness of the recording medium 10 is set to 0.1 mm, and the paper feed tray is raised beyond 0.1 mm from the paper feed position. If so, it becomes an overrun. As shown in FIG. 10A, in the conventional control in which the motor control current is increased simply in proportion to the passage of time, when the loaded paper weight is light, the arrival time to the upper limit position is short, but the increase speed is light. Results in an overrun amount that is outside the allowable range.

  In the control according to the second embodiment, as shown in FIG. 10C, when the load amount of the recording medium 10 is large, the weight increases and the drive elapsed time T becomes long. Therefore, the drive motor 351 is driven according to the time function. Power is increased. At this time, even if the loading capacity of the recording medium 10 is large, the increase speed does not increase too much due to the load, and the overrun amount is within the allowable range. On the other hand, as the loading amount of the recording medium 10 decreases, the load decreases and the elapsed driving time decreases, so that the driving force of the driving motor 351 is reduced according to the time function. At this time, even if the loading amount of the recording medium 10 is small and the rising speed is likely to increase, the elapsed time is shortened so that the rising speed is not excessively increased and the overrun amount is within an allowable range.

CR: Normal path DR: Paper discharge path FR ... Paper feed system transport path R ... Registration part SR ... Reverse path 10 ... Recording medium 100 ... Printing device 110 ... Head unit 120 ... Side paper feed tray 121 ... Paper feed tray 122, 122 ... both side walls 125 ... driving force transmission part 130 ... paper feed tray 140 ... paper discharge port 150 ... paper discharge stand 160 ... transport belt 161 ... driven roller 162 ... drive roller 170, 172 ... switching mechanism 220 ... side paper feed drive part 330 ... arithmetic processing unit 331 ... drive control unit 332 ... transition pattern storage unit 333 ... timing calculation unit 333a ... transition pattern selection unit 334 ... upper position detection unit 335 ... measurement value storage unit 336 ... paper type acquisition unit 337 ... print processing operation detection Unit 338 ... Image processing unit 339 ... Time function calculation unit 340 ... Operation panel 341 ... Image forming unit 351 ... Motor 401 ... upper position sensor 402 ... lower limit position sensor

Claims (2)

A paper feed tray on which recording media are loaded;
An upper position detection unit for detecting an upper surface position of the recording medium loaded on the paper feed table;
A drive unit for raising and lowering the paper feed table;
A drive control unit for controlling the operation of the drive unit;
A measurement value storage unit that stores a measurement value of the driving force of the driving unit at the time when the upper position detection unit detects the upper surface position;
A timing calculation unit that calculates a switching timing for changing the operation speed of the drive unit based on the measurement value stored in the storage unit;
A plurality of transition patterns for setting the transition of the operation speed of the drive unit, and a transition pattern storage unit for storing the drive elapsed time of the drive unit in association with each other, and the drive control unit is controlled by the timing calculation unit A transition pattern corresponding to the calculated switching timing is read, and the drive unit is controlled according to the read transition pattern to drive the paper feed table up, and the measured value detected by the upper position detection unit by the lift drive Is stored in the measured value storage unit for calculation of the next switching timing. A paper feed tray on which recording media are loaded;
An upper position detection unit for detecting an upper surface position of the recording medium loaded on the paper feed table;
A drive unit for raising and lowering the paper feed table;
A drive control unit that controls the operation of the drive unit, wherein the drive control unit controls the drive unit according to a time function that changes the operation speed of the drive unit, and drives the paper feed table up. A feed table lifting control device characterized by the above.