JP2006005552A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector even wherein an audible tone reproduction distance of an ultrasonic speaker is reduced and a short focal point projection lens is used that can produce a virtual sound source on a screen face and from which a user can listen to sound with presence. <P>SOLUTION: The projector uses the ultrasonic speaker for outputting a sound wave wherein a suction fan and an air intake duct are used to intake air to air-cool an internal heat generating source. It is characterized in that the ultrasonic speaker is located in the air intake duct and at an upwind side of the suction fan, an air intake opening of the air intake duct wherein the ultrasonic speaker is placed is located in a video projection direction of the projector, and a sound wave outputted from the ultrasonic speaker is emitted from the opening. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projector incorporating an ultrasonic speaker, and more particularly to a projector that performs intake air using an intake fan and an intake duct and air-cools an internal heat generation source. The present invention relates to a projector that can shorten the audible sound reproduction distance of a speaker.

  Conventionally, it is known that an ultrasonic speaker using the nonlinearity of a medium (air) with respect to an ultrasonic wave can reproduce a signal in an audible frequency band having a much sharper directivity than a normal speaker.

  As a configuration, a carrier signal in an ultrasonic frequency band is modulated by a signal from a signal source in an audible frequency band, amplified by a power amplifier, etc., and then converted into a sound wave of a finite amplitude level from an ultrasonic transducer (in the air) ), And the signal sound in the original audible frequency band is reproduced by the nonlinear parametric effect of the medium (air). In this case, the reproduction range of the reproduction signal in the audible frequency band is a beam-shaped range from the ultrasonic transducer toward the emission axis (see, for example, Patent Document 1).

  Technological development utilizing such characteristics of ultrasonic speakers has been actively conducted, and many inventions related to ultrasonic speakers have been disclosed. Of these, some prior art related to the present invention will be described.

  For example, a sound guide tube that guides primary sound waves (sound waves in the ultrasonic frequency band) from a parametric speaker (ultrasonic speaker) is provided to improve directivity and control means to adjust the fluid velocity in the sound guide tube is provided. An invention has been disclosed in which the efficiency of converting to a secondary sound wave (audible sound) is increased, the sound pressure of the secondary sound wave is controlled, and the temperature rise of the sound source is prevented (for example, see Patent Document 2).

  Also disclosed is an invention in which an ultrasonic speaker device is applied to a projection-type video projector. In this video projector, a plurality of sets of ultrasonic generators (ultrasonic speaker devices) in which a plurality of piezoelectric elements are combined are arranged in a projector main body. At this time, each ultrasonic generator arranged in the projector main body is directed to a screen surface or other wall surface that is a projection surface of the video projector. When ultrasonic waves are emitted from each ultrasonic generator toward the screen surface or wall surface, the sound image of the audible sound can be localized at a location where the ultrasonic waves emitted from these ultrasonic generators are reflected. Therefore, ultrasonic waves corresponding to the audio signals for the right channel, left channel, center channel, surround right channel, and surround left channel of the multi-channel sound source are emitted from each ultrasonic generator. By doing so, it is possible to provide the viewer with playback sound of a multi-channel sound source (see, for example, Patent Document 3).

  Also disclosed is an invention in which a projector disposed behind a viewer projects onto a screen, an audible sound beam is emitted from a parametric speaker device disposed above the projector to the screen, and a reflected wave from the screen is received by the viewer. (For example, see Patent Document 4).

  As described above, although the ultrasonic speaker has a very narrow directivity, a certain reproduction distance from the ultrasonic transducer (ultrasonic speaker) is required to generate the secondary sound wave (audible sound). . For this reason, a problem may arise when an image is projected on a screen, and a primary sound wave (a sound wave in an ultrasonic frequency band) is emitted to the screen to generate a secondary sound wave on the screen surface. That is, when the distance between the projector and the screen is short, after the primary sound wave (sound wave in the ultrasonic frequency band) is reflected by the screen, a secondary sound is generated between the screen and the viewer, and the virtual sound source is released from the screen surface. You may be away and your sense of presence may be reduced.

  In recent years, projectors have been used in small rooms for home use, and the projection distance of images has become shorter and shorter with the use of a short-focus projection lens, and the secondary sound generation distance of ultrasonic speakers has also been shortened to match the projection distance. Accordingly, there has been a demand for a solution to the problem that the virtual sound source is separated from the screen surface.

In addition, when a DVD movie is enlarged and projected by a projector with an audible speaker built in, the sound is not heard from the screen as in a movie theater, but the sound is heard from the projector. Therefore, in order to listen to a realistic surround sound, it is necessary to prepare a 5.1ch speaker system, which increases costs. Furthermore, a plurality of wirings are required, resulting in wasted space. For this reason, it has been desired to reduce the projection distance of the image and generate secondary sound waves on the screen surface.
JP 58-119293 A JP-A-3-265399 Japanese Patent Laid-Open No. 11-262084 JP 60-254992 A

  The present invention has been made to solve such a problem, and an object of the present invention is to make it possible to shorten the audible sound reproduction distance of an ultrasonic speaker, and even in a projector using a short focus projection lens, on the screen surface. It is an object of the present invention to provide a projector that can generate a virtual sound source and view a realistic sound.

The present invention has been made to solve the above problems, and the projector of the present invention performs intake using an intake fan and an intake duct, air-cools an internal heat generation source, and uses an ultrasonic speaker. In the projector that outputs sound waves, the ultrasonic speaker is disposed in the intake duct and is disposed on the windward side of the intake fan, and an intake opening of the intake duct in which the ultrasonic speaker is disposed is provided. It is provided in the image projection direction of the projector, and the sound wave output from the ultrasonic speaker is radiated from the opening.
With such a configuration, in a projector using an ultrasonic speaker, the ultrasonic speaker is arranged in an intake duct (cooling duct) for cooling a lamp, a power supply, etc., and an opening (intake hole) of the intake duct is formed. It is provided in the image projection direction (intake holes are arranged in front of the projector), and the sound of the ultrasonic speaker is output from the intake holes of the intake duct. In this way, the primary sound wave (sound wave in the ultrasonic frequency band) output from the ultrasonic speaker is output in the direction opposite to the air flow.
As a result, the wavelength of the primary sound wave (sound wave in the ultrasonic frequency band) is compressed, the wave number is increased, and the reproduction distance of the secondary sound wave (audible sound) can be shortened apparently. In addition, since the audible sound reproduction distance of the ultrasonic speaker can be shortened, even a projector using a short focus projection lens can generate a virtual sound source on the screen surface and view realistic sound. For example, this is effective when watching a movie on a large screen with a DVD at home.

In the projector according to the present invention, the intake ducts are arranged on the left and right sides of the projector, the ultrasonic speakers are arranged corresponding to the intake ducts arranged on the left and right sides, and the intake air of each of the left and right intake ducts And a sound wave output from the ultrasonic speaker is radiated from the opening.
With such a configuration, in a projector having a stereo reproduction function, two intake ducts are arranged on the left and right sides of the projector, and an ultrasonic speaker is arranged in each intake duct. In addition, an opening (intake hole) of the intake duct in which the ultrasonic speaker is disposed is provided in the image projection direction (the intake hole is disposed in front of the projector), and sound waves of the ultrasonic speaker are radiated from the intake hole.
Thereby, even in a projector having a stereo reproduction function, it is possible to reproduce the secondary sound wave (audible sound) by shortening the reproduction demodulation distance of the primary sound wave (ultrasonic frequency band sound wave). In addition, since the audible sound reproduction distance of the ultrasonic speaker can be shortened, a stereo virtual sound source can be generated on the screen surface even with a projector using a short focus projection lens, and a realistic sound can be viewed. For example, this is effective when watching a movie on a large screen with a DVD at home.

The projector of the present invention includes an intake duct that is sucked by one intake fan and has intake openings in a plurality of directions, and an ultrasonic speaker is disposed in at least one of the plurality of intake ducts. It is characterized by being.
With such a configuration, when a single intake fan performs intake from a plurality of intake ducts, an ultrasonic speaker is disposed in at least one intake duct, and sound waves from the ultrasonic speaker are opened to the intake duct. Radiates from the part (intake hole).
As a result, even when intake is performed from a plurality of intake ducts by a single intake fan, an ultrasonic speaker is arranged in the intake duct to shorten the reproduction demodulation distance of the primary sound wave (ultrasonic wave). Secondary sound waves (audible sound) can be reproduced. For example, even when the distance between the projector and the screen is short, secondary sound waves (audible sound) can be reproduced on the screen surface.

In the projector according to the aspect of the invention, the ultrasonic speaker may be an electrostatic ultrasonic transducer.
With such a configuration, even when an electrostatic ultrasonic transducer (ultrasonic speaker) is used in the projector, the reproduction demodulation distance of the primary sound wave (sound wave in the ultrasonic frequency band) is shortened and the secondary sound wave ( Audible sound). For example, even when the distance between the projector and the screen is short, secondary sound waves (audible sound) can be reproduced on the screen surface.

The projector according to the invention is characterized in that the ultrasonic speaker is composed of a resonance type ultrasonic transducer.
With such a configuration, even when a resonance (piezoelectric) type ultrasonic transducer (ultrasonic speaker) is used in the projector, the reproduction demodulation distance of the primary sound wave (sound wave in the ultrasonic frequency band) is shortened and the secondary wave is obtained. Sound wave (audible sound) can be reproduced. For example, even when the distance between the projector and the screen is short, secondary sound waves (audible sound) can be reproduced on the screen surface.

The projector of the present invention outputs a carrier wave signal source that generates a carrier wave signal in an ultrasonic frequency band, an audible frequency band signal oscillation source that generates a signal in an audible frequency band, and the carrier wave signal source. A carrier wave frequency setting unit that variably sets a frequency of a carrier wave signal in an ultrasonic frequency band; a modulation unit that modulates a carrier wave signal output from the carrier wave signal source with a signal in the audible frequency band; and the carrier And an ultrasonic speaker that is driven by a modulation signal obtained by modulating a wave signal with a signal in the audible frequency band, converts the modulation signal into a sound wave, and outputs the sound wave.
With such a configuration, a carrier wave signal in an ultrasonic frequency band (for example, a 40 kHz sine wave (Sin wave)) is generated by the carrier wave signal source. Also, an audible frequency band signal (for example, an audio signal) is generated by an audible frequency band signal oscillation source. The modulation unit modulates the carrier wave signal output from the carrier wave signal source with an audible frequency band signal, drives the ultrasonic speaker (ultrasonic transducer) with this modulation signal, and converts the modulation signal into a sound wave. Output. The carrier wave frequency setting unit variably sets the frequency of the carrier wave signal output from the carrier wave signal source.
As a result, in addition to the effect that the secondary sound wave (audible sound) can be reproduced by shortening the reproduction demodulation distance of the primary sound wave (sound wave in the ultrasonic frequency band), the position where the secondary sound wave (audible sound) is reproduced. It can be variably adjusted. For example, it can be adjusted so that a secondary sound wave (audible sound) is reproduced on the screen surface.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  First, an ultrasonic speaker that can be used in the projector of the present invention will be described. The ultrasonic speaker used in the projector of the present invention is not limited to the type of the ultrasonic speaker, and any ultrasonic speaker that uses a nonlinear parametric effect can be used. For example, an ultrasonic speaker illustrated in FIG. 7 can be used.

  FIG. 7 is a view showing an example of an ultrasonic speaker (ultrasonic transducer) used in the projector of the present invention. FIG. 7A shows a resonance (piezoelectric) type ultrasonic transducer, and FIG. Shows a configuration example of an electrostatic ultrasonic transducer.

  The ultrasonic transducer shown in FIG. 7A is a bimorph type ultrasonic transducer and includes two piezoelectric ceramics 61 and 62, a cone 63, a case 64, leads 65 and 66, and a screen 67. Has been. The piezoelectric ceramics 61 and 62 are bonded to each other, and a lead 65 and a lead 66 are connected to a surface opposite to the bonded surface, respectively. Since the resonance type ultrasonic transducer uses the resonance phenomenon of the piezoelectric ceramic, the transmission and reception characteristics of the ultrasonic wave are good in a relatively narrow frequency band around the resonance frequency.

  Also, the ultrasonic transducer shown in FIG. 7B is an electrostatic ultrasonic transducer and has a broadband frequency characteristic. As shown in FIG. 7B, the electrostatic ultrasonic transducer has a dielectric 81 (insulator) such as PET (polyethylene terephthalate resin) having a thickness of several μm (about 3 to 10 μm) as a vibrating body. Used. An upper electrode 82 formed as a metal foil is integrally formed on the upper surface of the dielectric 81 by a process such as vapor deposition, and a lower electrode (fixed electrode) 83 of brass is in contact with the lower surface. Is provided. This dielectric 81 forms a vibration film. The lower electrode 83 is connected to a lead 84 and is fixed to a base plate 85 made of bakelite or the like. The dielectric 81, the upper electrode 82, and the base plate 85 are caulked by the case 80 together with the metal rings 86, 87, and 88 and the mesh 89.

  Further, a plurality of minute grooves of about several tens to several hundreds μm having a non-uniform shape are formed on the surface of the lower electrode 83 on the dielectric 81 side. Since this minute groove becomes a gap between the lower electrode 83 and the dielectric 81, the electrostatic capacity distribution between the upper electrode 82 and the lower electrode 83 changes minutely. The random minute grooves can be formed by, for example, manually rubbing the surface of the lower electrode 83 with a file. In the electrostatic ultrasonic transducer, the frequency characteristics of the ultrasonic transducer are wide-banded by forming innumerable capacitors having different gap sizes and depths in this way.

  In the projector of the present invention, any type of ultrasonic speaker such as the above-described resonance (piezoelectric) ultrasonic transducer, electrostatic ultrasonic transducer, or the like can be used.

  FIG. 1 is a diagram showing a configuration example of a projector according to the present invention, and shows an example of a liquid crystal projector that has two ultrasonic speakers and reproduces and outputs sound in stereo.

  In FIG. 1, a projector 10 includes an ultra-high pressure mercury lamp 21 serving as a heat source and a power supply unit 22. The light emitting part of the ultrahigh pressure lamp of the ultrahigh pressure mercury lamp 21 becomes a high temperature of about 1000 degrees, and cooling is essential. In addition, the power supply unit 22 may have a high temperature (about 100 degrees) in the internal power transistor or the like, and cooling is necessary for ensuring reliability and safety.

  The projector 10 is provided with two left and right intake ducts 30 and 30a. The right intake duct 30 and the intake fan 31 draw outside air from an intake hole (opening) 32, and a power supply unit. Air is cooled by applying cooling air to 22. The warmed air used for cooling the power supply unit 22 is exhausted from the exhaust hole 33.

  Further, outside air is sucked from the suction hole (opening) 32a by the left suction duct 30a and the suction fan 31a, and the super-high pressure mercury lamp 21 is cooled by cooling air. The warmed air used for cooling the ultra high pressure mercury lamp 21 is exhausted from the exhaust hole 33a.

  In the case of a liquid crystal projector, a cooling fan is also used to cool a liquid crystal panel (not shown) used for image projection. It is a suction hole.

  FIG. 2 is a front view of the projector shown in FIG. 1, and shows a state in which a right intake hole 32 and a left intake hole 32a are provided on the front surface of the projector 10. FIG.

  Returning to FIG. 1, the ultrasonic speaker 15 is disposed in the right intake duct 30, and the ultrasonic speaker 15 is disposed on the windward side of the intake fan 31. A stereo R (right side) acoustic signal (primary sound wave in the ultrasonic frequency band) is output from the ultrasonic speaker 15, and an acoustic signal (primary sound wave in the ultrasonic frequency band) output from the ultrasonic speaker 15 is output. Advances in the opposite direction to the air flow in the intake duct 30 and is radiated to the outside through the intake holes 32.

  Similarly, an ultrasonic speaker 15a is disposed in the left intake duct 30a, and the ultrasonic speaker 15a is disposed on the windward side of the intake fan 31a. A stereo L (left side) acoustic signal (primary sound wave in the ultrasonic frequency band) is output from the ultrasonic speaker 15a, and an acoustic signal (primary sound wave in the ultrasonic frequency band) output from the ultrasonic speaker 15a. Advances in the opposite direction to the air flow in the intake duct 30a and is radiated to the outside through the intake holes 32a.

  Thus, by outputting the acoustic signal (primary sound wave in the ultrasonic frequency band) output from the ultrasonic speakers 15 and 15a in the direction opposite to the air flow, the wavelength of the primary sound wave is compressed, and the wave number As a result, the reproduction distance of the secondary sound wave (audible sound) can be shortened. Therefore, as shown in the arrangement example of the projector and the screen in FIG. 3, the distance D between the screen 1 and the projector 10 can be shortened, and the projector can be used in a small room for home use.

  The distance between the ultrasonic speaker 15 and the intake hole 32 is set to a necessary length in consideration of the reproduction distance of the secondary sound wave (audible sound).

  FIG. 4 is a diagram showing another configuration example of the projector according to the present invention, in which one intake fan 31 is used to intake air to the left and right intake ducts 30 and 30a. In this example, the configuration is the same as that of FIG. 1 except that the super-high pressure mercury lamp 21 is air-cooled by the intake fan 31.

  FIG. 5 is a block diagram showing an example of the circuit configuration of the projector, and shows a portion where an acoustic signal is output by an ultrasonic speaker directly related to the present invention.

  In FIG. 5, a carrier wave signal source 11 generates a carrier wave signal in an ultrasonic frequency band (for example, a 40 kHz sine wave). The audible frequency band signal oscillation source 12 generates an audible frequency band signal (for example, an audio signal). Note that an audible frequency band signal on the R (right) side and an audible frequency band signal on the L (left) side are generated from the audible frequency band signal oscillation source 12.

  The modulation unit 13 modulates the carrier wave signal output from the carrier wave signal source 11 with the audible frequency band signal (R side) received from the audible frequency band signal oscillation source 12 to generate a modulated signal. The power amplifier 14 amplifies the modulation signal received from the modulation unit 13.

  The ultrasonic speaker (ultrasonic transducer) 15 on the R side converts the modulation signal amplified by the power amplifier 14 into a sound wave (ultrasonic wave) of a finite amplitude level and radiates it in the medium (in the air).

  Similarly, the modulation unit 13a modulates the carrier wave signal output from the carrier wave signal source 11 with the audible frequency band signal (L side) received from the audible frequency band signal oscillation source 12, and generates a modulated signal. . The power amplifier 14a amplifies the modulation signal received from the modulation unit 13a.

  The L-side ultrasonic speaker (ultrasonic transducer) 15a converts the modulation signal amplified by the power amplifier 14a into a sound wave (ultrasonic wave) of a finite amplitude level and radiates it into the medium (in the air).

  The carrier wave frequency setting unit 11 a variably sets the frequency of the carrier wave output from the carrier wave signal source 11 and changes the frequency of the carrier wave signal according to the distance between the projector 10 and the screen 1. The secondary sound (audible sound) is adjusted to be reproduced on the surface of the screen 1.

  FIG. 6 is a diagram showing the state of the beam emitted from the ultrasonic speaker. As shown in FIG. 6, the beam width (directivity angle) of the ultrasonic wave emitted from the ultrasonic speaker 15 due to the level of the carrier wave frequency. θ) and the distance at which sound is reproduced (distance from the ultrasonic speaker 15) changes. For example, the 80 kHz beam and the 40 kHz beam have different spreads in the Z-axis direction and the sound reproduction distance, and the range in which the secondary sound (audible sound) is demodulated is adjusted by controlling the carrier frequency. Can do. For example, when the distance between the projector 10 and the screen 1 is short, a relatively high frequency carrier wave is used, and when it is far away, a relatively low frequency carrier wave is used. It can be set so that (audible sound) is demodulated.

  In the embodiment of the present invention described above, an example of a projector having a stereo reproduction function in which two ultrasonic speakers are arranged in two intake ducts is shown. However, the projector according to the present invention is an ultrasonic speaker. A mono reproduction projector that uses one of the above may be used. Further, a projector that reproduces an acoustic signal using three or more ultrasonic speakers may be used.

  Further, the projector of the present invention is not limited to a liquid crystal projector, but can also be applied to screen projection type electronic devices such as a DLP (registered trademark) projector and an LCOS (Liquid Crystal on Silicon) projector.

  Although the embodiment of the present invention has been described above, the projector of the present invention is not limited to the above illustrated example, and various modifications can be made without departing from the scope of the present invention. It is.

The figure which shows the structural example of the projector by this invention. The front view of the projector shown in FIG. The figure which shows the example of arrangement | positioning of a projector and a screen. The figure which shows the other structural example of the projector by this invention. The block diagram which shows the circuit structural example of a projector. The figure which shows the state of the beam radiated | emitted from an ultrasonic speaker. The figure which shows the example of the ultrasonic speaker used for the projector of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Screen, 10 ... Projector, 11 ... Carrier wave signal source 11a ... Carrier wave frequency setting part, 12 ... Audible frequency band signal oscillation source 13, 13 ... Modulation part, 14, 14a ... Power amplifier 15, 15a ... Ultrasonic speaker , 30, 30a ... Intake duct 31, 31a ... Intake fan, 32, 32a ... Intake hole, 33, 33a ... Exhaust hole

Claims (6)

In a projector that uses the intake fan and intake duct to intake air, cools the internal heat source, and outputs sound waves using an ultrasonic speaker.
The ultrasonic speaker is disposed in the intake duct, and is disposed on the windward side of the intake fan.
A projector characterized in that an intake opening of an intake duct in which the ultrasonic speaker is disposed is provided in a video projection direction of the projector, and a sound wave output from the ultrasonic speaker is radiated from the opening. Air intake ducts are arranged on the left and right of the projector, and the ultrasonic speakers are arranged in correspondence with the air intake ducts arranged on the left and right,
2. The projector according to claim 1, wherein an intake opening for each of the left and right intake ducts is provided in a video projection direction of the projector, and a sound wave output from the ultrasonic speaker is radiated from the opening. .   An intake duct that is inhaled by one intake fan and has openings for intake in a plurality of directions is provided, and an ultrasonic speaker is disposed in at least one of the plurality of intake ducts. The projector according to 1.   The projector according to claim 1, wherein the ultrasonic speaker includes an electrostatic ultrasonic transducer.   The projector according to claim 1, wherein the ultrasonic speaker is configured by a resonance type ultrasonic transducer. A carrier wave signal source for generating a carrier wave signal in an ultrasonic frequency band;
An audio frequency band signal oscillation source for generating an audio frequency band signal;
A carrier wave frequency setting unit that variably sets the frequency of the carrier wave signal in the ultrasonic frequency band output from the carrier wave signal source;
A modulator for modulating a carrier wave signal output from the carrier wave signal source with a signal in the audible frequency band;
An ultrasonic speaker that is driven by a modulation signal obtained by modulating the carrier wave signal with a signal in the audible frequency band, and that converts the modulation signal to a sound wave and outputs the sound wave. Projector.

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