JP2015194510A - Image projection device - Google Patents

Abstract

An image projection apparatus capable of generating sound satisfactorily. A housing includes a housing, a piezoelectric vibration unit having a piezoelectric element, a projection unit that is held by the housing and displays an image on a projection surface, and a control unit that controls the piezoelectric element. In a state where the load of the image projection device 10 itself is applied to the piezoelectric vibration unit 60, a sound signal is applied to the piezoelectric element 61 from the control unit, whereby the piezoelectric element 61 is deformed and the piezoelectric vibration unit 60 is deformed, Due to the deformation of the vibration unit 60, the contact surface 90 in contact with the image projection device 10 is vibrated to generate sound from the contact surface 90. [Selection] Figure 11

Description

  The present invention relates to an image projection device that generates a sound from a contact surface by vibrating a contact surface with which the image projection device contacts.

  For example, a conventional projector generates sound from a speaker provided in the projector. Dynamic speakers are the mainstream speakers used in conventional projectors. For example, Patent Document 1 describes a vibration generator having a dynamic speaker structure including a magnet, a voice coil, a diaphragm, and a case for housing them. The frequency characteristic of the sound generated from the dynamic speaker is affected by the size of the dynamic speaker. For example, in order to reproduce a bass, it is necessary to provide a large dynamic speaker.

Japanese Utility Model Publication No. 5-85192

  However, since the dynamic speaker mounted inside the projector uses various members such as a magnet, a voice coil, and a diaphragm, an increase in the number of components of the speaker is inevitable. In particular, a large speaker is attached to the projector. It ’s difficult. For this reason, the sound pressure in the low range is often insufficient.

  An object of the present invention made in view of such a viewpoint is to provide an image projection apparatus capable of generating sound satisfactorily.

An image projection apparatus according to the present invention that achieves the above object is as follows.
The body,
A piezoelectric vibration part having a piezoelectric element;
A projection unit that is held in the housing and displays an image on a projection surface;
A control unit for controlling the piezoelectric element,
In a state where the load of the image projection apparatus itself is applied to the piezoelectric vibration unit, the piezoelectric element is deformed by applying a sound signal from the control unit to the piezoelectric element, and the piezoelectric vibration unit is deformed, and the piezoelectric vibration unit is deformed. Due to the deformation of the vibration unit, the contact surface that is in contact with the image projection device is vibrated to generate sound from the contact surface.

  The piezoelectric vibration unit may be disposed within a predetermined distance from the center of gravity of the image projection apparatus and at a portion facing the contact surface.

Comprising a support for supporting the housing;
The piezoelectric vibration unit may be disposed at a portion of the support unit that faces the contact surface.

A front support portion disposed on the front side on which the projection surface is located across the center of gravity of the image projection apparatus, and a rear support portion disposed on the rear side opposite to the side on which the projection surface is located; With
The piezoelectric vibration part may be disposed on the rear support part.

A detection unit for detecting a contact state between the contact surface and the piezoelectric vibration unit;
The control unit may control the piezoelectric element based on the detected contact state.

With speakers,
The control unit may drive the speaker simultaneously with the piezoelectric element.

A storage unit for storing the frequency characteristics of the speaker;
The control unit may control the piezoelectric element based on the stored frequency characteristics of the speaker.

  The control unit may control a sound signal applied to the piezoelectric element so as to compensate for a lack of sound pressure in the stored frequency characteristics of the speaker.

A recording unit for recording frequency characteristics of sound generated from the contact surface;
The control unit may control the speaker based on the recorded frequency characteristic.

  The control unit may control the sound pressure of the frequency characteristic of the speaker so as to compensate for a lack of sound pressure of the recorded frequency characteristic.

  The piezoelectric element is a multilayer piezoelectric element, and may be elastically deformed along the stacking direction.

  The piezoelectric vibration unit may include a covering member that transmits vibration due to deformation of the piezoelectric element to the contact surface to vibrate the contact surface.

  The contact surface may be a placement surface on which the image projection device is placed.

  The contact surface may be a wall surface on which the image projector is hung.

  According to the present invention configured as described above, it is possible to provide an image projection apparatus capable of generating sound satisfactorily.

1 is an external perspective view, a front view, and a side view showing a schematic configuration of an image projection apparatus according to a first embodiment of the present invention. It is a schematic perspective view of the principal part which decomposes | disassembles and shows the bottom face side of the projector of FIG. It is a figure which shows the structure of the laminated piezoelectric element of FIG. It is a figure which shows the modification of a lamination type piezoelectric element. It is a partial expanded sectional view of the piezoelectric vibration part of FIG. It is a functional block diagram of the principal part of the projector of FIG. It is a flowchart which shows the process of the control part of FIG. It is a figure which shows an example of the frequency characteristic of the sound which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the frequency characteristic of the filter process by DSP of FIG. It is a figure which shows arrangement | positioning of the piezoelectric vibration part in the projector of FIG. It is the schematic for demonstrating operation | movement of the piezoelectric vibration part in the projector of FIG. It is the external appearance perspective view, front view, and side view which show schematic structure of the image projector which concerns on 2nd Embodiment of this invention. It is a figure which shows the comparison of the blurring of the projection image in the image projector which concerns on 2nd Embodiment of this invention. It is a side view which shows schematic structure of the image projector which concerns on 3rd Embodiment of this invention. It is a figure which shows three modifications of the holding | maintenance form of a piezoelectric vibration part. It is a figure which shows schematic structure of the principal part which shows the modification of a piezoelectric vibration part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1A, 1B, and 1C are an external perspective view, a front view, and a side view showing a schematic configuration of an image projection apparatus according to a first embodiment of the present invention. The image projection apparatus according to the present embodiment is a so-called placement-type projector 10, and includes a housing 20, a projection unit 30, a speaker 40, a piezoelectric vibration unit 60, a detection unit 70, and a microphone 81. The projector 10 is placed on a horizontal placement surface 90 such as a desk during use. At this time, the projector 10 is supported by the piezoelectric vibrating portion 60 and the rear bottom 20 b of the housing 20 and applies a load to the piezoelectric vibrating portion 60. The projector 10 includes various signal input terminals such as a USB terminal connected to a personal computer, a video input terminal for signal input, and a VGA (Video Graphic Array) terminal on the rear surface. The casing 20 has a substantially rectangular parallelepiped shape. The projection unit 30 is held by the housing 20. Here, the desk is an example of a contacted member, and the placement surface 90 is an example of a contact surface (mounting surface 90) with which the projector 10 comes into contact.

  The projection unit 30 is a projection lens for enlarging and displaying an image of the image display element on a projection surface such as a screen. The speaker 40 is a sound output device such as a dynamic speaker or a capacitor speaker.

  The detection unit 70 detects whether or not the piezoelectric vibration unit 60 is in contact with the placement surface 90, that is, the contact state between the placement 90 surface (contact surface) 90 and the piezoelectric vibration unit 60. The detection unit 70 is configured by a device that can detect a contact state between the piezoelectric vibration unit 60 and the mounting surface 90, such as an infrared sensor, an ultrasonic sensor, a proximity sensor, a mechanical switch, a camera, and a pressure sensor. In addition, the piezoelectric vibration unit 60 can be configured as the detection unit 70 by using the output of the piezoelectric vibration unit 60 as a sensor.

  The microphone 81 constitutes a recording unit that records frequency characteristics of sound generated from a contact surface (mounting surface 90) such as a desk with which the piezoelectric vibration unit 60 contacts together with a memory unit described later. The recording unit acquires the sound generated from the contact surface with the microphone 81 and records it in the memory unit. The memory unit is disposed inside the housing 20.

  FIG. 2 is a schematic perspective view of a main part in which the bottom side of the housing 20 of FIG. 1 is disassembled. The housing 20 includes a main body case 21 and a bottom lid 22. The main body case 21 is an exterior cover of the projector 10, and includes, for example, an image projection mechanism 23, a cooling mechanism 24, an electronic circuit board 25, a power supply unit 26, and the like. The image projection mechanism 23 has a light source and an image display element. For example, when the projector 10 is an LCD (Liquid-Crystal Display) system, liquid crystal is used, and when the projector 10 is a DLP (Digital Light Processing) system, a DMD (Digital Micromirror Device) is used. Is done. The light source driven by the power supply unit 26 emits projection light to the image display element and displays an image on the screen through the projection unit 30. The cooling mechanism 24 is a cooling fan that cools the image projection mechanism 23, for example, and exhausts heat from the exhaust port 27. The electronic circuit board 25 controls each mechanism unit included in the projector 10. The projector 10 according to the present embodiment includes a holding unit 100 that houses and holds the piezoelectric vibrating unit 60 on the bottom surface side of the housing 20. In other words, the piezoelectric vibration unit 60 is disposed at a portion facing the mounting surface (contact surface) 90 in the housing. The holding unit 100 includes, for example, a slit 101 that extends in a substantially vertical direction of the bottom cover 22 of the projector 10 and has a uniform width that opens to the bottom cover side of the housing 20. The bottom lid 22 is provided with a hole 22 a so that the piezoelectric vibrating portion 60 can come into contact with the placement surface (contact surface) 90.

  The piezoelectric vibration unit 60 includes a piezoelectric element 61, an O-ring 62, and an insulating cap 63 that is a covering member. A piezoelectric element is an element that expands or contracts or bends according to an electromechanical coupling coefficient of a constituent material by applying an electric signal (voltage). These elements are made of, for example, ceramic or quartz. The piezoelectric element may be a unimorph, bimorph or multilayer piezoelectric element. The multilayer piezoelectric element includes a multilayer bimorph element in which bimorphs are stacked (for example, 8 to 40 layers), a plurality of dielectric layers made of, for example, PZT (lead zirconate titanate), and the plurality of dielectrics. There is a stack type composed of a laminated structure with electrode layers arranged between layers. A unimorph expands and contracts when an electric signal is applied, a bimorph bends when an electric signal is applied, and a stack type stacked piezoelectric element expands and contracts along the stacking direction when an electric signal is applied.

  In the present embodiment, the piezoelectric element 61 is formed of a stack type stacked piezoelectric element. The laminated piezoelectric element 61 includes, for example, a dielectric 61a made of ceramics such as PZT and an internal electrode having a comb-like cross section, as shown in the enlarged cross-sectional view and plan view in FIGS. 61b are alternately stacked. The internal electrode 61b is formed by alternately laminating the electrode connected to the first side electrode 61c and the electrode connected to the second side electrode 61d, and electrically connects the first side electrode 61c or the second side electrode 61d, respectively. Connected to.

  The laminated piezoelectric element 61 shown in FIGS. 3A and 3B has, on one end face, a first lead connection portion 61e electrically connected to the first side surface electrode 61c and a second side surface electrode 61d. An electrically connected second lead connecting portion 61f is formed. A first lead wire 61g and a second lead wire 61h are connected to the first lead connecting portion 61e and the second lead connecting portion 61f, respectively. In addition, the first side electrode 61c, the second side electrode 61d, the first lead connection portion 61e, and the second lead connection portion 61f are connected to the first lead connection portion 61e and the second lead connection portion 61f, respectively. 61g and the second lead wire 61h are connected and covered with an insulating layer 61i.

  The stacked piezoelectric element 61 has a length in the stacking direction of, for example, 5 mm to 120 mm. Moreover, the cross-sectional shape in the direction orthogonal to the stacking direction of the multilayer piezoelectric element 61 can be, for example, a substantially square shape of 2 mm square to 10 mm square or an arbitrary shape other than the square shape. It should be noted that the number of laminated piezoelectric elements 61 and the cross-sectional area of the laminated piezoelectric element 61 are such that sound pressure or sound quality of sound generated from a contact surface such as a desk with which the piezoelectric vibrating unit 60 comes into contact can be sufficiently secured according to the weight of the projector 10. Is determined as appropriate.

  The laminated piezoelectric element 61 is supplied with a sound signal (reproduced sound signal) from the control unit via a digital signal processor (DSP). In other words, a voltage corresponding to the sound signal is applied to the multilayer piezoelectric element 61 from the control unit via the DSP. When the voltage applied from the control unit is an AC voltage, when a positive voltage is applied to the first side electrode 61c, a negative voltage is applied to the second side electrode 61d. Conversely, when a negative voltage is applied to the first side electrode 61c, a positive voltage is applied to the second side electrode 61d. When a voltage is applied to the first side electrode 61c and the second side electrode 61d, polarization occurs in the dielectric 61a, and the stacked piezoelectric element 61 expands and contracts from a state where no voltage is applied. The direction of expansion and contraction of the stacked piezoelectric element 61 is substantially along the stacking direction of the dielectric 61a and the internal electrode 61b. Alternatively, the expansion / contraction direction of the multilayer piezoelectric element 61 substantially coincides with the lamination direction of the dielectric 61a and the internal electrode 61b. Since the laminated piezoelectric element 61 expands and contracts substantially along the stacking direction, there is an advantage that the vibration transmission efficiency in the stretching direction is good.

  The present inventor has conceived that such a multilayer piezoelectric element 61 is effective as a vibration element for generating sound from a contact surface on which the image projection apparatus contacts a desk or the like.

  3A and 3B, the first side electrode 61c and the second side electrode 61d are alternately connected to the internal electrode 61b, and are connected to the first lead connection portion 61e and the second lead connection portion 61f. It can also be a through-hole connected to each other. 3 (a) and 3 (b), the first lead connecting portion 61e and the second lead connecting portion 61f are formed of a first side electrode 61c and a first side electrode 61c at one end of the multilayer piezoelectric element 61, as shown in FIG. You may form in the 2nd side electrode 61d.

  As shown in the partial enlarged cross-sectional view of FIG. 5, the laminated piezoelectric element 61 has one end side surface having the first lead connection portion 61 e and the second lead connection portion 61 f in the slit 101 of the holding portion 100 of the housing 20. It is fixed via an adhesive 102 (for example, epoxy resin). Further, a cap 63 is inserted into the other end portion of the multilayer piezoelectric element 61 and is fixed by the adhesive 102.

  The cap 63 is formed of a material that can reliably transmit the expansion and contraction vibration caused by the laminated piezoelectric element 61 to a mounting surface (contact surface) such as a desk, such as a hard plastic. When it is desired to suppress the mounting surface from being damaged, the cap 63 may not be a hard plastic but may be a relatively soft plastic. The cap 63 is formed with an entry portion 63 a located in the slit 101 and a projection 63 b protruding from the housing 20 in a state of being attached to the multilayer piezoelectric element 61, and located in the slit 101. An O-ring 62 is disposed on the outer periphery of the entry portion 63a. The O-ring 62 is made of, for example, silicone rubber. The O-ring 62 is used to move and hold the multilayer piezoelectric element 61 and at the same time makes it difficult for moisture or dust to enter the slit 101. The protrusion 63b has a hemispherical tip. Note that the tip of the protrusion 63b is not limited to a hemispherical shape, but has a shape that can reliably make point contact or surface contact with a mounting surface (contact surface) of a desk or the like to transmit expansion and contraction vibration by the stacked piezoelectric element 61. Any shape can be used. In FIG. 5, the gap between the O-ring 62 and the adhesion portion of the multilayer piezoelectric element 61 to the slit 101 can be filled with gel or the like to further enhance the dustproof and waterproof effect. The piezoelectric vibration unit 60 is attached to the holding unit 100, and the protruding portion 63 b of the cap 63 protrudes from the bottom surface 20 a of the housing 20 with the bottom cover 22 attached to the housing 20. Further, the protruding portion 63 b of the cap 63 has a facing surface 63 c that is a surface facing the bottom surface 20 a of the housing 20. As shown in FIG. 5, the opposing surface 63c is separated from the bottom surface 20a by a length d in a state where no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand or contract.

  FIG. 6 is a functional block diagram of a main part of projector 10 according to the present embodiment. The projector 10 includes a signal input unit 110, a DSP 120, a control unit 130, and a storage unit 140 in addition to the image projection mechanism 23, the projection unit 30, the speaker 40, the detection unit 70, the recording unit 80, and the stacked piezoelectric element 61 described above. Prepare. The image projection mechanism 23, the detection unit 70, the signal input unit 110, and the storage unit 140 are connected to the control unit 130. The recording unit 80 includes the microphone 81 and the memory unit 82 as described above. The memory unit 82 is connected to the control unit 130. The projection unit 30 is connected to the control unit 130 via the image projection mechanism 23. In addition, the speaker 40 and the multilayer piezoelectric element 61 are connected to the control unit 130 via the DSP 120. The DSP 120 may be built in the control unit 130. Further, the memory unit 82 and the storage unit 140 may be configured by one memory.

  The signal input unit 110 has a known configuration, and inputs signals such as a video signal and a sound signal to be viewed on the projector 10 from various signal input terminals. The control unit 130 is a processor that controls the overall operation of the projector 10. In the present embodiment, the control unit 130 is configured as a single control unit, but is not limited to this configuration. For example, you may comprise from a some control part for every function which the control part 130 has. The control unit 130 applies a sound signal to the stacked piezoelectric element 61 and the speaker 40 via the DSP 120. The sound signal may be based on music data stored in the internal memory, or may be included in the input signal.

  In addition, the control unit 130 controls a sound signal applied to the stacked piezoelectric element 61 and the speaker 40 according to the contact state between the piezoelectric vibration unit 60 and the placement surface 90 detected by the detection unit 70. For example, when the detection unit 70 detects that the piezoelectric vibration unit 60 and the placement surface 90 are in contact, the control unit 130 applies a sound signal to both the stacked piezoelectric element 61 and the speaker 40. . In this case, the piezoelectric vibration unit 60 and the speaker are driven simultaneously. On the other hand, when the detection unit 70 detects that the piezoelectric vibration unit 60 and the placement surface 90 are not in contact with each other, the control unit 130 does not apply a sound signal to the stacked piezoelectric element 61, and only the speaker 40. Apply sound signal to.

  FIG. 7 is a flowchart showing processing of the control unit 130 that applies a sound signal to the piezoelectric element and the speaker. First, the control unit 130 checks whether there is a sound signal to be applied (step S101). When there is no sound signal to be applied (No in step S101), the control unit 130 ends this flow without applying the sound signal to the stacked piezoelectric element 61 and the speaker 40. When there is a sound signal to be applied (Yes in step S101), the control unit 130 determines to apply the sound signal to the speaker 40 (step S102). Next, the control unit 130 confirms whether or not the detection unit 70 has detected contact between the piezoelectric vibration unit 60 and the placement surface 90 (step S103). When the detection unit 70 does not detect the contact between the piezoelectric vibration unit 60 and the placement surface 90 (No in step S103), the control unit 130 does not apply the sound signal to the multilayer piezoelectric element 61 and the speaker 40. Only a sound signal is applied (step S107). In this case, no sound is generated from the placement surface 90 and sound is generated from the speaker 40.

  On the other hand, when the detection unit 70 detects the contact between the piezoelectric vibration unit 60 and the mounting surface 90 (Yes in step S103), the control unit 130 determines to apply a sound signal to the multilayer piezoelectric element 61. (Step S104). And the control part 130 acquires the information regarding the frequency characteristic of a sound (step S105). Here, the information regarding the frequency characteristics of the sound is information regarding the frequency characteristics of the sound generated from the speaker 40 stored in the storage unit 140, for example. Based on the acquired information, the control unit 130 controls, for example, a sound signal applied to the multilayer piezoelectric element 61 (step S106), and applies a sound signal to the multilayer piezoelectric element 61 and the speaker 40 (step S107). Details of the sound signal control performed by the control unit 130 in step S106 will be described later. In this way, sound is generated from both the mounting surface 90 and the speaker 40. The control unit 130 repeats a series of operations in FIG. 7 when the projector 10 is activated, so that the speaker 40, the piezoelectric element 61, and the like are based on the contact state between the piezoelectric vibration unit 60 and the placement surface 90. The sound signal applied to the is controlled.

  Next, the sound signal control performed by the control unit 130 in step S106 will be described. The control unit 130 controls the sound signal based on information related to the frequency characteristics of the speaker 40 acquired from the storage unit 140. A region 200 in FIG. 8A shows an example of the frequency characteristic of the speaker 40 stored in the storage unit 140. Referring to FIG. 8A, as can be seen as a general tendency of the conventional dynamic speaker, the frequency characteristics of the speaker 40 have a low sound pressure in a low frequency band. Therefore, when the sound is generated using only the speaker 40, the projector 10 is in a state where it is difficult for the user who views the displayed image to hear the low sound. In particular, the sound pressure is 0 in the frequency band below the frequency f1, and the speaker 40 cannot generate sound below the frequency f1. Further, referring to the frequency characteristics of the speaker 40, a convex curve is drawn with the vicinity of the frequency f3 (> f1) as a vertex. That is, when sound is generated only by the speaker 40, sound near the frequency f3 is generated strongly, and sound is generated weaker as the frequency becomes higher and lower than the frequency f3.

  In step S106, the control unit 130 controls the sound signal applied to the piezoelectric element 61 so as to compensate for the lack of sound pressure in the frequency characteristics of the speaker 40. Here, to compensate for the lack of sound pressure in the frequency characteristics, for example, the sound pressure in the frequency band where the sound pressure is low is increased to make the sound in the frequency band easy to hear, or the sound pressure in the entire frequency band is increased. The sound volume in the frequency band is emphasized by increasing the overall volume or by increasing the sound pressure in a specific frequency band. For example, the control unit 130 controls the sound signal applied to the piezoelectric element 61 so as to show the frequency characteristic as in the region 210 of FIG. And the control part 130 applies the sound signal controlled in this way to the piezoelectric element 61 in step S107. By controlling the sound signal in this way, the sound pressure in the low frequency band increases. Further, in the frequency band from the frequency f2 (f1 <f2 <f3) to the frequency f4 (> f3), the sound pressure is substantially constant, and the difference in sound intensity for each frequency generated from the projector 10 is reduced.

  In step S105, the control unit 130 acquires information on the frequency characteristics of the sound generated from the contact surface recorded by the recording unit 80, and in step S106, the sound applied to the speaker 40 based on the acquired information. It can also be configured to control the signal. In this case, after the projector 10 is placed on the placement surface 90, before actual use, the control unit 130 applies a pure sound sweep signal of a certain level as a sound signal to the piezoelectric element 61 to vibrate the piezoelectric element 61. Sound is generated from the contact surface. The frequency characteristics of the generated sound are acquired by the microphone 81 of the recording unit 80 and recorded in the memory unit 82. Thereafter, in actual use, the control unit 130 acquires information on the recorded frequency characteristics, and controls a sound signal applied to the speaker 40 based on this information.

  A region 220 in FIG. 8B shows an example of frequency characteristics of sound generated from the contact surface recorded by the recording unit 80. For this recorded frequency characteristic, the control unit 130 compensates for the lack of sound pressure, for example, so that the frequency characteristic as shown by the region 230 in FIG. Control the signal. And the control part 130 applies the sound signal controlled in this way to the speaker 40 in step S107. Further, the control unit 130 may control both the sound signal applied to the piezoelectric element 61 and the sound signal applied to the speaker 40 so as to obtain a sound pressure having a desired frequency characteristic.

  The DSP 120 performs necessary signal processing such as equalizing processing, D / A conversion processing, boosting processing, and filter processing on the digital signal from the control unit 130, and outputs the required sound signal to the speaker 40 and the piezoelectric element 61. Apply.

  The maximum voltage of the reproduced sound signal applied to the multilayer piezoelectric element 61 can be, for example, 10 Vpp to 50 Vpp, but is not limited to this range, and the weight of the projector 10 and the speaker 40 and the multilayer piezoelectric element 61 It can be appropriately adjusted according to the performance. Further, the sound signal applied to the laminated piezoelectric element 61 may be biased with a DC voltage, and a maximum voltage may be set around the bias voltage.

  Further, not only the laminated piezoelectric element 61, the piezoelectric element generally has a larger power loss at higher frequencies. Therefore, the filter processing of the sound signal to the stacked piezoelectric element 61 by the DSP 120 has a frequency characteristic that attenuates or cuts at least part of a frequency component of about 10 kHz to 50 kHz, or the attenuation rate increases gradually or stepwise. It is set to have frequency characteristics. FIG. 9 shows frequency characteristics when the cutoff frequency is about 20 kHz as an example. Thus, by attenuating or cutting the high-frequency component, power consumption can be suppressed and heat generation of the multilayer piezoelectric element 61 can be suppressed.

  Next, the arrangement of the piezoelectric vibration unit 60 will be described with reference to FIG. FIG. 10 shows a usage state of the projector 10 and shows a state in which the projector 10 is placed on a horizontal placement surface 90 such as a desk. As shown in FIG. 10, the projector 10 is supported on the mounting surface 90 by the piezoelectric vibration unit 60 and the rear bottom 20 b of the housing 20. Point G is the center of gravity of projector 10. In FIG. 10, the piezoelectric vibrating portion 60 has a lowermost end portion 601. The lowermost end portion 601 is a portion of the piezoelectric vibrating portion 60 that comes into contact with the placement surface 90 when the housing 20 is placed on a horizontal placement surface 90 such as a desk with the bottom surface 20a side down. . The lowermost end 601 is, for example, the tip of the cap 63.

  In FIG. 10, a dotted line L1 is a line that passes through the center of gravity G of the projector 10 and is perpendicular to the placement surface 90 when the projector 10 is placed on the horizontal placement surface 90 such as a desk with the bottom surface 20a facing downward. (Virtual line). Area R1 is an area on the rear side that is partitioned by dotted line L1 in projector 10. The region R2 is a region on the front side that is delimited by the dotted line L1 in the projector 10. The rear bottom 20a is in contact with the placement surface 90 on the region R1 side. In addition, the piezoelectric vibrating portion 60 is provided on the bottom surface 20a on the region R2 side.

  The piezoelectric vibrating portion 60 is preferably provided within a predetermined distance from the dotted line L1 on the region R2 side of the bottom surface 20a, and more preferably provided at a position as close as possible to the dotted line L1. Here, the predetermined distance means that the decrease in sound pressure is within 5% as compared to the sound pressure of sound generated from the mounting surface (contact surface) 90 when the piezoelectric vibrating portion 60 is provided on the dotted line L1. A certain distance (first distance) is preferred. As a result, the load applied to the piezoelectric vibrating portion 60 becomes larger than when the piezoelectric vibrating portion 60 is provided at a position separated from the dotted line L1 on the region R2 side of the bottom surface 20a. However, when the sound pressure is strong, the predetermined distance can be a distance (second distance) in which the decrease of the sound pressure is within 10%, and when the sound pressure is sufficiently strong, the sound pressure It is possible to set a distance (third distance) in which the decrease in the distance is within 20%.

  The rear bottom 20b is preferably provided at a position as far as possible from the dotted line L on the region R1 side. That is, the center of gravity G is preferably in front of the projector 10. Thereby, even when the piezoelectric vibrating portion 60 is provided as close as possible to the dotted line L1, a sufficient distance between the rear bottom portion 20b and the piezoelectric vibrating portion 60 is secured, and the projector 10 can be stably placed on the mounting surface 90. Since it can be mounted, the projected image is displayed more stably.

  FIGS. 11A, 11B, and 11C are schematic diagrams for explaining an operation of sound generation by projector 10 according to the present embodiment. When a sound is generated from the placement surface 90 by the piezoelectric vibration unit 60 of the projector 10, the projector 10 places the bottom surface 20a side of the housing 20 downward, as shown in FIG. The cap 63 and the rear bottom 20b are placed so as to contact a placement surface (contact surface) 90 such as a desk. Thereby, the weight of the projector 10 is given to the piezoelectric vibration unit 60 as a load. In the state shown in FIG. 11A, the stacked piezoelectric element 61 does not expand and contract because no voltage is applied.

  In this state, when the multilayer piezoelectric element 61 of the piezoelectric vibration unit 60 is driven by the reproduction sound signal, the multilayer piezoelectric element 61 supports the rear bottom portion 20b as a fulcrum as shown in FIGS. 11B and 11C. As described above, the cap 63 is expanded and contracted according to the reproduced sound signal without being separated from the placement surface (contact surface) 90. The difference between the length of the laminated piezoelectric element 61 when it is most expanded and the length when it is most contracted is, for example, 0.05 μm to 50 μm. As a result, the expansion and contraction vibration of the multilayer piezoelectric element 61 is transmitted to the mounting surface 90 through the cap 63 and the mounting surface 90 vibrates, and the mounting surface 90 functions as a vibration speaker and generates sound from the mounting surface 90. To do. In addition, if the difference between the length when stretched most and the length when shrunk most is less than 0.05 μm, there is a possibility that the mounting surface cannot be vibrated properly. Therefore, there is a risk that the projector 10 will rattle.

  Here, the distance d between the bottom surface 20a and the facing surface 63c of the cap 63 shown in FIG. 5 is most reduced from the state in which no voltage is applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand and contract. It may be longer than the amount of displacement when the state is reached. Thereby, even when the laminated piezoelectric element 61 is in the most contracted state (the state shown in FIG. 11C), the bottom surface 20a of the housing 20 and the cap 63 can be hardly contacted. Therefore, it becomes difficult for the cap 63 to fall off the piezoelectric element 61.

  The arrangement location on the bottom surface 20a of the piezoelectric vibrating section 60, the length of the stacked piezoelectric element 61 in the stacking direction, the size of the cap 63, and the like are appropriately determined so as to satisfy the above-described conditions.

  According to the image projection apparatus according to the present embodiment, since the piezoelectric element is used as a vibration source and sound is generated from the mounting surface (contact surface) 90, the same volume that generates sound only from the dynamic speaker. In addition, it is possible to generate a sound having a favorable frequency characteristic as compared with a conventional image projector having a heavy weight. In addition, the piezoelectric element can reproduce low-frequency sound, which is difficult to obtain good frequency characteristics with a small dynamic speaker, so that the image projector can be downsized without providing a large dynamic speaker. Thinning can be realized. In particular, when a good frequency characteristic can be obtained with only the piezoelectric element, it is not necessary to provide a speaker, so that the image projection apparatus can be remarkably reduced in size and thickness. Furthermore, in the image projection apparatus according to the present embodiment, since sound is generated from the placement surface (contact surface) 90, the sound is compared with a conventional image projection apparatus that generates sound only from a dynamic speaker. High diffusivity. For this reason, in the conventional image projection apparatus, it is difficult for sound to reach a user who is not located in front compared to a user located in front of the speaker. However, the image projection apparatus according to the present embodiment is A homogeneous sound can be generated regardless of the position.

  Further, in the image projection apparatus according to the present embodiment, a stack type stacked piezoelectric element 61 is used as the piezoelectric element, and the expansion and contraction vibration is caused along the stacking direction by the reproduced sound signal, and the expansion and contraction vibration is placed on the mounting surface ( Since the vibration is transmitted to the contact surface 90, the vibration transmission efficiency in the expansion / contraction direction (deformation direction) with respect to the placement surface (contact surface) 90 is good, and the placement surface (contact surface) 90 can be vibrated efficiently. In addition, since the multilayer piezoelectric element 61 is brought into contact with the mounting surface (contact surface) 90 via the cap 63, the multilayer piezoelectric element 61 can be prevented from being damaged. Further, when the projector 10 is in use, if the cap 63 of the piezoelectric vibration unit 60 is brought into contact with the placement surface (contact surface) 90, the weight of the projector 10 is applied to the cap 63 as a load. Surface) 90 can be reliably brought into contact, and the expansion and contraction vibration of the piezoelectric vibrating portion 60 can be efficiently transmitted to the mounting surface (contact surface) 90.

  In addition, since the image projection apparatus according to the present embodiment can mainly transmit the vibration of the multilayer piezoelectric element directly to the contact surface (mounting surface), the vibration of the multilayer piezoelectric element can be transmitted to another elastic body. Unlike the prior art that conveys to the above, when generating sound, it does not depend on the limit frequency on the high frequency side where other elastic bodies can vibrate. The limit frequency on the high frequency side where the other elastic body can vibrate is the reciprocal of the shortest of the times from when the other elastic body is deformed by the piezoelectric element until it returns to the deformable state. In consideration of this, the image projection apparatus according to the present embodiment may have rigidity (bending strength) that does not cause bending deformation due to deformation of the piezoelectric element.

(Second Embodiment)
12A, 12B, and 12C are an external perspective view, a front view, and a side view showing a schematic configuration of an image projection apparatus according to the second embodiment of the present invention. The image projection apparatus according to the present embodiment is a so-called placement-type projector 10 similar to the first embodiment. Hereinafter, description of the same points as in the first embodiment will be omitted, and different points will be described.

  As shown in FIG. 12, the housing 20 has two front support portions 50 on the front side where the projection surface is located, and two rear support portions 51 on the opposite rear side. The front support portion 50 and the rear support portion 51 are in contact with the placement surface 90 and support the housing 20. The inclination angle of the housing 20 is provided so as to be adjustable by adjusting the height of the front support portion 50. The front support part 50 and the rear support part 51 may include an elastic member on the bottom surface. The elastic member is made of, for example, rubber, silicone, polyurethane, or the like. In this embodiment, two front support parts 50 and two rear support parts 51 are shown. However, the present invention is not limited to this, and one front support part 50, two rear support parts 51, or Two front support portions 50 and two rear support portions 51 may be used.

  The projector 10 according to the present embodiment includes a holding unit 100 that stores and holds the piezoelectric vibrating unit 60 on the bottom surface side of the rear support unit 51. In the present embodiment, only one of the two rear support parts 51 may include the piezoelectric vibration part 60, and both the two rear support parts 51 may include the piezoelectric vibration part 60. The holding unit 100 includes a slit 101 that extends in a direction substantially perpendicular to the bottom surface and has a uniform width that opens to the bottom surface.

  When the projector 10 is placed on a horizontal placement surface 90 such as a desk with the bottom surface 20a facing down, the elastic member is elastically deformed by the weight of the projector 10 being applied as a load. That is, the elastic member contracts in a direction perpendicular to the placement surface 90 due to the weight of the projector 10. The amount of elastic deformation of the elastic member in a state where the voltage is not applied to the multilayer piezoelectric element 61 and the multilayer piezoelectric element 61 does not expand and contract is the maximum amount of the elastic deformation of the multilayer piezoelectric element 61 from the state where the voltage is not applied and does not expand and contract. It may be larger than the amount of displacement. As a result, the elastic member is less likely to be separated from the placement surface 90 when the stacked piezoelectric element 61 is most extended, and the projector 10 is stably placed on the placement surface 90.

  In the present embodiment, the piezoelectric vibrating portion 60 can be disposed on the bottom surface side of the front support portion 50, but is preferably disposed on the rear support portion 51 in order to suppress blurring of the projected image. Here, the reason why the blurring of the projected image becomes smaller when the piezoelectric vibrating portion 60 is arranged on the rear support portion 51 than on the front support portion 50 will be described with reference to FIG. In FIG. 13, the position of the projection plane on which the image is displayed is indicated as S, the position of the front support part 50 is indicated as F, and the position of the rear support part 51 is indicated as B. The position F is located between the position S and the position B. Further, the vibration amplitude of the projector 10 due to the vibration of the piezoelectric vibration unit 60 is assumed to be a. Here, in FIG. 13, in order to show the blurring of the projected image in the same direction, the directions of vibration when the piezoelectric vibrating portion 60 is disposed on each of the front support portion 50 and the rear support portion 51 are shown in opposite directions. ing. That is, in FIG. 13, the front support portion 50 shows a case where the piezoelectric element 61 extends and is displaced upward from the reference position 300 by the amplitude a with respect to the reference position 300 when the piezoelectric vibrating portion 60 is not vibrating. The support portion 51 shows a case where the piezoelectric element 61 is contracted and displaced downward from the reference position 300 by the amplitude a. When the piezoelectric vibrating portion 60 is disposed on the front support portion 50, the projected image is displaced upward by a height H with the rear support portion 51 as a fulcrum. On the other hand, when the piezoelectric vibrating portion 60 is disposed on the rear support portion 51, the projection image is displaced upward by a height h with the front support portion 50 as a fulcrum. As is clear from FIG. 13, when there is a displacement of the same amplitude a in the support part, the displacement H of the projected image when the piezoelectric vibration part 60 is arranged in the front support part 50 is the piezoelectric vibration in the rear support part 51. It is larger than the displacement h when the part 60 is arranged. For this reason, when the piezoelectric vibrating portion 60 is disposed not on the front support portion 50 but on the rear support portion 51, the blur of the projected image is reduced and the image is easy to see.

(Third embodiment)
FIG. 14 is a side view showing a schematic configuration of an image projection apparatus according to the third embodiment of the present invention. The image projection apparatus according to the present embodiment is a so-called wall-mounted projector 10. Hereinafter, description of the same points as in the first embodiment will be omitted, and different points will be described.

  The projector 10 shown in FIG. 14 has an arm-shaped support portion 52 that extends toward the front of the projector 10 at the top of the housing 20. The front end portion of the support portion 52 has a bowl shape, and the projector 10 is held on the wall surface 91 by attaching the front end portion to a wall surface 91 such as a white board. A holding portion 100 that houses and holds the piezoelectric vibrating portion 60 is provided at a portion of the support portion 52 that contacts the wall surface 91. The holding unit 100 includes a slit 101 that extends along a direction perpendicular to the wall surface 91 when the projector 10 is used, and has a uniform width that opens at a contact portion of the support unit 52 with the wall surface 91. By supporting the projector 10 with the support portion 52, the load of the projector 10 is applied to the piezoelectric element portion 60 through the support portion 52, and sound is generated from the wall surface (contact surface) 91. This allows a user who is viewing the wall surface of a whiteboard or the like to hear a sound from the wall surface that is being viewed, thus creating a sense of realism similar to a so-called panel speaker that outputs sound from the display panel. Can be made.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, in the first embodiment, the piezoelectric vibration unit 60 may be disposed on the region R1 side in FIG. That is, the piezoelectric vibration unit 60 is disposed behind the center of gravity G of the projector 10. In this case, the projector 10 is supported by the piezoelectric vibrating portion 60 and the front bottom portion of the housing 20. In the above embodiment, the speaker 40, the detection unit 70, the recording unit 80, and the storage unit 140 may be omitted as appropriate.

  Moreover, in the said embodiment, the structure which fixes the piezoelectric vibration part 60 with respect to the holding | maintenance part 100 is not restricted to what is shown in FIG. For example, as shown in FIGS. 15A to 15C, the piezoelectric vibration unit 60 may be held by the holding unit 100. The holding unit 100 shown in FIG. 15A includes a wide slit 101a that opens to the bottom surface 20a, and a narrow slit 101b that continues to the slit 101a. The laminated piezoelectric element 61 has one end portion arranged in the narrow slit 101 b and the side surface fixed to the slit 101 b via the adhesive 102. Further, the wide slit 101 a is filled with a filler 103 such as silicone rubber or gel that does not hinder the expansion and contraction operation of the multilayer piezoelectric element 61 in the gap with the multilayer piezoelectric element 61. Thus, if the piezoelectric vibration part 60 is hold | maintained at the holding | maintenance part 100, the projector 10 can be waterproofed more reliably, without using waterproof packings, such as an O-ring. In addition, by covering the portion protruding from the bottom surface 20a of the multilayer piezoelectric element 61 with an insulating cap, the multilayer piezoelectric element 61 can be reliably insulated.

  The holding unit 100 shown in FIG. 15B includes a tapered slit 101c that expands toward the bottom surface 20a, and a narrow slit 101d that continues to the tapered slit 101c. The laminated piezoelectric element 61 has one end portion disposed in the narrow slit 101 d and the side surface fixed to the slit 101 d via the adhesive 102. The tapered slit 101 c is filled with a filler 103 such as silicone rubber or gel that does not hinder the expansion and contraction operation of the multilayer piezoelectric element 61 in the gap with the multilayer piezoelectric element 61. With this configuration, the same effect as that of the holding unit 100 of FIG. 15A can be obtained, and since the tapered slit 101c is provided, the multilayer piezoelectric element 61 can be easily assembled to the holding unit 100. There are advantages that can be made.

  The holding unit 100 shown in FIG. 15C has a slit 101 having a uniform width as in the above embodiment, but the laminated piezoelectric element 61 has an end surface on one end side with an adhesive 102 interposed therebetween. It is fixed to the slit 101. Further, an O-ring 62 is disposed at an appropriate position of the multilayer piezoelectric element 61 in the slit 101. Such a holding mode of the laminated piezoelectric element 61 is particularly suitable when the laminated piezoelectric element 61 has a lead wire connecting portion formed on a side electrode as shown in FIG. Etc. are advantageous.

  Further, in the above embodiment and the modified examples of FIGS. 15A to 15C, the piezoelectric vibrating portion 60 omits the cap 63, and the tip surface of the multilayer piezoelectric element 61 is formed directly or made of an insulating member or the like. You may make it contact a contact surface via a vibration transmission member. In addition, the piezoelectric element is not limited to the stack type stacked piezoelectric element described above, and a unimorph, bimorph, or stacked bimorph element may be used. FIG. 16 is a diagram showing a schematic configuration of a main part when a bimorph is used. The bimorph 65 has a long rectangular shape, one surface 65 a is exposed on the bottom surface 20 a of the housing 20, and both long ends are held by the holding unit 100. The holding unit 100 has an opening 101e that holds the bimorph 65, and the inner surface of the opening 101e on the back surface 65b side of the bimorph 65 is curved. According to this configuration, when the housing 20 is placed on the placement surface so that the bimorph 65 contacts the placement surface and the bimorph 65 is driven by the reproduction sound signal, the bimorph 65 bends (curves) and vibrates. Thereby, the vibration of the bimorph 65 is transmitted to the placement surface (contact surface), and the placement surface (contact surface) functions as a vibration speaker, and a reproduction sound is generated from the placement surface (contact surface). Note that a coating layer such as polyurethane may be formed on the surface 65 a of the bimorph 65.

  Moreover, although said to-be-contacted member was a desk or a wall surface and said contact surface was a horizontal mounting surface or a vertical wall surface of a desk in said embodiment, this invention is not limited to this. The contact surface need not be a horizontal or vertical surface. As another contacted member, for example, a partition for dividing a space can be cited.

  In the above embodiment, the image projection apparatus is described as the projector 10 having one projection unit. However, the image projection apparatus is not limited to this. For example, the present invention can be implemented in an arbitrary image projection apparatus capable of generating sound while displaying still images and moving images, such as a planetarium projector having a plurality of projection units.

10 Projector (image projection device)
20 Housing 20a Bottom 20b Rear bottom 21 Main body case 22 Bottom lid 22a Hole 23 Image projection mechanism 24 Cooling mechanism 25 Electronic circuit board 26 Battery 27 Exhaust port 30 Projection unit 40 Speaker 50 Front support unit 51 Rear support unit 52 Support unit 60 Piezoelectric Vibrating unit 61 Multilayer piezoelectric element (piezoelectric element)
62 O-ring 63 Cap 70 Detection unit 80 Recording unit 81 Microphone 82 Memory unit 90 Placement surface (contact surface)
91 Wall surface (contact surface)
DESCRIPTION OF SYMBOLS 100 Holding part 101 Slit 110 Signal input part 120 Digital signal processor (DSP)
130 control unit 140 storage unit 200, 210, 220, 230 area

Claims (14)

The body,
A piezoelectric vibration part having a piezoelectric element;
A projection unit that is held in the housing and displays an image on a projection surface;
A control unit for controlling the piezoelectric element,
In a state where the load of the image projection apparatus itself is applied to the piezoelectric vibration unit, the piezoelectric element is deformed by applying a sound signal from the control unit to the piezoelectric element, and the piezoelectric vibration unit is deformed, and the piezoelectric vibration unit is deformed. Vibrate the contact surface in contact with the image projection device by deformation of the vibration unit to generate sound from the contact surface;
Image projection device.   The image projection device according to claim 1, wherein the piezoelectric vibration unit is disposed within a predetermined distance from a center of gravity of the image projection device and at a portion facing the contact surface. Comprising a support for supporting the housing;
The image projection device according to claim 1, wherein the piezoelectric vibration unit is disposed at a portion of the support unit that faces the contact surface. A front support portion disposed on the front side on which the projection surface is located across the center of gravity of the image projection apparatus, and a rear support portion disposed on the rear side opposite to the side on which the projection surface is located; With
The image projection device according to claim 3, wherein the piezoelectric vibration unit is disposed on the rear support unit. A detection unit for detecting a contact state between the contact surface and the piezoelectric vibration unit;
The image projector according to claim 1, wherein the control unit controls the piezoelectric element based on the detected contact state. With speakers,
The image projector according to claim 1, wherein the control unit drives the speaker simultaneously with the piezoelectric element. A storage unit for storing the frequency characteristics of the speaker;
The image projection device according to claim 6, wherein the control unit controls the piezoelectric element based on the stored frequency characteristic of the speaker.   The image projection device according to claim 7, wherein the control unit controls a sound signal applied to the piezoelectric element so as to compensate for a lack of sound pressure in the stored frequency characteristics of the speaker. A recording unit for recording frequency characteristics of sound generated from the contact surface;
The image projector according to claim 6, wherein the control unit controls the speaker based on the recorded frequency characteristic.   The image projector according to claim 9, wherein the control unit controls the sound pressure of the frequency characteristic of the speaker so as to compensate for a lack of sound pressure of the recorded frequency characteristic.   The image projector according to any one of claims 1 to 10, wherein the piezoelectric element is a stacked piezoelectric element and expands and contracts along a stacking direction.   The image projection according to claim 1, wherein the piezoelectric vibration unit includes a covering member that transmits vibration due to deformation of the piezoelectric element to the contact surface to vibrate the contact surface. apparatus.   The image projection device according to claim 1, wherein the contact surface is a placement surface on which the image projection device is placed. The image projecting device according to claim 1, wherein the contact surface is a wall surface on which the image projecting device is hung.

Images