JP2016101067A - Apparatus and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem that there has been conventionally a technique of capable of performing an intermittent operation which further reduces a switching frequency to a predetermined frequency and under a light load, and temporarily stops switching itself; however, a sound is sometimes heard due to the intermittent operation.SOLUTION: The apparatus retains information concerning number of driving occurrences and driving frequency corresponding to an inclination of an output voltage and identifies an inclination of a change in an output voltage for a stopping period in an intermittent operation including an operation period and the stopping period. In addition, the apparatus outputs a driving signal in accordance with number of driving occurrences and driving frequency determined based on the identified inclination and the retained information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a switching power supply that generates a DC voltage from a commercial power supply.

  A switching power source is a power source that generates a DC voltage from a commercial power source, and an inkjet printer is a product that uses the switching power source. Inkjet printers are already common for home use. Therefore, the quietness of the ink jet printer has been strongly demanded.

  As described above, a switching power supply is generally used as a power supply used in an ink jet printer, but a loss of a switching operation is large. In particular, when the load is light (for example, the low power consumption mode (sleep mode) of the printer), the ratio of the switching loss to the energy transmitted to the secondary side of each switching increases due to the reduction of the switching pulse width, leading to a reduction in efficiency. In order to reduce the efficiency reduction at the time of this light load, the device which reduces the frequency | count of switching per time is made | formed. Further, there is a method of reducing the switching frequency to a predetermined frequency and performing an intermittent operation in which switching itself is temporarily stopped at a light load. However, a sound may be heard due to this intermittent operation.

  Patent Document 1 is disclosed as a method for reducing the operation sound of the apparatus as described above. In Patent Document 1, the first and last pulse widths of driving are changed to suppress the exciting current, thereby suppressing a rapid change in the exciting current in one driving period. By suppressing this abrupt change, the mechanical vibration of the transformer caused by the abrupt change can be reduced, and the excitation sound can be reduced.

JP 2006-246664 A

  However, in the technique of Patent Document 1, there is a possibility that sound cannot be reduced in a situation where the pulse width of the drive signal for intermittent operation is constant. In the present embodiment, the above-described problems are solved, and a configuration for reducing the sound of a transformer at a light load is proposed.

  An apparatus of the present application for solving the above-described problem is an apparatus for holding information on the number of times of driving and a driving frequency corresponding to the slope of the output voltage, and the pause in the intermittent operation having an operation period and a pause period. Specifying means for specifying an inclination of a change in output voltage during a period, and an output for outputting a drive signal in accordance with the number of times of driving and the driving frequency determined based on the specified inclination and the information held in the holding means Means are provided.

  The mechanical vibration of the transformer can be reduced and the sound can be reduced.

Schematic of the whole power supply of a present Example. Detailed view showing a control block of the first embodiment. FIG. FIG. Operation | movement explanatory drawing of a 1st Example. Operation | movement explanatory drawing of a 1st Example. Operation | movement explanatory drawing of a 1st Example. Operation | movement explanatory drawing of a 1st Example. Operation | movement explanatory drawing of a 2nd Example. Operation | movement explanatory drawing of a 2nd Example.

(First embodiment)
Before describing the embodiment of the present application, the reason why sound is generated during intermittent operation will be described with reference to FIG.

  In FIG. 3A, Vout is the output voltage of the power supply, VFB is a voltage signal that monitors the secondary side voltage in the power supply and is fed back to the primary side, and VDRV is a drive signal that drives the switching element on the primary side. . In VDRV, the start / stop of driving is determined by comparing the VFB voltage with a predetermined threshold value. In FIG. 3A, when the output voltage Vout decreases and VFB reaches the drive start voltage vfa, VDRV starts to drive the switching element on the primary side and Vout increases. As Vout rises, VFB falls with a delay in the feedback circuit, and VDRV stops when the drive stop voltage vfb is reached. At this time, the rate of increase and decrease of the output voltage Vout depends on the load of the power source. The driving period is determined by the energy input to the secondary side by driving and the load on the secondary side. Further, the period during which the drive is stopped depends on the load of the power source because it is a free discharge of the capacitor provided on the secondary side. The above operation determines the intermittent operation period Td1 including the VDRV operation period Ton1 during the intermittent operation and the VDRV pause period Toff1.

  In the above-described operation, when the load of the power source changes every moment, the VDRV operation period Ton1 and the VDRV operation period Toff1 also change, so the intermittent operation period also changes. On the other hand, when the secondary load is constant, Ton1 and Toff1 are also constant, and the frequency is fixed in the intermittent operation period Td1.

  In the operation of the ink jet printer, during the printing operation, the load is not constant and is heavy due to the reciprocating movement of the carriage in the main operation direction, the feeding / conveying / discharging of the recording medium, the head maintenance process, and the like. For this reason, in most cases where the printing operation is performed, normal continuous driving is performed instead of the intermittent operation described above. However, when the printing operation is not performed, the load is almost constant, and since the load is light, the operation is intermittent at a constant frequency.

  Next, the operation when the load of the power source becomes a lighter load will be described with reference to FIG.

  As described above with reference to FIG. 3A, the rate of increase and decrease of the output voltage Vout depends on the load of the power source. When the load on the power supply becomes lighter, the increase in Vout corresponding to the energy input to the secondary side in one drive increases, and VFB reaches the drive stop voltage vfb with a small number of drives. As a result, Vout increases in a shorter period than when the load is heavy. During the period of not being driven, the secondary-side capacitor is free-discharged. However, if the load is light, the time until the driving start voltage vfa is reached becomes longer. Therefore, when the load of the power source is further reduced during the intermittent operation, power is suddenly supplied to the secondary side, and the intermittent operation frequency is lowered.

  At this time, the power supplied to the secondary side is proportional to the current flowing through the switching element during the driving time, that is, proportional to the current flowing through the transformer. Therefore, the transformer itself generates mechanical vibration due to the current flowing through the transformer, and a part of the vibration component becomes the frequency of the intermittent operation. Although sound is generated from the transformer by this operation, when the frequency of the intermittent operation approaches the audible region, particularly 3 KHz, which is highly sensitive to human hearing, the sound is recognized by the user as sound even if the mechanical vibration of the transformer is small. As a result, a sound is generated during intermittent operation.

  Here, patent document 1 is demonstrated using FIG. In Patent Document 1, as a measure for reducing the sound of the transformer described above, in each drive period (also referred to as an operation period) during the intermittent operation, a sudden change in the excitation current of the transformer is suppressed to suppress the excitation sound. FIG. 4A is a diagram in which the driving at the light load shown in FIG. Since the excitation current flowing through the transformer increases linearly with a constant slope, the excitation current becomes a triangular wave that increases linearly while VDRV is ON. As before, VDRV is turned off when it reaches the voltage VFB of the photocoupler 108a, but is processed so that the pulse width of the VDRV is shortened before and after the driving period. As a result, the drive signal VRD during the drive period is controlled so that the pulse width gradually increases and gradually decreases. Details of this driving are shown in FIG. As described above, since the excitation current flowing through the transformer increases linearly with a constant slope, the maximum value of the excitation current also increases and decreases according to the increase and decrease of the pulse width of VDRV. In FIG. 4B, the rapid change of the exciting current in one driving period is suppressed by changing the first and last pulse widths of driving and suppressing the exciting current. By suppressing this sudden change, the mechanical vibration of the transformer caused by the sudden change can be reduced, and the excitation sound can be reduced.

  FIG. 1 is a diagram showing the configuration of the entire power supply of this embodiment.

In FIG. 1, a commercial power supply 101 is rectified by a diode bridge 102 and a smoothing capacitor 103, and reaches a ground via a transformer 104 via a switching element 106 and a current detection resistor 107. The diode 109 and the capacitor 110 generate Vcc for the control IC 105. The control IC 105 periodically turns on the VDR signal that drives the switching element 106, and compares the output VFB of the photocoupler 108a with the voltage Vcs of the current detection resistor 107 in the control IC. Then, the control IC 105 turns off the VDR signal when the voltage Vcs of the current detection resistor 107 reaches the voltage VFB of the photocoupler 108a.
The diode 111 and the capacitor 112 rectify the secondary output of the transformer 104 to generate an output Vout, and the Vout is divided by resistors 118 and 119 and connected to the reference terminal of the shunt regulator 115. Vout is connected to the photocoupler 108b via the current limiting resistor 113, and the cathode of 108b is connected to the shunt regulator 115. Resistor 117 and capacitor 116 determine the gain of the feedback circuit. The resistor 114 stabilizes the operation of the shunt regulator 115. Note that, for example, a print head is operated by this Vout. Although the present application will be described as a printing apparatus including the circuit and the print head illustrated in FIG. 1, the present application can be applied not only to the printing apparatus but also to other apparatuses.

  The internal configuration of the control IC 105 in this embodiment will be described with reference to FIG.

  The continuous / intermittent determining means 201 determines whether to perform continuous driving or intermittent driving based on the voltage value of VFB fed back to the primary side through the path described with reference to FIG. The continuous / intermittent determining means 201 performs control so that continuous driving is performed when the load of the power source is heavy and intermittent driving is performed when the load is light.

  In this embodiment, since the intermittent operation is described, the continuous / intermittent determining means 201 will be described on the premise that the intermittent operation is determined. As described above, the intermittent operation includes an operation period of the drive signal and a pause period of the drive signal, and transits from the operation period to the pause period. The VFB inclination measuring means 202 and the drive determining means 204 determine the driving condition of the switching element from the inclination of the waveform of the VFB voltage according to the procedure described later. When the VFB reaches a predetermined value, the drive start trigger generation 203 sends a trigger signal instructing the start of the intermittent operation drive period to the drive means 205. When the drive means 205 receives this trigger signal, the drive determination means 204 sends it. The VDRV signal is generated with the determined drive. When the driving unit 205 completes the driving determined by the driving determining unit 204, the driving unit 205 sends a driving end trigger to the continuous / intermittent determining unit 201 to perform the above-described continuous / intermittent determination.

  A VDRV signal generation procedure in the driving unit 205 will be described with reference to FIG. The driving number information and the period information from the driving determining means 204 are stored in the starting pulse means and the counter in the driving means 205, and a signal with a predetermined period is applied to the set terminal of the flip-flop a predetermined number of times. A voltage obtained by processing the voltage Vcs of the resistor 107 that detects the exciting current flowing through the transformer and the feedback voltage VFB of the secondary voltage is input to the comparator, and the output of the comparator is connected to the reset terminal of the previous flip-flop.

  The VDRV that drives the switching element 106 is turned on under a predetermined condition as described above. VFB indicates a value corresponding to the secondary side voltage Vout. When Vcs reaches a value obtained from VFB, VDRV is turned OFF. Therefore, VDRV has a pulse width corresponding to the secondary voltage.

  The VFB inclination measuring means 202 will be described with reference to FIG.

  FIG. 5A shows the waveform of each part at the time of measuring the VFB inclination, and Vout, VFB, and VDRV are as described above. Start_tr is a drive start trigger in FIG. 2A instructing the start of each operation period in the intermittent operation, and end_tr is a drive end trigger in FIG. 2A informing the end of each operation period in the intermittent operation. Ring Buf is a ring buffer that continues to record the VFB level as a digital value, and continues to record after rewriting from the head area when all of the fixed memory area is recorded.

  If VFB reaches a predetermined threshold value, the continuous / intermittent determination means 201 shifts to intermittent operation. Immediately after the transition, VDRV stops, so the voltage Vout decreases, and VFB starts to increase accordingly. If VFB rises to a predetermined value, drive a specified number of times, and then issue end_tr to notify that the specified number of times of driving has ended. After this, since the drive is not performed, the power is supplied only by discharging the capacitor in the power source and in the load. The VFB that continued to fall during driving starts to rise with the lag of the power supply feedback circuit. The rising of the Ring Buf is detected in the procedure described later, and if detected, the VFB value at that time is read from the Ring Buf. Next, when the VFB reaches a predetermined value, the VFB value at that time is read from the Ring Buf.

  With reference to FIG. 5B, the above-described detection procedure for starting the VFB rise will be described.

  The upper diagram of FIG. 5 (b) shows an enlargement of the portion where the VFB waveform changes from falling to rising, and at the same time shows the state of Ring Buf corresponding to this waveform. VFB values are recorded in Ring Buf as Vn, Vn + 1,... According to the sampling period. At the same time, each sampled time is recorded. The procedure will be described with reference to the flowchart of FIG. The flowchart of the present application is realized by the CPU reading and executing a program related to the flowchart from the memory.

  If the above-mentioned end_tr is issued, the CPU starts this processing (501) and resets the counter value n (502). The CPU determines whether the current VFB value is larger than the previous VFB value (503). If not, the CPU increments the counter n (504) and returns to 503. If it is determined at 503 that the current VFB value is larger than the previous VFB value, the CPU determines that the VFB has started to increase, and the current VFB value Vn and the recorded time Tn are respectively Vfb1 and Tfb1. To store. Next, the CPU waits for the VFB value to reach Vfb2 to start driving while incrementing the counter n (506, 507). If the VFB value reaches Vfb2, the time Tn at that time is stored in Tfb2.

  Next, a procedure for obtaining the VFB slope will be described with reference to FIG.

  The upper part of FIG. 5C shows the positions of Vfb1 and Vfb2 detected in FIG. 5B on the Ring Buf. Since it has a ring buffer configuration, after detecting end_tr, the value of VFB is continuously recorded with a certain period of time, and necessary data can be read when necessary. In the figure, it can be seen that the VFB value Vn is recorded with a time width, and the value Vfb1 when it has risen and the value Vfb2 when it is determined that the drive start voltage VFB has been reached. The lower part of FIG. 5C shows an equation for calculating the slope of VFB by calculation. Since Vout during the period of no drive is free discharge, the output Wout at that time can be known by obtaining the slope of VFB proportional to this. That is, the difference between Vfb1 and Vfb2 is divided by the difference between the measured times Tfb1 and Tfb2.

  Next, if the slope of VFB is calculated, an appropriate drive number and drive cycle are obtained to return this value, that is, the output voltage Vout to the specified value. Here, it is obtained from a table previously stored in the storage means. FIG. 6 shows a table. In the present application, a table in which the driving number and driving cycle corresponding to the inclination are associated is held, but not limited to the table, information on the driving number and driving cycle associated with the inclination is retained. Just do it. The apparatus holds the table of FIG. 6 in 204 of FIG. The table stores the driving number and the driving cycle for each Aw value of Aw1, Aw2,... Having a certain width, using the VFB gradient Aw obtained in the procedure described in FIG. Therefore, the drive number Nx and drive period fx of Awx including the slope Aw value of VFB obtained by the procedure described in FIG. 5 are obtained. In FIG. 6, the driving number Nx and the driving frequency fx for reducing mechanical noise and suppressing loss to the secondary side as much as possible are defined for each VFB gradient Awx. Therefore, an operation in which at least one of sound and loss is solved is realized by processing according to the slope Awx calculated in the processing of FIG. 5 and the driving number Nxto of the driving frequency fx determined based on the table of FIG. .

  FIG. 7 shows the state of intermittent operation when driving is performed with the driving number and driving cycle determined by the procedure described in FIGS. FIG. 7A is a diagram showing a relatively heavy load in the intermittent operation. Here, the VFB value vfa for determining the drive start of the intermittent operation is a value determined from the ripple voltage minimum value ΔVFB1 of Vout allowed during the intermittent operation. In this embodiment, the driving period Ton1 is obtained based on the time from when the VFB changes from falling to rising until it reaches the driving start voltage vfa. Here, the driving number Nx, The driving cycle fx is determined in advance and recorded in the table described with reference to FIG. Accordingly, in FIG. 7A, the VFB and the output voltage Vout have waveforms having the same rise and fall times.

The drive when the load of the power source becomes lighter than in FIG. 7A will be described using FIG.
The procedure is the same as that described with reference to FIG. 7A. However, since the load is lighter than in FIG. The time until the drive start voltage vfa is reached becomes longer, and the drive time Ton determined based on this becomes longer. In addition, since the amount of energy to be input from the primary side to the secondary side is reduced, the number of times of driving in each driving period is reduced, and at the same time, the driving frequency is lowered. The driving number Nx and the driving cycle fx in this case are also stored in the table described with reference to FIG. 6 corresponding to the VFB gradient Awx. FIG. 7C shows a waveform when the load of the power source becomes lighter than in FIG. 7B. Since it is the same as the above, the description is omitted.
The waveforms described in FIGS. 7A to 7C show that the driving during the driving period is gentle even when the load is light, and mechanical vibration due to the exciting current of the transformer can be suppressed, resulting in the operation sound of the device. Can be reduced. Next, how the load is reduced and the operation enters the continuous operation from the intermittent operation will be described with reference to FIG.

  When driving is started, driving is performed with a driving number Nx and a driving cycle fx according to the above-described procedure. However, when the amount of energy estimated from the VFB slope Awx is smaller than the actual load, the rise in Vout is reduced. In the present application, the inclination of Vout is also specified by specifying the inclination of VFB. Therefore, calculating Awx is to specify the slope of VFB and also to specify the slope of Vout.

  If it is within the range of the intermittent operation, an energy amount that matches the inclination of the increase in VFB in this state is input at the start of the next drive. However, if the increase in Vout does not reach the specified value even after the driving is completed, that is, if the VFB does not decrease completely, it is determined that the necessary amount of energy cannot be transmitted to the secondary side in the intermittent operation. In this case, the lower limit vfb of the VFB is determined in advance, and if the VFB does not reach vfb when the drive of the intermittent operation drive number Nx and the drive cycle fx is finished, the control of the intermittent operation is exited and the continuous operation is started. It is possible to shift to continuous operation by controlling to.

  Processing for calculating the inclination will be described with reference to a flowchart. The CPU determines whether or not VFB is less than vfb when driving of the predetermined intermittent operation number of driving Nx and driving period fx is completed (801). If VFB is less than vfb, the CPU determines that Vout has been sufficiently boosted, and sets the intermittent drive mode (802). At this time, if it is already in the intermittent mode, it is equivalent to maintaining the state. Next, the CPU drives with the driving number Nx and the driving cycle fx according to the procedure described in FIGS. 5 to 7 (803), and returns to 801. If the VFB at the end of driving in the driving cycle fx is not less than vfb in 801, the CPU determines that the required amount of energy cannot be transmitted to the secondary side in the intermittent operation, and performs continuous driving (804). ). Thereafter, the polling state 801 is entered.

  In the present embodiment, the driving number Nx and the driving cycle fx of the intermittent operation are obtained from a table prepared in advance. However, the same applies if obtained using a CPU / firmware. The same is true even if a plurality of VFB values vfb are prepared for driving start vfa and driving period fx, respectively, and used appropriately. Further, the means for obtaining the slope of VFB is the same even if it is obtained by detecting the measurement position by the peak hold of the upper and lower limits. In addition, the value recorded in the ring buffer is read for detecting vfa and vfb, but the same applies to the case where vfa and vfb are detected and recorded directly from the detection unit.

(Second embodiment)
In the first embodiment, the drive period during the intermittent operation and the non-drive period are described as the same length. In the second embodiment, the case where both periods are different will be described.

  FIG. 9A shows the same state as FIG. That is, driving is performed with the driving number and driving frequency corresponding to the slope of VFB, and the output voltage Vout, feedback voltage VFB, and driving signal VDRV at this time are shown. When VFB reaches the drive start voltage vfa, VDRV is driven a predetermined number of times and at a predetermined frequency. When the driving is completed, VFB increases as the output voltage Vout decreases, and when the driving start voltage vfa is reached, VDRV is driven again.

  FIG. 9B shows drive waveforms in the second embodiment.

  In the first embodiment, the driving period during the intermittent operation and the non-driving period have the same length, but the technique described in this specification is not limited to this. The driving period can be made longer and the transformer can be excited more rapidly. In FIG. 9B, the VDRV cycle is slower than in FIG. 9A. When driving is finished, Vout begins to drop, but during this period, the capacitor discharge period is established, and the slope of the drop of Vout depends on the load of the power supply. Therefore, the behavior of Vout and VFB during this period is the same as in the first embodiment. It is.

  The method for obtaining the drive period and drive frequency in the second embodiment will be described with reference to FIG.

  The method for obtaining the slope of VFB is the same as in the description of FIG. The method for selecting the drive period and drive frequency on the table from the inclination Aw is the same as in the description of FIG.

  Since the table shown in FIG. 10A is the same as FIG. 5, the VFB gradient Aw is the same as the drive cycle and drive frequency obtained from this table. In the second embodiment, processing is added to the drive cycle and drive frequency obtained here. If the driving time is lengthened, the period of intermittent operation becomes longer, so that the energy input to the secondary side must be increased by an amount corresponding to the amount that is longer than the energy before the lengthening. Therefore, the obtained VFB slope Aw is multiplied by the ratio of slowing the drive frequency, and the driving number Nxx and the drive frequency fww at the time of the slope Aww with a heavier load are obtained from the table. Since Nxx and fww are driving conditions with a heavier load, Vout will rise to an appropriate value or more in this state. For this reason, the drive frequency fww is made longer than the frequency at the time of Aw before correction, ie, the drive frequency fww is delayed by the ratio of reducing the frequency. Since the subsequent driving method is the same as that of the first embodiment, a description thereof will be omitted.

  By performing the above, it is possible to lengthen the drive period while keeping the average energy within one cycle of the intermittent operation the same.

  In the second embodiment, the table of FIG. 6 described in the first embodiment is used, and the drive cycle and the drive frequency are calculated based on the table. However, the second embodiment is similar to the first embodiment. The same effect can be obtained by using a table in which drive periods and drive frequencies suitable for the embodiment are written in advance.

[Other embodiments]
The present invention can also be realized by executing the following processing.

  That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

  101 Commercial power supply

Claims (8)

An apparatus for holding information on the number of driving times and the driving frequency corresponding to the slope of the output voltage,
A specifying means for specifying an inclination of a change in output voltage during the pause period in an intermittent operation having an operation period and a pause period;
An apparatus comprising: output means for outputting a drive signal according to the number of times of driving and the driving frequency determined based on the specified inclination and the held information. A first detection means for detecting a first voltage value when the feedback voltage is changed from a decrease to an increase with a decrease in the output voltage when the operation period transits to the pause period;
First storage means for storing a first time when the feedback voltage has changed from falling to rising;
Second storage means for storing a second time when the predetermined voltage value of the feedback voltage is reached;
2. The apparatus according to claim 1, wherein the specifying means specifies the slope by dividing a difference between the predetermined voltage value and the first voltage value by a difference between the second time and the first time. .   The apparatus according to claim 1, wherein pulse widths of the plurality of drive signals in the operation period are the same. The device has a printhead;
The output means outputs the driving signal to the print head according to the number of times of driving and the driving frequency determined based on the specified inclination and the held information. 4. The apparatus according to any one of items 3. A method in an apparatus for holding information on the number of driving times and the driving frequency corresponding to the slope of the output voltage,
A specifying step for specifying a slope of a change in output voltage during the idle period in an intermittent operation having an active period and an idle period;
A control method comprising: an output step of outputting a drive signal according to the number of times of driving and the driving frequency determined based on the specified inclination and the held information. A first detection step of detecting a first voltage value when the feedback voltage changes from a decrease to an increase with a decrease in the output voltage when the operation period transits to a pause period;
A first storage step for storing a first time when the feedback voltage has changed from falling to rising;
A second storage step of storing a second time when the predetermined voltage value of the feedback voltage is reached;
6. The control according to claim 5, wherein the specifying step specifies the slope by dividing a difference between the predetermined voltage value and the first voltage value by a difference between the second time and the first time. Method.   The control method according to claim 5 or 6, wherein pulse widths of the plurality of drive signals in the operation period are the same. The device has a printhead;
The output step outputs the drive signal to the print head according to the number of times of driving and the driving frequency determined based on the specified inclination and the held information. 8. The control method according to any one of 7 above.

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