JP2008083774A - Zero cross signal generation device, fixing controller, image forming apparatus, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a zero cross signal expressing an accurate zero cross point. <P>SOLUTION: A zero cross signal generation part is provided with: a basic pulse generation part 41 which performs the full wave rectification of a voltage to be supplied from a commercial power source, and generates a basic pulse signal S1 as a pulse signal which is turned into an ON state when a generated pulsating flow is a preliminarily set predetermined threshold voltage or less; a pulse width count circuit 421 which counts the count number of a clock signal equivalent to the pulse width of the basic pulse signal S1; a count value memory 422 which stores the count number detected by the pulse width count circuit 421; a count judgement circuit 423 which judges a point of time (zero cross point) when a time corresponding to the half of the pulse width has passed since a point of time when the basic pulse signal S1 is turned into an ON state; and a signal generation circuit 424 which generates the pulse signal which is turned into an ON state at the zero cross point as a zero cross signal S2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a zero cross signal generating device, a fixing control device, an image forming apparatus, and an electronic apparatus that generate a zero cross signal that is a pulse signal corresponding to a zero cross point of a voltage supplied from a commercial power source. In particular, the present invention relates to a copying machine, a facsimile machine, an Internet facsimile machine, a network printer, and a multifunction machine having at least one of these functions.

  Conventionally, in an image forming apparatus such as a copying machine, a pulse corresponding to a zero-cross point of a voltage supplied from a commercial power source is used to control the phase of a fixing unit that fixes an image on a recording sheet to form an image. A zero cross signal which is a signal is used.

For example, a zero-cross signal generating device that performs full-wave rectification on a voltage supplied from a commercial power source and generates a pulse signal that is turned on when the generated pulsating current is equal to or lower than a predetermined threshold voltage set as a zero-cross signal. Is disclosed (see FIG. 3 and Patent Document 1).
JP-A-2005-84546

  However, since the zero-cross signal generated by the zero-cross signal generating device is a pulse signal having a predetermined width centered on the zero-cross point, when performing phase control based on this zero-cross signal, control accuracy (particularly, In some cases, the control accuracy in a region where the duty ratio is small is not sufficient.

  SUMMARY An advantage of some aspects of the invention is that it provides a zero-cross signal generation device, a fixing control device, an image forming apparatus, and an electronic apparatus that generate a zero-cross signal that represents an accurate zero-cross point. .

  In order to achieve the above object, a zero-cross signal generation device according to claim 1 is a zero-cross signal generation device that generates a zero-cross signal that is a pulse signal corresponding to a zero-cross point of a voltage supplied from a commercial power source. A basic pulse generating means for full-wave rectifying a voltage supplied from a power source and generating a basic pulse signal that is a pulse signal that is turned on when a generated pulsating current is equal to or lower than a predetermined threshold voltage set in advance; , Width detection means for detecting the pulse width of the basic pulse signal, pulse width storage means for storing the pulse width detected by the width detection means, and reading the pulse width stored in the pulse width storage means, When the time corresponding to half of the pulse width has elapsed since the basic pulse signal was turned on, It is characterized by comprising a signal generating means for generating a scan signal.

  The zero-cross signal generating device according to claim 2 is the zero-cross signal generating device according to claim 1, wherein the signal generating means detects the zero-cross signal when the basic pulse signal changes from the ON state to the OFF state. Is in an OFF state.

  The zero-cross signal generation device according to claim 3 is the zero-cross signal generation device according to claim 1 or 2, wherein the pulse width storage unit is detected each time the width detection unit detects the pulse width. The pulse width stored in is updated.

  A zero-cross signal generation device according to claim 4 is the zero-cross signal generation device according to any one of claims 1 to 3, wherein the clock generation unit generates a clock signal having a predetermined multiple of the frequency of the commercial power supply. Counting means for counting the number of clock signals, and the width detecting means counts the width count number corresponding to the pulse width of the basic pulse signal via the counting means. Then, the counted width count number is detected as the pulse width, and when the time corresponding to half of the pulse width has elapsed, the signal generating means passes the counting means by the clock generating means. The determination is made by generating a clock signal having a count number that is half the width count number.

  A zero-cross signal generation device according to claim 5 is the zero-cross signal generation device according to any one of claims 1 to 3, further comprising an integration unit that integrates the basic pulse signal, and the width detection unit. However, when a reference integrated value, which is an integrated value obtained by integrating one pulse of the basic pulse signal by the integrating means, is detected as a pulse width, the signal generating means has passed a time corresponding to half of the pulse width. Is determined by the fact that the integral value of the basic pulse signal has reached the half of the reference integral value via the integrating means.

  A fixing control device according to a sixth aspect includes the zero-cross signal generation device according to any one of the first to fifth aspects, and the toner transferred based on the zero-cross signal generated by the zero-cross signal generation device. The image forming apparatus is characterized in that the fixing temperature of the fixing unit that forms an image by fixing the image on the recording paper is controlled by phase control.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising: a fixing unit that fixes the transferred toner onto a recording sheet to form an image; and a fixing control device according to the sixth aspect.

  An electronic device according to an eighth aspect includes the zero-cross signal generation device according to any one of the first to fifth aspects, and phase-controls the supply power based on the zero-cross signal generated by the zero-cross signal generation device. It is characterized by controlling by.

  According to the zero cross signal generation device of the first aspect, the voltage supplied from the commercial power supply is full-wave rectified, and is turned on when the generated pulsating current is equal to or lower than a predetermined threshold voltage. A basic pulse signal that is a pulse signal is generated, and a pulse width of the basic pulse signal is detected. Then, since the pulse signal that turns ON when the time corresponding to half of the pulse width has elapsed from the time when the basic pulse signal is turned ON is generated as a zero cross signal, a zero cross that represents an accurate zero cross point A signal can be generated.

  That is, the basic pulse signal, which is a pulse signal that is turned on when the voltage supplied from the commercial power supply is full-wave rectified and the generated pulsating current is equal to or lower than a predetermined threshold voltage, has a zero-cross point. Since the pulse signal has a predetermined width (= pulse width) at the center, the pulse signal that is turned on when the time corresponding to half of the pulse width has elapsed since the basic pulse signal was turned on is This is a pulse signal that is turned on at an accurate zero cross point.

  According to the zero cross signal generating device of claim 2, since the zero cross signal is turned off when the basic pulse signal is turned off from the on state, the zero cross signal is turned on at an accurate zero cross point. Can be generated with a simple configuration.

  According to the zero cross signal generating apparatus of the third aspect, since the stored pulse width is updated every time the pulse width is detected, a more accurate zero cross signal representing the zero cross point can be generated.

  According to the zero cross signal generation device according to claim 4, when the width count number that is the number of clock signals corresponding to the pulse width of the basic pulse signal is counted, and when the time corresponding to half of the pulse width has elapsed, Since it is determined by the generation of the clock signal having the half count number of the width count number, it is possible to generate a zero cross signal representing an accurate zero cross point with a simple configuration.

  According to the zero cross signal generating device of claim 5, a reference integrated value that is an integrated value obtained by integrating one pulse of the basic pulse signal is detected, and a time point corresponding to half of the pulse width has elapsed is the reference time. Since it is determined that the integral value of the basic pulse signal has reached the half of the integral value, a zero-cross signal representing an accurate zero-cross point can be generated with a simple configuration.

  According to the fixing control device of the sixth aspect, the zero cross signal generation device according to any one of the first to fifth aspects is provided, and the transfer is performed based on the zero cross signal generated by the zero cross signal generation device. Since the fixing temperature of the fixing unit that forms the image by fixing the toner on the recording paper is controlled by the phase control, the phase control of the fixing temperature can be performed accurately.

  According to the image forming apparatus of the seventh aspect, the image forming apparatus includes the fixing unit that fixes the transferred toner on the recording paper to form an image, and the fixing control apparatus according to the sixth aspect. An image forming apparatus capable of accurately performing phase control can be realized.

  According to the electronic device according to claim 8, the zero cross signal generation device according to any one of claims 1 to 5 is provided, and the supply power is phased based on the zero cross signal generated by the zero cross signal generation device. Since it is controlled by the control, it is possible to realize an electronic device that can accurately control the phase of the supplied power.

  Hereinafter, an example of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a schematic configuration of an image forming apparatus according to the present invention. Here, the case where the image forming apparatus is a printer will be described. However, the image forming apparatus may be another image forming apparatus (for example, a facsimile, an internet facsimile, a copying machine, a multifunction machine, etc.) that forms an image on recording paper. Good. As shown in FIG. 1, the printer 100 includes a control unit 1, an operation unit 2, a display unit 3, a power supply unit 4, and a print processing unit 5. The printer 100 is communicably connected to an unillustrated personal computer (PC) or the like, receives an image from the personal computer (PC) or the like, and forms an image corresponding to the received image on a recording sheet.

  The control unit 1 controls the overall operation of the printer 100, and includes a CPU (Central Processing Unit) 11, a RAM (Random Access Memory) 12, and a ROM (Read Only Memory) (not shown).

  The operation unit 2 receives an operation input from a user, generates operation input information corresponding to the received operation input, and outputs the operation input information to the control unit 1 (CPU 11). The operation unit 2 includes, for example, various buttons such as a numeric keypad and a start button, and a touch panel formed integrally with an LCD (Liquid Crystal Display) disposed on the display unit 3.

  The display unit 3 includes an LCD, an LED (Light Emitting Diode), and the like, and displays setting information, guidance information, message information, and the like so as to be visible to the user based on an instruction from the control unit 1 (CPU 11).

  The power supply unit 4 generates a predetermined DC voltage (for example, 5 V) using an AC voltage (for example, 100 V, 60 Hz) supplied from a commercial power source, and supplies it to the control unit 1, the operation unit 2, the display unit 3, and the like. A zero cross signal generator 41 to 43 is provided. The zero cross signal generation units 41 to 43 generate a zero cross signal that is a pulse signal corresponding to a zero cross point of a voltage supplied from a commercial power source.

  The print processing unit 5 forms an image (here, an image corresponding to a document image) on a recording paper by an electrophotographic method, and includes a developing unit 51, a photosensitive unit 52, and a fixing unit 53. . The developing unit 51 forms a toner image by attaching toner to an electrostatic latent image formed on a photosensitive drum provided in the photosensitive unit 52. The photosensitive unit 52 includes a photosensitive drum. First, the surface of the photosensitive drum is substantially uniformly charged by a charging roller, and then an electrostatic latent image is formed by a laser beam scanning unit (not shown). By 51, a toner is attached to form a toner image, and the toner image formed on the photosensitive drum is transferred to a recording sheet.

  The fixing unit 53 melts and fixes the toner image by fixing the toner image transferred from the photosensitive drum to the recording paper by the photosensitive unit 52 by sandwiching the recording paper with a pair of heating rollers. The heating part 531 and the temperature sensor 532 are provided. The heating unit 531 includes a heating roller pair, and heats the heating roller by Joule heat (or induction heating) such as a halogen lamp. The heating unit 531 has a phase based on the zero cross signals generated by the zero cross signal generation units 41 to 43. Heating control is performed using a control method. The temperature sensor 532 measures the surface temperature of the heating roller and includes a thermistor or the like.

  In the fixing unit 53, the power supplied to the heating unit 531 is accurately controlled to maintain the surface temperature of the heating roller (= fixing roller) at the fixing temperature (or standby temperature). Here, a phase control method and a half-wave control method are known as heater control methods.

  FIG. 2 is a waveform diagram of a voltage (or current) generated by the phase control method and the half-wave control method when the duty ratio is 50%. (A) is a waveform diagram of a voltage (or current) generated by the phase control method, and (b) is a waveform diagram of a voltage (or current) generated by the half-wave control method. When the phase control method or the half-wave control method is applied, the surface temperature of the fixing roller can be controlled by controlling the duty ratio of the supplied power.

  For example, in the phase control method, a zero cross signal that is a pulse signal corresponding to a zero cross point of power supplied from a commercial power source is used to control the duty ratio. That is, a desired duty ratio (here, by setting the ON state when a predetermined time (for example, half the time of a half cycle) has elapsed from the time when the zero cross signal is detected and turning OFF when the zero cross signal is detected. 50%) is obtained.

  FIG. 3 is a circuit diagram showing an example of a conventional zero-cross signal generator (= basic pulse generator constituting a part of the zero-cross signal generator according to the present invention). The zero-cross signal generation unit (basic pulse generation unit) 41 includes a full-wave rectification circuit 411 and a photocoupler 412. The full-wave rectifier circuit 411 performs full-wave rectification on the AC voltage from the commercial power source to generate a pulsating current, and supplies the generated pulsating current to the light emitting diode of the photocoupler 412 connected in series to the current limiting resistor R1. Is.

  The photocoupler 412 includes a light emitting diode and a phototransistor, and turns on the phototransistor when the voltage supplied to the light emitting diode exceeds a predetermined threshold (threshold values SHA and SHB shown in FIG. 4). It is. The emitter of the phototransistor is grounded, and a predetermined voltage (for example, 5 V) is applied to the collector of the phototransistor via the pull-up resistor R2. Also, a zero cross signal (= basic pulse signal) S1 is output from the phototransistor collector of the photocoupler 412.

  Next, the operation of the zero cross signal generation unit (= basic pulse generation unit) 41 will be described. When the voltage supplied to the light emitting diode of the photocoupler 412 is equal to or higher than a predetermined threshold (for example, threshold SHA), the phototransistor of the photocoupler 412 is turned on, the collector of the phototransistor is grounded, and the zero cross signal (= Basic pulse signal) S1 becomes Low level (OFF state). When the voltage supplied to the light emitting diode of the photocoupler 412 becomes less than a predetermined threshold (for example, the threshold SHA), the phototransistor of the photocoupler 412 is turned off, and the collector voltage of the phototransistor is applied to the pull-up resistor R2. The predetermined voltage (here, 5V) is set, and the zero-cross signal (= basic pulse signal) S1 becomes the high level (ON state).

  FIG. 4 is a timing chart showing an example of the operation of the zero cross signal generator (= basic pulse generator) 41 shown in FIG. In order from the top of the figure, the waveform of the voltage (full wave rectification waveform) supplied from the full wave rectifier circuit 411 shown in FIG. 3 to the light emitting diode, the zero cross signal (= basic pulse signal) S1 output from the collector of the phototransistor, S1 ′ and a zero-cross signal S2 representing the exact zero-cross point position ZCP. Here, the zero cross signal (= basic pulse signal) S1 corresponds to a predetermined threshold SHA, and the zero cross signal (= basic pulse signal) S1 'corresponds to a predetermined threshold SHB.

  As shown in FIG. 4, the zero-cross signals (= basic pulse signals) S1 and S1 'output from the collector of the phototransistor are pulse signals having a predetermined width with the position ZCP of the zero-cross point as a substantial center. That is, the zero-cross signals S1 and S1 ′ generated by the conventional zero-cross signal generation unit 41 are signals indicating the zero-cross point position ZCP (= the rising position of the signal or the falling position of the signal is the zero-cross point position ZCP). It is not a matching signal.

  Therefore, when performing phase control of the power supplied to the heating unit 531 based on the zero-cross signals S1 and S1 ′ generated by the conventional zero-cross signal generation unit 41, control accuracy (particularly, control in a region where the duty ratio is small). Accuracy) may not be sufficient. Note that the pulse widths of the zero-cross signals S1 and S1 'are determined by the threshold level set in advance by the photocoupler 412. The smaller the threshold value, the narrower the pulse width.

  FIG. 5 is a circuit diagram showing an example of a zero-cross signal generator according to the first embodiment of the present invention. Note that the zero-cross signal generation unit (corresponding to a zero-cross signal generation device) according to the first embodiment of the present invention includes a basic pulse generation unit 41 and a zero-cross signal generation unit 42 shown in FIG. The zero cross signal generation unit 42 includes a clock generation circuit (not shown), a pulse width count circuit 421, a count value memory 422, a count determination circuit 423, and a signal generation circuit 424.

  The clock generation circuit (corresponding to clock generation means) generates a clock signal CLK having a predetermined frequency (for example, 6 kHz). Here, as the frequency of the clock signal CLK generated by the clock generation circuit is higher, the accuracy of the zero cross signal S2 generated by the zero cross signal generation unit 42 is improved. For example, the frequency is preferably 100 times (= 6 kHz) or more of the frequency (for example, 60 Hz) of the commercial power source. In this case, 50 pulses of the clock signal CLK are included in a half cycle of the frequency of the commercial power supply (for example, 60 Hz), so that a phase angle accuracy of ± 2% can be obtained in the phase control.

  The pulse width count circuit 421 (corresponding to width detection means) counts a count number CNT that is the number of clock signals CLK included in the basic pulse signal S1. Specifically, the pulse width count circuit 421 starts counting the number of clock signals CLK from the time when the basic pulse signal S1 rises (= becomes ON), and the basic pulse signal S1 falls ( The width count number TCNT, which is the count number CNT up to the time point (when the state is OFF), is detected as a pulse width, and is stored in the count value memory 422 each time the width count number TCNT is detected. The pulse width count circuit 421 starts counting the number of clock signals CLK from the time when the basic pulse signal S1 rises, and outputs the count number CNT to the count determination circuit 423.

  The count value memory 422 (corresponding to the pulse width storage means) stores the width count number TCNT counted by the pulse width count circuit 421.

  The count determination circuit 423 (corresponding to a part of the signal generation means) determines the time when the time corresponding to half of the pulse width of the basic pulse signal S1 has elapsed by the clock generation circuit via the pulse width count circuit 421. This determination is made by generating a clock signal having a count number HCNT that is half of the count number TCNT. Specifically, the count determination circuit 423 calculates a count number HCNT that is half of the width count number TCNT stored in the count value memory 422, and the count number CNT input from the pulse width count circuit 421 is the width count number. When the count number HCNT is half that of TCNT (= when the zero cross position ZCP is reached), a signal to that effect (hereinafter referred to as a zero cross point detection signal) is output to the signal generation circuit 424.

  The signal generation circuit 424 (corresponding to a part of the signal generation means) sets the pulse of the zero cross signal S2 when the zero cross point detection signal is output from the count determination circuit 423 (= when the zero cross position ZCP is reached). When the basic pulse signal S1 falls, the zero cross signal S2 falls (= turns off) when the basic pulse signal S1 falls, thereby generating the zero cross signal S2.

  FIG. 6 is a timing chart showing an example of the operation of the zero-cross signal generator 42. In the figure, in order from the top, there are a clock signal CLK, a basic pulse signal S1, a signal S3 corresponding to the count number CNT by the pulse width count circuit 421, and a zero cross signal S2. However, the clock signal CLK shown in the drawing is not an accurate 6 kHz signal but a conceptual diagram for convenience.

  An arrow written below the basic pulse signal S1 indicates a counting period which is a period during which the pulse width count circuit 421 counts the count number CNT. As shown in the figure, the counting period is from the rising point of the basic pulse signal S1 to the falling point of the basic pulse signal S1. Within this counting period, the total count number counted by the pulse width count circuit 421 corresponds to the width count number TCNT.

  Then, when the count number CNT (= signal S3) counted by the pulse width count circuit 421 coincides with the count number HCNT which is half the width count number TCNT (= zero cross position ZCP), the count determination circuit 423 performs zero cross inspection. The output signal is output to the signal generation circuit 424, and the pulse of the zero cross signal S2 is raised by the signal generation circuit 424 (= turned on). Furthermore, the pulse of the zero cross signal S2 is lowered (= turned off) by the signal generation circuit 424 at the time of falling of the basic pulse signal S1.

  FIG. 7 is a circuit diagram showing an example of a zero-cross signal generation unit according to the second embodiment of the present invention. Note that the zero-cross signal generation unit (corresponding to a zero-cross signal generation device) according to the second embodiment of the present invention includes a basic pulse generation unit 41 and a zero-cross signal generation unit 43 shown in FIG. The zero cross signal generation unit 43 includes an integrator 431, an integral value memory 432, a comparator 433, and a signal generation circuit 434.

  An integrator 431 (corresponding to an integration unit and a width detection unit) integrates the basic pulse signal S1. Specifically, the integrator 431 starts the integration process from the time when the basic pulse signal S1 rises (= becomes ON), and the basic pulse signal S1 falls (= becomes OFF). The integral value (= reference integral value) TV up to the time is detected as a pulse width, and is stored in the integral value memory 432 every time the integral value TV is detected. The integrator 431 starts integration processing from the time when the basic pulse signal S1 rises, and outputs a signal S4 indicating the integration value to the comparator 433.

  The integral value memory 432 (corresponding to the pulse width storage means) stores a reference integral value TV, which is an integral value obtained by the integrator 431 and corresponding to the pulse width of the basic pulse signal S1.

  Comparator 433 (corresponding to a part of the signal generating means) passes the time point corresponding to half of the pulse width of the basic pulse signal S1 through the integrator 431 to a value half of the reference integrated value TV. Is determined when the integral value of the basic pulse signal S1 has reached. Specifically, the comparator 433 calculates an integral value HV that is half the reference integral value TV stored in the integral value memory 432, and the integral value input from the integrator 431 is half the reference integral value TV. When it coincides with the integrated value HV (= when the zero cross position ZCP is reached), a signal to that effect (hereinafter referred to as a zero cross point detection signal) is output to the signal generation circuit 434.

  The signal generation circuit 434 (corresponding to a part of the signal generation means) raises the pulse of the zero cross signal S2 when the zero cross point detection signal is output from the comparator 433 (= when the zero cross position ZCP is reached). When the basic pulse signal S1 falls (= ON state), the zero-cross signal S2 is generated by lowering the pulse of the zero-cross signal S2 (= OFF state).

  FIG. 8 is a timing chart showing an example of the operation of the zero cross signal generator 43. In the figure, in order from the top, there are a basic pulse signal S1, a signal S4 corresponding to an integration value by the integrator 431, and a zero-cross signal S2.

  When the integral value (= signal S3) obtained by the integrator 431 coincides with the integral value HV which is half of the reference integral value TV (= zero cross position ZCP), the comparator 433 generates a zero cross point detection signal as a signal generation circuit. The signal generation circuit 434 raises the pulse of the zero-cross signal S2 (= ON state). Furthermore, the pulse of the zero cross signal S2 is lowered (= turned off) by the signal generation circuit 434 at the time of falling of the basic pulse signal S1.

  In this way, the basic pulse signal S1, which is a pulse signal that is turned on when the voltage supplied from the commercial power supply is full-wave rectified and the generated pulsating current is equal to or lower than a predetermined threshold voltage set in advance, is The pulse width of the basic pulse signal S1 is detected. Then, since the pulse signal that is in the ON state when the time corresponding to half of the pulse width has elapsed from the time when the basic pulse signal is in the ON state is generated as the zero cross signal S2, it represents an accurate zero cross point. A zero-cross signal S2 can be generated.

  That is, the basic pulse signal is a pulse signal that is turned on when the voltage supplied from the commercial power supply is full-wave rectified and the generated pulsating current is equal to or lower than a predetermined threshold voltage SHA (or threshold voltage SHB) set in advance. Since the pulse signal S1 is a pulse signal having a predetermined width (= pulse width) centered on the zero cross point, a time corresponding to half of the pulse width has elapsed since the basic pulse signal S1 was turned on. The pulse signal that is turned on at the time becomes a pulse signal that is turned on at an accurate zero cross point.

  In addition, since the zero cross signal S2 is turned off when the basic pulse signal S1 changes from the ON state to the OFF state, the pulse signal that is turned on at an accurate zero cross point is configured with a simple configuration as the zero cross signal S2. Can be generated.

  Further, each time a pulse width (= width count number TCNT or reference integral value TV) is detected, the stored pulse width (= width count number TCNT or reference integral value TV) is updated, so that more accurate zero crossing is performed. A zero-cross signal S2 representing a point can be generated.

  In addition, according to the zero cross signal generation unit (= basic pulse generation unit 41 and zero cross signal generation unit 42) of the first embodiment, the width count number TCNT which is the number of clock signals corresponding to the pulse width of the basic pulse signal S1. Is counted, and the time when the time corresponding to half of the pulse width has elapsed is determined by the generation of the clock signal having the count number HCNT that is half the width count number. Therefore, an accurate zero cross point can be obtained with a simple configuration. A zero-cross signal S2 can be generated.

  Further, according to the zero cross signal generation unit (= basic pulse generation unit 41 and zero cross signal generation unit 43) of the second embodiment, a reference integral value TV which is an integral value obtained by integrating one pulse of the basic pulse signal S1 is detected. Since the point in time corresponding to half of the pulse width has elapsed is determined by the fact that the integral value of the basic pulse signal has reached the half value HV of the reference integral value TV, an accurate zero cross point can be obtained with a simple configuration. Can be generated.

  Furthermore, the zero cross signal generation unit (= basic pulse generation unit 41 and zero cross signal generation unit 42) of the first embodiment or the zero cross signal generation unit (= basic pulse generation unit 41 and zero cross signal generation unit 43 of the second embodiment). ), The fixing temperature of the fixing unit 53 for fixing the transferred toner on the recording paper to form an image is controlled by the phase control based on the zero-cross signal S2 generated by the above), so that the phase control of the fixing temperature is accurately performed. It can be carried out.

The present invention can also be applied to the following forms.
(A) In the first embodiment and the second embodiment, the case where the electronic device is the printer 100 has been described. However, the electronic device may be another electronic device that controls supply power by phase control based on a zero-cross signal. . For example, it may be an electronic device (HDD (Hard Disk Drive), air conditioner, etc.) that controls electric power supplied to a motor (spindle motor such as a hard disk or optical disk, or a fan motor of an air conditioner) by phase control.

  (B) In the first embodiment and the second embodiment, the signal generation circuit 424 and the signal generation circuit 434 cause the pulse of the zero cross signal S2 to fall (= set to the OFF state) when the basic pulse signal S1 falls. However, the signal generation circuit 424 and the signal generation circuit 434 may be configured to cause the pulse of the zero-cross signal S2 to fall (= turn off) at other preset timings.

  For example, the signal generation circuit 424 and the signal generation circuit 434 lower the pulse of the zero-cross signal S2 after a predetermined time (for example, 5 msec) has elapsed since the time when the pulse of the zero-cross signal S2 was raised (= when the signal was turned ON). (= OFF state) may be used. In this case, even when the voltage of the commercial power supply fluctuates, the pulse width of the zero cross signal S2 is constant, and a stable zero cross signal S2 is obtained.

FIG. 2 is a block diagram illustrating an example of a schematic configuration of a printer according to the present invention. These are waveform diagrams of the voltage (or current) generated by the phase control method and the half-wave control method when the duty ratio is 50%. These are circuit diagrams which show an example of the conventional zero cross signal generation part (= basic pulse generation part which constitutes a part of zero cross signal generation part concerning the present invention). These are timing charts which show an example of operation | movement of the zero cross signal generation part (= basic pulse generation part) shown in FIG. These are circuit diagrams which show an example of the zero cross signal generation part which concerns on 1st Embodiment of this invention. These are timing charts which show an example of operation | movement of the zero cross signal production | generation part shown in FIG. These are circuit diagrams which show an example of the zero cross signal production | generation part which concerns on 2nd Embodiment of this invention. These are timing charts which show an example of operation | movement of the zero cross signal production | generation part shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Printer 1 Control unit 4 Power supply unit 41 Basic pulse generation part (Basic pulse generation means, a part of zero cross signal generation device)
411 Full-wave rectifier circuit 412 Photocoupler 42 Zero-cross signal generator (part of zero-cross signal generator)
421 Pulse width count circuit (counting means, width detecting means)
422 Count value memory (pulse width storage means)
423 Count determination circuit (part of signal generation means)
424 signal generation circuit (part of signal generation means)
5 Print Processing Unit 53 Fixing Unit 531 Heating Unit 532 Temperature Sensor

Claims (8)

A zero-cross signal generating device that generates a zero-cross signal that is a pulse signal corresponding to a zero-cross point of a voltage supplied from a commercial power source,
Basic pulse generation means for full-wave rectifying the voltage supplied from the commercial power source and generating a basic pulse signal which is a pulse signal that is turned on when the generated pulsating current is equal to or lower than a predetermined threshold voltage set in advance. When,
Width detecting means for detecting a pulse width of the basic pulse signal;
Pulse width storage means for storing the pulse width detected by the width detection means;
The pulse width stored in the pulse width storage means is read, and the pulse signal that is turned on when a time corresponding to half of the pulse width has elapsed from when the basic pulse signal is turned on is zero-crossed. Signal generating means for generating a signal;
A zero-cross signal generating apparatus comprising:   2. The zero cross signal generating apparatus according to claim 1, wherein the signal generating means sets the zero cross signal to an OFF state when the basic pulse signal changes from an ON state to an OFF state.   3. The zero-cross signal generation apparatus according to claim 1, wherein the width detection unit updates the pulse width stored in the pulse width storage unit every time the pulse width is detected. Clock generation means for generating a clock signal of a predetermined multiple of the frequency of the commercial power supply;
Counting means for counting the number of the clock signals;
With
The width detection means counts the width count number that is the number of the clock signals corresponding to the pulse width of the basic pulse signal via the counting means, and detects the counted width count number as the pulse width. ,
When the time corresponding to half of the pulse width has elapsed, the signal generating means has generated a clock signal having a count number half the width count number by the clock generating means via the counting means. The zero-cross signal generation apparatus according to claim 1, wherein the determination is made by: Integrating means for integrating the basic pulse signal;
The width detecting means detects a reference integrated value, which is an integrated value obtained by integrating one pulse of the basic pulse signal by the integrating means, as a pulse width,
The signal generation means determines when a time corresponding to half of the pulse width has elapsed by the fact that the integral value of the basic pulse signal has reached the half of the reference integral value via the integration means. The zero-cross signal generation apparatus according to claim 1, wherein the zero-cross signal generation apparatus according to claim 1 is used. A zero-cross signal generation device according to any one of claims 1 to 5,
A fixing control device that controls the fixing temperature of a fixing unit that forms an image by fixing the transferred toner on a recording sheet based on a zero-cross signal generated by the zero-cross signal generating device. A fixing unit that forms an image by fixing the transferred toner on a recording paper; and
A fixing control device according to claim 6;
An image forming apparatus comprising: A zero-cross signal generation device according to any one of claims 1 to 5,
An electronic apparatus that controls supply power by phase control based on a zero-cross signal generated by the zero-cross signal generation device.

Images