JP2011242495A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the consumption power associated with an operation to eliminate a deformation tendency of a belt of a electrostatic belt conveyance system.SOLUTION: An image forming apparatus equipped with belt driving means for intermittently driving a conveyance belt during power saving comprises a first voltage conversion circuit (conversion circuit A 19a) in which the primary-to-secondary conversion efficiency is approximately maximized during power saving, and a second voltage conversion circuit (conversion circuit A19b) in which the primary-to-secondary conversion efficiency is approximately maximized when the conveyance belt is driven during power saving. During driving the conveyance belt by the belt driving means, power supply control by the first voltage conversion circuit is switched to power supply control by the second voltage conversion circuit.

Description

  The present invention relates to an image forming apparatus. More specifically, the present invention relates to an image forming apparatus suitable for reducing power consumption.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, and a multifunction machine of these, for example, an apparatus including a recording head composed of a liquid discharge head is used, and a recording medium (hereinafter also referred to as paper, although the material is not limited). In addition, while transporting the recording medium, recording paper, transfer material, recording paper, etc., the image is formed by attaching ink as a liquid to the paper (recording, printing, printing, printing is also synonymous) There is a so-called ink jet type image forming apparatus.

  Further, for example, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier, and the electrostatic latent image on the photosensitive drum is developed with a toner or the like as a developer to be a visible image. There is an electrophotographic image forming apparatus in which a toner is transferred onto a recording paper by a transfer device to carry an image, and a toner image on the recording paper is fixed by a fixing device using pressure or heat.

  By the way, an electrostatic belt conveyance method is known as a method for conveying a recording medium in an image forming apparatus. In the electrostatic belt conveyance method, when the printing operation is not performed for a long time, there is a problem that the electrostatic conveyance belt (also simply referred to as a conveyance belt or a belt) is wrinkled, that is, the flatness of the belt cannot be ensured.

  To solve this problem, the power-saving mode (energy-saving mode, energy-saving mode, power-saving mode) is entered when the printing operation or panel operation by the user is not performed for a predetermined time with the image forming apparatus turned on. A technique is known in which the conveyor belt is driven intermittently at predetermined time intervals to ensure the flatness of the conveyor belt. Hereinafter, this is called a conveyor belt scooping operation.

  Patent Document 1 discloses a normal PSU (Power Supply Unit) and a high-efficiency PSU dedicated to charging a secondary battery and a secondary battery for the purpose of improving the efficiency of power consumption during energy saving. An invention is disclosed in which the overall efficiency is increased by switching the PSUs that are provided and operated according to the operating state of the image forming apparatus.

  However, when performing the above-described scooping operation of the conveyor belt, the belt is driven at a constant interval, and thus there is a problem that power consumption increases accordingly. Japanese Patent Application Laid-Open No. 2003-228561 discloses a configuration for switching a PSU that operates according to the operation state of the image forming apparatus, but does not disclose improvement in power efficiency related to the belt scraping operation. Could not be resolved.

  Therefore, the present invention provides a first voltage conversion circuit in which the primary secondary conversion efficiency at the time of power saving is substantially maximized, and a second voltage conversion in which the primary secondary conversion efficiency is substantially maximized when the conveyor belt is driven. Circuit, and when driving the conveyor belt, by switching from the power supply control by the first voltage conversion circuit to the power supply control by the second voltage conversion circuit, the power consumption associated with the belt scraping operation of the electrostatic belt conveyance system is reduced. An object of the present invention is to provide an image forming apparatus capable of suppressing the increase.

  In order to achieve this object, an image forming apparatus according to claim 1 is a first-secondary conversion efficiency in power saving in an image forming apparatus including a belt driving unit that intermittently drives a conveyor belt during power saving. A first voltage conversion circuit having a substantially maximum value, and a second voltage conversion circuit having a first-order secondary conversion efficiency that is substantially maximum when the conveyance belt is driven during power saving. At the time of driving, the power supply control by the first voltage conversion circuit is switched to the power supply control by the second voltage conversion circuit. Therefore, during the belt scraping operation of electrostatic belt conveyance in energy saving mode, only when driving the conveyance belt, the primary / secondary conversion efficiency by the power supply device is changed to one suitable for belt driving to save energy. During the mode period, power supply control is continuously performed using a voltage conversion circuit having a high primary and secondary conversion efficiency.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, a determination unit that determines variation in the load on the conveyor belt and a plurality of second voltage conversions having different primary and secondary conversion efficiencies. And selecting a second voltage conversion circuit that maximizes the primary-secondary conversion efficiency among a plurality of second voltage conversion circuits according to the determination result of the determination means.

  According to a third aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image forming apparatus further includes a determination unit that determines a variation in the load on the conveyor belt, and the second voltage conversion circuit is input. According to the analog voltage value, it has means capable of switching the primary and secondary conversion efficiency, and by inputting a different analog voltage value to the second voltage conversion circuit according to the determination result of the determination means, The primary and secondary conversion efficiency of the second voltage conversion circuit is maximized.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the first voltage conversion circuit uses the first voltage conversion circuit a predetermined time before the start of driving the conveyor belt by the belt driving unit. The power supply control is switched to the power supply control by the second voltage conversion circuit.

  ADVANTAGE OF THE INVENTION According to this invention, the increase in the power consumption accompanying the scraping operation | movement of the belt in an electrostatic belt conveyance system can be suppressed.

1 is a schematic side view illustrating an entire configuration of a mechanism unit of an embodiment of an image forming apparatus according to the present invention. 2 is a plan view illustrating an overall configuration of a mechanism unit of the image forming apparatus. FIG. 3 is a block diagram illustrating an example of a control unit of the image forming apparatus. FIG. It is a functional block diagram of an image forming apparatus having a conventional configuration. FIG. 5 is a circuit diagram relating to power saving control of the image forming apparatus illustrated in FIG. 4. 5 is a flowchart of a conveyor belt scooping operation performed by the image forming apparatus shown in FIG. 4. 5A is a graph showing the relationship between elapsed time and current consumption during the energy saving mode of the image forming apparatus shown in FIG. 4, and FIG. 5B is a graph showing the relationship between elapsed time and power consumption during the energy saving mode. (A) An explanatory diagram of AC-DC conversion by the image forming apparatus shown in FIG. 4, (b) a graph showing a conversion efficiency curve, (c) and a graph shown in FIG. It is the graph which added the conversion efficiency. (A) It is explanatory drawing of AC-DC conversion by the image forming apparatus which concerns on this invention, (b) The graph which shows a conversion efficiency curve, (c), The graph which attached the conversion efficiency in each time slot | zone. 1 is a functional block diagram of an image forming apparatus according to a first embodiment. FIG. 11 is a circuit diagram relating to power saving control of the image forming apparatus illustrated in FIG. 10. 11 is a flowchart of a conveyor belt scooping operation performed by the image forming apparatus shown in FIG. 10. It is an example of a regulator selection table. FIG. 6 is a functional block diagram of an image forming apparatus according to a second embodiment. FIG. 15 is a circuit diagram relating to power saving control of the image forming apparatus illustrated in FIG. 14. 15 is a flowchart of a conveyor belt scooping operation performed by the image forming apparatus shown in FIG. FIG. 10 is a functional block diagram of an image forming apparatus according to a third embodiment. FIG. 18 is a circuit diagram relating to power saving control of the image forming apparatus illustrated in FIG. 17. It is an example of a regulator setting table. FIG. 18 is a flowchart of a conveyor belt scooping operation executed by the image forming apparatus shown in FIG. 17. FIG. 10 is another example of a flowchart of the conveyor belt scooping operation performed by the image forming apparatus according to the fourth embodiment.

  Hereinafter, the configuration according to the present invention will be described in detail based on embodiments shown in the drawings.

(Configuration of image forming apparatus)
1 and 2 are diagrams showing a schematic configuration of an ink jet recording apparatus as an example of an image forming apparatus. FIG. 1 is a top view and FIG. 2 is a side view of the front of the apparatus. Hereinafter, an inkjet image forming apparatus will be described as an embodiment of the image forming apparatus, but an image forming apparatus of another printing system such as an electrophotographic system may be used. Also, the recording medium is not limited to paper.

  In this ink jet recording apparatus, a carriage 100 is held by a guide lot 104 that is horizontally mounted on left and right side plates (not shown). The carriage 100 is moved and scanned in the main scanning direction by the main scanning motor 105 via the timing belt 102 passed between the driving pulley 106 and the driven pulley 107.

  The carriage 100 includes a recording head (simply referred to as a head) 120 including four liquid discharge heads that discharge ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (K). Are arranged in a sub-scanning direction perpendicular to the main scanning direction, and are mounted with the ink discharge port direction facing downward. Although an independent droplet discharge head is used here, a configuration in which one or a plurality of heads having a plurality of nozzle rows that discharge droplets of recording liquid of each color can be used. Further, the number of colors and the arrangement order are not limited to this.

  Examples of the ink jet head constituting the recording head 120 include a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a metal phase caused by a temperature change. A shape memory alloy actuator using a change, an electrostatic actuator using an electrostatic force, or the like provided as pressure generating means for generating a pressure for discharging a droplet can be used.

  The carriage 100 is provided with an encoder scale 103 having slits along the main scanning direction. The carriage 100 is provided with an encoder sensor (not shown) for detecting the slit of the encoder scale 103, and these constitute a linear encoder 213 (see FIG. 3) for detecting the position of the carriage 100 in the main scanning direction. ing.

  On the other hand, a conveyance belt (electrostatic conveyance belt) 101 is provided as a conveyance means for electrostatically adsorbing the recording paper 108 and conveying it at a position facing the recording head 120. The conveyance belt 101 is an endless belt, and is configured to wrap around the conveyance roller 109 and the tension roller 110 so as to circulate in the belt conveyance direction (sub-scanning direction). Is charged (charged).

  Next, an outline of a control unit as a control unit of the image forming apparatus will be described. FIG. 3 is a block diagram showing an outline of the control unit 200 of the ink jet recording apparatus.

  The control unit 200 also serves as a means for controlling the conveyance operation of the recording paper 108 and the movement operation of the recording head 120, which controls the entire image forming apparatus, the program executed by the CPU 201, and other fixed data. ROM 202 for storing, RAM 203 for temporarily storing image data and the like, rewritable non-volatile memory (NVRAM) 204 for holding data even while the apparatus is powered off, various signal processing for image data, And an ASIC 205 for processing input / output signals for controlling image processing for performing rearrangement and the like and other devices.

  Further, the control unit 200 generates a host I / F 206 for transmitting and receiving data and signals to and from the host side, and a drive waveform for driving the recording head 120, and selects a pressure generating unit for the recording head 120. A print control unit 207 that outputs image data to be driven and various data associated therewith to the head driver 208, a main scanning motor driving unit 209 for driving the main scanning motor 105, and sub scanning for driving the sub scanning motor 210. I / O for inputting detection pulses from a motor drive unit 211, an AC bias supply unit 212 for supplying an AC bias to the charging roller 113, a linear encoder 213 and a wheel encoder 214, and other various sensors. O215 etc. are provided.

  Further, an operation panel 216 (display unit) for inputting and displaying information necessary for the apparatus is connected to the control unit 200.

  The control unit 200 prints data generated by the printer driver 217 of a host device (information processing device, external device) such as an information processing device such as a personal computer, an image reading device such as an image scanner, or an imaging device such as a digital camera, and printing. A job or the like is received by the host I / F 206 via a cable or a network.

  Then, the CPU 201 of the control unit 200 reads and analyzes the print data in the reception buffer included in the host I / F 206, performs necessary image processing, data rearrangement processing, and the like in the ASIC 205, and sends it to the print control unit 207. The image data and the drive waveform are output from the print control unit 207 to the head driver 208 at a required timing.

  For example, even when font data is stored in the ROM 202, the dot pattern data for outputting the image is generated by the host-side printer driver 217 and converted to bitmap data and transferred to the image forming apparatus. You may make it do.

  A drive waveform generation unit (not shown) of the print control unit 207 includes a D / A converter and an amplifier that perform D / A conversion on drive pulse pattern data stored in the ROM 202 and read by the CPU 201. A drive waveform composed of a drive pulse or a plurality of drive pulses is output to the head driver 208.

  The head driver 208 forms a drive pulse that forms a drive waveform supplied from the drive waveform generation unit of the print control unit 207 based on image data (dot pattern data) corresponding to one line of the recording head 120 input serially. Is selectively applied to the pressure generating means of the recording head 120 to drive the recording head. The head driver 208, for example, shifts the level of the shift register that receives a clock signal and serial data that is image data, a latch circuit that latches the register value of the shift register using a latch signal, and the output value of the latch circuit. A level conversion circuit (level shifter) and an analog switch array (switch means) whose on / off is controlled by this level shifter, etc., and the required drive pulse included in the drive waveform by controlling the on / off of the analog switch array Is selectively applied to the pressure generating means of the recording head 120.

(Conveyor belt scraping operation)
[Reference example]
First, for comparison with the image forming apparatus according to the present invention, a preferential reference example (conventional configuration) will be described with reference to FIGS.

  FIG. 4 is a functional block diagram of the image forming apparatus (conventional configuration). In this image forming apparatus, a power supply voltage (AC 100 V) is converted into a DC voltage (voltage 2) by a PSU (power supply device) 10 and supplied to a control unit (controller, CTL) 20. In addition, the control unit 20 (referred to as a control unit related to power supply control in the control unit 200 in FIG. 3) controls the motor driver 21 (corresponding to the sub-scanning motor drive unit 211 in FIG. 3) for the electrostatic conveyance belt. A drive signal is output to the drive motor 31 (corresponding to the sub-scanning motor 210 in FIG. 3). Further, the belt rotation amount of the electrostatic conveyance belt 30 (corresponding to the conveyance belt 101) is converted into a pulse amount by the encoder sensor 32, and fed back to the calculation unit 22 of the control unit 20 to adjust the motor drive signal. It is.

  FIG. 5 is a circuit diagram relating to energy saving control in the PSU 10 shown in FIG. First, the power supply voltage (AC 100 V) on the primary side (AC) is smoothed by the diode bridge 11. On the secondary side (DC), the voltage of the transformer 15 is monitored by the shunt regulator 16 and the resistance, and fed back to the primary side through the photocoupler (secondary side photocoupler 13b, primary side photocoupler 13a). The generated voltage 1 (for example, 37V) is created.

  This voltage 1 is used for a drive system (motor, head, paper feed clutch, etc.) in a printing operation. Further, the voltage 1 is stepped down by the regulator 18 to create a voltage 2 (voltage 2 <voltage 1; for example, 10 to 20V). This voltage 2 is a voltage dedicated to the conveyor belt scraping operation, and is supplied to the motor 31 to execute the belt scraping operation. Here, since the belt scraping operation only drives the belt at a low speed, it is more efficient to use the voltage 2 than the voltage 1. The CPU and sensor are driven at a low voltage (not shown) (for example, 3.3V to 5V).

  FIG. 6 is a flowchart of the conveyor belt scooping operation performed by the image forming apparatus shown in FIG. First, when the power is turned on (S101), a standby state is entered (S102), and when a print job is received (S103: YES), printing is executed (S104). In the standby state, when a predetermined time (for example, 15 minutes) or more has elapsed since the previous printing (S105: YES), and during that time there is no user operation (S106: NO), the mode shifts to the energy saving mode (S107). ). At this time, as described above, the voltage 1 is stopped and switched to the voltage 2, and is fixed to the voltage 2 during the energy saving mode.

  In the energy saving mode, when the energy saving mode is entered or when a predetermined time (for example, 30 seconds) or more has elapsed since the previous belt removing operation (S108: YES), the belt removing operation is executed. (S109). The belt scooping operation is executed by driving the motor 31 for 1 second, for example.

  FIG. 7A is a graph showing the relationship between elapsed time and current consumption during the energy saving mode of the image forming apparatus shown in FIG. FIG. 7B is a graph showing the relationship between elapsed time and power consumption during the energy saving mode. From FIG. 7, it can be seen that during the belt scraping operation, the motor 31 is driven, so that the current consumption increases and the power consumption increases accordingly. Here, the current consumption increases, but the voltage is fixed at the voltage 2 as described above.

  As described above, the image forming apparatus shown in FIG. 4 performs AC-DC conversion by the conversion circuit 19 (FIG. 5) of the PSU 10 (FIG. 8A). Here, since the AC-DC conversion efficiency changes depending on the secondary-side current consumption, the AC-DC conversion circuit is normally configured so that the efficiency becomes maximum at the secondary-side power consumption in the energy saving mode. Is done.

  FIG. 8B shows a graph showing a relationship between the secondary side consumption current and the AC-DC conversion efficiency (hereinafter referred to as a conversion efficiency curve). As shown in FIG. 8B, the conversion efficiency curve is configured so that the conversion efficiency is maximized (in this example, efficiency is 90%) at the secondary side power consumption (100 mA) in the energy saving mode. However, as described above, since the current consumption increases (900 mA) during the belt scraping operation, the conversion efficiency decreases (efficiency 80%). FIG. 8C shows a graph in which conversion efficiency in each time zone is added to the graph shown in FIG. 7B.

[First Embodiment]
Therefore, an image forming apparatus according to the present invention is an image forming apparatus provided with belt driving means (motor driver 21, motor 31 and the like) that intermittently drives a conveyor belt during power saving. A first voltage conversion circuit (conversion circuit A19a, regulator A18a) with which conversion efficiency is substantially maximum, and a second voltage conversion circuit with which primary and secondary conversion efficiency is substantially maximum when driving the conveyor belt during power saving (Conversion circuit B19b, regulator B18b), and by the control unit (control unit 20), when the conveyor belt is driven by the belt driving means, the power supply control by the second voltage conversion circuit is changed from the power supply control by the first voltage conversion circuit. To switch to.

  That is, with respect to the drive circuit at the time of the belt belt scraping operation in the energy saving mode, the circuit is optimized for conversion efficiency when the belt scraping operation is not performed (when the belt is not driven). There are two circuits, a circuit that is sometimes optimal (when the belt is driven), and the circuit is switched between when the belt scraping operation is performed and when it is not performed.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS. In addition, about the structure similar to what is shown in FIGS. 4-8, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 9A, the image forming apparatus according to the present embodiment outputs a signal from the control unit 20 to the PSU 10, and switches between the conversion circuit A 19a and the conversion circuit B 19b to be driven. Here, the conversion circuit A 19a and the conversion circuit B 19b are designed to have different conversion efficiency curves. As shown in FIG. 9B, in the AC-DC conversion by the conversion circuit A 19a, the conversion efficiency curve A (Corresponding to the conversion efficiency curve in FIG. 8B), and in the AC-DC conversion by the conversion circuit B19b, the conversion efficiency indicated by the conversion efficiency curve B is obtained.

  The image forming apparatus including the conversion circuit A 19a and the conversion circuit B 19b performs AC-DC conversion using the conversion circuit A 19a in the energy saving mode except during the belt scraping operation, and starts the belt scraping operation in the energy saving mode. When switching to the conversion circuit B19b to perform AC-DC conversion and returning to AC-DC conversion by the conversion circuit A19a at the end of the belt scraping operation, as shown in FIG. The image forming apparatus is operated at a conversion efficiency (90% in this embodiment).

  FIG. 10 is a functional block diagram of the image forming apparatus according to the present embodiment. The point that the conversion efficiency control signal is supplied from the control unit 20 is different from the configuration shown in FIG.

  FIG. 11 is a circuit diagram related to energy saving control in the PSU 10 shown in FIG. In FIG. 11, the conversion circuit A 19a corresponds to the regulator A 18a, the conversion circuit B 19b corresponds to the regulator B 19b, and the PSU 10 receives the conversion efficiency control signal from the control unit 20. The conversion efficiency control signal is input to the enable terminals (ENBL) of the regulator A 18a and the regulator B 18b to switch the regulator drive. In the present embodiment, the regulator A is driven when the conversion efficiency control signal = L, and the regulator B is driven when the conversion efficiency control signal = H.

  FIG. 12 is a flowchart of the conveyor belt scooping operation performed by the image forming apparatus according to the present embodiment. First, when the power is turned on (S201), the regulator A is driven with the conversion efficiency control signal = L (S202), and enters a standby state (S203). When a print job is received from this state (S204: YES), printing is executed (S205). In the standby state, when a predetermined time (for example, 15 minutes) or more has elapsed since the previous printing (S206: YES), and there is no user operation during that time (S207: NO), the process shifts to the energy saving mode (S208). ). At this time, as described above, the voltage 1 is stopped and switched to the voltage 2, and is fixed to the voltage 2 during the energy saving mode.

  In the energy saving mode, when the energy saving mode is entered or when a predetermined time (for example, 30 seconds) or more has elapsed since the last belt scraping operation (S209: YES), the conversion efficiency control signal = H and the regulator B Is driven (S210), and the belt scraping operation is executed (S211). After the belt scraping operation is completed, the regulator A is driven with the conversion efficiency control signal = L (S212). Thus, in the present embodiment, the regulator B is driven during the conveyor belt scraping operation.

  By doing in this way, the increase in the power consumption accompanying the belt scraping operation | movement in an electrostatic belt conveyance system can be suppressed. Hereinafter, other embodiments of the image forming apparatus according to the present invention will be described. Note that a description of the same points as in the first embodiment will be omitted.

[Second Embodiment]
Here, it is known that the electrostatic conveyance belt may have variations in load weight. When there is variation in the weight of the load as described above, the power consumption necessary for driving the motor also varies. Therefore, it is preferable to adjust the conversion efficiency curve according to the required power consumption.

  Therefore, the image forming apparatus according to the present embodiment further includes a determination unit (an encoder sensor 32, a calculation unit 22, etc.) that determines the variation in the load on the conveyor belt, and a plurality of second types having different primary and secondary conversion efficiencies. A second voltage conversion circuit that includes a voltage conversion circuit (regulator A18a to regulator I18i) and has the maximum primary-secondary conversion efficiency among the plurality of second voltage conversion circuits according to the determination result of the determination unit. The circuit is selected.

  The variation in the load can be determined based on the number of encoder pulses from the encoder sensor 32 fed back when a constant current is passed through the motor 31 for a certain period of time. It will be light. A regulator having a different conversion efficiency curve is provided according to the load variation (the number of encoder pulses) thus obtained.

  Here, for example, as shown in FIG. 13, the selection of the regulator is stored in advance as a table (regulator selection table) in the storage unit (ROM 202 or the like) with the correspondence relationship between the number of encoder pulses to be measured and the regulator to be selected. You can let it go. In the present embodiment, a configuration in which nine efficiency curves (regulators A to I) are selected and AC-DC conversion is performed according to load variation will be described. However, the number of regulators used is an example, and It is not limited to.

  FIG. 14 is a functional block diagram of the image forming apparatus according to the present embodiment. The point from which three conversion efficiency control signals (conversion efficiency control signals 0 to 2) are supplied from the control unit 20 is different from the configuration shown in FIG.

  FIG. 15 is a circuit diagram relating to energy saving control in the PSU 10 shown in FIG. Three conversion efficiency control signals output from the control unit 20 are input to the PSU 10. The PSU 10 includes a decoder 40, and the decoder 40 controls enable of the nine regulators 18A to 18I. As the decoder 40, a general-purpose logic IC (functional model number 138 or the like) may be used.

  FIG. 16 is a flowchart of the conveyor belt scooping operation performed by the image forming apparatus according to the present embodiment. First, when the power is turned on (S301), the regulator A is selected by the conversion efficiency control signal (S302), and a standby state is entered (S303). When a print job is received from this state (S304: YES), printing is executed (S305). In the standby state, when a predetermined time (for example, 15 minutes) or more has elapsed since the previous printing (S306: YES), and there is no user operation during that time (S307: NO), the mode shifts to the energy saving mode (S308). ). At this time, as described above, the voltage 1 is stopped and switched to the voltage 2, and is fixed to the voltage 2 during the energy saving mode.

  In the energy saving mode, when the energy saving mode is entered, or when a predetermined time (for example, 30 seconds) or more has elapsed since the previous scraping operation (S309: YES), the motor 31 is operated for a predetermined time (for example, 1 second). At the same time, the number of encoder pulses is counted, and a regulator corresponding to the counting result is selected from the regulator selection table and stored (S311). The stored regulator is selected (S312), the belt scraping operation is executed (S313), and after the belt scraping operation is finished, the regulator A is driven by the conversion efficiency control signal. (S314). Thereafter, the belt is trimmed by the selected regulator (S312 to S315).

  According to the present embodiment, it is possible to further consider variations in the load on the conveyor belt. Even when the loads vary, the variation is corrected and the belt is scraped in the electrostatic belt conveyance method. The accompanying increase in power consumption can be suppressed.

[Third Embodiment]
In the second embodiment, a plurality of conversion efficiency curves are switched using a plurality of control lines. However, conversion efficiency can be further improved by performing stepless control using analog values. It becomes possible.

  Therefore, the image forming apparatus according to the present embodiment further includes a determination unit (an encoder sensor 32, a calculation unit 22, and the like) that determines variations in the load on the conveyor belt, and a second voltage conversion circuit (regulator 18). ) Has means capable of switching the primary / secondary conversion efficiency according to the input analog voltage value, and the analog voltage value which is different to the second voltage conversion circuit according to the determination result of the determination means. To maximize the primary / secondary conversion efficiency of the second voltage conversion circuit.

  FIG. 17 is a functional block diagram of the image forming apparatus according to the present embodiment. The point that a conversion efficiency control signal that is an analog value is supplied from the control unit 20 is different from the above-described configuration.

  FIG. 18 is a circuit diagram related to energy saving control in the PSU 10 shown in FIG. In the present embodiment, the regulator 18 is an IC having a terminal for switching the conversion efficiency with an analog value, and has an optimal efficiency curve for a current consumption of 1 A at 1 V, and thereafter has a linear characteristic. Is used. The control unit 20 refers to a regulator setting table as shown in FIG. 19 according to the counted number of encoder pulses, and outputs a conversion efficiency control signal (analog value) and inputs it to the PSU 10.

  FIG. 20 is a flowchart of the conveyor belt scooping operation performed by the image forming apparatus according to the present embodiment. First, when the power is turned on (S401), the conversion efficiency control signal is set to an efficiency curve for current consumption when the belt is not driven (S402), and a standby state is entered (S403). When a print job is received from this state (S404: YES), printing is executed (S405). In the standby state, when a predetermined time (for example, 15 minutes) or more has elapsed since the previous printing (S406: YES), and there is no user operation during that time (S407: NO), the process shifts to the energy saving mode (S408). ). At this time, as described above, the voltage 1 is stopped and switched to the voltage 2, and is fixed to the voltage 2 during the energy saving mode.

  In the energy saving mode, when the energy saving mode is entered, or when a predetermined time (for example, 30 seconds) or more has elapsed since the previous scraping operation (S409: YES), the motor 31 is operated for a predetermined time (for example, 1 second). At the same time, the number of encoder pulses is counted, and a voltage value corresponding to the counting result is selected from the regulator setting table and stored (S411). The stored voltage value is selected (S412), the belt scraping operation is executed (S413), and after the belt scraping operation is completed, the current consumption when the belt is not driven is also converted by the conversion efficiency control signal. This is set to the efficiency curve (S414). Thereafter, the belt scraping operation is performed based on the stored voltage value (S412 to S415).

  In this way, it is possible to further consider variations in the load of the conveyor belt, and even if the load varies, the variation is corrected and the belt is scraped in the electrostatic belt conveyance method. The accompanying increase in power consumption can be suppressed.

[Fourth Embodiment]
Here, immediately after the switching of the regulator, the voltage behavior is not stable, and a desired efficiency curve may not be obtained due to variations in IC characteristics. Therefore, the image forming apparatus according to the present embodiment further performs the second voltage conversion circuit from the power supply control by the first voltage conversion circuit (conversion circuit A19a) before the start of driving of the conveyor belt by the belt driving unit. Switching to power supply control by (conversion circuit B19b) is performed. The predetermined time before here is preferably, for example, 10 to 300 msec. In this embodiment, an example in which switching is performed before 100 msec will be described.

  FIG. 21 is a flowchart of the conveyor belt scooping operation performed by the image forming apparatus according to the present embodiment. First, when the power is turned on (S501), the regulator A is driven with the conversion efficiency control signal = L (S502), and enters a standby state (S503). When a print job is received from this state (S504: YES), printing is executed (S505). In the standby state, when a predetermined time (for example, 15 minutes) or more has elapsed since the previous printing (S506: YES), and there is no user operation during that time (S507: NO), the mode shifts to the energy saving mode (S508). ). At this time, as described above, the voltage 1 is stopped and switched to the voltage 2, and is fixed to the voltage 2 during the energy saving mode.

  In the energy saving mode, when the energy saving mode is entered, or when a predetermined time (for example, 30 seconds) has elapsed since the previous scraping operation (S509: YES), the regulator B is driven with the conversion efficiency control signal = H. (S510), wait for the elapse of a predetermined time (100 msec) (S511), execute the belt scooping operation (S512), and wait for the elapse of the predetermined time (100 msec) after the belt scooping operation ends ( S513), the regulator A is driven with the conversion efficiency control signal = L (S514).

  By thus switching the conversion circuit after waiting for a predetermined timing, it is possible to further stably suppress an increase in power consumption accompanying the belt scraping operation in the electrostatic belt conveyance method.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

10 PSU (Power supply unit)
11 Diode bridge 12 Power supply control IC
13a Primary side photocoupler 13b Secondary side photocoupler 14 FET
15 Transformer 16 Shunt Regulator 17 Electrolytic Capacitor 18 Regulator 18a to i Regulator A to I
19 Conversion Circuit 19a Conversion Circuit A
19b Conversion circuit B
20 Control unit (CTL)
21 Motor Driver 22 Calculation Unit 30 Electrostatic Conveyance Belt 31 Motor (Electrostatic Conveyance Belt Drive Motor)
32 Encoder sensor 40 Decoder 100 Carriage 101 Conveying belt 102 Timing belt 103 Encoder scale 104 Guide lot 105 Main scanning motor 106 Driving pulley 107 Driven pulley 108 Recording medium (recording paper)
109 Conveying roller 110 Tension roller 113 Charging roller 120 Recording head (head)
200 control unit 201 CPU
202 ROM
203 RAM
204 NVRAM
205 ASIC
206 Host I / F
207 Print control unit 208 Head driver 209 Main scanning motor driving unit 210 Sub scanning motor 211 Sub scanning motor driving unit 212 AC bias supply unit 213 Linear encoder 214 Wheel encoder 215 I / O
216 Operation panel (display unit)
217 Printer driver

JP 2008-233265 A

Claims (4)

In the image forming apparatus provided with a belt driving unit that intermittently drives the conveyor belt during power saving,
A first voltage conversion circuit in which primary and secondary conversion efficiency during power saving is substantially maximized;
A second voltage conversion circuit having a primary and secondary conversion efficiency that is substantially maximized when the conveyor belt is driven during power saving;
An image forming apparatus that switches from power supply control by the first voltage conversion circuit to power supply control by the second voltage conversion circuit when the conveyor belt is driven by the belt driving unit. Determining means for determining variations in load of the conveyor belt;
A plurality of the second voltage conversion circuits having different primary and secondary conversion efficiencies;
The second voltage conversion circuit that maximizes the primary-secondary conversion efficiency is selected from the plurality of second voltage conversion circuits according to a determination result of the determination unit. The image forming apparatus described. Determining means for determining variations in the load on the conveyor belt; and
The second voltage conversion circuit has means capable of switching primary and secondary conversion efficiency in accordance with an input analog voltage value.
According to the determination result of the determination means, a different primary voltage conversion efficiency of the second voltage conversion circuit is maximized by inputting different analog voltage values to the second voltage conversion circuit. The image forming apparatus according to claim 1.   4. The power supply control by the first voltage conversion circuit is switched to the power supply control by the second voltage conversion circuit before a predetermined time before the driving of the conveyor belt by the belt driving means starts. The image forming apparatus according to any one of the above.

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