JP2012250502A - Image forming apparatus and method for controlling motor drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that reduces power to be consumed in printing by fixing the position of a carriage and a sheet with a method other than motor excitation and stopping supply of drive power to the motor.SOLUTION: The image forming apparatus includes: a first motor for driving a main scanning part; a second motor for driving a sub-scanning part; and a drive control circuit for drive controlling the first motor and the second motor. The drive control circuit is provided with a hold control means for the first motor and the second motor with short brake.

Description

  The present invention relates to an ink-jet image forming apparatus equipped with a main scanning motor and a sub-scanning motor, and a motor drive control method.

  Inkjet image forming apparatuses are equipped with at least two motors: a sub-scanning motor for transporting paper and a main scanning motor that scans a carriage on which a print head is mounted at right angles to the paper transport direction. Yes.

  Most of the power consumption at the time of printing in the ink jet type image forming apparatus is consumed by the main scanning motor and the sub scanning motor. In general, a DC (direct current) motor or a stepping motor is used as these motors.

  An ink tube for supplying ink is connected to the carriage. When the carriage is to be fixed at a predetermined position, the carriage moves from the predetermined position due to the ink tube.

  In addition, a conveyance belt for conveying the sheet is mounted on the sheet conveyance unit, and there is also a phenomenon that the sheet moves due to the habit of the conveyance belt even when it is desired to fix the sheet at a predetermined position.

  Therefore, in order to fix and stop the carriage and paper at predetermined positions, an operation of stopping the motor in an excited state (hereinafter referred to as hold control) is performed. However, since this hold control excites the motor, large electric power is consumed during this time. In order to reduce power consumption, there is already known a control method in which the hold control is not performed in the print standby state and the motor is not excited.

  For example, in Patent Document 1, the power consumption during motor stop is intended to be smaller, and it is not necessary to keep the motor fixed in the print standby mode in which no print operation is performed. A control method in which no excitation is performed is disclosed.

  However, the conventional control methods that do not perform motor excitation in the print standby state can reduce power consumption, but there is a problem that it does not lead to reduction of power consumption during printing.

  That is, in the invention described in Patent Document 1, since it is still necessary to perform hold control at the time of printing, the problem of reducing the power consumption of the motor cannot be solved.

  The present invention has been made in view of the above. The purpose of the invention is to fix the position of the carriage and paper by a method other than excitation to the motor, and to reduce the power consumption during printing by stopping the driving power to the motor. It is to reduce.

  In order to solve the above problems, an image forming apparatus of the present invention includes a first motor that drives a main scanning unit, a second motor that drives a sub-scanning unit, the first motor, and the second motor. The image forming apparatus includes a drive control circuit that controls the driving of the first motor and the second motor by a short brake.

  In order to solve the above problem, a motor drive control method according to the present invention includes a first motor that drives a main scanning unit and a second motor that drives a sub-scanning unit, which are mounted on an image forming apparatus. A motor drive control method for drive control, comprising a hold control step of the first motor and the second motor by a short brake.

  According to the present invention, it is possible to reduce the power consumption of the motor during printing by holding the carriage and the paper transport unit without exciting the motor.

1 is a diagram illustrating an outline of electrical connection of an image forming apparatus according to an embodiment of the present invention. It is the schematic explaining the scanning direction of a carriage and paper conveyance. It is a circuit diagram explaining the circuit of a motor drive part. It is a wave form diagram explaining a motor drive control method. It is a wave form diagram explaining the hold control method of a motor. It is a circuit diagram explaining the hold control by the short brake of one Embodiment of this invention. It is a wave form diagram explaining concretely hold control by short brake of one embodiment of the present invention. It is (a) block diagram explaining the function of the control signal of the PWM drive by the short brake of one embodiment of the present invention, and (b) circuit diagram. It is a figure explaining the control which performs forward / reverse rotation PWM drive at the time of the motor drive of one Embodiment of this invention. It is a figure explaining the position detection method of the main scanning part of one Embodiment of this invention. It is a schematic diagram about the structure of the rotary encoder of the sub-scanning part of one Embodiment of this invention. It is a figure explaining the hold control of the motor when there is a change in the encoder signal of one embodiment of the present invention. It is a figure explaining the control which turns off the power supply of an encoder sensor at the time of the hold control of the motor of one Embodiment of this invention. It is a figure explaining the conventional main scanning drive control. It is a figure explaining the conventional subscanning drive control. It is (a) block diagram explaining the function of the control signal of the conventional forward rotation and reverse rotation PWM drive, and (b) waveform diagram.

  An embodiment of the present invention will be described. The present invention has the following characteristics in the hold control of the main scanning motor (first motor) and the sub-scanning motor (second motor) during printing of the inkjet head printing apparatus.

In other words, the motor power consumption during hold control is reduced by holding the motor using a short brake (short-circuit braking) instead of alternately exciting forward and reverse voltages during hold control of the main and sub-scan motors. It is characterized by letting.
The characteristics of the present invention described above will be described in detail below.

  First, an outline of electrical connection of an image forming apparatus related to control of a main scanning motor and a sub-scanning motor according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 shows a main configuration of a control board 1 that controls the main scanning motor and the sub-scanning motor. The inside of the broken line is the function of the control board 1, and the outside of the broken line shows each unit connected to the control board.

  An operation panel 2 for inputting and displaying information necessary for the apparatus is connected to the control board 1.

  The control board 1 receives print data or the like from a host side such as an information processing device such as a personal computer, an image reading device such as an image scanner, an imaging device such as a digital camera, etc., via a cable or a network at the host I / F 11. .

  The CPU 12 reads and analyzes the print data in the reception buffer included in the host I / F 11, performs necessary image processing, data rearrangement processing, and the like in the ASIC 16, and transfers the image data to the head drive control unit. To do.

  The ASIC is an abbreviation that stands for “Application Specific Integrated Circuit” and is an IC for a specific application.

  The generation of dot pattern data for image output may be performed, for example, by storing font data in the ROM 13, or the image data is developed into bitmap data by a host-side printer driver and transferred to the image forming apparatus. You may make it do.

  When the head control unit 20 receives image data (dot pattern data) corresponding to one line of the recording head, the dot pattern data for one line is sent to the carriage 4 as serial data in synchronization with the clock signal. In addition, a latch signal is sent to the carriage 4 at a predetermined timing.

  Here, the latch signal is a signal for starting or ending another signal such as a data signal, or a mark for active / inactive signal.

  The head drive unit 19 is a waveform generation circuit including a DAC 18 serving as a D / A converter for reading pattern data of a drive waveform (head drive signal) stored in the ROM 13, and D / A converting the drive waveform data, and an amplifier. A drive waveform generation circuit configured is provided.

  The carriage 4 includes a shift register that inputs a clock signal from the head control unit 19 and serial data that is image data, a latch circuit that latches a register value of the shift register using a latch signal from the head control unit, and the latch circuit A level conversion circuit (level shifter) for changing the output value of the output signal, an analog switch array (switch means) whose ON / OFF is controlled by the level shifter, and the like.

  The carriage 4 controls the ON / OFF of the analog switch array to selectively apply a required driving waveform included in the driving waveform to the actuator means of the recording head mounted in the carriage to drive the head. .

  Further, the CPU 12 reads the detection signal of the A sensor 3a via the ADC 17 which is an A / D converter for A / D conversion.

  The main scanning motor driving unit 21 and the sub scanning motor driving unit 22 send drive signals to the main scanning motor 5 and the sub scanning motor 6 in response to a command signal from the CPU 12 to excite the main scanning motor 5 and the sub scanning motor 6. The main scanning motor 5 and the sub scanning motor 6 are driven and controlled.

  The A sensor 3a is an analog signal sensor for detecting an analog signal such as a temperature detection thermistor, and the D sensor 3b is a digital signal sensor for detecting a digital signal such as an encoder signal for position detection described later.

  Next, the carriage 4 mounted on the image forming apparatus according to the embodiment of the present invention and the paper scanning direction will be described with reference to FIG.

  The recording paper 100 is transported by a transport roller 101 driven by a sub-scanning motor 6 and a transport belt 103 driven by a tension roller 102 that operates in accordance with the transport roller 101, that is, a paper transport unit. The scanning direction.

  An ejection head used in an inkjet image forming apparatus is attached to the carriage 4.

  The carriage 4 drives the main scanning motor 5 to scan the guide rod 107 on the guide rod 107 at a right angle with respect to the sub-scanning direction by the driving pulley 104, the driven pulley 105, and the timing belt 106. This scanning direction is defined as the main scanning direction.

  An ink tube 109 for supplying ink from the ink cartridge 108 to the ejection head is connected to the carriage 4.

  Next, the circuits of the main scanning motor driving unit 21 and the sub scanning motor driving unit 22 will be described with reference to FIG.

  The circuit configuration of the main scanning motor driving unit 21 and the sub-scanning motor driving unit 22 is an H bridge circuit as shown in FIG. (A) represents a circuit diagram in the case of forward rotation operation, and (b) represents a circuit diagram in the case of reverse rotation operation.

  By switching FETs (Field Effect Transistors: field effect transistors A, B, C, and D) that turn ON the forward rotation operation and the reverse rotation operation, the path of the drive current to the main scanning motor 5 and the sub scanning motor 6 is changed. Yes.

  That is, the broken line arrow 201 represents the path of the drive current in the forward rotation operation (A and D are ON), and the broken line arrow 202 represents the path of the drive current in the reverse rotation operation (B, C ON). The rotation directions of the main scanning motor 5 and the sub-scanning motor 6 are switched by switching the current path.

  FIG. 4 is a diagram for explaining a drive control method for the main scanning motor 5 and the sub-scanning motor 6.

  The drive control of the main scanning motor 5 and the sub scanning motor 6 is performed by PWM control (Pulse Width Modulation).

As shown in FIG. 4, the motor is driven and controlled by changing the ratio of the time during which high level (PWM ON) and low level (PWM OFF) signals are output during the pulse.
The ratio (t / T) of the high level (t) period in one cycle (T) is referred to as the duty (duty) ratio (%).

  That is, the PWM duty ratio is increased (a) when it is desired to send and accelerate a PWM signal at a constant period, and the PWM duty ratio is decreased (b) when it is desired to decelerate.

  When the PWM is turned on, the FETs (A, D) for passing a current in the forward rotation direction in FIG. 3 are turned on when the PWM is turned on, and the current is passed in the reverse direction when the PWM is turned off. FET (B, C) is turned ON.

  In other words, during forward rotation, force is applied in the forward rotation direction when PWM is ON, and force is applied in the reverse rotation direction when PWM is OFF. Therefore, when the PWM is ON, that is, when the duty ratio exceeds 50%, the motor rotates in the forward direction, and when it becomes less than 50%, the motor rotates in the reverse direction (c).

  FIG. 5 is a diagram for explaining the hold control of the main scanning motor 5 and the sub-scanning motor 6.

  By setting the duty ratio of the PWM signal for controlling the driving of the motors to 50%, the same force is applied in the forward direction and the reverse direction and is held at the fixed position.

  Here, in describing the image forming apparatus according to the embodiment of the present invention, first, how the drive control of the conventional main scanning motor is performed will be described with reference to FIG.

  The carriage 4 continuously reciprocates in the main scanning direction. The driving mode of the main scanning motor 5 is controlled in three modes. The three modes are an acceleration period, a constant speed period, and a hold period, respectively. The control during this time is performed by the PWM control described above.

  In the acceleration period shown in FIG. 14, the PWM duty ratio is increased, in the constant speed period, the PWM duty ratio is decreased compared to the acceleration period, and in the hold period, the PWM duty ratio is 50%.

  Next, conventional sub-scan motor drive control will be described with reference to FIG.

  Paper conveyance is driven in the sub-scanning direction. The driving mode of the sub-scanning motor 6 is controlled in three modes like the main scanning motor 5. The three modes are an acceleration period, a constant speed period, and a hold period, respectively. The control during this time is performed by the PWM control described above.

  In the acceleration period shown in FIG. 15, the PWM duty ratio is increased, in the constant speed period, the PWM duty ratio is decreased compared to the acceleration period, and in the hold period, the PWM duty ratio is 50%.

  The sub-scanning motor 6 is controlled so as to perform operations of paper feeding, paper feeding, and paper discharging for one page of paper. All the operations are held and controlled, and the position of the paper transport unit is fixed so that the paper does not move. The sub-scanning motor 6 is always energized until one page of paper is fed from the paper to the paper.

  From the above, it can be seen that both the main scanning motor and the sub-scanning motor consume power for the control because the drive control of each motor is performed even during the hold period.

  Further, a method for detecting the position of the carriage 4 as the main scanning unit and the sheet conveying unit as the sub-scanning unit will be described with reference to FIGS.

  An encoder is used as a position detection unit in the carriage 4 and the sheet conveyance unit. The encoder includes a linear encoder that detects a linear displacement amount and a rotary encoder that detects a detection target as a rotation angle or a rotation amount of an input shaft.

  As shown in FIG. 10, the linear encoder used in the carriage 4 includes an encoder sensor composed of a light emitting element and a light receiving element, and an encoder scale 110 including a plurality of slits 110a that allow light from the light emitting element to pass through.

  This encoder sensor is composed of a photosensor 111a as a light receiving element, a photosensor 111b, and a light emitting diode 111c as a light emitting element. The encoder scale 110 has a light shielding effect represented by the slit 110a described above and the shaded portion in FIG. Part 110b.

  As shown in FIG. 10, the photosensor 111a and the photosensor 111b are provided in the carriage 4, and the encoder scale 110 is positioned in parallel with the scanning direction of the carriage 4, and the photosensor and the light emitting diode 111c are sandwiched between the encoder scale 110. Are located opposite to each other.

  The position of the carriage 4 is detected by reading the relative phases of the A-phase rectangular wave signal and the B-phase rectangular wave signal generated by the passage of light through the slit 110a and the light shielding by the light shielding unit 110b. Also, as shown in FIG. 10, the A-phase and B-phase rectangular wave signals usually have a phase difference of 90 °.

  The rectangular wave signal is converted into an electric signal strength by the photosensor 111a and the photosensor 111b, and the waveform is shaped and output.

  As shown in FIG. 10B, when the A phase is delayed from the B phase (in the case of the delayed phase), it can be seen that the carriage 4 is moving in the forward direction, as shown in FIG. .

  Conversely, as shown in FIG. 10C, when the A phase is advanced from the B phase (in the case of the advanced phase), the carriage 4 is moving in the Backward direction as shown in FIG. I understand that.

  That is, the position of the carriage 4 is detected by the relative phase change of the A-phase and B-phase rectangular wave signals.

  On the other hand, a rotary encoder is used for position detection in the paper transport unit. The operation principle of the rotary encoder is the same as that of the linear encoder. However, unlike the encoder scale of the linear encoder, the rotary encoder uses a slit disk 113 provided at one end of the shaft 112 serving as the rotating shaft shown in FIG.

  That is, as shown in FIG. 11, a slit 113a that allows light to pass is provided on the outer periphery of the slit disk 113, and the light receiving elements 111a and 111b receive the light from the light emitting element 111c that has passed through the slit 113a, and this and the light shielding portion By detecting the relative phase between the A-phase rectangular wave signal and the B-phase rectangular wave signal generated by the light shielding, the rotational position of the conveying roller 101 serving as the sheet conveying unit is detected.

  Based on the above description, motor hold control by short brake (short circuit braking) according to the image forming apparatus of one embodiment of the present invention will be described with reference to FIG.

  When PWM is ON, force is applied in the forward direction, when PWM is OFF, force is applied in the reverse direction, and the duty ratio is 50%. When PWM is ON, force is applied in the forward direction (A, D Is ON), and when the PWM is OFF, the short brake shown in FIG. 6 is used (C and D are ON).

  By turning off PWM during hold control, the motor is in a short brake state, and the motor is hold-controlled without supplying current from the power source.

  Furthermore, the hold control by the above short brake will be specifically described with reference to FIG.

  That is, as shown in FIG. 7, during the acceleration and constant speed periods, the forward rotation drive is performed when PWM is ON, the short brake is used when PWM is OFF, and the PWM drive is turned ON and OFF, and the PWM is OFF (Duty) during hold control. Ratio 0%).

  With this duty setting, the motor is in a short brake state, and the motor is hold-controlled without supplying current from the power source.

  In other words, the carriage 4 and the paper transport unit can be held and controlled without excitation to the motor, so that power consumption to the motor during printing can be reduced.

  Next, the function of the control signal of the PWM drive control by the short brake of the motor according to the image forming apparatus of one embodiment of the present invention will be described using FIG. 8, FIG. 9, and FIG.

  First, the function of a conventional forward / reverse PWM drive control signal will be described with reference to FIG.

  That is, as shown in FIG. 16, it can be seen that the PWM signal conventionally serves as both motor speed control and direction control.

  As shown in FIG. 8, when the conventional PWM driving by forward rotation and reverse rotation is changed to PWM driving by motor driving and short brake, the direction control cannot be performed by the PWM signal by using the short brake.

  Therefore, as shown in FIG. 8, one additional direction control signal is added compared to the conventional method.

  Therefore, as shown in FIG. 9, in order to avoid the addition of signals, during the motor drive period, PWM drive is performed by normal rotation and reverse rotation as usual, and short brake control is performed by ON / OFF by the motor enable signal. Therefore, it is not necessary to add a direction control signal, and the number of signals can be reduced.

  FIG. 12 is a diagram for explaining motor hold control when the encoder signal changes in the image forming apparatus according to the embodiment of the present invention.

  Even if the short brake function of the motor is used at the time of hold control, the motor drive unit is energized, so that power is consumed in the motor drive unit.

  Therefore, at the time of hold control, the encoder signal is monitored by the position detection encoder described above. Only when there is a change in the encoder signal, the motor drive unit is energized and hold control is performed. When there is no change in the encoder signal, the motor drive circuit that has received the signal change performs control to turn off the power of the motor drive unit.

  The case where the encoder signal has changed corresponds to the case where the relative phase of the A-phase and B-phase rectangular wave signals has changed, as described with reference to FIG.

  Specifically, when the carriage 4 is controlled to hold, the motor stops, so the motor drive power is turned off. Here, a case where an external load is applied to the stopped carriage 4, that is, the motor, due to the ink tube 109 becoming hazy or the like.

  That is, when an external load is applied to the carriage 4, a change is seen in the encoder signal being monitored, so hold control is required, and therefore the motor drive power must be turned on again.

  That is, when the motor stops (step S301), the motor drive unit power is turned off (step S302). The encoder sensor 111 monitors the encoder signal (step S303). When the encoder signal is changed (step S303, Yes), the motor drive unit power is turned on (step S304), and the motor hold control is performed. This is performed (step S305).

  On the other hand, when there is no change in the encoder signal (step S303, No), the power of the motor drive unit remains off and the monitoring of the encoder signal is continued.

  Therefore, the power consumed by the motor drive unit can be reduced.

  FIG. 13 is a diagram illustrating control for turning off the power of the encoder sensor 111 during motor hold control in the image forming apparatus according to the embodiment of the present invention.

  Since the motor is held during hold control, the carriage 4 and the paper transport unit do not move. Therefore, it is not necessary to energize the encoder sensor 111 for position detection during that time.

  Therefore, at the time of motor hold control, control to turn off the power of the encoder sensor 111 is performed.

  When the motor stops (step S401) and the motor hold control is performed (step S402), the power supply of the encoder sensor 111 is turned off (step S403).

  When it is ready to start driving the motor again (step S404), the encoder sensor 111 is turned on (step S405), and the motor driving is resumed (step S406).

  Therefore, during hold control, the encoder sensor 111 is turned off, so that power consumption for the encoder sensor can be reduced, and waste of power as the entire image forming apparatus can be saved.

  Each of the above-described embodiments is a preferred embodiment of the present invention, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Control board 4 Carriage 5 Main scanning motor 6 Sub scanning motor 19 Head drive part 20 Head control part 21 Main scanning motor drive part 22 Sub scanning motor drive part 101 Conveyance roller 102 Tension roller 103 Conveyance belt 104 Drive pulley 105 Driven pulley 106 Timing Belt 107 Guide rod 108 Ink cartridge 109 Ink tube 110 Encoder scale 111a, 111b Encoder sensor (light receiving element)
111c Encoder sensor (light emitting element)
112 Conveying roller rotating shaft shaft 113 Slit disk 201, 202 Drive current path

JP 2003-001812 A

Claims (8)

A first motor for driving the main scanning unit;
A second motor for driving the sub-scanning unit;
An image forming apparatus having a drive control circuit for driving and controlling the first motor and the second motor,
The image forming apparatus, wherein the drive control circuit includes hold control means for the first motor and the second motor by a short brake.   The image forming apparatus according to claim 1, wherein the hold control unit further includes a short brake control unit that controls a short brake by an enable signal of a motor. A position detector that detects the positions of the first motor and the second motor;
The drive control circuit further includes drive power control means for controlling the drive power of the first motor and the second motor when the detection result of the position detector changes. Item 2. The image forming apparatus according to Item 1.   4. The image forming apparatus according to claim 3, further comprising: a detection power source control unit that turns off the power source of the position detection unit when the first motor and the second motor are under hold control. 5. A motor drive control method for driving and controlling a first motor for driving a main scanning unit and a second motor for driving a sub-scanning unit, which are mounted on an image forming apparatus,
A motor drive control method comprising a hold control step of the first motor and the second motor by a short brake.   6. The motor drive control method according to claim 5, wherein the hold control step further includes a short brake control step of controlling the short brake by an enable signal. A position detecting step for detecting positions of the first motor and the second motor,
6. The motor drive according to claim 5, further comprising a drive power supply control step of controlling drive power supply of the first motor and the second motor when a detection result in the position detection step is changed. Control method.   The motor drive control according to claim 7, further comprising a detection power supply control step of turning off a power supply in the position detection step when the first motor and the second motor are hold-controlled. Method.

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