Projection display device and method for controlling the same

An electricity storage section that stores power from an external power source and supplies the stored power as operating power is provided, and, when an interruption of the external power source to a projection display device is detected, control to reduce the power consumption of a device main body and control to drive an exhaust port shutter so that it is closed by the power supplied from the electricity storage section are performed.

The entire disclosure of Japanese Patent Application No. 2010-229795, filed Oct. 12, 2010 is expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to projection display devices and methods for controlling the projection display device.

2. Related Art

A projection display device (a projector) having an opening and closing mechanism (a shutter) that opens and closes an exhaust port (an opening for ventilation) and uses a drive motor as a drive source of the opening and closing mechanism has been proposed (see, for example, Japanese Patent No. 3,453,775 (Patent Documents 1) and JP-A-2009-98481 (Patent Document 2)). The projection display device of this kind generally operates by using an external power source as operating power, and is operable when a power cable extending from the projection display device is connected to a receptacle via a plug.

In the configuration of Patent Document 1, when the plug is disconnected, the opening and closing mechanism cannot be driven and therefore the exhaust port cannot be closed. If the exhaust port is not closed, dust and insects enter the device. Moreover, in the existing configuration, since the opening and closing mechanism is driven by the drive motor, it takes time before the exhaust port is completely closed, and the user has to wait for the exhaust port to be completely closed. In this case, there is a possibility that the user disconnects the plug before the exhaust port is completely closed and the exhaust port is left open.

On the other hand, in Patent Document 2, a configuration is described in which power is supplied from a standby power source section when an interruption of an external power source is detected and, after cooling is performed by a cooling device for a predetermined time, the exhaust port is closed.

However, in the configuration of Patent Document 2, it is necessary to supply power to the cooling device after the interruption of the external power source. As a result, there is a possibility that power is consumed before the exhaust port is closed, making it impossible to close the exhaust port. Moreover, the standby power source section increases in capacity.

A state in which the exhaust port is not closed when the external power source is interrupted is an undesirable state for, in particular, a projection display device to which dust prevention measures are applied so that the device can be used in a dust-prone region, that is, a dustproof projection display device (a dustproof projector).

SUMMARY

An advantage of some aspects of the invention is to provide a projection display device that closes an opening reliably when an external power source is interrupted and a method for controlling the projection display device.

An aspect of the invention is directed to a projection display device using an external power source as operating power, including: a device main body including an image projecting section projecting an image; a shutter that opens and closes an opening for ventilation, the opening of the device main body; an electricity storage section storing power from the external power source and supplying the stored power as operating power when the external power source is interrupted; an interruption detecting section detecting an interruption of the external power source; and a control section that transitions the state to a state in which the power consumption of the device main body is reduced and drives the shutter so that the shutter is closed when an interruption of the external power source is detected.

With this configuration, when an interruption of the external power source is detected, the state is made to transition to a state in which the power consumption of the device main body is reduced and the shutter is driven so that it is closed. Therefore, it is possible to reduce the power consumption of the portion that is irrelevant to the shutter control, assign finite power stored in the electricity storage section to the driving to close the shutter, and close the opening reliably when the external power source is interrupted. Moreover, it is possible to reduce unnecessary electric power consumption and reduce costs and size by optimizing the storage parts inside a power source.

According to this configuration, by making a distinction between an instantaneous power failure and an interruption of the external power source, it is possible to prevent the occurrence of a malfunction. Moreover, when an instantaneous power failure occurs, it is possible to operate the projection display device continuously. This improves the usability of the projection display device.

That is, when a discharge lamp is adopted as a light source device of the projection display device, a predetermined waiting time is necessary to turn on a discharge lamp again, the discharge lamp which has been turned off. However, according to this configuration, even when a voltage drop in the external power source is detected due to the occurrence of an extreme brief instantaneous power failure, the power supply to the light source device is not immediately stopped. Therefore, the discharge lamp can stay on. If the power supply to the discharge lamp is immediately stopped when a voltage drop in the external power source is detected, an image cannot be displayed until a waiting time necessary for turning on the discharge lamp again has elapsed. In this configuration, such a problem does not arise.

According to this configuration, it is possible to reduce the power consumption of the light source immediately after the occurrence of a power failure or after a plug is disconnected, making it possible to save the stored power of the electricity storage section.

According to this configuration, it is possible to stop the driving of the portion that is irrelevant to the shutter control, and thereby reduce the electric power consumption and secure power necessary for the driving to close the shutter.

According to this configuration, it is possible to close the shutter in a short time as compared to a case in which the shutter is driven by a motor so that it is closed. This makes it possible to prevent the entry of dust and insects and achieve reduction in cost and size by reducing the capacity of the electricity storage section.

According to this configuration, the amount of power necessary for the driving to close the shutter is small. This also makes it possible to close the shutter reliably and provide a low-cost and long-life product.

According to this configuration, the entry of dust and insects through a suction port is prevented by a dust filter, and, by closing an exhaust port with the shutter, a vent hole of the projection display device is closed, whereby the entry of dust and insects into the projection display device is reliably prevented.

Another aspect of the invention is directed to a method for controlling a projection display device which uses an external power source as operating power including a device main body provided with an image projecting section projecting an image and a shutter that opens and closes an opening of the device main body for ventilation, wherein when an interruption of an external power source is detected, the state is made to transition to a state in which the power consumption of the device main body is reduced and the shutter is driven so that the shutter is closed, using stored power from an electricity storage section that stores power from the external power source. According to this configuration, it is possible to reduce the power consumption of the portion that is irrelevant to the shutter control, assign finite power stored in the electricity storage section to the driving to close the shutter, and close the opening reliably when the external power source is interrupted. In addition, it is possible to reduce unnecessary electric power consumption and reduce costs and size by optimizing the storage parts inside the power source.

According to the aspects of the invention, it is possible to close the opening reliably when the external power source is interrupted.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1is a diagram showing an internal structure of a projector (a projection display device)10according to the embodiment of the invention, andFIG. 2is a block diagram showing a functional configuration of the projector10.

As shown inFIG. 1, the projector10is a device including an image projecting section21projecting an image light representing an image and making the image projecting section21display an image (a projected image) on a screen (not shown) which is a projection surface. The projector10includes, inside a casing11, a device main body12in which projector component parts such as the image projecting section21are provided and an outer cover (not shown) covering the device main body12.

The casing11has a virtually rectangular shape in a plan view. In one of left and right side faces (shorter sides)11L and11R of the casing11, a suction port15is provided, and, in the other side face, an exhaust port16is provided. Here, inFIG. 1, a front face of the casing11(a face in which a projection lens53of the image projecting section21is exposed) is assigned a reference character11A, and aback face of the casing11is assigned a reference character11B. A side face of the casing11which is located on the left side when the casing11is viewed from the front face11A is depicted as a left side face11L, and a side face of the casing11which is located on the right side when the casing11is viewed from the front face11A is depicted as a right side face11R.

Inside the casing11, a cooling fan31is disposed on the side of the suction port15, an exhaust port shutter32is disposed on the side of the exhaust port16, and, in a region between the cooling fan31and the exhaust port shutter32, the image projecting section21and a power source section22are disposed. Moreover, inside the casing11, a circuit board33having a control section44and the like shown inFIG. 2is also provided. The outer cover covers the casing11other than the suction port15and the exhaust port16. As a result, outside air is introduced into the casing11through the suction port15by the cooling fan31and is exhausted through the exhaust port16after the individual sections such as the image projecting section21are cooled by the cooling air.

In the projector10with this structure, as shown inFIG. 1, in the suction port15which is one side of an opening for ventilation, a dust filter34is disposed, and, in the exhaust port16which is the other side of the opening for ventilation, the exhaust port shutter32that opens and closes the exhaust port16is disposed. Therefore, it is possible to prevent the entry of dust and insects through the openings15and16. That is, the projector10is configured as a “dustproof projector” that is suitable for the use in a dust-prone region.

Moreover, the projector10with this structure is configured so that it can perform cooling by the cooling fan31when the individual sections such as the image projecting section21are operating and make it unnecessary to perform cooling by the cooling fan31immediately after the operations of the individual sections are stopped to improve the materials of these sections, for example.

The circuit board33has a signal processing section41, a projection system driving section42, a storing section43, a control section44, a sound driving section45, a fan driving section46, a lamp driving section47, a terminal driving section48, and an exhaust port shutter driving section49(seeFIG. 2).

As shown inFIG. 2, the signal processing section41includes an image processing system that receives a video signal SA (in this configuration, a signal containing only an image or a signal containing both an image and sound) from an external device (such as a personal computer and a DVD player)18which is connected via a cable and performs image processing on image data corresponding to the signal SA and a sound processing system that performs sound processing on sound data corresponding to the signal SA.

Here, the image processing system performs IP conversion by which the format of the image data is converted from interlaced to progressive, resolution conversion processing on the image data subjected to IP conversion to increase or reduce the size, various kinds of color correction such as adjustment of the lightness and color saturation, and the like.

The projection system driving section42functions as a liquid crystal panel driving section and a light source driving section that drive a liquid crystal panel52and a light source device51, respectively, of the image projecting section21. The projection system driving section42drives the liquid crystal panel52and the light source device51based on the image data on which image processing has been performed by the signal processing section41and thereby makes the liquid crystal panel52and the light source device51display an image.

As shown inFIG. 1, the image projecting section21has a virtually L shape in a plan view, the L shape extending along the back face11B which is one of the longer sides of the casing11and extending to the front face11A along the side faces11L and11R which are shorter sides of the casing11, and includes the light source device51functioning as a light source, the liquid crystal panel (which is also referred to as the liquid crystal light valve)52(52R,52G,52B), and the projection lens53.

The light source device51includes a xenon lamp, an ultra-high pressure mercury lamp, or the like. The liquid crystal panel52is formed as a transmissive liquid crystal panel in which a plurality of pixels are arranged in a matrix. The liquid crystal panel52modulates an illumination light (indicated by a reference character L inFIG. 1) from the light source device51into an image light representing an image by changing the light transmittance of each pixel by the driving of the projection system driving section42, and makes the image light exit from the projection lens53.

In this embodiment, a case in which the projector10is a three LCD projector is shown. In this case, as shown inFIG. 1, three liquid crystal panels52R,52G, and52B corresponding to three colors R, G, and B and optical components (such as lenses321to324,341, and343, a dimmer325, dichroic mirrors331and332, reflection mirrors333,342, and344, polarizing plates351and353, and a prism354) for performing separation and condensing of the light from the light source device51are provided.

With this configuration, it is possible to generate a color image by separating the light from the light source device51into lights of three colors R, G, and B, making the lights pass through the liquid crystal panels52R,52G, and52B, and combining the lights with the prism354. Incidentally, the configuration of the image projecting section21is not limited to the configuration shown inFIG. 1, and a wide range of publicly known configurations can be adopted. Moreover, a publicly known configuration having one liquid crystal panel52may be adopted.

As shown inFIG. 2, various kinds of program products such as a control program product and various kinds of data are stored in the storing section43.

The control section44functions as a computer controlling the individual sections of the projector10by reading and executing the control program product stored in the storing section43.

The projector10is further provided with a sound outputting section35formed of a speaker and the like, an indicator lamp (in this embodiment, a light emitting diode (LED))36for notifying the user of the operating state (power-on, a standby state, an error state, and the like) of the projector10, an output terminal37(a TriggerOut terminal outputting TriggerOut to an unillustrated external device, a USB terminal, and the like) outputting TriggerOut and a power signal (USB bus power), an operating section38having various kinds of operators used by the user to giving various instructions, and the like.

Under control of the control section44, the sound driving section45drives the sound outputting section35of the projector10and makes the sound outputting section35produce various kinds of sound corresponding to the sound data output from the signal processing section41, such as sound, operation sound, and beep sound.

Under control of the control section44, the lamp driving section47turns on/off each indicator lamp36by driving/not driving a plurality of indicator lamps (notifying sections)36(including making them flash) selectively, and thereby notifies the user of power-on, a standby state (a state in which greater power savings are achieved than in a power-on state: a state in which part of functions is enabled (for example, a state in which operation of a main body operating section (the operating section38) and operation of an unillustrated remote control are accepted and a standby monitor out function is enabled)), an error state, and the like.

Under control of the control section44, the terminal driving section48outputs TriggerOut for notifying an external device (such as a screen apparatus) of power-on of the projector10and a power signal for supplying power to a USB external device to the outside via the output terminal37.

Under control of the control section44, the exhaust port shutter driving section (the shutter driving section)49drives the exhaust port shutter32so that the exhaust port shutter32is opened/closed. When the power is turned on by the operation performed on the operating section38, the exhaust port shutter driving section drives the exhaust port shutter32so that it is opened; when the power is turned off by the operation performed on the operating section38, the exhaust port shutter driving section drives the exhaust port shutter32so that it is closed.

The opening/closing detecting section50is a switch mechanism that detects opening and closing of the exhaust port shutter32. The control section44can detect the open/closed state of the exhaust port shutter32by obtaining the detection result of the opening/closing detecting section50.

Here,FIG. 3is a perspective view showing an open state of the exhaust port shutter32, andFIG. 4is an exploded perspective view of the exhaust port shutter32.FIG. 5is a diagram showing a closed state of the exhaust port shutter32.

As shown inFIGS. 3 to 5, the exhaust port shutter32includes a frame33A having a shape of a rectangular frame, a plurality of (in this structure, eight) louvers33B which are placed at regular spacings in a longitudinal direction in such away as to be able to open and close an opening (an opening communicating with the exhaust port16) of the frame33A, a cam plate33C which is slidably placed in the frame33A, and a solenoid33D that operates the cam plate33C.

As shown inFIG. 4, the frame33A includes a plate-like member33E forming part of an upper frame as a separate component, and turnably supports a turning shaft J1jutting from the upper and lower ends of each louver33B by a lower frame of the frame33A and the plate-like member33E.

On the plate-like member33E, the cam plate33C is slidably supported, and a projecting shaft J2jutting upward with a space left between the projecting shaft J2and the turning shaft J1of each louver33B is placed through the cam plate33C.

As a result, when the cam plate33C is slid, all the louvers33B turn about the turning shafts J1and open and close the opening of the frame33A.

The solenoid33D is fixed to the frame33A, and a plunger P of the solenoid33D is connected to one end of the cam plate33C. Incidentally, in the drawing, a reference character33K denotes a circuit board for driving the solenoid.

In the exhaust port shutter32, a biasing member (in this embodiment, an extension spring)33S which biases the cam plate33C to a shutter close side. The biasing member33S makes it possible to keep the exhaust port shutter32in a closed state reliably.

The solenoid33D is a keep solenoid (also called a self-holding solenoid). As a result of the cam plate33C being pulled toward the solenoid33D against the biasing force of the biasing member33S by the exhaust port shutter driving section49, the exhaust port shutter32is driven so that it is opened (sucking operation of the solenoid), and the exhaust port shutter32is kept in an open state as a result of the plunger P of the solenoid33D sticking to a built-in permanent magnet thereto by the magnetomotive force of the built-in permanent magnet (sticking operation of the solenoid).

Moreover, the solenoid33D drives the exhaust port shutter32so that it is closed by restoring to its former state by a reverse magnetomotive force which is generated by a coil and cancels out the magnetomotive force of the built-in permanent magnet by the exhaust port shutter driving section49(restoring operation of the solenoid).

Incidentally, the opening/closing detecting section50that detects opening and closing of the exhaust port shutter32is formed as a switch mechanism that is attached to the plate-like member33E of the exhaust port shutter32and opens and closes in accordance with the position of the cam plate33C.

FIG. 6is a diagram showing the power source section22along with peripheral components.

The power source section22is supplied with power of an external power source which is a commercial power source sent from an electric power company by being connected, via an unillustrated plug, to a receptacle located inside a building or the like, and supplies power to the individual sections of the projector10. That is, the projector10is driven by using the external power source as operating power.

Incidentally, since the projector10with this configuration is a dustproof projector, if the exhaust port shutter32is left open when the external power source is interrupted as a result of a power failure or the plug being disconnected, entry of dust cannot be prevented. Such a situation is undesirable.

Therefore, to improve substantive dust-proofness, this configuration includes the following configuration so that control to close the exhaust port shutter32reliably is performed when the external power source is interrupted. Hereinafter, the above configuration will be described in detail.

First, the power source section22includes an external power source detecting section22A outputting an output signal PWDS whose signal level is switched when the power supply of the external power source is unexpectedly interrupted due to a power failure or disconnection of the plug and an electricity storage section22B that stores power of the external power source and supplies alternative power when the external power source is interrupted.

The output signal PWDS of the external power source detecting section22A described above is output to the control section44, and the control section44determines whether or not the external power source is interrupted based on the signal level of the output signal PWDS. That is, the external power source detecting section22A and the control section44function as an interruption detecting section detecting an interruption of the external power source.

Incidentally, inFIG. 6, resistances denoted by reference characters R1and R2are resistance values forming a voltage-dividing circuit that divides a power-source voltage at a predetermined division ratio, and the power-source voltage value obtained by voltage dividing performed by the voltage-dividing circuit is used as the output signal PWDS.

As the electricity storage section22B, a capacitor such as an electric double layer capacitor is used. Since the electric double layer capacitor physically performs charging and discharging without using an electrochemical reaction, the electric double layer capacitor suffers minimal performance degradation and possesses outstanding long-term reliability.

Next, interruption control (direct power off) which is performed when the external power source of the projector10is unexpectedly interrupted will be described.

FIG. 7is a flowchart showing the interruption control. The interruption control is processing which is performed repeatedly with a predetermined interrupt period when power is supplied from the external power source and the projector is turned on.

Here, in the following description, when the exhaust port shutter driving section49and the other driving sections42to48are described separately, as shown inFIG. 2andFIG. 6, the other driving sections42to48are collectively expressed as a driving section K1, and the objects to be driven by the driving section K1are collectively expressed as a driven section K2.

First, the control section44determines whether or not the power supply from the external power source is stopped based on the output signal PWDS of the external power source detecting section22A (step S1). Specifically, since the signal level of the output signal PWDS is reduced when the power supply is stopped, the control section44determines that the power supply from the external power source is stopped when the output signal PWDS is switched from H level to L level with reference to a predetermined threshold value.

When the power supply from the external power source is stopped (step S1: YES), the control section44immediately starts light amount reduction processing by the projection system driving section42, the light amount reduction processing by which the amount of light (lamp brightness) of the light source device51is reduced to a previously set low level (step S2), and starts instantaneous power failure determination processing by which it is determined whether or not there is an instantaneous power failure based on the power supply stop time TBD (step S3). Incidentally, when the power supply is stopped, power from the electricity storage section22B is immediately supplied as operating power, whereby the individual sections can continue operating.

In the instantaneous power failure determination processing, if the stop time TBD exceeds a previously set reference time (in this embodiment, 50 msec), the control section44determines that a power failure that is not an instantaneous power failure (that is, an interruption of the external power source (a power failure)) has occurred (step S3: YES); if the power supply is resumed before the stop time TBD exceeds the reference time, the control section44determines that an instantaneous power failure has occurred (step S3: NO). Incidentally, in the light amount reduction processing, the power consumption is reduced by reducing the amount of light to an extent that the user can continue viewing the images.

If an instantaneous power failure has occurred (step S3: NO), the control section44ends the light amount reduction processing and thereby increases the amount of light (lamp brightness) of the light source device51to a normal light amount, and transitions from a first power saving mode to a normal operation mode (step S10). This allows the user to continue viewing the bright images.

That is, in this configuration, when the power supply from the external power source is stopped, the mode transitions to the first power saving mode in which the power consumption of the light source device51whose power consumption is highest in the driven section K2is immediately reduced. In the first power saving mode, the amount of light is reduced to an extent that the user or the like can continue viewing the images. This makes it possible to reduce the power consumption efficiently while allowing the user or the like to continue viewing the images.

If an instantaneous power failure has occurred (step S3: NO) or the power supply of the external power source is not stopped (step S1: NO), since the projector10is in a power source state in which the projector10remains in a power-on state and can perform normal operation, it is possible to keep the exhaust port shutter32in an open state, end the interruption control, and return to normal operation.

On the other hand, if the external power source is interrupted (a power failure has occurred) (step S3: YES), the control section44transitions the mode to a second power saving mode in which the power consumption of the driven section K2other than the exhaust port shutter32is reduced by the driving section K1(step S4).

FIG. 8is a flowchart showing the second power saving mode.

As shown inFIG. 8, the control section44stops the driving of the light source device51(turns the light off) by the projection system driving section42(step S11), and stops the driving of the liquid crystal panel52after performing charge draining processing on the liquid crystal panel52by the projection system driving section42(step S12). Then, the control section44stops the driving of the sound outputting section35by the sound driving section45(step S13), stops the driving of the cooling fan31by the fan driving section46(step S14), stops the driving of the output terminal37by the terminal driving section48(step S15), and stops the driving of the indicator lamp36by the lamp driving section47(step S16). Incidentally, the driving of the individual sections is stopped in descending order of the amount of electric power consumption. Thus, it is possible to reduce the electric power consumption efficiently. It is to be noted that, inFIG. 8, a case in which the control section44stops the driving of the individual sections one after another is shown; however, when the control section44can perform parallel processing, the control section44may quickly stop the driving of the individual sections concurrently.

By doing so, it is possible to make the power consumption of the projector10lower than that in the first power saving mode and reduce the electric power consumption of the electricity storage section22B efficiently. Incidentally, there is a write period in which an electric charge corresponding to the brightness of each pixel is accumulated when the liquid crystal panel52is driven, and the charge draining processing described above is processing for draining (discharging) the accumulated electric charge. This makes it possible to stop the driving in a state in which the liquid crystal panel52is reset.

When the mode transitions to the second power saving mode in this manner, the control section44immediately performs control to drive the exhaust port shutter32so that it is closed by the exhaust port shutter driving section49(step S5). Specifically, the control section44passes electric current with inverse characteristics to those of the sucking operation to return the plunger P of the solenoid33D and makes the sucking/sticking holding force smaller, thereby detaching the plunger P by the biasing force of the biasing member33S. By this returning operation of the solenoid33D, the control section44closes the exhaust port shutter32. Incidentally, the time during which electric current is passed in this case is a previously set time sufficient for the returning operation of the solenoid33D, and, when this time has elapsed, the control section44stops passing electric current through the solenoid33D. This is the end of the description of the interruption control (direct power off).

As described above, in this configuration, when an interruption of the external power source (a power failure) is detected, the control section44transitions the mode to the second power saving mode which is a state in which the power consumption of the device main body12is reduced, that is, the power consumption of the driven section K2other than the exhaust port shutter32is reduced by the driving section K1other than the exhaust port shutter driving section49, and drives the exhaust port shutter32so that it is closed by the exhaust port shutter driving section49. Therefore, it is possible to reduce the power consumption of the portion which is irrelevant to the shutter control and assign finite power stored in the electricity storage section22B to the driving to close the exhaust port shutter32. This makes it possible to secure power necessary for the driving to close the exhaust port shutter32.

Therefore, it is possible to close the exhaust port16of the projector10by reliably closing the exhaust port shutter32when the external power source is interrupted while reducing the storage capacity of the electricity storage section22B. Moreover, according to this configuration, even when the plug of the projector10is disconnected from the receptacle, the exhaust port shutter32is reliably closed, whereby it is possible to close the exhaust port16of the projector10.

In addition, it is possible to reduce unnecessary electric power consumption and reduce costs and size by optimizing the storage parts inside the power source.

As described above, since the projector10with this configuration is provided with the dust filter34in the suction port15, the entry of dust and insects through the suction port15is prevented by the dust filter34. Therefore, by closing the exhaust port16with the exhaust port shutter32, a vent hole of the projector10is closed, whereby the entry of dust and insects into the projector10is reliably prevented.

Therefore, the projector10can reliably prevent the entry of dust and insects from the outside both in a power source interrupted state in which the external power source is unexpectedly interrupted and a power source interrupted state in which the user intentionally disconnects the plug.

As a result, with this configuration, it is possible to provide a dustproof projector that achieves reduction in cost and size by size-reduction of the electricity storage section22B, the dustproof projector in which the opening is reliably closed when a power failure occurs or in a state in which a plug is disconnected and the entry of dust and insects is reliably prevented.

Moreover, when the external power source detecting section22A and the control section44which function as the interruption detecting section detect that the power supply from the external power source is stopped, the external power source detecting section22A and the control section44start the instantaneous power failure determination processing by which it is determined whether or not there is an instantaneous power failure based on the stop time TBD. When it is detected in the instantaneous power failure determination processing that a power failure which is not an instantaneous power failure has occurred, the external power source detecting section22A and the control section44detect that the external power source is interrupted. Therefore, by making a distinction between an instantaneous power failure and an interruption of the external power source, it is possible to prevent the occurrence of a malfunction. In this case, when an instantaneous power failure occurs, it is possible to operate the projector10continuously without closing the exhaust port shutter32, stopping the function, or performing a restart. This improves the usability of the projector10.

That is, when a discharge lamp (hereinafter also referred to as a lamp) is adopted as the light source device51of the projection display device10, a predetermined waiting time is necessary to turn on a lamp again, the lamp which has been turned off. However, according to this configuration, even when a voltage drop in the external power source is detected due to the occurrence of an extreme brief instantaneous power failure, the power supply to the light source device51is not immediately stopped. Therefore, the lamp can stay on. If the power supply to the lamp is immediately stopped when a voltage drop in the external power source is detected, an image cannot be displayed until a waiting time necessary for turning the lamp on again has elapsed. In this configuration, such a problem does not arise.

Furthermore, when the instantaneous power failure determination processing is started, the control section44reduces the amount of light emitted from the light source device (the light source)51by the driving section K1, and, when it is determined that a power failure that is not an instantaneous power failure has occurred, the control section44stops the driving of the light source device51by the driving section K1. Therefore, it is possible to reduce the power consumption of the light source device51immediately after the occurrence of the power failure or after the plug is disconnected, making it possible to save the stored power of the electricity storage section22B. Moreover, in case of an instantaneous power failure, the driving is not stopped while reducing the power consumption of the light source device51. This allows the user or the like to continue viewing the images.

Moreover, when an interruption of the external power source is detected, the driving section K1stops the driving of the cooling fan31, stops the driving of the liquid crystal panel52after charge draining processing, stops the driving of the sound outputting section35, and stops the driving of the output terminal37and the indicator lamp36. This makes it possible to stop the driving of all the portions that are irrelevant to the shutter control, reduce the electric power consumption to a minimum, and secure power necessary for the driving to close the exhaust port shutter32.

Furthermore, since the exhaust port shutter32is opened and closed by the driving of the solenoid33D and the exhaust port shutter driving section49drives the exhaust port shutter32so that it is closed by passing electric current through the solenoid33D, it is possible to close the exhaust port shutter32in a short time as compared to a case in which the exhaust port shutter32is driven by a motor so that it is closed. This also makes it possible to prevent the entry of dust and insects and achieve reduction in cost and size by reducing the capacity of the electricity storage section22B.

In addition, in this configuration, the biasing member33S that biases the exhaust port shutter32to a close side is provided, and the exhaust port shutter32is closed by the biasing force of the biasing member33S by releasing the holding force of the solenoid33D. Therefore, the amount of power necessary for the driving to close the exhaust port shutter32is small. This also makes it possible to close the exhaust port shutter32reliably and provide a low-cost and long-life product.

The embodiment described above is merely an embodiment of the invention, and any modifications and applications are possible within the scope of the subject matter of the invention.

For example, in the embodiment described above, a case in which driving of all the portions that are irrelevant to the shutter control is stopped has been described; however, the invention is not limited thereto. The driving of at least any one of the portions that are irrelevant to the shutter control may be stopped. For example, the driving of the indicator lamp36may not be stopped because the power consumption of the indicator lamp36is small, so that notification of the operating state (power-on, a standby state, an error state, and the like) of the projector10is continuously provided by the indicator lamp36.

Moreover, the configuration is not limited to a configuration in which the power consumption of the individual section is reduced to zero by stopping the driving of the individual sections. The power consumption may be reduced by reducing the amount of light emitted from the light source device (the light source)51, reducing the number of revolutions of the cooling fan31, or bringing the sound outputting section35into a mute state.

Furthermore, the configuration of the electricity storage section22B is not limited to an electric double layer capacitor. It is also possible to adopt various kinds of elements, such as an electrolytic capacitor, as the configuration of the electricity storage section22B.

In addition, an LED may be used as the light source device51. When the LED is used as the light source device51, it is possible to turn on the light source again immediately after the light source is turned off. Therefore, instead of the light amount reduction processing (step S2) by which the amount of emitted light is reduced, the light source device51may be turned off completely by stopping the driving of the light source device51.

Moreover, in the embodiment described above, a case in which the exhaust port shutter32is provided has been described; however, the invention is not limited thereto. A shutter may be provided in the suction port15, or the projection lens53may be provided with a shutter for protecting a lens (a lens shutter). In short, the invention can be widely applied to a technique of controlling a shutter which should be closed when the external power source is interrupted (including a case in which the plug is disconnected).

Furthermore, in the embodiment described above, a case in which the external power source detecting section22A and the control section44function as the interruption detecting section that detects an interruption of the external power source has been described; however, the invention is not limited thereto. The control section44may not be used as part of the interruption detecting section, and the interruption detecting section may be provided separately.

Moreover, the projector10described above is a projector that projects an image onto a screen by using the transmissive liquid crystal panel52. However, the projector10may be a projector using a reflective liquid crystal panel or a DMD projector using a digital mirror device. Furthermore, the invention is not limited to a three LCD projector that projects a color image by the three liquid crystal panels52; the invention can also be applied to a projector that projects a color image by displaying an image corresponding to RGB by time division by using one liquid crystal light valve, a single-panel DMD projector provided with a color wheel, and a three DMD projector. In short, the invention can be widely applied to a projection display device having a shutter.