JP2019160873A - Piezoelectric element, piezoelectric transformer, piezoelectric transformer device, and electronic device - Google Patents

Abstract

To provide a piezoelectric element and a piezoelectric transformer in which vibration inhibition at a support position in an element driven at a high vibration speed is reduced, and output and driving stability are excellent.SOLUTION: There is provided a piezoelectric element in which a piezoelectric material includes a primary region including one end of the piezoelectric material sandwiched by a plurality of electrodes, and a secondary region including the other end, and a support member is in contact with the geometric center in the long side direction of the piezoelectric material, and the geometric center of the support member in the long side direction is located on the primary region side from the geometric center of the piezoelectric material. There is also provided a piezoelectric transformer including the piezoelectric element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric element. The present invention also relates to a piezoelectric transformer, a piezoelectric transformer device, and an electronic device using the piezoelectric element.

  A piezoelectric transformer is obtained by attaching a primary electrode and a secondary electrode to a single plate or laminated piezoelectric material (for example, piezoelectric ceramics), and polarizing the piezoelectric ceramic in a predetermined direction. When an alternating voltage is applied to the primary electrode of the piezoelectric transformer to apply electric energy, the piezoelectric ceramic expands and contracts by the inverse piezoelectric effect of the piezoelectric ceramic on the primary electrode side, and the electric energy is converted into elastic energy. Due to this expansion and contraction, the piezoelectric ceramic on the secondary electrode side generates a voltage due to the positive piezoelectric effect, and the elastic energy becomes electric energy again and is taken out from the secondary electrode. That is, a voltage is applied to the primary electrode, and a low voltage or a high voltage is generated in the secondary electrode through mechanical vibration such as expansion and contraction to obtain a transformed output.

  A piezoelectric transformer has a function of transforming (boosting or stepping down) an applied voltage in the same manner as a winding transformer (also called an electromagnetic transformer), but does not generate magnetic noise and has less energy loss than a winding transformer. There is an advantage that it is flame retardant.

  A conventional Rosen-type piezoelectric transformer has a primary resonance frequency of longitudinal vibration in the longitudinal direction (piezoelectric ceramic element length is 1/2 wavelength vibration; λ / 2 mode) or a secondary resonance frequency (piezoelectric ceramic element length). There are vibrations that have the same wavelength.

  Regarding the support structure of piezoelectric ceramics constituting these conventional piezoelectric transformers, Patent Documents 1 and 2 disclose structures that suppress a portion that becomes a node of a vibration mode at a resonance frequency of the piezoelectric ceramics. Specifically, in the λ mode, the piezoelectric ceramic is supported at a position that is ¼ length from the end in the length direction, and in the λ / 2 mode, it is supported at the center position in the length direction. In other words, when driving in the λ / 2 mode is assumed, in the conventional technology, the piezoelectric element is supported by the support member at a position half the length of the piezoelectric element.

  Piezoelectric transformers convert the applied voltage into mechanical vibration, then convert it back into voltage and output it. Depending on the support structure of the piezoelectric ceramic, mechanical vibration is hindered, leading to lower output and lower drive stability. .

JP-A-8-228031 JP 2009-253021 A

  The present invention has been made to solve such a problem, and provides a piezoelectric element and a piezoelectric transformer that reduce the inhibition of vibration and have excellent output and drive stability. The present invention also provides a piezoelectric transformer device and an electronic device using the piezoelectric transformer.

  The present invention is a piezoelectric element comprising a rectangular parallelepiped piezoelectric material, three or more electrodes, and a support member for holding the piezoelectric material, wherein the piezoelectric material is sandwiched by a plurality of electrodes. The support member has a primary region including one end of the material and a secondary region including the other end, the support member is in contact with a geometric center in the long side direction of the piezoelectric material, and the support member in the long side direction The geometric center is located on the primary region side of the geometric center of the piezoelectric material.

  The present invention also provides a piezoelectric transformer having the above piezoelectric element and an exterior part.

  The present invention also provides a piezoelectric transformer device comprising the piezoelectric transformer and a drive circuit for supplying an alternating voltage to the piezoelectric transformer.

  The present invention also provides an electronic device having an electronic component and a piezoelectric element or the piezoelectric transformer or the piezoelectric transformer device.

  The present invention provides a piezoelectric element or a piezoelectric transformer suitable for a piezoelectric transformer, which provides an appropriate support structure for a piezoelectric element, reduces the inhibition of vibration caused by the support, and has excellent output and drive stability. In addition, the present invention can provide a piezoelectric transformer device and an electronic device using the piezoelectric transformer.

1 is a schematic side view showing an embodiment of a configuration of piezoelectric elements (a) and (b) and piezoelectric transformers (c) and (d) for use in a piezoelectric transformer of the present invention. It is the side surface schematic diagram which shows one embodiment of the structure of the displacement distribution (109) of (lambda) / 2 mode in the piezoelectric element of the comparative form 1-0, and the piezoelectric transformer of this invention. It is the schematic which showed the fixed position of embodiment and the comparison form in the piezoelectric element for piezoelectric transformers of this invention. It is a figure which shows the relationship between the fixed position and step-up ratio in embodiment and comparative form of this invention. It is a circuit schematic diagram which shows one embodiment of the structure of the piezoelectric transformer apparatus of this invention. 1 is a schematic configuration diagram illustrating an embodiment of a configuration of an electronic device according to the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and includes various forms within the scope of the gist of the present invention.

  The piezoelectric element according to the first aspect of the present invention is a piezoelectric element including a rectangular parallelepiped piezoelectric material, three or more electrodes, and a support member that holds the piezoelectric material, and has the following characteristics. That is, the piezoelectric material has a primary region including one end of the piezoelectric material sandwiched by a plurality of electrodes and a secondary region including the other end.

  The support member is in contact with the geometric center in the long side direction of the piezoelectric material, and the geometric center of the support member in the long side direction is located on the primary region side from the geometric center of the piezoelectric material. It is characterized by that.

  Furthermore, a piezoelectric element according to a second aspect of the present invention is a piezoelectric element including a rectangular parallelepiped piezoelectric material, three or more electrodes, and a support member that holds the piezoelectric material, and has the following characteristics. Have.

  That is, the piezoelectric material has a primary region including one end of the piezoelectric material sandwiched by a plurality of electrodes and a secondary region including the other end. The geometric center of the support member in the long side direction is located on the primary region side from the geometric center of the piezoelectric material, and is between the geometric center of the support member and the geometric center in the long side direction of the piezoelectric material. The distance is 1% or more and less than 5% with respect to the long side of the piezoelectric material.

  Furthermore, the piezoelectric transformer according to the present invention is a piezoelectric transformer including the piezoelectric element and an exterior part, and the piezoelectric element and the exterior part are supported by the support member. Furthermore, if the piezoelectric element and the exterior portion are supported only by the support member, vibration inhibition can be further suppressed, which is even better.

  Furthermore, the piezoelectric transformer device according to the present invention is a piezoelectric transformer device comprising the piezoelectric element or the piezoelectric transformer and a drive circuit for supplying an alternating voltage to an electrode in a primary region of the piezoelectric element. Still further, an electronic device according to the present invention is an electronic device characterized by including an electronic component and the piezoelectric transformer device.

  The characteristics of the piezoelectric element of the first form and the characteristics of the piezoelectric element of the second form satisfy both, or satisfy only one of them, and are within the scope of the present invention.

  FIG. 1 is a schematic side view showing an embodiment of the configuration of piezoelectric elements (a) and (b) and piezoelectric transformers (c) and (d) for use in a piezoelectric transformer according to the present invention. By providing the piezoelectric element of the present invention on a base material that is a part of the object, the object can have a function as a piezoelectric transformer. Or it can also unitize by providing the exterior part 111, and can also provide in the desired position of a target object.

  In FIG. 1, a rectangular plate-shaped piezoelectric material 104 includes two regions, a primary region 105 that is a power input side and a secondary region 106 that is a power output side. In the primary region 105, an input electrode 101 and an electrode 102 are provided so as to face each other with the piezoelectric material 104 interposed therebetween. An output electrode 103 is provided in the secondary region 106. The piezoelectric material 104 includes a primary region 105 and a secondary region 106 at a position 107 (a geometric center in the long side direction of the piezoelectric material) that indicates a half position of the longitudinal length L of the piezoelectric material 104. A white arrow drawn inside the piezoelectric material 104 indicates the polarization direction of the piezoelectric material.

  In the piezoelectric element of the first form shown in FIG. 1A, the support member 108 is in contact with the piezoelectric material 104. However, the second form shown in FIG. It may be in contact with or away from the geometric center 107 in the long side direction. However, as shown in any of FIGS. 1A to 1D, the geometric center of the support member 108 in the L direction (long side direction of the piezoelectric material) is on the primary region 105 side.

  As described above, the present invention is characterized by the support structure of the piezoelectric material, and the reason for the configuration is as follows. In general, in a Rosen-type piezoelectric element (the length in the long side direction is L), the primary region has input electrodes arranged on the upper and lower surfaces in the polarization direction, and the potential is controlled (input potential). On the other hand, the electrode on the secondary region side is an open end (output electrode). A Rosen-type piezoelectric element can take many shapes, but the piezoelectric material constituting the piezoelectric element has a plurality of regions with different polarization directions, and the longitudinal vibration of the piezoelectric material is used to drive the element. Is used.

The compliance constant, which is the reciprocal of the Young's modulus, shows different values depending on the electric field control condition and the open condition, but there is a correlation through the electromechanical coupling coefficient. Generally, the compliance constant in the open condition is smaller than the compliance constant in the short state. Have the relationship.
For this reason, in the Rosen element, the primary region exhibits a smaller Young's modulus than the secondary region during driving. Reflecting the difference in characteristics depending on the region, the position of the node of the primary resonance mode of the longitudinal longitudinal vibration in the piezoelectric element is from the position of L / 2 to the primary region where the Young's modulus becomes small when a voltage is applied. I understood that it was shifted to the side.

  In other words, when driving in the λ / 2 mode is assumed, if the piezoelectric material is supported at a position that is half the length of the piezoelectric element as in the prior art, vibration is hindered because it is different from the true position of the vibration node. It was found that sufficient output could not be obtained.

  Accordingly, the present invention supports the position of the true node in the vibration generated when a voltage is applied by the support member, thereby reducing the vibration inhibition at a high vibration speed, and excellent in the output and driving stability of the element. Is to provide.

  Here, as illustrated in FIGS. 1C and 1D, the support member 108 may be in contact with or away from the geometric center of the piezoelectric material 104 in the long side direction.

  As a specific support method, a mode in which an elastic body such as rubber is used as a support member and the piezoelectric element is held between the upper and lower sides is preferable. Moreover, it is good to install so that a piezoelectric material may be crossed in the direction which cross | intersects a long side direction.

  Since the geometric center of the support member is shifted to the primary region side with respect to the geometric center of the piezoelectric material, vibration inhibition during driving of the element is reduced. If the shift amount is too small, a sufficient effect cannot be obtained. If the shift amount is too large, the primary region of the element is fixed greatly exceeding the vibration node, which also inhibits drive vibration. The distance x between the geometric center of the support member and the geometric center of the piezoelectric material is preferably 1% or more and less than 5% with respect to the long side L of the piezoelectric material. It is more preferable that the distance is 2.5% or more and 4.5% or less with respect to the long side of the piezoelectric material because the step-up ratio is high.

  As shown in FIG. 1A, the support member may be in contact with the geometric center of the piezoelectric material or may be separated as shown in FIG. In addition, it is preferable that the piezoelectric element and the exterior portion 111 are supported only at the position where the support member is disposed from the viewpoint of removing the cause of vibration inhibition due to contact with other members.

  As shown in FIGS. 1 (a) and 1 (b), the connection of the primary electrode is provided with a lead electrode through a support member, which also eliminates the cause of vibration inhibition due to contact with other members. It is preferable from the viewpoint.

  The exterior portion does not need to surround the entire piezoelectric material, and may have a shape that does not hinder when incorporated in a drive circuit or an electronic device.

  In the example of FIGS. 1A and 1B, the electrode 101 and the electrode 102 cover almost the entire upper and lower surfaces of the piezoelectric material 104 in the primary region 105, leaving a margin for short-circuit prevention at the end. Of course, the entire upper surface or lower surface of the primary region 105 of the piezoelectric material 104 may be covered, or a larger margin may be provided.

  An output electrode 103 is provided in the secondary region 106. In the example of FIG. 1A, the electrode 103 covers most of the end face, but may cover the entire end face or have a larger margin. Further, the output electrode 103 may be provided on a part of the upper surface of the secondary region, a part of the lower surface, or both.

  Hereinafter, a piezoelectric element, a piezoelectric transformer, a piezoelectric transformer device, and an electronic device for carrying out the present invention will be described in more detail.

  As shown below, a fixed region having a length Lf and a width wf is provided on the front and back surfaces (or one surface) of a piezoelectric element for a Rosen type piezoelectric transformer having a length L, a width w, and a thickness d. The step-up ratio (output voltage / input voltage) in the / 2 mode was confirmed. In that case, it confirmed using finite element method package software "ANSYS" (ANSYS Inc.). As the material characteristics used for the simulation, the physical property values of commercially available lead zirconate titanate-based materials were mainly used.

(Embodiments 1-1 to 1-5)
FIG. 3 is a schematic view showing fixed positions of the embodiment and the comparative embodiment in the piezoelectric element for use in the piezoelectric transformer of the present invention.

  In an L (= 20 mm) Rosen-type piezoelectric element as shown in FIG. 3, an example in which the support position by the support member was shifted was prepared, and the ratio of the output voltage to the input voltage, that is, the step-up ratio was estimated. In this examination, it is assumed that the coordinates of the support position do not change at all due to vibration, but it is desirable that the force applied to the fixed position is small in an actual element. The following embodiments and comparative embodiments were also carried out under the same conditions.

  The support position of the piezoelectric element by the support member was a band-shaped region having a length Lf = 0.4 mm in contact with the front and back surfaces of the element in a shape (width wf = w = 4 mm) across the element in the short side direction. This belt-like region (only one is shown) indicates the position where the support member is disposed, and the center (110) of the belt-like region in the figure corresponds to the geometric center of the support member.

  In FIG. 3, the half position (107) of the length of the piezoelectric element corresponds to the geometric center in the long side direction of the piezoelectric material.

  Starting from the half position (107) of the length of the piezoelectric element, the deviation of the center value (110) of the belt-like region toward the primary region side was x (mm).

  The results of Embodiments 1-1 to 1-5 when the value of x / L (%) is 1, 2.5, 3.5, 4.5, 4.9% are shown in Table 1 and FIG. Show. This indicates how much the geometric center of the support member in the long side direction is shifted to the primary region side from the geometric center of the piezoelectric material.

  As shown in Table 1, the result that the boost ratio was improved as compared with Comparative Example 1-1 (prior art) was obtained.

  Table 1 shows the fixed position dependency of the step-up ratio using the λ / 2 mode in a Rosen piezoelectric element having a length L (= 20 mm). This result shows the characteristics when a support member having a length of 0.4 mm and a width of 4 mm is used in contact with the front and back surfaces of the element so as to cross the piezoelectric element in the short side direction.

(Comparative forms 1-1 to 1-3)
Table 1 and FIG. 4 show the results of estimating the step-up ratio when x is 0, 0.5, and 5% of the element having the same shape as in Embodiment 1-1. The step-up ratio is lower than in the embodiment.

(Comparative Form 1-0)
In the element having the same shape as that of Embodiment 1-1, the step-up ratio when the support member is not provided was estimated. A distribution of displacement amounts as shown in FIG. 2 was observed in the length direction of the element, and it was confirmed that the region serving as a node during driving shifted to the primary region side. In practice, a configuration without a support member is not possible, so the boost ratio in this comparative embodiment is only a reference value.

(Embodiments 2-1 to 2-4)
In the Rosen type piezoelectric element of L (= 20 mm) as shown in FIG. 3, the boosting ratio was estimated by shifting the support position by the support member. Compared to Embodiments 1-1 to 1-5, the width wf is small.

  The indication position by the support member has a width wf = 0.4 mm and a length Lf = 0.4 mm, which is a substantial point support structure. The area in contact with the front and back surfaces of the piezoelectric element was fixed. Table 2 shows cases where the value of x is 1, 2.5, 3.5, and 4.5% of L. It was obtained that the step-up ratio was improved as compared with Comparative Example 1-1 and Comparative Example 2-1 (prior art) described later.

  Table 2 shows the fixed position dependency of the step-up ratio using the λ / 2 mode in a Rosen piezoelectric element having a length L (= 20 mm). The result of fixing a region having a length of 0.4 mm and a width of 0.4 mm in contact with the front and back surfaces of the element is shown.

  Starting from the half position (107) of the length of the piezoelectric element, the deviation of the center value (110) of the belt-like region toward the primary region side was x (mm).

(Comparison 2-1)
Table 2 shows the results of estimating the step-up ratio when x is 0 in the elements having the same shapes as those of Embodiments 2-1 to 2-4. The step-up ratio is lower than in the embodiment.

(Embodiments 3-1 to 3-4)
In the Rosen type piezoelectric element of L (= 20 mm) as shown in FIG. 3, the boosting ratio was estimated by shifting the support position by the support member.

  The region of the element was fixed in a region of width wf = 1 mm and length Lf = 0.4 mm in contact with the front and back surfaces of the element. The size of the width wf is between the first and second embodiments.

  Table 3 shows cases where the value of x / L (%) is 1, 2.5, 3.5, 4.5%. It was obtained that the step-up ratio was improved as compared with Comparative Example 1-1 and Comparative Example 3-1 (prior art) described later.

  Table 3 shows the fixed position dependency of the step-up ratio using the λ / 2 mode in a Rosen piezoelectric element having a length L (= 20 mm). The result of fixing a region having a length of 0.4 mm and a width of 1 mm in contact with the front and back surfaces of the element is shown.

  Starting from the half position (107) of the length of the piezoelectric element, the deviation of the center value (110) of the belt-like region toward the primary region side was x (mm).

(Comparative Form 3-1)
Table 3 shows the result of estimating the step-up ratio when x is 0 in the elements having the same shapes as those of Embodiments 3-1 to 3-4. The step-up ratio is lower than in the embodiment.

(Embodiments 4-2 and 4-4)
In the Rosen type piezoelectric element of L (= 20) mm as shown in FIG. 3, the boosting ratio was estimated by shifting the support position by the support member. The length Lf is shorter than those in the first to third embodiments, and the width wf is the same as the width of the piezoelectric element as in the first embodiment.

  The region of the element was fixed in the region of width wf = 4 mm and length Lf = 0.2 mm in contact with the front and back surfaces of the element. Table 4 shows the case where the value of x is 2.5 and 4.5% of L. It was obtained that the step-up ratio was improved as compared with Comparative Example 1-1 and Comparative Example 4-1 (prior art) described later.

  Table 4 shows the fixed position dependency of the step-up ratio using the λ / 2 mode in a Rosen piezoelectric element having a length L (= 20 mm). A result of fixing a region having a length of 0.2 mm and a width of 4 mm in contact with the front and back surfaces of the element in a direction crossing the element in the short side direction is shown.

  Starting from the half position (107) of the length of the piezoelectric element, the deviation of the center value (110) of the belt-like region toward the primary region side was x (mm).

(Comparative Form 4-1)
Table 4 shows the result of estimating the step-up ratio when x is 0 in the element having the same shape as in Embodiments 4-2 and 4-4. The step-up ratio is lower than in the embodiment.

(Embodiment 11-1)
In the L (= 30) mm Rosen-type piezoelectric element as shown in FIG. 3, the step-up ratio was estimated by shifting the support position by the support member.

  The element was fixed at a width wf = 0.4 mm and a length Lf = 4 mm, and the area in contact with the front and back surfaces of the element was fixed. Table 5 shows the case where the value of x is 2.5% of L. It was obtained that the step-up ratio was improved as compared with Comparative Example 11-1 (prior art) described later.

(Comparative form 11-1)
Table 5 shows the result of estimating the step-up ratio when x is 0 in the element having the same shape as in Embodiment 11-1. The step-up ratio is lower than in the embodiment.

  Table 5 shows the fixed position dependency of the step-up ratio using the λ / 2 mode in a Rosen piezoelectric element having a length L (= 30) mm. The result of fixing a region having a length of 0.4 mm and a width of 4 mm in contact with the front and back surfaces of the element is shown. Starting from the half position (107) of the length of the piezoelectric element, the deviation of the center value (110) of the belt-like region toward the primary region side was x (mm).

  Further, if the element can be fixed, it is preferable that the fixing is performed only on one side.

  For example, in the embodiment 1-2, under the condition that only one side is fixed, a step-up ratio of 138 times can be obtained at 76 kHz. By fixing the node of the mode you want to use, it is considered that the effect of suppressing the loss due to the mixing of unnecessary modes can be obtained.

  In addition, even when a piezoelectric material having a composition different from that of the lead zirconate titanate material is used, the effect of the present invention can be obtained as long as the configuration satisfies the requirements of the present invention.

  In addition, in the Rosen-type piezoelectric element, the effect of the present invention can be expected even in an element having a configuration in which the length of the primary region is less than half the length of the piezoelectric element.

(Piezoelectric transformer device)
The piezoelectric transformer device of the present invention preferably includes the piezoelectric element or the piezoelectric transformer of the present invention and a drive circuit that supplies an alternating voltage to the piezoelectric element.

  FIG. 5 is a schematic circuit diagram showing an example of the configuration of the piezoelectric transformer device of the present invention.

  However, this configuration is merely an example, and the present invention is not limited to these configurations.

  The circuit shown here is a piezoelectric transformer device as a high voltage power source, and includes the piezoelectric transformer 1001 of the present invention. The electrical output from the piezoelectric transformer 1001 is rectified and smoothed to a positive voltage by the diodes 1002 and 1003 and the high voltage capacitor 1004 and supplied to a load (in the case of a color laser printer described later, a transfer roller or the like). That is, the diodes 1002 and 1003 and the high-voltage capacitor 1004 serve as a rectifier circuit. Further, an LC resonance circuit using an FET 1011 as a switching element is used as a drive circuit for supplying an alternating voltage to the piezoelectric transformer 1001. As described above, the piezoelectric transformer device for generating a DC high voltage includes a drive circuit and a piezoelectric transformer, and includes a rectifier circuit as necessary.

  The output voltage is divided by resistors 1005, 1006, and 1007, and is input to the non-inverting input terminal (+ terminal) of the operational amplifier 1009 through the protective resistor 1008. On the other hand, a high-voltage power supply control signal (Vcont), which is an analog signal, is input to the inverting input terminal (−terminal) of the operational amplifier via a resistor 1014. By configuring the operational amplifier 1009, the resistor 1014, and the capacitor 1013 as shown in the figure, it functions as an integrating circuit for the control signal Vcont. A control signal smoothed with an integration time constant determined by the component constants of the resistor and the capacitor is input to the operational amplifier 1009. The output terminal of the operational amplifier 1009 is connected to a voltage controlled oscillator (VCO) 1010, and the voltage controlled oscillator (VCO) 1010 switches the switching element 1011 at a frequency corresponding to the output voltage of the operational amplifier 1009. The voltage is amplified by the inductor 1012 and supplied to the primary side of the piezoelectric transformer.

  The drive circuit preferably sweeps the alternating voltage in a predetermined frequency band, and the frequency band preferably includes a natural resonance frequency of the piezoelectric ceramic. When the frequency band includes the natural resonance frequency of the piezoelectric ceramic, the vibration displacement amplitude of the piezoelectric ceramic portion is increased. By using the piezoelectric element or the piezoelectric transformer of the present invention, excellent output and driving stability can be obtained.

(Electronics)
FIG. 6 is a cross-sectional view showing a schematic configuration of a color laser printer as an image forming apparatus as an example of an electronic apparatus having the piezoelectric transformer device of the present invention. This color laser printer is equipped with a piezoelectric transformer device as a high voltage power source. In FIG. 6, the color laser printer 401 includes a deck 402 for storing the recording paper 32, a deck paper presence / absence sensor 403 for detecting the presence / absence of the recording paper 32 in the deck 402, and a pickup roller 404 for feeding the recording paper 32 from the deck 402. . Further, the color laser printer 401 is paired with a deck paper feeding roller 405 that conveys the recording paper 32 fed by the pickup roller 404 and a deck feeding roller 405, and a retard roller 406 for preventing double feeding of the recording paper 32. Also have. A registration roller pair 407 that synchronously conveys the recording paper 32 and a pre-registration sensor 408 that detects the conveyance state of the recording paper 32 to the registration roller pair 407 are disposed downstream of the deck paper feeding roller 405.

  Further, an electrostatic attraction transfer belt (hereinafter referred to as ETB) 409 is disposed downstream of the registration roller pair 407. Since the image forming apparatus is a color laser printer, a plurality of color process cartridges 410 are mounted and can be replaced. Formed on the ETB 409 is an image forming unit comprising process cartridges 410Y, 410M, 410C, 410Bk for four colors (yellow Y, magenta M, cyan C, black Bk) and scanner units 420Y, 420M, 420C, 420Bk. A color image is formed by sequentially superimposing the transferred images on the transfer rollers 430Y, 430M, 430C, and 430Bk. The formed color image is transferred onto the recording paper 32, and the recording paper 32 is conveyed downstream. In the downstream, a pair of a fixing roller 433 and a pressure roller 434 each having a heater 432 for heating is provided in order to thermally fix the toner image transferred onto the recording paper 32. Further, a fixing paper discharge roller pair 435 for conveying the recording paper 32 from the fixing roller 433 and a fixing paper discharge sensor 436 for detecting the conveyance state from the fixing unit are provided.

  Each of the scanner units 420 scans the photosensitive drum 305 with a laser unit 421 that emits laser light modulated based on each image signal sent from the video controller 440 and the laser light from each laser unit 421. For this purpose, it comprises a polygon mirror 422, a scanner motor 423, and an imaging lens group 424. Each of the process cartridges 410 includes a photosensitive drum 305, a charging roller 303, a developing roller 302, and a toner storage container 411 necessary for a known electrophotographic process. The scanner units 420 are configured to be detachable from the color laser printer 401 main body. Furthermore, when the video controller 440 receives image data sent from an external device 441 such as a personal computer, the video controller 440 develops the received image data into bitmap data and generates an image signal for image formation.

  The engine controller 201 of the color laser printer 401 includes a CPU 207 that is a control unit including a RAM 207a, a ROM 207b, a timer 207c, a digital input / output port 207d, and a D / A port 207e, various input / output control circuits (not shown), and the like. It consists of The piezoelectric transformer device (high voltage power source) 202 is configured as follows. A transfer high voltage power supply (not shown) using a charging high voltage power supply (not shown) corresponding to each process cartridge 410, a development high voltage power supply (not shown), and a piezoelectric transformer capable of outputting a high voltage corresponding to each transfer roller 430. is there. In the present specification, the image forming apparatus has been described by taking a tandem color image forming apparatus as an example, but the piezoelectric transformer device of the present invention can be applied to any image forming apparatus using a high voltage power source. .

  Here, the laser printer has been described as the electronic device of the present invention. However, the piezoelectric transformer device of the present invention is an AC adapter, a sound recording / reproducing device, an image input / output device, a plasma generator such as an air cleaner or an air conditioner, and an information terminal. It can be applied to various electronic devices.

  The piezoelectric element of the present invention, the piezoelectric transformer, or the piezoelectric transformer device of the present invention can be appropriately used by the user of the present invention depending on the application. For example, even if it does not have an exterior part, the piezoelectric element of the present invention can be incorporated by using one part of the object as an exterior, and the function as a piezoelectric transformer can be used. In addition, a piezoelectric transformer device having a drive circuit may be incorporated into an object as a unit.

  By using the piezoelectric element, the piezoelectric transformer of the present invention, or the piezoelectric transformer device of the present invention, an electronic apparatus having excellent output and driving stability can be obtained.

  As described above, the present invention controls a support position in a piezoelectric transformer and other uses of piezoelectric elements, thereby reducing vibration inhibition resulting from the support of the elements, and improving the output and driving stability of the elements. An element is provided. In addition, the present invention can provide a piezoelectric transformer, a piezoelectric transformer device, and an electronic device using the piezoelectric element. In addition, the piezoelectric transformer of this invention can be utilized for various uses, such as a booster and a step-down voltageer, using the characteristic as a transformer.

DESCRIPTION OF SYMBOLS 101 Electrode 102 Electrode 103 Electrode 104 Piezoelectric ceramics 105 Primary area | region 106 Secondary area | region 107 L / 2 position standard line (geometric center of the long side direction of piezoelectric material)
108 Support Position 109 Longitudinal Vibration Displacement 110 Geometric Center of Support Member in L Direction (Long Side Direction of Piezoelectric Material) 111 Exterior Part 201 Engine Controller 202 Piezoelectric Transformer Device (High Voltage Power Supply)
401 Color Laser Printer 441 External Device 1001 Piezoelectric Transformer 1009 Operational Amplifier 1010 Voltage Controlled Oscillator (VCO)
1011 Switching element 32 Recording paper

Claims (13)

A piezoelectric element comprising a rectangular parallelepiped piezoelectric material, three or more electrodes, and a support member for holding the piezoelectric material,
The piezoelectric material has a primary region including one end of the piezoelectric material sandwiched between a plurality of electrodes, and a secondary region including the other end,
The support member is in contact with the geometric center in the long side direction of the piezoelectric material, and the geometric center of the support member in the long side direction is located on the primary region side from the geometric center of the piezoelectric material. A piezoelectric element characterized by comprising: A piezoelectric element comprising a rectangular parallelepiped piezoelectric material, three or more electrodes, and a support member for holding the piezoelectric material,
The piezoelectric material has a primary region including one end of the piezoelectric material sandwiched between a plurality of electrodes, and a secondary region including the other end,
The geometric center of the support member in the long side direction is located on the primary region side of the geometric center of the piezoelectric material, and the geometric center of the support member and the geometric center in the long side direction of the piezoelectric material. The distance between is between 1% and less than 5% with respect to the long side of the piezoelectric material.   The piezoelectric element according to claim 2, wherein the distance is 2.5% to 4.5% with respect to the long side of the piezoelectric material.   The piezoelectric element according to claim 3, wherein the support member is not in contact with a geometric center in a long side direction of the piezoelectric material.   5. The piezoelectric element according to claim 1, wherein the support member is installed so as to cross the rectangular parallelepiped piezoelectric material in a direction intersecting the long side direction. 6.   The piezoelectric element according to claim 1, wherein the piezoelectric element is driven in a λ / 2 mode of longitudinal vibration of the piezoelectric element.   7. A piezoelectric transformer having the piezoelectric element according to claim 1 and an exterior part, wherein the piezoelectric element and the exterior part are supported by the support member.   The piezoelectric transformer according to claim 7, wherein the piezoelectric element and the exterior portion are supported only at a position where the support member is disposed.   9. The piezoelectric transformer according to claim 8, wherein the electrode in the primary region is provided with an extraction electrode through the support member. The piezoelectric element according to any one of claims 1 to 6, or the piezoelectric transformer according to any one of claims 7 to 9,
A drive circuit for supplying an alternating voltage to the electrode of the primary region of the piezoelectric element;
A piezoelectric transformer device comprising:   11. The piezoelectric transformer device according to claim 10, wherein the drive circuit sweeps the alternating voltage in a predetermined frequency band, and the frequency band includes a resonance frequency of λ / 2 mode of longitudinal vibration in the longitudinal direction of the piezoelectric element.   The piezoelectric transformer device according to claim 10 or 11, wherein the drive circuit and the primary electrode are connected via the support member. Electronic components,
The piezoelectric element according to any one of claims 1 to 6, the piezoelectric transformer according to any one of claims 7 to 9, or the piezoelectric transformer device according to any one of claims 10 to 12. ,
Electronic equipment having

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