CN101359870B - Piezoelectric transformer type high-voltage power apparatus and image forming apparatus - Google Patents

Piezoelectric transformer type high-voltage power apparatus and image forming apparatus Download PDF

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Publication number
CN101359870B
CN101359870B CN200810145516XA CN200810145516A CN101359870B CN 101359870 B CN101359870 B CN 101359870B CN 200810145516X A CN200810145516X A CN 200810145516XA CN 200810145516 A CN200810145516 A CN 200810145516A CN 101359870 B CN101359870 B CN 101359870B
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China
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voltage
driving
frequency
control unit
piezoelectric transformer
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CN101359870A (en
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近藤孝志
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Hewlett Packard Development Co LP
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Samsung Electronics Co Ltd
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/065—Arrangements for controlling the potential of the developing electrode
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/80—Details relating to power supplies, circuits boards, electrical connections
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dc-Dc Converters (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Direct Current Feeding And Distribution (AREA)

Abstract

A piezoelectric convertor type high voltage power source device applies the driving voltage confirmed by the driving frequency value to the convertor and provides the outputting voltage output by the piezoelectric convertor to the load. The device comprises an outputting voltage detecting unit comparing the outputting voltage to the reference voltage controlling the outputting voltage, and maintaining the outputting voltage to a predetermined value; and detecting the changing of the outputting voltage as the digital value; and a driving control unit for executing the driving control for the piezoelectric convertor according to the digital value. The high voltage power source executes the stable frequency control, which never enter the abnormal vibration or the non controllable state, outputting the high voltage in a short ascending time period.

Description

Piezoelectric transformer type high-voltage power apparatus and image processing system
The cross reference of related application
The application require to enjoy on August 1st, 2007 in the sequence number of Japanese Department of Intellectual Property application be 2007-200793 Japanese patent application rights and interests and be the rights and interests of the korean patent application of 2007-118097 on November 19th, 2007 in the sequence number of Korea S Department of Intellectual Property application, in the disclosure of introducing above-mentioned application herein, can be for reference.
Technical field
The present invention relates to use supply unit and the image processing system thereof of piezoelectric transformer.
Background technology
In the processing procedure of electronic type photography, form in the image processing system of image, if adopt the method for direct transfer printing (transfer) that a transfer printing unit is contacted with transferred image with photoreceptor, this transfer printing unit adopts one to have the conductive rubber of roll form of rotating shaft as conductor.In this case, control the driving of transfer printing unit according to the processing speed of photoreceptor.In addition, utilize direct current (DC) bias voltage as the voltage that is applied on the transfer printing unit, and make the polarity of dc offset voltage identical with the polarity of the transfer voltage that utilizes corona discharge process.
Therefore, for by utilizing transfer roll to carry out reliable image transfer printing, usually should apply the voltage (by required microampere order electric current) of about 3kV.According to the technology of routine, form required high pressure in order to generate for image, used a kind of coil form electronic type converter (transformer).Yet coil form electronic type converter utilizes copper conductor, bobbin and magnetic core to form.When utilizing coil form electronic type converter to apply the voltage of about 3kV, its output current value very low (being microampere order) should minimize leakage current in each parts.For this leakage current is minimized, used a module of utilizing organic insulating material to make to manufacture the method for the coil of coil form electronic type converter.Yet, when using the method, exist because of the overheated danger that causes producing smoke and fire, and, need a more relative huge electronic type converter with power supply.Therefore, be difficult to reduce size and the weight of coil form electronic type converter.
In order to solve the problems referred to above that are associated with coil form electronic type converter, considered a kind of method of utilizing tiny, lightweight and high output piezoelectric transformer to generate high output voltage.That is, if adopt a piezoelectric transformer that utilizes ceramic material, can generate high output voltage, its efficient is equal to or higher than the efficient of coil form electronic type converter.In addition, because the combination of piezoelectric transformer and its primary side and primary side is irrelevant, can arrange the distance between the electrode of primary side and primary side, need not resume module, eliminate the danger of generation smoke and fire.As a result, generate the method for high output voltage by utilizing piezoelectric transformer, make it possible to make small size and lightweight high-voltage power apparatus.
Yet, in utilizing the high-voltage power apparatus of piezoelectric transformer, utilize analog signal processing circuit to carry out FREQUENCY CONTROL, so the FREQUENCY CONTROL operation is unsettled.That is, if the control quick changes in voltage, so that the output voltage of (or reduction) high-voltage power apparatus that raises rapidly, the resonance frequency of piezoelectric transformer is exceeded, just can not the control output voltage.In addition, in the time need to being equal to or greater than the power of piezoelectric transformer capacity owing to unexpected situation, the driving frequency of piezoelectric transformer surpasses resonance frequency, output voltage that just can not the control piezoelectric transformer, with this so that generate bad picture signal.In addition, even when the output voltage of piezoelectric transformer can not be controlled, the vibration of circuit operation still occurs at high-voltage power apparatus.
In addition, because the parasitic driving frequency from when reaching expection setting output voltage values the control signal of connecting high-voltage power apparatus is input to operational amplifier, ending, so that the rise time appearance postpones.
And, because to a plurality of resonant frequency points of piezoelectric transformer existence with respect to output voltage, therefore can be by the scope of the output voltage of piezoelectric transformer output in order to increase, cause the interior frequency of scope of inefficient Voltage-output to be used, it has reduced the gross efficiency of high-voltage power apparatus on the whole.
In addition, for reducing output voltage, the driving frequency of piezoelectric transformer changes too greatly apart from master (primary) resonance frequency, and this driving frequency is near next resonance frequency, and the result is after reaching minimum voltage, and output voltage begins to increase.For this reason, utilize piezoelectric transformer to be difficult to realize the low-voltage output of high-voltage power apparatus.
Summary of the invention
Several aspect of the present invention and example embodiment provide a kind of high-voltage power apparatus and image processing system that is equipped with piezoelectric transformer, wherein can realize stable driving frequency control, and can not enter unusual vibration or non-controllable state, and can be within the short rise time stable output high voltage.
Other side of the present invention and or advantage will partly in following explanation, narrate, and partly obviously found out by this explanation, maybe can recognize by putting into practice the present invention.
According to example embodiment of the present invention, a kind of supply unit is provided, wherein will utilize the driving voltage of predetermined driving frequency control to be applied to piezoelectric transformer, to export an output voltage, this device comprises: the output voltage detecting unit, output voltage and one is used for the control output voltage compares to the reference voltage of a predetermined value, and according to its comparative result, detect the variation of the output voltage that changes with the digital value representative; And driving control unit, according to the driving control of the digital value execution that detects to piezoelectric transformer.
According to another aspect of the present invention, a kind of supply unit is provided, wherein will utilize the driving voltage of predetermined driving frequency control to be applied to piezoelectric transformer, to export an output voltage, this device comprises: driving control unit, be used for the control output voltage to the reference voltage of a predetermined value according to output voltage and, calculate the variable quantity of output voltage, and utilize the driving frequency of Digital Signal Processing control piezoelectric transformer according to the variable quantity that calculates.
According to another aspect of the present invention, a kind of supply unit is provided, wherein will utilize the driving voltage of predetermined driving frequency control to be applied to piezoelectric transformer, to export an output voltage, this device comprises: the output voltage detecting unit, output voltage and one is used for the control output voltage compares to the reference voltage of a predetermined value, and according to its comparative result, detect the variation of the output voltage that changes with the digital value representative; Driving control unit is according to the driving control of the digital value execution that detects to piezoelectric transformer; And driving voltage control unit, according to the comparative result of output voltage and reference voltage, change and control are applied to the supply voltage of piezoelectric transformer.
According to another aspect of the present invention, a kind of image processing system is provided, comprise: charhing unit, identically to the surface charging of latent image carrier; Exposing unit forms sub-image in its surface behind the latent image carrier surface charging; Developing cell is with this image development; Transfer printing unit is transferred to the toner image that is formed on the latent image carrier on one transfer materials; And supply unit, with voltage be provided in charhing unit, exposing unit, developing cell and the transfer printing unit at least one of them; Wherein this supply unit is one to comprise the supply unit of piezoelectric transformer.
Comprise according to supply unit of the present invention: the output voltage detecting unit is used for the control output voltage with output voltage and and compares to the reference voltage of a predetermined value, and according to its comparative result, detects the variation of the output voltage that changes with the digital value representative; And driving control unit, according to the driving control of the digital value execution that detects to piezoelectric transformer.Therefore, can carry out stable FREQUENCY CONTROL, and can not enter unusual vibration or non-controllable state, and can be within the short rise time output HIGH voltage.
According to example embodiment of the present invention, a kind of method that generates driving voltage is provided, it drives the piezoelectric transformer of high-voltage power apparatus according to the output voltage of piezoelectric transformer, comprise: output voltage is compared with a reference voltage, with the signal of generating digital incremented/decremented (up/down) counting; Utilize the signal of this numeral incremented/decremented counting, increase or reduce the count value of the driving frequency that represents piezoelectric transformer; And in this count value with represent between the preset frequency value of predetermined driving frequency scope of piezoelectric transformer and compare, and relatively generate driving voltage in a predetermined voltage range, to drive piezoelectric transformer according to this count value and this.
According to example embodiment of the present invention, a kind of piezoelectric transformer type high-voltage power apparatus, generate driving voltage, drive piezoelectric transformer with the output voltage according to piezoelectric transformer, comprise: the first comparator, output voltage is compared with a reference voltage with generating digital incremented/decremented count signal; Counter utilizes this numeral incremented/decremented count signal, increases or reduce the count value of the driving frequency that represents piezoelectric transformer; With the second comparator, in this count value with represent between the preset frequency value of predetermined driving frequency scope of piezoelectric transformer and compare, with a voltage generator, relatively generate driving voltage in a voltage range of being scheduled to, to drive piezoelectric transformer according to this count value and this.
Except above-mentioned example embodiment and aspect, by reference accompanying drawing and the following explanation of research, other aspect and embodiment will become clearly.
Description of drawings
According to following detailed explanation to example embodiment and claim, clearly will understand better the present invention when read in conjunction with the accompanying drawings, institute's drawings attached consists of the part of the disclosure of invention.Although the following disclosure of writing and illustrating concentrates on and discloses example embodiment of the present invention, it should be clearly understood that them only as descriptive and exemplary, the present invention is not limited.The spirit and scope of the present invention are only limited by appended claim.The below carries out brief description to accompanying drawing, wherein:
Fig. 1 is the block diagram of common piezoelectric transformer type high-voltage power apparatus;
Fig. 2 is the schematic diagram of the first waveform that is described in the driving frequency of the piezoelectric transformer in the common piezoelectric transformer type high-voltage power apparatus;
Fig. 3 is the schematic diagram of the second waveform that is described in the driving frequency of the piezoelectric transformer in the common piezoelectric transformer type high-voltage power apparatus;
Fig. 4 is the block diagram according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Fig. 5 is the block diagram according to the piezoelectric transformer driver element in the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Fig. 6 is the waveform schematic diagram according to the driving frequency of the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Fig. 7 A-7J describes the first sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Fig. 8 A-8J describes the second sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Fig. 9 is the block diagram according to the improved piezoelectric transformer driver element in the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Figure 10 is the block diagram according to the piezoelectric transformer type high-voltage power apparatus of another example embodiment of the present invention;
Figure 11 A-11D is depicted in according to the inductor supply voltage that occurs when the voltage increases in the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention and the schematic diagram of the relation between the work wave;
Figure 12 is the waveform schematic diagram according to the driving frequency of the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Figure 13 is the block diagram according to the piezoelectric transformer driver element in the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Figure 14 A-14K describes the first sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Figure 15 A-15K describes the second sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention;
Figure 16 is according to the again block diagram of the piezoelectric transformer type high-voltage power apparatus of an example embodiment of the present invention; With
Figure 17 A-17C is depicted in the schematic diagram according to the relation between UP/DOWN signal in the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention and the V_DRIVE signal;
Embodiment
The detailed description example of the present invention is described example embodiment in the accompanying drawings now, and wherein similar label refers to similar element in each accompanying drawing.In order to explain that the present invention illustrates example embodiment below with reference to the accompanying drawings.
Before the piezoelectric transformer type high-voltage power apparatus of explaining according to example embodiment of the present invention, explain common high-voltage power apparatus with reference to Fig. 1-3, in order to make between according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention and common piezoelectric transformer type high-voltage power apparatus structural difference clear.
Fig. 1 is the block diagram of common high-voltage power apparatus.In this common high-voltage power apparatus, use piezoelectric ceramic transducer as the piezoelectric transformer T1001 that power is provided.The interchange of piezoelectric transformer T1001 (AC) output is carried out rectification and level and smooth by diode D1002, D1003 and high-voltage capacitor C1004, to form constant output voltage.Be provided to the transfer roll (not shown) of image processing system (not shown) through rectification and level and smooth constant output voltage.In addition, will be through rectification and level and smooth constant output voltage dividing potential drop by resistor R1005, R1006 and R1007, and be input to the in-phase input end (+end) of operational amplifier Q1009 by protective resistor R1008;
Simultaneously, be input to the inverting input (end) of operational amplifier Q1009 by resistor R1014 from direct current (DC) controller (not shown) as the control signal (Vcont) of the high voltage source of analog signal.Operational amplifier Q1009, resistor R1014 and capacitor C1013 form an integrating circuit, and export this carries out integral processing according to the integral constant of being determined by the numerical value of resistor R1014 and capacitor C1013 control signal (Vcont) from operational amplifier Q1009.
The output of operational amplifier Q1009 is connected to voltage controlled oscillator (VCO) 1010, voltage controlled oscillator (VCO) 1010 drivings one are connected to the transistor Q1011 of inductor L1012, provide the primary side of the power of particular drive frequency to piezoelectric transformer T1001 with this.In this manner, provide common piezoelectric transformer T1001 to be created on the power that uses in the image processing system.
Fig. 2 and Fig. 3 are the waveform schematic diagrames of the driving frequency of the piezoelectric ceramic type converter in common high-voltage power apparatus.Fig. 2 illustrates the general characteristic of common piezoelectric ceramic type converter, and wherein maximum output voltage occurs in resonance frequency f0, and reduces at upper frequency side and the frequency side less output voltage of resonance frequency f0.Therefore, by controlling the driving frequency of common piezoelectric transformer, can control the output voltage of common piezoelectric transformer.Be higher than resonance frequency f0 by driving frequency fx is changed into, can change the output voltage of piezoelectric transformer.
The high voltage source of image processing system has the high-voltage power circuit of a plurality of same types as shown in Figure 2, and utilizes the bias voltage output that is used for charging, development and transfer process to form image.Yet, because common high-voltage power apparatus is controlled the driving frequency of piezoelectric transformer as shown in Figure 2 by Analog signals, so time of origin postpones before reaching the output control voltage of expection.
In addition, in piezoelectric transformer, can there be a plurality of resonance points.For example, as shown in Figure 3, in piezoelectric transformer, can there be 4 resonance points with respect to driving frequency.As shown in Figure 3, if apply the driving voltage with first corresponding resonance frequency f1, there is the first resonance point of the output voltage that wherein can obtain about 3.5kV.In the upper frequency side of resonance frequency f1, exist as peaked the second resonance point of local output voltage (corresponding to the second resonance frequency f2) and the 3rd resonance point (corresponding to the 3rd resonance frequency f3).As shown in Figure 3, because each resonance point is that an output voltage at this place's piezoelectric transformer becomes peaked point, if so the frequency shift to of the driving voltage of piezoelectric transformer is higher or lower than the frequency of resonance frequency, then output voltage descends along with frequency shift.
Yet even when this frequency changes from resonance frequency, if the maximum of output voltage is set in several kilovolts the scope, the scope of output voltage can not drop to several hectovolts or less.This is due to the fact that: even frequency change is very large, this frequency can not cover 0 volt, but, near next resonance frequency.Therefore, when frequency change, after reaching a certain valley voltage, output voltage increases again, until reach the next local maximum with resonance frequency.
In the frequency range corresponding to driving voltage, there is the frequency range that can obtain most effectively the output voltage of piezoelectric transformer T201 within it, for example near the scope the first resonance frequency f1.Yet, in order to increase the voltage range of output voltage, also must use the frequency in the voltage range of low output voltage, it causes the effect (poor efficiency in Fig. 3) of bad efficient for the output voltage that generates appointment, and therefore, reduce on the whole the efficient of high-voltage power apparatus.
In order to solve the problem that exists such as the described common high-voltage power apparatus of contact Fig. 1, design is according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention, it utilizes the driving frequency of Digital Signal Processing control piezoelectric transformer, and the operation of stable piezoelectric transformer, within the short rise time, to realize high voltage output.The below is with reference to the piezoelectric transformer type high-voltage power apparatus of Fig. 4-8 explanation according to example embodiment of the present invention.
Fig. 4 is the block diagram according to the piezoelectric transformer type high-voltage power apparatus 10 of example embodiment of the present invention.As shown in Figure 4, high-voltage power apparatus 10 comprises: driver element 20, piezoelectric transformer driving control unit 30, rectification smooth unit 40 and output voltage detecting unit 50.
Driver element 20 comprises piezoelectric transformer T201, inductor L201, resistor R201 and switch mosfet device S201.If with power supply V DDBe connected to inductor L201, driving voltage is input to switch mosfet S201, and this driving voltage carries out FREQUENCY CONTROL by piezoelectric transformer driving control unit 30, and the back will make an explanation.ON/OFF (on/off) state of input driving voltage control switch device S201, the power subsystem that maybe this is applied with this supply voltage of being applied of raising is converted to quasi-sine-wave.Then, the supply voltage of changing is applied to piezoelectric transformer T201.
The piezoelectric transformer T201 of driver element 20 has a piezoelectric transducer, the secondary electrode that it has the primary electrode of the primary side of being configured in and is configured in primary side.In primary side, piezoelectric transformer T201 broad ways produces polarization, and the polarization end is facing each other, disposes piezoelectric transducer between the polarization end.In primary side, piezoelectric transformer T201 produces polarization along its length.Piezoelectric transformer T201 is contained in the resin enclosure (not shown).Piezoelectric transducer is made by piezoelectric ceramic (for example lead zirconate titanate (PZT)), and has writing board shape.Along the length direction of piezoelectric transducer, for example the end from piezoelectric transducer disposes primary electrode to its middle part, and secondary electrode is configured in the other end.Be applied to primary side if will have the driving voltage of suitable resonance frequency (its measuring length by piezoelectric transducer is determined), because reciprocal piezoelectric effect causes very strong mechanical resonant, because the piezoelectric effect output high output voltage corresponding with its vibration.
The frequency (driving frequency) of piezoelectric transformer driving control unit 30 control driving voltages is with the piezoelectric transformer T201 of control driver element 20.As shown in Figure 4, piezoelectric transformer type high-voltage power apparatus 10 is characterized in that this fact: the Digital Signal Processing control that the driving frequency of piezoelectric transformer T201 is carried out by piezoelectric transformer driving control unit 30.The back will be explained this piezoelectric transformer driving control unit 30 in more detail.
Rectification smooth unit 40 comprises capacitor C401 and diode D401 and D403.The interchange of piezoelectric transformer T201 (AC) output is by diode D401 and D403 and output capacitor C401 rectification and be constant voltage (dc voltage) smoothly, and is provided to a load that can be the transfer roll (not shown) of image processing system (not shown) as output voltage.
Output voltage detecting unit 50 comprises: capacitor C501 and C503, voltage grading resistor R501 and R503 and comparator (COMP) 501.Utilization the voltage grading resistor R501 of output voltage detecting unit 50 and R503 to this by 40 rectifications of rectification smooth unit smoothly for the output voltage of direct voltage carries out dividing potential drop, and be input to the inverting input (end) of comparator 501 as error-detecting voltage (Feedback).In this example, the capacitor C501 in parallel with voltage grading resistor R501 and R503 difference and the AC and DC component in the C503 regulation output voltage.In addition, become direct voltage and be used for control from the output control voltage of the output voltage of the output of piezoelectric transformer driving control unit 30, be input to the in-phase input end (+end) of comparator 501 as reference voltage (Reference_Volt).
Comparator 501 will be exported control voltage (Reference_Volt) and compare corresponding to the value of the error-detecting voltage (Feedback) of output voltage, and the output comparative result.If output voltage (Feedback) (or error-detecting voltage) is greater than output control voltage (Reference_Volt), then the output of comparator 501 is in low logic level, if output voltage (Feedback) (or error-detecting voltage) is less than output control voltage (Reference_Volt), then the output of comparator 501 is in high logic level.Because comparator 501, can be represented by a digital value from the analog variation (as represented by error-detecting voltage (Feedback)) of the output voltage of the output of driver element 20.The digital value of exporting from comparator 501 is a control signal (UP/DOWN) for the frequency control unit (as shown in Figure 9) that is controlled at piezoelectric transformer driving control unit 30, and is imported into piezoelectric transformer driving control unit 30.
In addition, piezoelectric transformer type high-voltage power apparatus 10 also comprises: provide reset signal reset cell 101, the clock unit 103 of clock signal is provided and the controller 105 of drive control signal is provided to piezoelectric transformer T201.Utilize resistor R101 (not shown), R103, R105 and the switching device S101 will be anti-phase by the drive control signal (ON/OFF signal) that controller 105 provides, and change the open collector output that is input to piezoelectric transformer driving control unit 30 into.
Fig. 5 is the more detailed block diagram according to the piezoelectric transformer driving control unit 30 as shown in Figure 4 of example embodiment of the present invention.This piezoelectric transformer driving control unit 30 comprises: change and control this driving piezoelectric transformer T201 driving voltage frequency driving frequency control unit (following discussion) and generate the driving voltage generating unit (following discussion) of driving voltage.
With reference to Fig. 5, piezoelectric transformer driving control unit 30 comprises: the driving frequency control unit, it comprises again: incremented/decremented counter 301, register 303 and the first comparator 305.Provide high-speed clock signal by clock unit 103 to incremented/decremented counter 301, this high-speed clock signal generates according to required FREQUENCY CONTROL precision.When no matter when clock signal is in high logic level, and if be in high logic level from the control signal (UP/DOWN) of output voltage detecting unit 50, then the count value of incremented/decremented counter 301 increases progressively by X.On the other hand, when no matter when clock signal is in high logic level, and if control signal (UP/DOWN) be in low logic level, then the count value of incremented/decremented counter 301 is successively decreased by X.In addition, by setting low order M bit value, the bit number of FREQUENCY CONTROL counter can have { the bit number (N) of driving voltage generation counter+low order M bit, (N+M) } form also can carry out stable control to piezoelectric transformer T20 1 with the gain of this correction error feedback voltage (or error-detecting voltage).Even the value of controlling voltage (Reference_Volt) when output voltage (Feedback) and output each other mutually the variation of the count value of Sihe incremented/decremented counter 301 become very hour, if the bit number of FREQUENCY CONTROL counter forms (N+M), high-order N bit is also constant, even also like this when low order M bit change.Therefore, the counting of incremented/decremented counter 301 can stably carry out.
Here, for the gain of correction error feedback voltage, but counter incremented/decremented value X is the also register value of free setting, and also can be set by the peripheral control unit (not shown), or is a fixed value.The set point of counter incremented/decremented value X is stored in the register 303, and ought no matter when need to be by 301 references of incremented/decremented counter.
Fig. 6 is the waveform schematic diagram of the driving frequency of the piezoelectric transformer type high-voltage power apparatus shown in Fig. 4.Here, this output voltage is with respect to the frequency change that is applied to the driving voltage on the piezoelectric transformer T201.The output voltage of piezoelectric transformer T201 has 3 extreme values (resonance point), as shown in Figure 6.Near the first resonance frequency f1 of the lower frequency side of waveform schematic diagram, obtain maximum output voltage.When frequency increased towards the second resonance frequency f2 of the high frequency side of waveform schematic diagram and the 3rd resonance frequency f3, output voltage values reduced.Therefore, in order to obtain most effectively the output voltage of piezoelectric transformer T201, can use near the driving frequency the first resonance frequency f1.
Therefore, the count value of incremented/decremented counter 301 that is used for the driving voltage frequency of control piezoelectric transformer T201 should cover in as shown in Figure 6 fmin and this frequency range between the fmax.By the fmin value being taken as minimum frequency and the fmax value is taken as peak frequency, can obtain this frequency range.The fmin value is the frequency values of manufacturing erratic behavior that is reflected in the piezoelectric transformer at the first resonance frequency f1 place, and the fmax value is to be right after at the frequency values of output voltage curve before rising between the first resonance frequency f1 and the second resonance frequency f2.In this example, fmin and fmax are the register values that is stored in the register 303, and can be set by peripheral control unit, maybe can be a fixed value.
High-order N bit in the count value is output to the first comparator 305 and the second comparator 309.When no matter when being transfused to from the clock signal of clock unit 103, by the first comparator 305 count value of incremented/decremented counter 301 is compared with fmin register value and fmax register value.If the count value of comparative result indication incremented/decremented counter 301 is boundary values of frequency range, then will output to from the control signal of the first comparator 305 incremented/decremented counter 301, and stop the incremented/decremented counting operation of incremented/decremented counter 301.In addition, if reset signal is provided to incremented/decremented counter 301 from reset cell 101, then incremented/decremented counter 301 is set to fmin with count value.
Therefore, if controlling the comparative result indication output voltage of voltage (Reference_Volt) and output voltage (Feedback) as the output of a direct current voltage is higher value, then the count value of incremented/decremented counter 301 reduces, and the driving voltage frequency increases.In addition, if output voltage is a lower value, then the count value of FREQUENCY CONTROL incremented/decremented counter 301 increases, and the driving voltage frequency reduces.As a result, remain on the driving voltage frequency (ftarget is with reference to Fig. 6) of expection by the frequency with driving voltage, output voltage values is relatively exported control voltage (Reference_Volt) (direct voltage) and is kept constant.
In addition, when exporting (that is, coming the drive control signal of self-controller 105) when being in the OFF state, output control voltage (Reference_Volt) becomes greater than output voltage, and therefore driving frequency is reduced to gradually fmin and then stops.Simultaneously, when output was in the ON state, output control voltage (Reference_Volt) became less than output voltage, and therefore driving frequency is increased to a target frequency (ftarget) gradually.
Maximum fmax and minimum value fmin as the driving frequency of the register 303 storage piezoelectric transformer T201 of an example embodiment of excursion memory cell.In addition, the incremented/decremented count value X of register 303 storage incremented/decremented counters 301.In addition, register 303 output incremented/decremented count value X perhaps output to the first comparator 305 with fmax or fmin to incremented/decremented counter 301.
High-order N bit in the count value of incremented/decremented counter 301, and the value of fmax and fmin be input to the first comparator 305.Whether the first comparator 305 is compared the value of count value with the value of fmax and fmin, and identical with the borderline value of the frequency range of piezoelectric transformer T201 with this input count value of determining incremented/decremented counter 301.If the high-order N bit in the count value is greater than the minimum value fmin of frequency range, or less than maximum fmax, then the first comparator 305 is exported high logic levels, and sends the incremented/decremented stop signal as control signal, to stop the incremented/decremented counting operation of incremented/decremented counter 301.
With reference to Fig. 5, piezoelectric transformer driving control unit 30 comprises conversely: the driving voltage generating unit, its comprise again N digital bit counter reset 307, the second comparator 309,1 bit counter 311 and with door 313 and 315.For synchronous with incremented/decremented counter 301, N digital bit counter reset 307 (hereinafter referred to as the N bit counter) have from clock unit 103 input with incremented/decremented counter 301 identical high-frequency clocks.When no matter when clock signal is in high logic level, and the count value of N bit counter 307 increases progressively 1.
In addition, if a low logic level signal is input to the replacement input of N bit counter 307, N bit counter 307 is reset, and the count value vanishing of N bit counter 307.By the anti-phase modification of the output signal (COMPARE_OUT) of system's reset signal of being provided by reset cell 101 and the second comparator 309 is carried out AND operation (with door 315) generate the reset signal that is input to N bit counter 307, wherein when power connection this system's reset signal with all logical circuit initialization.
When the count value of the count value of incremented/decremented counter 301 and N bit counter 307 is identical, the output signal of the second comparator 309 (COMPARE_OUT) is in high logic level, wherein the count value of incremented/decremented counter 301 is the count values for FREQUENCY CONTROL, and the count value of N bit counter 307 is the count values that generate for driving voltage.Therefore, utilize the count value realization of incremented/decremented counter 301 to the control of driving voltage frequency.
Namely, the count value of the count value of incremented/decremented counter 301 (high-order N bit) and N bit counter 307 is input to the second comparator 309, if and the count value of N bit counter 307 is equal to or greater than the count value of incremented/decremented counter 301, then export high logic level.In addition, if be input to the second comparator 309 from the reset signal of reset cell 101, then the second comparator 309 is reset.
Utilize the output signal of the second comparator 309 to trigger 1 bit counter 311, and no matter when the output of the second comparator 309 is in high logic level, is inverted from the output voltage of its output.The output signal of 1 bit counter 311 is input to and door 313.In addition, if from reset cell 101 input reset signals, then 1 bit counter 311 is reset.
As being input to and door 313 from the anti-phase modification of the ENABLE signal of the on/off control signal of controller 105 output with from the output signal of 1 bit counter, 311 outputs.According to the operation result of door 313, carry out ON/OFF (on/off) control to high voltage source output.That is, if the ENABLE signal is in low logic level, then from the driving voltage not anti-phase with door 313 outputs, and the output of output high voltage source.If the ENABLE signal is in high logic level, then will forces to be in low logic level with the output of door 313, and stop the output of high voltage source output.
Anti-phase modification from the output signal (COMPARE_OUT) of the reset signal of reset cell 101 and the second comparator 309 is imported into and door 315, generates the reset signal of N bit counter 307.Be imported into the replacement end of N bit counter 307 with the output of door 315.
In addition, piezoelectric transformer driving control unit 30 comprises: digital-to-analogue (D/A) transducer 317, its output signal with controller 105 changes analog signal into, to generate output control voltage (Reference_Volt).In this example, D/A converter 317 is not limited to the D/A converter of particular type, can use normally used D/A converter as D/A converter 317.The output control voltage (Reference_Volt) that generates by the conversion process in D/A converter 317 is imported into the comparator 501 that is included in the output voltage detecting unit 50.In addition, can substitute D/A converter 317 and use pulse-width modulation (PWM) signal generator.
The above has illustrated the structure of piezoelectric transformer type high-voltage power apparatus 10.Each element in the aforesaid high-voltage power apparatus 10 can form by using general module or circuit; Perhaps can also be by using the hardware formation to the customizing functions of each element.Therefore, can suitably improve its structure according to required technical merit.
Fig. 7 A-7J describes the first sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention; And Fig. 8 A-8J describes the second sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention.Explain in detail the operation of piezoelectric transformer type high-voltage power apparatus referring now to Fig. 7 A-7J and Fig. 8 A-8J.
Fig. 7 A-7J explains the control operation sequential chart the one-period of (be off state-＞on-＞target High voltage output state) from the High voltage output standby condition to target High voltage output state.Specifically, Fig. 7 A represents the reset signal from reset cell 101; Fig. 7 B represents from the clock signal of clock unit 103 generations; Fig. 7 C represents to come the ENABLE signal of the startup high-voltage power apparatus of self-controller 105; Fig. 7 D represents from the N bit counter signal of N bit counter 307 generations; Fig. 7 E represents the incremented/decremented counter signals from incremented/decremented counter 301; Fig. 7 F represents the COMPARE_OUT signal from the second comparator 309; Fig. 7 G represents from the FREQ_OUT signal of piezoelectric transformer driving control unit 30 outputs; Fig. 7 H represents Reference_Volt signal and Feed_Back_Volt signal: Fig. 7 I represents the UP/DOWN signal from comparator 501; And Fig. 7 J represents from the FREQ_DRIVE_OUT of piezoelectric transformer output.
In High voltage output standby condition (or standby condition), shown in Fig. 7 A-7J, because output is controlled voltage (Reference_Volt) greater than output voltage (Feedback), driving frequency (FREQ_OUT) is fmin.If the ENABLE signal is in low logic level and high-voltage power apparatus is in ON (connection) state, then output voltage (Feed_Back-Volt) (or feedback) raises gradually and is input to incremented/decremented counter 301 as the UP signal of up/down signal.In addition, if output voltage (Feed_Back-Volt) is then exported the DOWN signal as the up/down signal greater than output control voltage (Reference_Volt), incremented/decremented counter 301 reduces count value.In Fig. 7 E, " CntDown " expression " count-down " (countdown) is to reduce count value.
If the count value of incremented/decremented counter 301 reduces, then the higher limit of the count value of N bit counter 301 also reduces.As a result, driving frequency (FREQ_OUT) moves towards high frequency side from the fmin frequency, until reach the ftarget as the target drives frequency.In Fig. 7 D, " ft " in the N bit counter refers to " ftarget ".
Fig. 8 A-8J explain from target High voltage output state to the High voltage output standby condition (be target High voltage output state-＞the off state-＞the High voltage output standby condition) one-period the control operation sequential chart.Specifically, Fig. 8 A represents the reset signal from reset cell 101; Fig. 8 B represents the clock signal by clock unit 103 generations; Fig. 8 C represents to come the ENABLE signal of the startup high-voltage power apparatus of self-controller 105; Fig. 8 D represents from the N bit counter signal of N bit counter 307 generations; Fig. 8 E represents the incremented/decremented counter signals from incremented/decremented counter 301; Fig. 8 F represents the COMPARE_OUT signal from the second comparator 309; Fig. 8 G represents from the FREQ_OUT signal of piezoelectric transformer driving control unit 30 outputs; Fig. 8 H represents Reference_Volt signal and Feed_Back_Volt signal; Fig. 8 I represents the UP/DOWN signal from comparator 501; And Fig. 8 J represents from the FREQ_DRIVE_OUT of piezoelectric transformer output.
As shown in Fig. 8 A-8J, therein in the state of export target high pressure, N bit counter 307 and incremented/decremented counter 301 continue counting, until count value becomes ftarget ft, and output voltage (Feed_Back_Volt) become to export control voltage (Reference_Volt) similar.Here, if the ENABLE signal is in high logic level and high-voltage power apparatus is in the OFF state, then the value of output voltage (Feed_Back_Volt) reduces and exports the value increase of control voltage (Reference_Volt) gradually.As a result, the UP signal is as the output of up/down signal, and therefore, the incremented/decremented counter increases this count value.In Fig. 8 E, " CntUp " expression " count-up " is to increase count value.
Shown in Fig. 8 E, if the count value of incremented/decremented counter 301 increases, then the higher limit of the count value of N bit counter 307 also correspondingly increases.As a result, the driving frequency (FREQ_OUT) as shown in Fig. 8 G moves towards lower frequency side from ftarget, until reach it as the fmin frequency of the frequency that maximum output voltage occurs.
Turn to again image processing system, wherein utilize the piezoelectric transformer type high-voltage power apparatus according to example embodiment of the present invention, a kind of like this image processing system is equipped with the exposing unit (not shown) that forms sub-image to the charhing unit (not shown) of the surface charging of latent image carrier (not shown), after its charging on the surface of latent image carrier usually, with the developing cell (not shown) of image development with will be transferred at the toner image of the surface of latent image carrier formation the transfer printing unit (not shown) of transfer materials (not shown).
Provide predetermined biasing (or voltage) from the high-voltage power apparatus of (as shown in Figure 4) as shown in the figure to charhing unit, developing cell and transfer printing unit.In other words, image processing system adopts piezoelectric transformer type high-voltage power apparatus shown in Figure 4 as supply unit, be used for to charhing unit, developing cell and transfer printing unit one of them provides voltage at least.
Because piezoelectric transformer type high-voltage power apparatus 10 can stably be carried out FREQUENCY CONTROL and can not enter unusual vibration or non-controllable state, utilizes charhing unit, developing cell and the transfer printing unit of the image processing system of piezoelectric transformer type high-voltage power apparatus 10 stably to work.In addition since can be within the short rise time output HIGH voltage, process required time in the image processing system each and can reduce.
Fig. 9 is the block diagram of another example embodiment of the piezoelectric transformer driving control unit 30 shown in Fig. 4.As shown in Figure 9, also be equipped with feedback circuit unit 60.Driver element 20 and rectification smooth unit 40 have respectively the 26S Proteasome Structure and Function identical with driver element 20 in the piezoelectric transformer type high-voltage power apparatus shown in Figure 4 and 5 and rectification smooth unit 40, and therefore omit the detailed explanation to them.Yet design piezoelectric transformer driving control unit 30 as shown in Figure 9 is with the frequency of control driving voltage, and this driving voltage is controlled the piezoelectric transformer T201 in driver element 20.As a result, piezoelectric transformer is characterised in that this fact: the driving frequency of piezoelectric transformer T201 is controlled by the Digital Signal Processing that piezoelectric transformer driving control unit 30 is carried out.
Feedback circuit unit 60 comprises: capacitor C601 and C603 and resistor R601 and R603.Utilize voltage grading resistor R601 and the R603 will be by rectification smooth unit 40 rectifications and smoothly be the output voltage dividing potential drop of direct voltage, and output voltage as analog signal without be imported into piezoelectric transformer driving control unit 30 anti-phasely.In addition, respectively with voltage grading resistor R601 be connected with R603 the capacitor C601 that is connected and the AC and DC component in the C603 regulation output voltage.
In addition, provide reset cell 101 to generate reset signal; Provide clock unit 103 to generate clock signal; And provide controller 105 to generate the drive control signal of piezoelectric transformer T201.Utilize resistor R101 (not shown), R103 or R105 or the switching device S101 will be anti-phase by the drive control signal (ON/OFF signal) that controller 105 provides, and drive control signal (ON/OFF signal) be converted into the collector electrode output of open circuit and be input to piezoelectric transformer driving control unit 30.
Explain in detail piezoelectric transformer driving control unit 30 referring now to Fig. 9.Piezoelectric transformer driving control unit 30 comprises: change and control this driving piezoelectric transformer T201 driving voltage frequency the driving frequency control unit and generate the driving voltage generating unit of driving voltage.
With reference to Fig. 9, piezoelectric transformer driving control unit 30 comprises a driving frequency control unit, and it comprises again the first comparator 305, A/D converter 351, digital filter 353 and incremented/decremented counter 355.A/D converter 351 will be converted to digital signal as the feedback signal of analog signal 60 outputs from the feedback circuit unit.A/D converter 351 is not limited to the A/D converter of particular type, can use normally used A/D converter as A/D converter 351.The feedback signal that is converted to digital signal by A/D converter 351 outputs to digital filter 353.
Feedback signal and be input to digital filter 353 from the Reference_Volt signal of D/A converter 317, it is carried out digital value and calculates.353 pairs of input feedback signals of digital filter and Reference_Volt signal are carried out compare operation, and calculate incremented/decremented count value X.The incremented/decremented count value X that calculates outputs to incremented/decremented counter 355.
The high-speed clock signal that generates according to required FREQUENCY CONTROL precision is provided to incremented/decremented counter 355 from clock unit 103.When no matter when clock signal is in high logic level, and the count value of incremented/decremented counter 355 increases progressively according to the incremented/decremented count value X that is provided by digital filter 353.Namely, if send the signal that this count value of expression from digital filter 353 increases progressively according to X, then incremented/decremented counter 355 increases progressively count value according to X, if and sent the signal that successively decreases according to X from this count value of expression of digital filter 353, then incremented/decremented counter 355 would successively decrease count value according to X.
In addition, by setting low order M bit value, the bit number of FREQUENCY CONTROL counter can have { the bit number (N) of driving voltage generation counter+low order M bit, (N+M) } form also can carry out stable control with the gain of this correction error feedback voltage (or error-detecting voltage).Even when the value of output voltage (Feedback) and output control voltage (Reference_Volt) each other the variation of the value of close and incremented/decremented counter 355 become very hour, if the bit number of FREQUENCY CONTROL counter forms (N+M), then high-order N bit is constant, even also like this when low order M bit change.Therefore, can stably be counted by incremented/decremented counter 355.
In addition, as utilize the incremented/decremented counter 301, the count value that is used for the incremented/decremented counter 355 of control frequency should cover this frequency range that is positioned at as shown in Figure 6.By the fmin value being taken as minimum frequency and the fmax value is taken as peak frequency, can obtain this frequency range, wherein the fmin value is the frequency values of manufacturing erratic behavior that is reflected in the piezoelectric transformer at the first resonance frequency f1 place, and the fmax value is to be right after at the frequency values of output voltage curve before rising between the first resonance frequency f1 and the second resonance frequency f2.In this example, fmin and fmax are the register values that is stored in the register 357, and can be set by peripheral control unit, maybe can be a fixed value.
High-order N bit in this count value outputs to the first comparator 305 and the second comparator 309.Input the clock signal from clock unit 103 when no matter when, by the first comparator 305 count value of incremented/decremented counter 305 is compared with fmin register value and fmax register value.If the count value of comparative result indication incremented/decremented counter 355 is boundary values of a frequency range, then will output to from the control signal of the first comparator 305 incremented/decremented counter 355, and stop the incremented/decremented counting operation of incremented/decremented counter 355.In addition, if provide reset signal from reset cell 101 to incremented/decremented counter 355, then incremented/decremented counter 355 is set to this fmin value with count value.
Therefore, if the output control voltage (Reference_Volt) as direct voltage is indicated with the comparative result of output voltage (Feedback): output voltage is higher value, and then the count value of incremented/decremented counter 355 reduces and the increase of driving voltage frequency.In addition, if output voltage is lower value, then the count value of incremented/decremented counter 355 increases and the reduction of driving voltage frequency.As a result, the output voltage values according to the driving voltage frequency (ftarget is with reference to Fig. 6) of expecting is maintained constant with respect to (Reference_Volt) (direct voltage).
In addition, when the output of the output that comes self-controller 105 was in the OFF state, output control voltage (Reference_Volt) became greater than output voltage, and, so driving frequency is reduced to fmin value gradually, then stops reduction.Simultaneously, when the output of controller 105 was in the ON state, output control voltage (Reference_Volt) became less than output voltage, and, so driving frequency is increased to gradually until reach target frequency (ftarget).
Maximum fmax and minimum value fmin as the driving frequency of the register 357 storage piezoelectric transformer T201 of the example embodiment of excursion memory cell.In this example, register 357 output fmax values or fmin value are to the first comparator 305.Comparator 305 has structure and the effect identical with comparator 305 in the piezoelectric transformer type high-voltage power apparatus 10, therefore, no longer repeats the detailed explanation to comparator 305.
Conversely with reference to Fig. 9, piezoelectric transformer driving control unit 30 comprises: the driving voltage generating unit, its comprise again N digital bit counter reset (N bit counter) the 307, second comparator 309,1 bit counter 311 and with door 313 and 315.Driving voltage generating unit among Fig. 9 has structure and the effect identical with driving voltage generating unit among Fig. 5, therefore, no longer repeats the detailed explanation to it.
In addition, piezoelectric transformer driving control unit 30 comprises: digital-to-analogue (D/A) transducer 317, its output signal with controller 105 changes analog signal (Reference_Volt) into.D/A converter 317 is not limited to the D/A converter of particular type, can use normally used D/A converter as D/A converter 317.The signal Reference_Volt that generates by the conversion process in D/A converter 317 is input to digital filter 353.
When the piezoelectric transformer driving control unit 30 that is described in shown in Fig. 9, the feedback voltage that discussion utilizes A/D converter 351 that the analog form of the variable quantity that is provided by feedback circuit unit 60 will be provided is converted to numerical data, and is sampled and processed by 353 pairs of these variations of digital filter.Yet, this example embodiment of the present invention is not limited to this processing, and relevant with the feedback voltage as the analog form of the variable quantity that provides from feedback circuit unit 60, also can passing ratio-integration-differential (PID) control technology calculate this variation.
The above has illustrated the structure of piezoelectric transformer type high-voltage power apparatus 10.Each element in the above-mentioned high-voltage power apparatus can utilize general module or circuit to form, and perhaps can also form by the hardware of utilization to the customizing functions of each element.Therefore, can suitably revise its structure according to required technical merit.
In order to solve the problem such as the described common piezoelectric transformer type high-voltage power apparatus of contact Fig. 1, design is according to the piezoelectric transformer type high-voltage power apparatus of another example embodiment of the present invention, to utilize the driving frequency of Digital Signal Processing control piezoelectric transformer, and the operation of stable piezoelectric transformer is so that the high voltage that is implemented in the short rise time is exported.In addition, except the driving frequency of control piezoelectric transformer, be applied to the supply voltage of piezoelectric transformer by control, can improve the efficient that generates the output voltage that obtains from piezoelectric transformer.Below with reference to Figure 10-15, explain now the piezoelectric transformer type high-voltage power apparatus 10 according to another example embodiment of the present invention.
Figure 10 is the block diagram according to the piezoelectric transformer type high-voltage power apparatus 10 of another example embodiment of the present invention.As shown in figure 10, high-voltage power apparatus 10 comprises: driver element 20, piezoelectric transformer driving control unit 30, rectification smooth unit 40, driving voltage control unit 70 and output voltage detecting unit 80.
Driver element 20 comprises: piezoelectric transformer T201, inductor L201, resistor R201 and switch mosfet device S201.In driver element 20, if the supply voltage (V_DRIVE) that provides from driving voltage control unit 70 is connected to inductor L201, the driving voltage that then carries out FREQUENCY CONTROL by piezoelectric transformer driving control unit 30 is input to switching device S201, so that the open/close state of control switch device S201, raise from the voltage (V_DRIVE) of driving voltage control unit 70 outputs with this, perhaps will be converted to quasi-sine-wave from the voltage (V_DRIVE) of driving voltage control unit 70 outputs.Then, will be applied to piezoelectric transformer T201 through the voltage of conversion.
Piezoelectric transformer T201 in the driver element 20 has a piezoelectric transducer, and it has one at the primary electrode (not shown) of just utmost point side configuration and the secondary electrode (not shown) that disposes in inferior utmost point side.In primary side, the polarization of piezoelectric transformer T201 broad ways and its polarization end face with each other, the vibrating body of configuration between the polarization end.In primary side, piezoelectric transformer T201 polarizes along its length.These elements all are contained in (not shown) in the resin enclosure.Piezoelectric transducer is made by piezoelectric ceramic (for example lead zirconate titanate (PZT)), and has writing board shape.Along the length direction of piezoelectric transducer, for example the end from piezoelectric transducer disposes primary electrode to its middle part, and secondary electrode is configured in the other end.Be applied to primary side if will have the driving voltage of suitable resonance frequency (its measuring length by piezoelectric transducer is determined), then because reciprocal piezoelectric effect causes very strong mechanical resonance, and owing to the piezoelectric effect output high output voltage corresponding with its vibration.
Figure 11 A-11D is depicted in the inductor supply voltage that occurs in as shown in figure 10 the piezoelectric transformer type high-voltage power apparatus 10 and the schematic diagram of the relation between the work wave when voltage increases.Specifically, Figure 11 A represents the inductor supply voltage; Figure 11 B represents the piezoelectric transformer driving voltage, and Figure 11 C represents FET (TR) driving voltage waveform; And Figure 11 D represents FET (TR) current waveform.Explain in detail the inductor supply voltage of appearance when voltage raises and the relation between the work wave referring now to Figure 11 A-11D.
If will be applied to switching device S201 (FET or transistor) from the driving voltage (shown in Figure 11 C) of piezoelectric transformer driving control unit 30, then switching device S201 switches to the ON state, and electric current flows through inductor L201.In this example, at the electric current that flows among the switching device S201 (shown in Figure 11 D, (I)=driving voltage (ON time/L, wherein L is the inductance of inductor L201).
Therefore, mobile phase is about the electric current (I) of the value of supply voltage (V_DRIVE), and in inductor L201 accumulation energy ((U)=1/2 (LI 2)).Then, if switching device S201 switches to the OFF state, then at capacitor C201 be connected between the inductor L201 of primary side and cause resonance.In this example, be applied to the voltage value of piezoelectric transformer T201 according to the value increase of the energy that in inductor L201, accumulates (U).Therefore, if inductor supply voltage (supply voltage that namely provides from driving voltage control unit 70 (V_DRIVE)) increases, then the output from piezoelectric transformer T201 can increase.
Conversely with reference to Figure 10, piezoelectric transformer driving control unit 30 is controlled the frequency of driving voltages again, the piezoelectric transformer T201 in this driving voltage control driver element 20.Piezoelectric transformer type high-voltage power apparatus 10 among Figure 10 is characterized in that this fact: the driving frequency of utilizing the Digital Signal Processing control piezoelectric transformer T201 that is carried out by piezoelectric transformer driving control unit 30.To explain in more detail this piezoelectric transformer driving control unit 30 after a while.
Rectification smooth unit 40 comprises: capacitor C401-and diode D401 and D403.Utilize diode D401 with D403 and capacitor C401 exchanging of piezoelectric transformer T201 to be exported rectification and smoothly be constant voltage (direct voltage), and be provided to load (for example transfer roll (not shown)).
Driving voltage control unit 70 comprises: the transistor T R701 of capacitor C701, C703 and C705, resistor R701, R703, R705 and R707, for example bipolar transistor and computing comparison amplifier (AMP) 701.Utilize voltage grading resistor R701, the R703 will be by 40 rectifications of rectification smooth unit and smoothly be the output voltage dividing potential drop of direct voltage, and be input to the inverting input (end) of computing comparison amplifier 701 as output voltage (Feedback).In addition, will be input to as the output control voltage (for the direct voltage of control output voltage) of reference voltage (Reference_Volt) in-phase input end (+end) of computing comparison amplifier 701.
The value of the output voltage that computing comparison amplifier 701 will be inputted (Feedback) and output control voltage (Reference_Volt) is compared, and increases or reduce magnitude of voltage according to comparative result.More particularly, if Feedback greater than Reference_Volt, then computing comparison amplifier 701 reduces these magnitudes of voltage, if Feedback less than Reference_Volt, then computing comparison amplifier 701 increases these magnitudes of voltage.Utilize the output current of transistor buffers increase computing comparison amplifier 701, and the output of computing comparison amplifier 701 becomes the supply voltage (V_DRIVE) of the inductor L201 that outputs in driver element 20.Depend on the driving frequency value that is applied to piezoelectric transformer T201 from the value of the output voltage of piezoelectric transformer T201 output, and also depend on the value of the power supply power supply (V_DRIVE) that is provided to piezoelectric transformer T201.
Figure 12 is the waveform schematic diagram of driving frequency of the piezoelectric transformer of piezoelectric transformer type high-voltage power apparatus as shown in Figure 10.As shown in figure 12, the value of the output voltage of piezoelectric transformer is relevant to the magnitude variations of the supply voltage that is provided to piezoelectric transformer.For example, when identical driving frequency is applied to piezoelectric transformer, by being provided, higher supply voltage can obtain higher output voltage.Therefore, when power output that hope obtains being scheduled to from piezoelectric transformer, not only can be applied to by control the driving frequency of piezoelectric transformer, but also can be applied to by control the supply voltage of piezoelectric transformer, realize predetermined power output.
Therefore, in piezoelectric transformer type high-voltage power apparatus 10 as shown in figure 10, as mentioned above, to compare with the value of output control voltage from the value of the output voltage of piezoelectric transformer T201, and change and control the supply voltage (V_DRIVE) that is provided to inductor L201 with this.Simultaneously, by controlling simultaneously the driving frequency that is applied to piezoelectric transformer T201, can more effectively obtain target output voltage from piezoelectric transformer T201.
For example, when the needs low output voltage, provide in the common device of predetermined voltage to inductor therein, the driving frequency that is applied to piezoelectric transformer will be moved to high frequency side, if and required output voltage is too low so that can not obtain in effective frequency range, should use near the poor efficiency frequency range the second resonance frequency f2.Yet, in piezoelectric transformer type high-voltage power apparatus 10, can reduce the supply voltage that is applied to inductor L201, as shown in figure 12, and can reach lower frequency near the effective frequency range fmin with this.
In addition, although Figure 12 only illustrates two curves of explanation driving frequency and output voltage Relations Among, shown in relation between the curve is not limited only to those, and according to the value of the supply voltage that provides (V_DRIVE), (V_DRIVE) can obtain more curve according to the supply voltage that provides.In addition, in the driving voltage control unit 70 according to this example embodiment, if come the ON/OFF control signal of self-controller 105 to become the signal of an indication OFF, then will be provided to the voltage control of inductor L201 to maximum voltage.
Referring again to Figure 10, output voltage detecting unit 80 comprises conversely: capacitor C801 and C803, resistor R801 and R803 and a comparator C OMP 801.Utilize 40 rectifications of rectification smooth unit and smoothly be the output voltage of direct voltage, to its dividing potential drop, and be input to the inverting input (end) of comparator 801 as error-detecting voltage (Feedback) by the voltage grading resistor R801 in the output voltage detecting unit 80 and R803.In this example, the capacitor C801 in parallel with voltage grading resistor R801 and R803 difference and the AC and DC component of C803 regulation output voltage.In addition, be imported into the in-phase input end (+end) of comparator 801 as output control voltage (Referenc_Volt) as the voltage of the control output voltage of direct voltage.
Comparator 801 will be exported the value of control voltage (Referenc_Volt) and the value of output voltage (Feedback) is compared, and the output comparative result.If the output of comparator 801 indication: output voltage (Feedback) is greater than output control voltage (Referenc_Volt), then the output of comparator 801 is in low logic level, if output voltage (Feedback) is less than output control voltage (Referenc_Volt), then the output of comparator 801 is in high logic level.Because comparator 801, the analog variation of output voltage can represent with digital value.The digital value of comparator 801 outputs is a control signal (UP/DOWN), and it is controlled at the frequency control unit in the piezoelectric transformer driving control unit 30, and is input to piezoelectric transformer driving control unit 30.
In addition, piezoelectric transformer type high-voltage power apparatus 10 as shown in figure 10 comprises: provide reset signal reset cell 101, the clock unit 103 of clock signal is provided, and provide the controller 105 of drive control signal to piezoelectric transformer T201.Utilize resistor R101 (not shown), R103, R105 and the switching device S101 will be anti-phase from the drive control signal (ON/OFF signal) that controller 105 provides, and change it into open collector output, and be input to piezoelectric transformer driving control unit 30.
Figure 13 is the block diagram of another embodiment of piezoelectric transformer driving control unit 30 as shown in figure 10.As shown in figure 13, piezoelectric transformer driving control unit 30 comprises: change and control are for the driving frequency control unit of the frequency of the driving voltage that drives piezoelectric transformer T201 and the driving voltage generating unit of generation driving voltage.
With reference to Figure 13, the piezoelectric transformer driving control unit 30 among Figure 13 comprises the driving frequency control unit, and it comprises again: incremented/decremented counter 301, register 303 and the first comparator 305.Provide high-speed clock signal from clock unit 103 to incremented/decremented counter 301, this signal generates according to required FREQUENCY CONTROL precision.When no matter when clock signal is in high logic level, if the voltage sense signal (UP/DOWN) that reaches from output voltage detecting unit 80 is in high logic level, then count value increases progressively by X.In addition, when no matter when clock signal is in high logic level, is in low logic level if reach voltage sense signal (UP/DOWN), and then this count value is successively decreased by X.
In addition, by setting the value of M bit of low order, the bit number of FREQUENCY CONTROL counter can have the form of { bit number (N) of driving voltage generation counter+low order M bit, (N+M) }, also can carry out stable control with the gain of this correction error feedback voltage.Even when output voltage (Feedback) and output control voltage (Reference_Volt) the two value each other variation close and incremented/decremented counter 301 become very hour, if the bit number of FREQUENCY CONTROL counter forms (N+M), then high-order N bit is constant, even also like this when low order M bit change.Therefore, the counting of incremented/decremented counter 301 can stably carry out.
Here, for the gain of correction error feedback voltage, but counter incremented/decremented value X is the also register value of free setting, and also can be set by the peripheral control unit (not shown), or can be a fixed value.The set point of counter incremented/decremented value X is stored in the register 303, and ought no matter when need to be by 301 references of incremented/decremented counter.
With reference to Figure 12, output voltage is with respect to the frequency change of the driving voltage that is applied to piezoelectric transformer T201 conversely.As shown in figure 12, the output voltage of piezoelectric transformer T201 has 3 extreme values (resonance point).Near the first resonance frequency f1 of lower frequency side, provide the highest output voltage, and along with the frequency shifts of driving voltage to the second resonance point f2 and the 3rd resonance point f3 at high frequency side, output voltage values reduces.Therefore, in order to obtain most effectively the output voltage of piezoelectric transformer T201, can use near the driving frequency the first resonance frequency f1.
Therefore, the count value that is used for the incremented/decremented counter 301 of control frequency should cover frequency range as shown in Figure 6.The fmin value is taken as minimum frequency and the fmax value is taken as peak frequency, can obtain this frequency range, wherein the fmin value is the frequency values of manufacturing erratic behavior that is reflected in the piezoelectric transformer at the first resonance frequency f1 place, and the fmax value is to be right after at the frequency values of output voltage curve before rising between the first resonance frequency f1 and the second resonance frequency f2.In this example, fmin and fmax are the register values that is stored in the register 303, and can be set by peripheral control unit, maybe can be a fixed value.
High-order N bit in the count value of incremented/decremented counter 301 outputs to the first comparator 305 and the second comparator 309.When no matter when from clock unit 103 input clock signals, the first comparator 305 is compared the count value of incremented/decremented counter 301 with fmin register value and fmax register value.If the count value of comparative result indication incremented/decremented counter 301 is boundary values of frequency range, then will output to from the control signal of the first comparator 305 incremented/decremented counter 301, and stop the incremented/decremented counting operation of incremented/decremented counter 301.In addition, if reset signal is provided to incremented/decremented counter 301 from reset cell 101, then incremented/decremented counter 301 is set to fmin with count value.
Therefore, if controlling the comparative result indication output voltage of voltage (Reference_Volt) and output voltage (Feedback) as the output of a direct current voltage is higher value, then the count value of incremented/decremented counter 301 reduces, and the driving voltage frequency increases.In addition, if comparative result indication output voltage is a lower value, then the count value of FREQUENCY CONTROL incremented/decremented counter 301 increases, and the driving voltage frequency reduces.As a result, by one being the driving voltage frequency (ftarget is with reference to Figure 12) of target, output voltage values is relatively exported control voltage (Reference_Volt) (direct voltage) and is maintained one constant.
In addition, when the output of controller 105 was in the OFF state, output control voltage (Reference_Volt) became greater than output voltage, and therefore driving frequency reduces gradually until reach fmin, then stops to reduce.Simultaneously, when the output of controller 105 was in the ON state, output control voltage (Reference_Volt) became less than output voltage, and therefore driving frequency increases gradually until reach a target frequency (ftarget).
Maximum fmax and minimum value fmin as the driving frequency of the register 303 storage piezoelectric transformer T201 of an example embodiment of excursion memory cell.In addition, the incremented/decremented count value X of register 303 storage incremented/decremented counters 301.In addition, register 303 output incremented/decremented count value X perhaps output to the first comparator 305 with fmax or fmin to incremented/decremented counter 301.
High-order N bit in the count value of incremented/decremented counter 301 and fmax and fmin are input to the first comparator 305, the first comparators 305 as the example embodiment of frequency range control unit.The first comparator 305 is compared the value of count value with fmax and fmin, and determines the whether boundary value of the frequency range of piezoelectric transformer T201 of an input count value with this.If the high-order N bit in the count value is greater than the minimum value fmin of frequency range, or less than maximum fmax, then the first comparator 305 is exported high logic levels, and sends the incremented/decremented stop signal as control signal, to stop the incremented/decremented counting operation of incremented/decremented counter 301.
With reference to Figure 13, the piezoelectric transformer driving control unit 30 among Figure 13 comprises conversely: the driving voltage generating unit, its comprise again N digital bit counter reset 307, the second comparator 309,1 bit counter 311 and with door 313 and 315.For synchronous with incremented/decremented counter 301, N digital bit counter reset 307 (hereinafter referred to as the N bit counter) has from the identical high-frequency clock of the clock with incremented/decremented counter 301 of clock unit 103 inputs.When no matter when clock signal is in high logic level, and count value increases progressively by 1.In addition, if a low logic level signal is input to the replacement input of N bit counter 307, N bit counter 307 is reset, and the count value vanishing.Generate the reset signal that is input to N bit counter 307 carrying out AND operation with door 315 by the inversion signal to the output signal (COMPARE_OUT) of system's reset signal of being provided by reset cell 101 and the second comparator 309, wherein when power connection this system's reset signal with all logical circuit initialization.When the count value (it is the count value of driving voltage generation) of the count value of incremented/decremented counter (it is for being used for the count value of FREQUENCY CONTROL) and N bit counter 307 was identical, the output of the second comparator 309 was in high logic level.Therefore, utilize the count value realization of incremented/decremented counter 301 to the control of driving voltage frequency.
The count value of the count value of incremented/decremented counter 301 (high-order N bit) and N bit counter 307 is input to the second comparator 309, if and the count value of N bit counter 307 is equal to or greater than the count value of incremented/decremented counter 301, then export high logic level.In addition, if be input to the second comparator 309 from the reset signal of reset cell 101, then the second comparator 309 is reset.Utilize the output signal of the second comparator 309 to trigger 1 bit counter 311, and no matter when the output of the second comparator 309 is in high logic level, is inverted from the output voltage of output.The output signal of 1 bit counter 311 is imported into and door 313.In addition, if from reset cell 101 input reset signals, then 1 bit counter 311 is reset.
One conduct is input to and door 313 from anti-phase modification and the output signal from 311 outputs of 1 bit counter of the ENABLE signal of the ON/OFF control signal of controller 105 outputs.According to the operation result of door 313, carry out the ON/OFF control to high voltage source output.That is, if the ENABLE signal is in low logic level, then from the driving voltage not anti-phase with door 313 outputs, and the output high voltage source.If the ENABLE signal is in high logic level, then will forces to be in low logic level with the output of door 313, and stop high voltage output.
Come the anti-phase modification of the output signal (COMPARE_OUT) of the reset signal of self reset power supply 101 and the second comparator 309 to be imported into and door 315, generate the reset signal of N bit counter 307.Be imported into the replacement end of N bit counter 307 with the output of door 315.
In addition, piezoelectric transformer driving control unit 30 comprises: digital-to-analogue (D/A) transducer 317, its output signal with controller 105 changes analog signal into, to generate output control voltage (Reference_Volt).In this example, D/A converter 317 is not limited to specific D/A converter, can use normally used D/A converter as D/A converter 317.The output control voltage (Reference_Volt) that generates by the conversion process at D/A converter 317 is imported into the computing comparison amplifier 701 that is configured in the driving voltage control unit 70 and the comparator 801 that is configured in the output voltage detecting unit 80.In addition, can substitute D/A converter 317 and use pulse-width modulation (PWM) signal generator.
As mentioned above, in piezoelectric transformer type high-voltage power apparatus 10 as shown in figure 10, the output that will become direct voltage is controlled voltage (Reference_Volt) and is compared from the output voltage of driver element 20 outputs.If output voltage increases, the count value (count value of incremented/decremented counter) that then is used for FREQUENCY CONTROL reduces, increase the frequency of driving voltage with this, and be reduced in simultaneously the supply voltage output (V_DRIVE) of the inductor in the driver element 20.As a result, the lower voltage of exporting from piezoelectric transformer.Simultaneously, if output voltage reduces, the count value (count value of incremented/decremented counter) that then is used for FREQUENCY CONTROL increases, simultaneously, the supply voltage output (V_DRIVE) of the inductor in driver element 20 increases, with this, increase the output voltage (V_DRIVE) that is used for rising piezoelectric transformer driving voltage.Because output control voltage (Reference_Volt) and reach a target output voltage from the output voltage of piezoelectric transformer output, control simultaneously the driving voltage frequency and the supply voltage of inductor is exported (V_DRIVE), and can keep the constant output voltage value from piezoelectric transformer.
In addition, in above-mentioned example embodiment, using can be with the comparator with simple circuit structure of variable quantity high-speed transitions as numerical data, as the output voltage detecting unit that is used for by output voltage and output control voltage are compared the analog variation of output voltage being converted to digital value.Yet, the present invention is not limited thereto, for example, also can use and wherein utilize A/D converter that the variable quantity of analog form is converted to numerical data with this structure that this variation is sampled, and, this variation can be processed by digital filter and so on, perhaps utilizes the PID control technology to calculate this variation.
The above has illustrated the structure of the piezoelectric transformer type high-voltage power apparatus 10 among Figure 10.Each element in the above-mentioned high-voltage power apparatus can form by using general module or circuit; Perhaps can also be by using the hardware formation to the customizing functions of each element.Therefore, can suitably improve its structure according to required technical merit.
Figure 14 A-14K describes the first sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention; Figure 15 A-15K describes the second sequential chart according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention.Referring now to Figure 14 A-14K and Figure 15 A-15K the operation of piezoelectric transformer type high-voltage power apparatus is explained in detail.
Figure 14 A-14K explains the control operation sequential chart the one-period of (be off state-＞on-＞target High voltage output) from the High voltage output standby condition to the target High voltage output.Specifically, Figure 14 A represents the reset signal from reset cell 101; Figure 14 B represents from the clock signal of clock unit 103 generations; Figure 14 C represents to come the ENABLE signal of the startup high voltage unit device of self-controller 105; Figure 14 D represents the N bit counter signal by 307 generations of N bit counter; Figure 14 E represents the incremented/decremented counter signals from incremented/decremented counter 301; Figure 14 F represents the COMPARE_OUT signal from the second comparator 309; Figure 14 G represents from the FREQ_OUT signal of piezoelectric transformer driving control unit 30 outputs; Figure 14 H represents Reference_Volt signal and Feed_Back_Volt signal; Figure 14 I represents the UP/DOWN signal from comparator 801; Figure 14 J represents the V_DRIVE signal from driving voltage control unit 70, and Figure 14 K represents from the FREQ_DRIVE_OUT of piezoelectric transformer output.
In standby condition, shown in Figure 14 A-14K, because output control voltage (Reference_Volt) is greater than output voltage (Feedback), driving frequency (FREQ_OUT) is fmin, and supply voltage (V_DRIVE) becomes maximum.If the ENABLE signal is in low logic level and this device and is in ON (connection) state, then output voltage (Feedback) raises gradually and is input to the incremented/decremented counter as the UP signal of up/down signal.In addition, if output voltage (Feedback) then export the DOWN signal as the up/down signal, and the incremented/decremented counter reduces count value greater than output control voltage (Reference_Volt).Simultaneously, supply voltage (V_DRIVE) is also reduced by driving voltage control unit 70.In Figure 14 E, " Cnt Down " expression reduces " count-down " (countdown) of count value.
If the count value of incremented/decremented counter reduces, then the higher limit of the count value of N bit counter also reduces.As a result, the driving frequency (FREQ_OUT) among Figure 14 G moves and is controlled as the ftarget as the target drives frequency from the fmin frequency towards high frequency side.In Figure 14 D, " ft " in N bit counter line refers to " ftarget ".In addition, because being provided to the supply voltage of piezoelectric transformer, control reduces gradually, reduce gradually from the output voltage (FREQ_DRIVE_OUT) of piezoelectric transformer output, and when reaching target voltage, control output voltage (FREQ_DRIVE_OUT) maintains this target voltage.
Figure 15 A-15K explain from the target High voltage output time one-period to realize the High voltage output standby condition (the target High voltage output-＞the off state-＞the High voltage output standby condition) the control operation sequential chart of one-period.Specifically, Figure 15 A represents the reset signal from reset cell 101; Figure 15 B represents the clock signal by clock unit 103 generations; Figure 15 C represents to come the ENABLE signal of the startup high-voltage power apparatus of self-controller 105; Figure 15 D represents from the N bit counter signal of N bit counter 307 generations; Figure 15 E represents the incremented/decremented counter signals from incremented/decremented counter 301; Figure 15 F represents the COMPARE_OUT signal from the second comparator 309; Figure 15 G represents from the FREQ_OUT signal of piezoelectric transformer driving control unit 30 outputs; Figure 15 H represents Reference_Volt signal and Feed_Back_Volt signal; Figure 15 I represents the UP/DOWN signal from comparator 801; Figure 15 J represents the V_DRIVE signal from driving voltage control unit 70, and Figure 15 K represents from the FREQ_DRIVE_OUT of piezoelectric transformer output.
Shown in Figure 15 A-15K, therein in the high-tension state of export target, N bit counter and incremented/decremented counter continue counting, until count value becomes ftarget ft, and output voltage (Feedback) becomes with to export control voltage (Reference_Volt) close.Here, if the ENABLE signal is in high logic level and this device is in the OFF state, then the value of output voltage (Feedback) reduces and exports the magnitude of voltage increase of control voltage (Reference_Volt) gradually.As a result, the UP signal is as the output of up/down signal, and therefore, the incremented/decremented counter increases this count value.Simultaneously, supply voltage (V_DRIVE) is also increased by driving voltage control unit 70.In Figure 15 E, " Cnt Up " expression increases " count-up " (increasing progressively counting) of count value.
Shown in Figure 15 E, if the count value of incremented/decremented counter increases, then the higher limit of the count value of N bit counter also correspondingly increases.As a result, driving frequency (FREQ_OUT) moves towards lower frequency side from ftarget, and controls to the fmin as the minimum value in this frequency range.In addition, controlling the supply voltage that is applied to piezoelectric transformer increases gradually until finally reach maximum voltage.
Turn to again the image processing system of wherein using according to the piezoelectric transformer type high-voltage power apparatus of an example embodiment of the present invention, such image processing system disposes charhing unit (not shown) to the surface charging of latent image carrier (not shown) usually, after its charging at the exposing unit of the surface of latent image carrier formation sub-image, with the developing cell of image development with will be transferred at the toner image that latent image carrier forms the transfer printing unit of transfer materials.
In this example, provide predetermined biasing (voltage) from the high-voltage power apparatus of (as shown in figure 10) as shown in the figure to charhing unit, developing cell and transfer printing unit.In other words, image processing system adopts piezoelectric transformer type high-voltage power apparatus shown in Figure 10 as supply unit, be used for to charhing unit, developing cell and transfer printing unit one of them provides voltage at least.
Because piezoelectric transformer type high-voltage power apparatus 10 is control frequency and can not enter unusual vibration or non-controllable state stably, utilize charhing unit, developing cell and transfer printing unit in the image processing system of piezoelectric transformer type high-voltage power apparatus 10 stably to work.In addition since can be within the short rise time output HIGH voltage, process required time in the image processing system each and can reduce.
Referring now to the piezoelectric transformer type high-voltage power apparatus of Figure 16-17 explanation according to another example embodiment.Figure 16 is the block diagram according to the piezoelectric transformer type high-voltage power apparatus 10 of an again example embodiment of the present invention.As shown in figure 16, piezoelectric transformer type high-voltage power apparatus 10 comprises: the level and smooth output unit 90 of driver element 20, piezoelectric transformer driving control unit 30, rectification smooth unit 40, output voltage detecting unit 80 and driving voltage rectification.
Driver element 20, piezoelectric transformer driving control unit 30 and rectification smooth unit 40 have respectively the 26S Proteasome Structure and Function identical with driver element 20 in piezoelectric transformer type high-voltage power apparatus 10 as implied above, piezoelectric transformer driving control unit 30 and rectification smooth unit 40.Therefore no longer repeat the detailed explanation to them.
Output voltage detecting unit 80 comprises: capacitor C801 and C803, resistor R801 and R803 and comparator (COMP) 801.Voltage grading resistor R801 and the R803 of utilization in output voltage detecting unit 80 smoothly is the output voltage dividing potential drop of direct voltage to this by 40 rectifications of rectification smooth unit, and is input to the inverting input (end) of comparator 801 as error-detecting voltage (Feedback).In addition, the capacitor C801 that is connected in parallel respectively with voltage grading resistor R801 and R803 and the AC and DC component in the C803 regulation output voltage.In addition, as the output control voltage of DC voltage control output voltage, be input to the in-phase input end (+end) conduct of comparator 801 with reference to voltage (Reference_Volt).
Comparator 801 will be exported the value of control voltage (Reference_Volt) and the value of output voltage (Feedback) is compared, and the output comparative result.If the output of comparator indication output voltage (Feedback) is greater than output control voltage (Reference_Volt), then the output of comparator 801 is in low logic level, if and output voltage (Feedback) is less than output control voltage (Reference_Volt), then the output of comparator 801 is in high logic level.Because comparator 801, the analog variation of output voltage can be represented by a digital value.Be one to be controlled at the control signal (UP/DOWN) of the frequency control unit the piezoelectric transformer driving control unit 30 from the digital value of comparator 801 output, and be imported into piezoelectric transformer driving control unit 30.In addition, the UP/DOWN signal from comparator 801 outputs is input to below with the level and smooth output unit 90 of driving voltage rectification of explaining.
The level and smooth output unit 90 of driving voltage rectification is by utilizing from the UP/DOWN signal of output voltage detecting unit 80 outputs, and control is provided to the driving voltage (V_DRIVE) of piezoelectric transformer T201.The level and smooth output unit 90 of driving voltage rectification comprises inverter (INVERT) 901, transistor T R901 and TR902, resistor R901 and R902, capacitor C901 and diode D901.Carry out polarity inversion from the UP/DOWN signal of output voltage detecting unit 80 outputs by inverter 901, and be imported into as V DDThe base stage of the transistorized transistor T R901 of voltage transitions.The UP/DOWN signal that is input to the base stage of transistor T R901 carries out polarity inversion again, and is transformed into V DDLevel.
Be transformed into V DDThe UP/DOWN signal of level is input to the base stage as the transistor T R902 of buffer transistor.Output signal from transistor T R902 is carried out rectification and level and smooth by diode D901 and capacitor C901, and (V_DRIVE) exports as driving voltage (supply voltage).
Figure 17 A-17C is illustrated in the schematic diagram according to the relation between UP/DOWN signal and the V_DRIVE signal in the piezoelectric transformer type high-voltage power apparatus 10 of example embodiment of the present invention.With reference to Figure 17 A-17C, if UP/DOWN signal output is in high logic level, then from the V_DRIVE signal of level and smooth output unit 90 outputs of driving voltage rectification corresponding to V DD, (specifically, V DDThe voltage of the voltage of-buffer transistor TR902-diode D901), and if UP/DOWN signal output be in low logic level, then V_DRIVE becomes 0.In addition, if the high logic level output time is identical with the low logic level output time, then V_DRIVE becomes V DD/ 2.
Turn to the image processing system that wherein utilizes according to the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention, such image processing system usually be equipped with to the charhing unit of the surface charging of latent image carrier, after its charging at the exposing unit of the surface of latent image carrier formation sub-image, with the developing cell of image development with will be transferred at the toner image that latent image carrier forms the transfer printing unit of transfer materials.
In this example, provide predetermined biasing (voltage) from the high-voltage power apparatus of (as shown in figure 16) as shown in the figure to charhing unit, developing cell and transfer printing unit.In other words, image processing system adopts piezoelectric transformer type high-voltage power apparatus shown in Figure 16 as supply unit, to charhing unit, developing cell and transfer printing unit one of them provides voltage at least.
Because according to the piezoelectric transformer type high-voltage power apparatus 10 of example embodiment of the present invention control frequency and can not enter unusual vibration or non-controllable state stably, utilize charhing unit, developing cell and transfer printing unit in the image processing system of piezoelectric transformer type high-voltage power apparatus 10 stably to work.In addition since can be within the short rise time output HIGH voltage, can reduce in the image processing system each and process the required time.
As mentioned above, in piezoelectric transformer type high-voltage power apparatus, form the driving voltage generating unit of piezoelectric transformer by the N bit counter as counter reset, by the incremented/decremented counter forming frequency control unit as digital processing circuit.In addition, the variation control range of frequency change control incremented/decremented counter can be set register value fmin and maximum frequency range by minimum frequency scope and sets register value fmax and set.In this manner, setpoint frequency scope, and control frequency and can not make driving voltage enter unusual vibration or non-controllable state stably.
As mentioned above, in the piezoelectric transformer type high-voltage power apparatus of each example embodiment of the present invention and modified embodiment of the present invention subsequently, form the driving voltage generating unit of piezoelectric transformer by the N bit counter as counter reset, by the incremented/decremented counter forming frequency control unit as digital processing circuit.In addition, the variation control range of frequency change control incremented/decremented counter can be set register value fmin and maximum frequency range by minimum frequency scope and sets register value fmax and set.In this manner, setpoint frequency scope, and control frequency and can not make driving voltage enter unusual vibration or non-controllable state stably.
In addition, in the piezoelectric transformer type high-voltage power apparatus of each example embodiment of the present invention and modified embodiment of the present invention subsequently, when utilizing outside ON/OFF control signal to make output be in the OFF state, the piezoelectric transformer driving control unit is controlled this frequency and is become minimum frequency fmin, it can change, and becomes maximum in this High voltage output value.Therefore, when output is in the ON state, within the short rise time, cause high voltage output.
And then, in the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention, detect with frequency change control from this variation of installing the High voltage output voltage of output, control the supply voltage that is provided to driver element in variable mode.By this way, driving frequency can move to from the maximum fmax of the frequency range of poor efficiency the minimum value fmin of high efficiency frequency range.As a result, improved output voltage efficient.
Therefore, in the piezoelectric transformer type high-voltage power apparatus of example embodiment of the present invention, can realize stable FREQUENCY CONTROL and the ability of output High voltage output voltage within the short rise time.In addition, can provide efficient piezoelectric transformer type high-voltage power apparatus and image processing system, it can stably be controlled maximum output voltage and be equal to or less than the output that several hectovolts arrive several kilovolts.
And then, have the piezoelectric transformer driving control unit of logical circuit by formation, can be installed in common application-specific integrated circuit (ASIC) (ASIC), and the cost of frequency control unit can reduce.
The result, according to example embodiment of the present invention, a kind of piezoelectric transformer type high-voltage power apparatus can be carried out stable FREQUENCY CONTROL and driving voltage can not enter unusual vibration or non-controllable state, can within the short rise time, export High voltage output voltage, and the image processing system that uses this high-voltage power apparatus can be provided.
Although described and illustrated the said apparatus that is considered to example embodiment of the present invention, person of skill in the art will appreciate that, along with technical development, can carry out various changes and modifications, can replace its element with equivalent, and not exceed actual range of the present invention.Can much improve, replace, interpolation and recombinant so that technology of the present invention adapts to specific occasion, and do not exceed scope of the present invention.For example, although in above-mentioned example embodiment, explained by detecting the output voltage variation and making the constant constant voltage of controlling of magnitude of voltage, but can substitute constant voltage control and carry out constant current control, wherein detect the variation of output current, and make current value constant.Even when carrying out constant current control, this operation is identical with constant voltage control.Correspondingly, therefore, it is intended that the present invention and is not limited to disclosed various example embodiment, and is that the present invention comprises all embodiment in the scope that drops on the claim that proposes.

Claims (18)

1. a supply unit wherein will be applied to piezoelectric transformer by the driving voltage that the driving frequency value is determined, to export an output voltage, this device comprises:
The output voltage detecting unit, the reference voltage that output voltage and is used for the control output voltage is compared, and according to its comparative result, detects the variation of output voltage and represent this variation with digital value; With
Driving control unit is controlled the driving of piezoelectric transformer by utilizing driving voltage to carry out according to the digital value of the variation that detects, so that output voltage is maintained predetermined value.
2. device as claimed in claim 1, wherein driving control unit comprises:
The driving frequency control unit changes and controls the driving frequency of this piezoelectric transformer according to the digital value of the conversion that detects, and
The driving voltage generating unit generates driving voltage to drive piezoelectric transformer according to the driving frequency by the output of driving frequency control unit.
3. device as claimed in claim 2, if wherein output voltage is greater than reference voltage, this digital value makes the driving frequency control unit increase driving frequency, and if output voltage less than reference voltage, this digital value makes the driving frequency control unit reduce driving frequency.
4. device as claimed in claim 2, wherein this driving control unit also comprises:
Memory cell, the scheduled frequency range value of storing driver frequency; With
The frequency range control unit, according to the driving frequency that is stored in the scheduled frequency range value in the memory cell and is exported by the driving frequency control unit, the control driving frequency changes to the value in scheduled frequency range.
5. device as claimed in claim 4, if wherein the driving frequency by the output of driving frequency control unit surpasses the scheduled frequency range value, then the frequency range control unit is exported control signal, with increase or the reduction that stops driving frequency, with the driving frequency control unit according to the control signal from frequency range control unit input, stop increase or the reduction of driving frequency.
6. a supply unit wherein will be applied to piezoelectric transformer by the driving voltage that the driving frequency value is determined, to export an output voltage, this device comprises:
Driving control unit according to output voltage be used for the variation that the reference voltage of control output voltage calculates output voltage, so that output voltage is maintained predetermined value, and is utilized the driving frequency of Digital Signal Processing control piezoelectric transformer according to the variation of calculating.
7. device as claimed in claim 6, wherein driving control unit comprises:
A/D converter is converted to numerical data with output voltage;
The digital value computing unit is according to the digital value of the output voltage that is converted to numerical data and reference voltage calculating output voltage;
The driving frequency control unit is according to the driving frequency of the digital value change of calculating and control piezoelectric transformer; With
The driving voltage generating unit generates the driving voltage that drives piezoelectric transformer according to the output valve of driving frequency control unit.
8. device as claimed in claim 7, if wherein output voltage is greater than reference voltage, this digital value makes the driving frequency control unit increase driving frequency, and if output voltage less than reference voltage, this digital value makes the driving frequency control unit reduce driving frequency.
9. device as claimed in claim 7, wherein this driving control unit also comprises:
Memory cell, the scheduled frequency range value of storing driver frequency; With
The frequency range control unit is used for basis and is stored in the scheduled frequency range value of memory cell and the driving frequency of being exported by the driving frequency control unit, and the control driving frequency changes to the value in scheduled frequency range.
10. device as claimed in claim 9, if wherein the driving frequency by the output of driving frequency control unit surpasses the scheduled frequency range value, then the frequency range control unit is exported control signal, with increase or the reduction that stops driving frequency, and the driving frequency control unit stops increase or the reduction of driving frequency according to the control signal from the input of frequency range control unit.
11. device as claimed in claim 7, wherein the digital value computing unit is by utilizing calculating or the proportion of utilization-integration-differential PID control technology carried out by digital filter to calculate this digital value.
12. a supply unit wherein will be applied to piezoelectric transformer by the driving voltage that the driving frequency value is determined, to export an output voltage, this device comprises:
The output voltage detecting unit, the reference voltage that output voltage and is used for the control output voltage is compared, and according to its comparative result, detects the variation of output voltage and indicate this variation with digital value;
Driving control unit is controlled the driving of piezoelectric transformer according to the digital value execution of the variation that detects, so that output voltage is maintained predetermined value; With
Driving voltage control unit, according to the comparative result of output voltage and reference voltage, change and control are applied to the supply voltage of piezoelectric transformer.
13. device as claimed in claim 12, if wherein output voltage is less than reference voltage, then driving voltage control unit increases supply voltage, and if output voltage greater than reference voltage, then driving voltage control unit reduces supply voltage.
14. device as claimed in claim 13, wherein driving control unit comprises:
The driving frequency control unit is according to the digital value change of the variation that detects and the driving frequency of control piezoelectric transformer; With
The driving voltage generating unit generates driving voltage to drive piezoelectric transformer according to the driving frequency by the output of driving frequency control unit.
15. device as claimed in claim 14, if wherein output voltage is greater than reference voltage, this digital value makes the driving frequency control unit increase driving frequency, and if output voltage less than reference voltage, this digital value makes the driving frequency control unit reduce driving frequency.
16. device as claimed in claim 14, wherein this driving control unit also comprises:
Memory cell, the scheduled frequency range value of storing driver frequency; With
The frequency range control unit, according to the driving frequency that is stored in the scheduled frequency range value in the memory cell and is exported by the driving frequency control unit, the control driving frequency changes to the value in scheduled frequency range.
17. device as claimed in claim 16, if wherein the driving frequency by the output of driving frequency control unit surpasses the scheduled frequency range value, then the frequency range control unit is exported control signal, with increase or the reduction that stops driving frequency, and the driving frequency control unit stops increase or the reduction of driving frequency according to the control signal from the input of frequency range control unit.
18. an image processing system comprises:
Piezoelectric transformer type high-voltage power apparatus as claimed in claim 1;
Charhing unit is to the surface charging of latent image carrier;
Exposing unit forms sub-image in its surface after the latent image carrier charging;
Developing cell is with this image development; With
Transfer printing unit is transferred to the toner image that is formed on the latent image carrier on one transfer materials;
Wherein this supply unit with voltage be provided in charhing unit, exposing unit, developing cell and the transfer printing unit at least one of them.
CN200810145516XA 2007-08-01 2008-08-01 Piezoelectric transformer type high-voltage power apparatus and image forming apparatus Expired - Fee Related CN101359870B (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2007200793A JP5559456B2 (en) 2007-08-01 2007-08-01 Piezoelectric transformer type high-voltage power supply device and image forming apparatus
JP200793/07 2007-08-01
KR1020070118097A KR101141277B1 (en) 2007-08-01 2007-11-19 High voltage power apparatus of piezoelectric transformer type and image forming apparatus
KR118097/07 2007-11-19

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