JP2013134462A - Voltage output device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect any abnormality of AC power supply in a voltage output device that outputs an AC voltage output from an AC power supply source.SOLUTION: A voltage output device 61 comprises an output unit 56 that outputs an AC voltage output from an AC power supply source 50, a detector 58 that detects the AC voltage, and a controller 60. The controller executes zero-crossing point detection processing to detect a zero-crossing point where the absolute value of the AC voltage becomes zero; peak number detection processing to detect the number of peaks at which the voltage value of the AC voltage reaches at least one of the maximum and the minimum; and judgment processing to compare a first number of points, which is the number of zero-crossing points in a prescribed period of time, and a second number of points, which is the number of peaks detected in the prescribed period of time, and judges that the AC power supply source 50 is normal when the difference between the first number of points and the second number of points is included in a prescribed range determined according to the length of the prescribed period of time and that the AC power supply source 50 is abnormal when the difference is not included in the prescribed range.

Description

  The invention disclosed in this specification relates to a technique for detecting an abnormality in an AC power supply that outputs an AC voltage.

  Conventionally, a technique has been disclosed in which a zero-cross point where the absolute value of an AC voltage output from an AC power supply is zero is detected, and energization of the AC voltage to the fixing heater is controlled based on this zero-cross point (for example, Patent Document 1). The prior art further discloses a technique for detecting a peak voltage of an AC voltage and detecting a power supply environmental condition of the AC power supply from the detected voltage value of the peak voltage.

JP-A-9-101718

An abnormality that cannot be detected even when the voltage value of the peak voltage of the AC voltage is detected may occur in the AC power supply.
For example, when an uninterruptible power supply is used as an AC power supply, or when the AC power supply is also used as a power supply for other devices such as a heating device, noise occurs in the AC voltage output from the AC power supply. There is. Since this noise has a smaller amplitude than the amplitude of the AC voltage, it does not affect the detection of the voltage value of the peak voltage of the AC voltage. However, when this noise occurs in the vicinity of the zero cross point, in addition to the zero cross point where the absolute value of the AC voltage becomes zero, there is a problem that an abnormal timing at which the absolute value of the AC voltage becomes zero is detected due to the noise. It was.

  In addition, an AC voltage having an abnormal waveform similar to a rectangular wave may be output from the AC power source. This AC voltage has a large voltage change rate at the zero cross point compared to a normal AC voltage, and the zero cross point cannot be detected.

  As described above, there has been a problem that the zero cross point cannot be accurately detected based on the abnormality of the AC power supply. Unless the zero-cross point is accurately detected, the internal devices such as the fixing heater cannot be controlled normally.

  The invention disclosed in this specification discloses a technique for detecting an abnormality in an AC power supply in a voltage output device that outputs an AC voltage output from the AC power supply.

  The voltage output device disclosed in the present specification includes an output unit that outputs an AC voltage output from an AC power source, a detection unit that detects the AC voltage, and a control unit. A zero-cross point detection process for detecting a zero-cross point where the absolute value of the AC voltage is zero, a peak number detection process for detecting the number of peaks where the voltage value of the AC voltage is at least one of a maximum and a minimum, and a specified period A first number that is the number of detected zero-cross points is compared with a second number that is the number of detected peaks during the specified period, and the difference between the first number and the second number is It is determined that the AC power supply is normal when it is included in a specified range determined according to the length of a specified period, and the AC power supply is abnormal when the difference is not included in the specified range. A determination process for determining Row.

  Further, in the voltage output device, the control unit further includes a first calculation process for calculating a first period that is a period of the zero-cross point from the specified period and the first number; the specified period; And a second calculation process for calculating a second period that is a period of the peak from a second number, and in the determination process, the difference between the first period and the second period is compared with the specified range. And it is good also as a structure which judges the abnormality of the said AC power supply.

  In the voltage output device, the frequency range of the AC voltage that can be output is set in advance, and the lower limit cycle indicating the boundary value on the shorter side of the boundary values at both ends of the specified range is the first cycle. The value is set to a value obtained by subtracting the first time from two periods, and in the determination process, when the first period is smaller than the lower limit period, it is determined that the frequency of the AC voltage is larger than the frequency range. It is good also as composition to do.

  In the voltage output device, the frequency range of the AC voltage that can be output is set in advance, and the upper limit cycle indicating the boundary value on the longer cycle side of the boundary values at both ends of the specified range is the first cycle. It is set to a value obtained by adding a second time to two periods, and in the determination process, if the first period is greater than the upper limit period, it is determined that the frequency of the AC voltage is less than the frequency range. It is good also as composition to do.

  In the voltage output device, the detection unit includes a zero cross pulse generation unit that generates a zero cross pulse according to a period in which the absolute value of the AC voltage is less than a predetermined value, and the voltage value of the AC voltage is a maximum. A peak voltage detector that detects at least one of the minimum peak voltages, and in the zero-cross point detection process, the zero-cross point is obtained from the zero-cross pulse generated by the zero-cross pulse generator, and the peak number detection process Then, it is good also as a structure which detects the number of the peaks in the said regulation period from the said peak voltage which the said peak voltage detection part detected.

  The voltage output device includes a fixing device including a fixing heater, and the power output device according to claim 1 that outputs an AC voltage to the fixing device. The control unit further includes: When the AC power source is determined to be normal, it is determined that the AC voltage can be output to the fixing heater, and when the AC power source is determined to be abnormal, the fixing heater is It is good also as a structure which performs the operation | movement determination process which determines that an alternating voltage cannot be output.

  In the voltage output device disclosed in this specification, when the number of zero-cross points detected by the zero-cross point detection process and the number of peaks detected by the peak-number detection process are different from each other over a specified range, the alternating current Judge that the power supply is abnormal. According to this image processing apparatus, whether the AC power supply is normal or abnormal is determined based on the number of peaks that can be accurately detected regardless of noise, abnormal waveforms, etc., so that the AC power supply abnormality can be accurately detected. Can do.

Cross section of printer Block diagram of power output device Circuit diagram of selector switch Circuit diagram of zero-clock pulse generator Circuit diagram of peak voltage detection circuit Flow chart showing abnormality determination processing A graph showing abnormalities with excessive frequency Graph showing anomalies that cause the frequency to be too low

<Embodiment>
One embodiment will be described with reference to FIGS.

1. Overall Configuration of Printer FIG. 1 is a side sectional view showing a schematic configuration of a printer 10 of the present embodiment. The printer 10 is an example of an image forming apparatus. As shown in FIG. 1, the printer 10 is a direct transfer tandem laser printer that forms a monochrome image using a single color toner, and is configured in a casing 12.

  A supply tray 14 is provided on the inner bottom of the casing 12, and a sheet material 16 such as paper is stacked on the supply tray 14. The supply tray 14 is configured to be openable and closable with respect to the casing 12. When the sheet material 16 is supplied to the supply tray 14 by the user and stored in the casing 12, the sheet material 16 is pressed against the pickup roller 20 by the pressing plate 18. The sheet material 16 is conveyed to the conveyance roller 22 and the registration roller 24 by the rotation of the pickup roller 20. The sheet material 16 is conveyed to the image forming unit 30 after skew correction is performed by the registration roller 24.

  The image forming unit 30 includes a pair of support rollers 32 and 34, a belt 36, and a plurality of transfer rollers 37. The belt 36 is provided between the support rollers 32 and 34 and has a ring shape. The transfer rollers 37 are arranged at equal intervals inside the ring-shaped belt 36. The support rollers 32 and 34 are rotated counterclockwise by a motor (not shown), and the belt 36 is moved accordingly.

  An image forming unit 40 is provided on the upper side of the belt 36. The image forming unit 40 includes a scanner unit 42 and a process unit 44. The process unit 44 includes a photosensitive drum 48, a developing cartridge 46, and the like. The developing cartridge 46 is filled with toner and a developing roller 47 is provided. A developing bias is applied to the developing roller 47 of the developing cartridge 46 from a high voltage power source (not shown), and the developing cartridge 46 is provided. The toner is supplied to the photosensitive drum 48.

The scanner unit 42 is disposed above the photosensitive drum 48 of the process unit 44. The scanner unit 42 irradiates the photosensitive drum 48 of the process unit 44 with the laser beam L based on image data sent from a memory 64 such as a RAM or ROM by a central processing unit (see FIG. 2; hereinafter referred to as CPU) 62 described later. . As a result, an electrostatic latent image corresponding to the image to be formed on the surface of the photosensitive drum 48 is formed. A developing bias is applied from the high voltage power source to the developing roller 47 of the developing cartridge 46, and the toner of the developing cartridge 46 is supplied to the electrostatic latent image, whereby a toner image is formed on the surface of the photosensitive drum 48.

  When the toner image formed on the surface of the photosensitive drum 48 passes the transfer position with the belt 36, a transfer bias is applied from the high voltage power source to the transfer roller 37, and the toner image on the photosensitive drum 48 is transferred onto the sheet material 16. Transcribed. As a result, an image is formed on the sheet material 16. As the belt 36 moves, an image is formed on the sheet material 16. The image formed on the sheet material 16 is sent to the fixing device 52. The fixing device 52 includes a fixing heater 54 for heating and fixing the image. When an AC voltage is output from the AC power supply 50 to the fixing heater 54, the image formed on the sheet material 16 is fixed. The sheet material 16 is conveyed by a conveyance roller 26 to a paper discharge tray 38 provided on the upper portion of the casing 12.

  The AC power supply 50 outputs an AC voltage supplied from an external power supply (not shown). The power supply line DL that outputs an AC voltage from the AC power supply 50 to the fixing heater 54 is provided with an output unit 56 that outputs the AC voltage output from the AC power supply 50 to the fixing heater 54. In the casing 12, a detection unit 58 that detects the AC voltage output to the power supply line DL is provided, and a control unit 60 that controls the output unit 56 and the detection unit 58 is provided. The output unit 56, the detection unit 58, and the control unit 60 constitute a voltage output device 61 that outputs an AC voltage output from the AC power supply 50 to the fixing device 52.

2. Configuration of Voltage Output Device FIG. 2 is a block diagram schematically showing the configuration of the voltage output device 61. As shown in FIG. 2, in the voltage output device 61, the output unit 56 and the detection unit 58 are connected in parallel to the AC power supply 50, and the control unit 60 is connected to the output unit 56 and the detection unit 58. Yes.

(Output part)
The output unit 56 includes a pair of output terminals 70 a and 70 b, and a switch circuit 72 that switches whether to output an AC voltage to the fixing heater 54 to a power supply line DL between the output terminal 70 b and the fixing heater 54. Is provided. FIG. 3 shows a circuit diagram of the output unit 56 including the switch circuit 72. The switch circuit 72 includes triacs TR1 and TR2 and resistors R1 and R2. The resistor R1, the triac TR1, and the resistor R2 are connected in series between the output terminal 70b and the fixing heater 54 in this order, and the triac TR2 is connected in parallel with these elements between the output terminal 70b and the fixing heater 54. Has been.

  The triac TR1 constitutes a photodiode D1 and a photocoupler PC1. In the control unit 60, when the transistor Q1 connected in series to the photodiode D1 is turned on by the CPU 62, a current flows through the photodiode D1 via the resistor R3, and the photodiode D1 emits light. As a result, the triac TR1 is turned on, and a current flows through the triac TR1. The gate terminal G of the triac TR2 is connected between the resistor R1 and the triac TR1, and when an on-voltage higher than the threshold voltage is applied to the gate terminal G by turning on the triac TR1, the triac TR2 is turned on. An AC voltage is output to the fixing heater 54 via TR2. That is, the output unit 56 is controlled by the control unit 60, and switches whether to output an AC voltage to the fixing heater 54 under the control of the CPU 62.

(Detection unit)
Detection unit 58 includes a zero cross pulse generation unit 74 and a peak voltage detection unit 76 connected in parallel to power supply line DL.
The zero cross pulse generator 74 detects the AC voltage output to the power supply line DL, and is a high voltage during a period when the absolute value is equal to or higher than the first reference value KV1, and a period when the absolute value is less than the first reference value KV1 A zero cross pulse having a low voltage is generated (see FIGS. 7 and 8). The first reference value KV1 is an example of a predetermined value. FIG. 4 shows a circuit diagram of the zero cross pulse generator 74. The zero cross pulse generator 74 is configured by a resistor R3, a rectifier circuit W1, and a photodiode D6. The rectifier circuit W1 is a diode bridge that full-wave rectifies an AC voltage using four diodes D2 to D5, and is connected to the AC power supply 50 via a resistor R4. The AC voltage that has been full-wave rectified by the rectifier circuit W1 is output to the photodiode D6.

  The photodiode D6 constitutes a transistor Q2 and a photocoupler PC2. When the voltage value of the AC voltage that has been full-wave rectified by the rectifier circuit W1 is equal to or greater than the first reference value KV1 determined from the on-resistance of the photodiode D6, a current flows through the photodiode D6 and the photodiode D6 emits light. Then, the transistor Q2 is turned on. On the other hand, when the voltage value of the full-wave rectified AC voltage becomes less than the first reference value KV1, no current flows through the photodiode D6, and the transistor Q2 is turned off. That is, the transistor Q2 is turned on during a period when the voltage value of the full-wave rectified AC voltage is greater than or equal to the threshold value K and turned off during a period when the voltage value is less than the threshold value K.

  In the control unit 60, when the transistor Q2 is turned on, a current flows to the transistor Q2 via the resistor R5, and the voltage value of the terminal TN1 disposed between the resistor R5 and the transistor Q2 decreases from a high voltage to a low voltage. The CPU 62 has an analog terminal AC1, and detects the voltage of the terminal TN1 via the NOT circuit H1. In the NOT circuit H1, when the voltage value of the terminal TN1 decreases from the high voltage to the low voltage, the voltage value of the output voltage increases from the low voltage to the high voltage. On the other hand, when the transistor Q2 is turned off, no current flows through the transistor Q2, the voltage value of the terminal TN1 increases from the low voltage to the high voltage, and the voltage value of the output voltage from the NOT circuit H1 decreases from the high voltage to the low voltage. To do. As a result, the CPU 62 detects a zero cross pulse through the analog terminal AC1.

  The peak voltage detector 76 detects the AC voltage output to the power supply line DL, and detects the peak voltage (absolute value of the peak voltage) at which the voltage value is maximum and minimum. In addition, the peak voltage detector 76 outputs a peak pulse according to the timing when the peak voltage is reached. Specifically, the peak voltage detection unit 76 generates a high voltage during the period in which the absolute value of the AC voltage is equal to or higher than the second reference value KV2 that is set to a value larger than the first reference value KV1, and the absolute value thereof is the first value. 2 A peak pulse having a low voltage is generated during a period of less than the reference value KV2 (see FIGS. 7 and 8). FIG. 5 shows a circuit diagram of the peak voltage detector 76. The peak voltage detector 76 includes resistors R6 and R7, a rectifier circuit W2, a diode D11, a capacitor C, and a photodiode D12. The rectifier circuit W2 is a diode bridge that full-wave rectifies an AC voltage using four diodes D7 to D10, and is connected to the AC power supply 50 via a resistor R6. The AC voltage that is full-wave rectified by the rectifier circuit W2 is output to an element such as the diode D11.

  The capacitor C, the resistor R7, and the photodiode D12 are connected in parallel, and the diode D11 is connected in series to these elements. The diode D11 rectifies the AC voltage that has been full-wave rectified by the rectifier circuit W2. The capacitor C accumulates electric charge according to the voltage value of the AC voltage rectified by the diode D11 and generates an interelectrode voltage. The resistor R7 discharges the electric charge stored in the capacitor C. The photodiode D12 constitutes the transistor Q3 and the photocoupler PC3. When the voltage value of the interelectrode voltage generated in the capacitor C becomes equal to or higher than the second reference value KV2 determined from the on-resistance of the photodiode D12, A current flows through the diode D12, the photodiode D12 emits light, and the transistor Q3 is turned on. On the other hand, when the voltage value of the interelectrode voltage generated in the capacitor C becomes less than the second reference value KV2, no current flows through the photodiode D12 and the transistor Q3 is turned off. That is, the transistor Q3 is turned on during a period when the voltage value of the full-wave rectified AC voltage is greater than or equal to the second reference value KV2, and is turned off during a period when the voltage value is less than the second reference value KV2.

  In the peak voltage detection unit 76, an AC voltage is output to the capacitor C through the diode D11 during an increase period in which the voltage value of the full-wave rectified AC voltage increases, and the voltage value of the interelectrode voltage generated in the capacitor C is AC. The voltage value is almost equal to the voltage value of the voltage. In the control unit 60, when the voltage value of the interelectrode voltage of the capacitor C becomes a peak voltage and becomes equal to or higher than the second reference value KV2, a current flows through the transistor Q2 via the resistor R8, and is arranged between the resistor R8 and the transistor Q3. The voltage value at the terminal TN2 drops from a high voltage to a low voltage. The CPU 62 has an analog terminal AC2, and detects the voltage of the terminal TN2 via the NOT circuit H2. In the NOT circuit H2, when the voltage value of the terminal TN2 decreases from the high voltage to the low voltage, the voltage value of the output voltage increases from the low voltage to the high voltage.

  In the peak voltage detector 76, when the voltage value of the full-wave rectified AC voltage is switched from the increase period to a decrease period in which the voltage value decreases, the output of the AC voltage to the capacitor C is blocked by the diode D11. As a result, the voltage between the electrodes of the capacitor C is temporarily held at the peak voltage of the full-wave rectified AC voltage, and this peak voltage is detected by the peak voltage detector 76.

  Further, in the peak voltage detection unit 76, the charge accumulated in the capacitor C is discharged through the resistor R7 with the passage of the decrease period, and the voltage value of the interelectrode voltage generated in the capacitor C decreases. In the control unit 60, when the voltage value of the interelectrode voltage of the capacitor C becomes less than the second reference value KV2, no current flows through the transistor Q3, the voltage value of the terminal TN2 increases from the low voltage to the high voltage, and the NOT circuit H2 The voltage value of the output voltage from is reduced from a high voltage to a low voltage. As a result, the CPU 62 detects a peak pulse via the analog terminal AC2.

(Control part)
The control unit 60 includes a CPU 62, a memory 64, photocouplers PC1 to PC3, and the like. The memory 64 stores various programs for controlling the operation of the printer 10. The CPU 62 controls each unit according to the program read from the memory 64 and detects an abnormality of the AC power supply 50. The various processes are executed. The CPU 62 is connected to the switch circuit 72 of the output unit 56 via the photocoupler PC1 and controls whether or not an AC voltage is output to the fixing heater 54.

  The CPU 62 is connected to the zero cross pulse generator 74 of the detector 58 via the photocoupler PC2, and detects the zero cross pulse. When detecting the zero-cross pulse, the CPU 62 obtains the center timing of the period during which the voltage value becomes a low voltage, and executes the zero-cross point detection process for detecting the timing as the zero-cross point where the voltage value of the AC voltage is zero.

  The CPU 62 is connected to the peak voltage detection unit 76 of the detection unit 58 via the photocoupler PC3, and detects the peak pulse. The CPU 62 detects the period in which the peak pulse voltage value is a high voltage, thereby detecting that the peak voltage detection unit 76 has detected the peak voltage, and the number of peaks in which the voltage value of the AC voltage becomes maximum and minimum. Execute peak number detection processing to detect. In addition to this, the CPU 62 executes various processes such as a first calculation process, a second calculation process, a determination process, and an operation determination process which will be described later.

3. AC Power Supply Abnormality Detection Processing Next, processing for detecting an abnormality of the AC power supply 50 will be described with reference to FIG. As an abnormality of the AC power supply 50, as shown in FIG. 7, a noise generation abnormality in which noise occurs near the zero cross point of the AC voltage output from the AC power supply 50, or an AC output from the AC power supply 50 as shown in FIG. There is a waveform abnormality in which the voltage waveform is rectangular. In the abnormality detection process for the AC power supply 50, the abnormality of the AC power supply 50 is detected, and the type of abnormality that has occurred is also specified.

FIG. 6 shows a flowchart of processing executed by the CPU 62 in accordance with a predetermined program. The CPU 62 executes this processing prior to outputting an AC voltage to the fixing heater 54. A predetermined period T for detecting a zero cross point and a peak is stored in the memory 64 in advance, and when the process starts, the CPU 62 executes a zero cross point detection process over the predetermined period T, and the zero cross point is detected during the predetermined period T. Measure the first number N1 in which is detected. The CPU 62 further executes a first calculation process, and measures the cycle Tz of the zero cross point from the measured first number N1 and the specified period T (S2). The period Tz can be obtained as follows, for example.
Tz = T / N1

Further, the CPU 62 performs the peak number detection process over the specified period T, and measures the second number N2 in which the peak is detected in the specified period T. The measurement of the first number N2 and the measurement of the second number N2 are not necessarily performed at the same time, but are preferably performed at the same time. The CPU 62 further executes a second calculation process, and measures the peak period Tp from the measured second number N2 and the specified period T (S4). The period Tp can be obtained as follows.
Tp = T / N2

Next, the CPU 62 compares the measured period Tz with the period Tp (S6). The CPU 62 sets a specified range on the basis of the cycle Tp, and determines whether or not the cycle Tz is included in the specified range. The CPU 62 subtracts the first time TM1 from the period Tp and sets a lower limit period TMIN that is a boundary value on the side where the period of the specified range is shorter. Further, the CPU 62 adds the second time TM2 to the period Tp, and sets an upper limit period TMAX that is a boundary value on the side where the period of the specified range is longer.
TMIN = Tp-TM1, TMAX = Tp + TM2

  When the period Tz is included in the specified range, the CPU 62 determines that the AC power supply 50 is normal (S12). In the operation determination process for determining whether or not the AC voltage output from the AC power supply 50 can be output to the fixing heater 54, the CPU 62 determines that the AC voltage can be output to the fixing heater 54 (S14). The abnormality detection process ends. As a result, an AC voltage is output to the fixing heater 54, and the output time and the like are controlled based on the zero-cross point of the AC voltage.

  On the other hand, when the cycle Tz is not included in the specified range and the cycle Tz is smaller than the lower limit cycle TMIN, the CPU 62 determines that the AC power supply 50 is abnormal (S8). In this case, the CPU 62 determines that an abnormality of a type in which the frequency of the AC power supply 50 such as an abnormality in noise generation is greater than the frequency range that can be output to the fixing heater 54 has occurred. The CPU 62 determines that the AC voltage cannot be output to the fixing heater 54 (S10), and notifies the user of the abnormal situation using notification means such as a display unit (not shown), and ends the abnormality detection process. To do.

  Further, when the cycle Tz is not included in the specified range and the cycle Tz is larger than the upper limit cycle TMAX, the CPU 62 determines that the AC power supply 50 is abnormal (S16). In this case, the CPU 62 determines that an abnormality of a type in which the frequency of the AC power supply 50 such as a waveform abnormality is lower than the frequency range that can be output to the fixing heater 54 has occurred. The CPU 62 determines that the AC voltage cannot be output to the fixing heater 54 (S18), informs the user of the abnormality using the notification means such as a display unit, and ends the abnormality detection process.

4). Advantages of the present embodiment (1) In the voltage output device 61 of the present embodiment, the zero-cross point cycle Tz calculated using the first number N1 detected in the zero-cross point detection process in the specified period T, and the specified period T The peak period Tp calculated using the second number N2 detected in the peak number detection process is compared. When there is no abnormality in the AC power supply 50, these periods Tz and Tp are equal values. In this voltage output device 61, it is determined that the AC power supply 50 is abnormal when the periods Tz and Tp differ beyond the specified range.

  A noise generation abnormality which is one of the abnormality of the AC power supply 50 will be described with reference to FIG. As shown in FIG. 7, the noise occurrence abnormality means an abnormality in which noise accompanying vibration of the voltage value is added to the AC voltage. Therefore, in the case where the zero cross pulse is generated using the first reference value KV1 in the zero cross pulse generation unit 74, if noise that causes the voltage value of the AC voltage to oscillate exceeds the first reference value KV1, a circle 90 in FIG. As shown, the zero cross pulse due to this noise is generated, and the first number N1 measured in the specified period T is increased compared to the normal case. On the other hand, since the peak voltage detection unit 76 includes the capacitor C having a noise removal effect, the voltage value of the interelectrode voltage is suppressed from exceeding the second reference value KV2. Therefore, the peak voltage detector 76 does not generate a peak pulse due to noise, and the second number N2 is accurately measured. Therefore, when noise generation abnormality occurs, the first number N2 is smaller than the second number N2, and the cycle Tz of the zero cross point is longer than the peak cycle Tp.

  Moreover, the waveform abnormality which is one of the abnormality of AC power supply 50 is demonstrated using FIG. As shown in FIG. 8, the waveform abnormality means an abnormality in which the waveform of the AC voltage becomes a rectangular wave. Therefore, when the zero cross pulse is generated in the zero cross pulse generation unit 74 using the first reference value KV1, the zero cross pulse is generated by shortening the period during which the absolute value of the AC voltage is lower than the first reference value KV1. (Refer to circle 92 in FIG. 8), the first number N1 measured in the specified period T is reduced compared to the normal case. On the other hand, in the peak voltage detector 76, since the second reference value KV2 is set to a value larger than the first reference value KV1, even if the waveform of the AC voltage is rectangular, the second reference value KV2 is set. Beyond that, the voltage value of the interelectrode voltage oscillates, and the second number N2 is measured. Therefore, when a waveform abnormality occurs, the first number N2 becomes larger than the second number N2, and the cycle Tz of the zero cross point becomes shorter than the peak cycle Tp.

  As described above, the zero cross point serving as a reference for controlling the fixing heater 54 varies in the number measured due to the abnormality of the AC power supply 50, while the peak does not vary in the number measured due to the abnormality in the AC power supply 50. According to this voltage output device 61, the AC power supply is based on the peak period Tp that can be accurately calculated by comparing the period Tz of the zero crossing point with the peak period Tp regardless of noise, abnormal waveform, or the like. 50 normality or abnormality can be determined, and abnormality of the AC power supply 50 can be accurately detected.

(2) In the voltage output device 61 of this embodiment, it is determined whether the cycle Tz of the zero cross point is larger or smaller than a specified range set with the peak cycle Tp as a reference. For this reason, when it is determined that the AC power supply 50 is abnormal, the abnormality occurring in the AC power supply 50 is greater than the frequency range in which the frequency of the AC power supply 50 such as noise generation abnormality can be output to the fixing heater 54. It is possible to determine whether there is a type of abnormality that occurs, or whether there is a type of abnormality in which the frequency of the AC power supply 50 is lower than the frequency range that can be output to the fixing heater 54, such as a waveform abnormality. it can.

(3) In the voltage output device 61 of the present embodiment, the abnormality detection process of the AC power supply 50 is executed prior to outputting the AC voltage to the fixing heater 54, so that the AC power output from the abnormal AC power supply 50 is fixed. Output to the heater 54 is prevented.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings, and for example, the following various aspects are also included in the technical scope of the present invention.
(1) Although the above embodiment has been described using an apparatus having a printer function, the present invention is not limited to this. The present invention is not limited to an apparatus having a printer function as long as the apparatus includes a voltage output device 61 that detects an abnormality of the AC power supply 50 and outputs an AC voltage output from the AC power supply 50. .

(2) In the above embodiment, the detection unit 58 has been described using an example in which the zero cross pulse generation unit 74 and the peak voltage detection unit 76 are provided. One generation unit having the function of the unit 76 may be provided. In this case, the generation unit has a configuration in which the voltage value of the reference value can be switched. When generating the zero cross pulse, the reference value is set to the first reference value KV1, and the peak pulse is set. When it is generated, the reference value may be controlled to be set to the second reference value KV2.

(3) In the above embodiment, the description has been made using the example in which the AC power supply 50 is determined to be normal by comparing the cycle Tz of the zero cross point and the peak cycle Tp. It may be determined whether the AC power supply 50 is normal by comparing the first number N1 in which the zero cross point is detected with the second number N2 in which the peak is detected in the specified period T. In this case, if the specified period T becomes longer, the first number N1 and the second number N2 become larger. Therefore, the specified range is preferably determined according to the length of the specified period T.

(4) In the above-described embodiment, the printer 10 is described using an example in which various processing is executed by one CPU 62, but the present invention is not limited to this. For example, various processes may be shared by different CPUs, ASICs, and the like.

(5) Further, the program executed by the CPU 62 is not necessarily stored in the ROM 12, and may be stored in the CPU 62 itself or in another storage device.

(6) The switch circuit 72, the zero cross pulse generator 74, and the peak voltage detector 76 described in the above embodiment are merely one embodiment, and may be configured in other forms.

10: Printer, 50: AC power supply, 52: Fixing device, 54: Fixing heater, 56: Output unit, 58: Detection unit, 60: Control unit, 61: Voltage output device, 72: Switch circuit, 74: Zero cross pulse generation , 76: peak voltage detector, KV1: first reference value, KV2: second reference value, N1: first number, N2: second number, TMAX: upper limit period, TMIN: lower limit period, Tp: peak period , Tz: Zero-cross point period

Claims (6)

An output unit that outputs an AC voltage output from an AC power source;
A detection unit for detecting the AC voltage;
A control unit;
With
The controller is
Zero-cross point detection processing for detecting a zero-cross point where the absolute value of the AC voltage is zero;
A peak number detection process for detecting the number of peaks in which the voltage value of the AC voltage is at least one of a maximum and a minimum; and
A first number that is the number of detected zero-cross points in a specified period and a second number that is the number of detected peaks in the specified period are compared, and the first number and the second number are compared. When the difference is included in a specified range determined according to the length of the specified period, it is determined that the AC power supply is normal, and when the difference is not included in the specified range, A determination process for determining an abnormality,
Execute the voltage output device. The voltage output device according to claim 1,
The controller is
Furthermore,
A first calculation process for calculating a first period which is a period of the zero cross point from the specified period and the first number;
A second calculation process for calculating a second period which is a period of the peak from the specified period and the second number;
Run
In the determination process, a voltage output device that determines an abnormality of the AC power source by comparing a difference between the first period and the second period with the specified range. The voltage output device according to claim 2,
The frequency range of AC voltage that can be output is preset,
Of the boundary values at both ends of the specified range, the lower limit cycle indicating the boundary value on the shorter cycle side is set to a value obtained by subtracting the first time from the second cycle,
In the determination process, when the first period is smaller than the lower limit period, the voltage output apparatus determines that the frequency of the AC voltage is larger than the frequency range. The voltage output device according to claim 2 or 3, wherein
The frequency range of AC voltage that can be output is preset,
Of the boundary values at both ends of the specified range, the upper limit cycle indicating the boundary value on the longer cycle side is set to a value obtained by adding a second time to the second cycle,
In the determination process, when the first period is larger than the upper limit period, the voltage output apparatus determines that the frequency of the AC voltage is less than the frequency range. The voltage output device according to any one of claims 1 to 4,
The detector is
A zero-cross pulse generator that generates a zero-cross pulse according to a period in which the absolute value of the alternating voltage is less than a predetermined value;
A peak voltage detector that detects a peak voltage at which the voltage value of the AC voltage is at least one of a maximum and a minimum; and
With
In the zero cross point detection process, the zero cross point is determined from the zero cross pulse generated by the zero cross pulse generation unit,
In the peak number detection process, a voltage output device that detects the number of peaks in the specified period from the peak voltage detected by the peak voltage detection unit. A fixing device including a fixing heater;
The power supply output device according to any one of claims 1 to 5, wherein an AC voltage is output to the fixing device.
With
The controller is
Furthermore,
When it is determined that the AC power supply is normal, it is determined that the AC voltage can be output to the fixing heater, and when it is determined that the AC power supply is abnormal, the AC power is supplied to the fixing heater. An image forming apparatus that executes an operation determination process for determining that a voltage cannot be output.

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