Projection apparatus and control method of the projection apparatus

Abstract

To provide a projection apparatus that has a simple configuration and has reduced flicker in a projected image.SOLUTION: A projection apparatus includes a light source, a light modulation device, a projection unit, a fan, a control unit, and a housing. A vibration sensor is attached to the fan. A resonance range in which vibration resonates in the housing is detected by the vibration sensor. In duty ratio setting of a drive signal for driving the fan, the control unit drives the fan using the drive signal having a duty ratio that avoids a resonance duty ratio corresponding to the resonance range.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a projection device and a method for controlling a projection device. [Background technology]

[0002] For example, Patent Document 1 discloses a projector with a vibration sensor attached to the projection lens. According to this document, the vibration sensor detects vibrations in the projection lens unit, generates a drive signal that is in the opposite phase to the detected vibrations, and drives an actuator using the generated drive signal to suppress vibrations occurring in the projection lens unit.

[0003] Furthermore, Patent Document 2 discloses a projector equipped with an optical device that shifts the axis of image light emitted from an optical modulator such as a liquid crystal panel in order to increase the resolution of the projected image beyond that of the optical modulator. Such an optical device is also called an optical path shift device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-42125 [Patent Document 2] Japanese Patent Publication No. 2022-69064 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there was room for improvement in the projector of Patent Document 1. Specifically, it required a dedicated actuator to suppress vibration, resulting in a complex configuration. Also, since the optical path shift device of Patent Document 2 is easily affected by vibration, there was a need for technology to suppress flickering in the projected image. In other words, there has been a demand for a projection device and a control method for a projection device that has a simple configuration and produces projected images with little flicker. [Means for solving the problem]

[0006] A projection device according to one aspect of the present application comprises a light source, an optical modulation device, a projection unit, a fan, a control unit, and a housing, wherein a vibration sensor is attached to the fan, and the vibration sensor detects a resonance range in which vibrations resonate in the housing, and the control unit drives the fan using a drive signal with a duty ratio that avoids a resonance duty ratio that corresponds to the resonance range when setting the duty ratio of the drive signal that drives the fan.

[0007] A control method for a projection device according to one aspect of the present application is a control method for a projection device that includes a light source, an optical modulation device, a projection unit, a fan, and a housing, wherein a vibration sensor is attached to the fan, and the method includes measuring a resonance range in which vibrations resonate in the housing, and setting a duty ratio of a drive signal that drives the fan, and driving the fan with the drive signal having a duty ratio that avoids a resonance duty ratio that corresponds to the resonance range. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a projector according to a first embodiment. [Figure 2] FIG. 10 is an explanatory diagram showing the shift of the image display position caused by the light path shift unit. [Figure 3] FIG. 10 is a flowchart showing the flow of measuring the resonance range. [Figure 4] FIG. 4 is a flowchart showing the flow of driving the cooling fan. [Figure 5] FIG. 4 is a graph showing the duty ratio of a drive signal. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 ***Projector Overview*** FIG. 1 is a plan view showing a schematic configuration of a projector according to a first embodiment. As shown in FIG. 1, the projector 100 of this embodiment is a projection device that projects an image onto an external screen Sc from a projection optical system 23 provided on one end surface of a rectangular parallelepiped housing 99. FIG. 1 is a schematic plan view of the projector 100 viewed from above. The housing 99 is rectangular, and the projection optical system 23 is provided on one short side. FIG. 1 illustrates three mutually perpendicular axes: the X axis, the Y axis, and the Z axis. The direction along the X axis is referred to as the "X direction," the direction along the Y axis is referred to as the "Y direction," and the direction along the Z axis is referred to as the "Z direction." In this embodiment, the direction along the long side of the housing 99 is referred to as the X direction, the direction along the short side is referred to as the Y direction, and the thickness direction of the housing 99 is referred to as the Z direction. The tip of the arrow in each axis direction is referred to as the "plus side," and the base of the arrow is referred to as the "minus side." In the following figures, for ease of understanding, dimensions and scales may be different from the actual dimensions.

[0010] The projector 100 is composed of a control unit 10, a memory unit 11, an IF unit 12, an image information input unit 13, an image information processing unit 14, an OSD processing unit 15, an optical device 28, an operation signal receiving unit 17, an operation unit 18, an intake fan 31, a cooling fan 32, an exhaust fan 33, etc. The control unit 10 is configured with one or more processors and performs overall control of the operation of the projector 100 by operating in accordance with a control program stored in the storage unit 11. The control unit 10 is configured, for example, with a central processing unit (CPU) including an interface with peripheral devices, an arithmetic unit, and a register. Note that some or all of the functions of the control unit 10 may be realized by hardware such as a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The control unit 10 executes various processes in parallel or sequentially.

[0011] The storage unit 11 is configured to include a RAM (Random Access Memory) and a ROM (Read Only Memory). The RAM is used for temporary storage of various data, and the ROM stores control programs for controlling the operation of the projector 100, associated data, and the like. The control programs store a startup program that instructs the order and content of processes when starting up the projector 100, a resonance range measurement program (to be described later), a fan drive program, and the like. The associated data includes a threshold value for vibration detection values ​​(to be described later), a resonance duty ratio, and the like. In other words, the control unit 10 is provided with the storage unit 11. The IF unit 12 is an interface with external devices, and includes a plurality of connection terminals including an HDMI (registered trademark; High-Definition Multimedia Interface) terminal and a USB (Universal Serial Bus) terminal.

[0012] Image information input unit 13 receives image information such as an image signal from an external image signal supply device such as a computer. The image signal supply device is not limited to a computer and may be any device that can supply image information, such as a BD (Blu-ray (registered trademark) Disc) player or a streaming media player. Based on the control of control unit 10, image information processing unit 14 performs necessary image processing on the image information input from image information input unit 13 and outputs the processed image information to OSD processing unit 15.

[0013] The OSD processing unit 15 performs processing for superimposing and displaying an OSD (On-Screen Display) image such as a message image or a menu image on an image under the control of the control unit 10. The OSD processing unit 15 includes an OSD memory (not shown) that stores OSD image information representing graphics, fonts, and the like for forming the OSD image. When the control unit 10 instructs the OSD image to be superimposed, the OSD processing unit 15 reads the necessary OSD image information from the OSD memory and combines this OSD image information with the image information input from the image information processing unit 14 so that the OSD image is superimposed at a predetermined position on the image.

[0014] The optical device 28 comprises a light source section 21, three liquid crystal light valves 22R, 22G, and 22B as light modulation devices, a light valve driving section 24, a projection optical system 23, an optical path shift section 25, and the like. The optical device 28 modulates the light emitted from the light source unit 21 using the liquid crystal light valves 22R, 22G, and 22B to form image light, and projects this full-color image light onto the screen Sc in an enlarged form from the projection optical system 23. When the light path shift unit 25 is driven, an image with a higher resolution than the resolution of the liquid crystal light valves 22R, 22G, and 22B is projected. Details of the light path shift unit 25 will be described later.

[0015] The light source unit 21 is configured to include a solid-state light source such as a light-emitting diode or a semiconductor laser. Note that a discharge-type light source lamp such as an ultra-high pressure mercury lamp or a metal halide lamp may also be used. The light emitted from the light source unit 21 is converted into light with a substantially uniform luminance distribution by an integrator optical system (not shown), and is then separated into the three primary colors of light, red (R), green (G), and blue (B), by a color separation optical system (not shown), and then each of the light components enters the liquid crystal light valves 22R, 22G, and 22B, respectively. The liquid crystal light valves 22R, 22G, and 22B are each composed of a transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates. Each liquid crystal panel has a plurality of pixels arranged in a matrix, and a drive voltage can be applied to each pixel. The liquid crystal light valves 22R, 22G, and 22B are collectively referred to as the liquid crystal light valve 22.

[0016] The light valve driver 24 forms an image in the image forming area of ​​the liquid crystal light valve 22. Specifically, the light valve driver 24 applies a drive voltage corresponding to the image information input from the OSD processor 15 to each pixel in the image forming area, and sets the light transmittance of each pixel according to the image information. The light emitted from the light source 21 is modulated for each pixel as it passes through the liquid crystal light valve 22, and image light corresponding to the image information is formed for each color light. The formed image light of each color is combined for each pixel by a color combining optical system (not shown) to become image light representing a color image, and is output to the projection optical system 23 side.

[0017] In the above description, the transmissive liquid crystal light valves 22R, 22G, and 22B are used as the light modulation devices, but a reflective light modulation device such as a reflective liquid crystal light valve may also be used. Also, a digital mirror device may be used that modulates the light emitted from the light source unit 21 by controlling the emission direction of incident light for each micromirror pixel. Also, the configuration is not limited to one having multiple light modulation devices for each color of light, and one light modulation device may modulate multiple color lights in a time-division manner. In addition, the image information input unit 13, the image information processing unit 14, and the OSD processing unit 15 may be configured by one or more processors, or may be configured by dedicated processing devices such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0018] The projection optical system 23 is a projection unit and includes a plurality of concave and convex lenses. The operation signal receiving unit 17 receives an operation signal from the remote control 3 using infrared communication, decodes it, and transmits it to the control unit 10. Note that the configuration is not limited to infrared communication, and any configuration that allows short-range wireless communication may be used. For example, the remote control 3 and the operation signal receiving unit 17 may be configured to include a communication device that complies with Bluetooth (registered trademark). The remote control 3 includes a power key for switching the power of the projector 100 on and off, a menu key, a selection key, an enter key, and the like. The operation unit 18 is an operation unit provided on a housing 99 of the projector 100, and is provided with a plurality of operation keys similar to those on the remote control 3.

[0019] ***Outline of the light path shift section*** FIG. 2 is an explanatory diagram showing the shift of the image display position caused by the light path shift unit. As shown in FIG. 1, the optical path shift unit 25 is provided between the liquid crystal light valve 22 and the projection optical system 23. By shifting the optical path of the image light L in a direction perpendicular to the optical axis, an image with a higher resolution than the resolution of the liquid crystal light valve 22 can be projected onto the screen Sc. For example, if the resolution of the liquid crystal light valve is full high definition, a 4K image can be displayed. Note that shifting the optical path of the image light L is also referred to as "pixel shift." In other words, the projection optical system 23 includes the optical path shift unit 25 as a drive mechanism that drives the liquid crystal light valve 22 as a light modulation device in a direction perpendicular to the optical axis of the light incident thereon.

[0020] In a preferred example, the light path shift unit 25 includes, as a light path shift device, the optical device shown in FIG. 3 of Patent Document 2. As described in the document, the optical device serving as the light path shift unit 25 includes a glass plate that shifts the optical path of the image light L emitted from the liquid crystal light valve 22. As shown in FIG. 2, when the glass plate swings in a first swing direction, the optical path of the light incident on the glass plate shifts in a first direction F1. When the glass plate swings in a second swing direction, the optical path of the light incident on the glass plate shifts in a second direction F2 that intersects with the first direction F1. As a result, the pixels Px displayed on the screen Sc are displayed shifted in both the first direction F1 and the second direction F2.

[0021] The light path shift unit 25 increases the apparent number of pixels by combining the shift of the light path in the first direction F1 and the shift of the light path in the second direction F2, thereby increasing the resolution of the image projected onto the screen Sc. For example, as shown in FIG. 2, the light path shift unit 25 moves the pixel Px to a position shifted by half a pixel (i.e., half the pixel Px) in both the first direction F1 and the second direction F2. This allows the image display position on the screen Sc to be shifted to an image display position P2 shifted by half a pixel in the first direction F1 from the image display position P1, an image display position P3 shifted by half a pixel in both the first direction F1 and the second direction F2 from the image display position P1, and an image display position P4 shifted by half a pixel in the second direction F2 from the image display position P1.

[0022] 2, an optical path shift operation is performed so that an image is displayed for a fixed period of time at each of image display positions P1, P2, P3, and P4, and the display content of the liquid crystal light valve 22 is changed in synchronization with the optical path shift operation. This makes it possible to display pixels A, B, C, and D that appear smaller than pixel Px.

[0023] ***Cooling fan overview*** Return to Figure 1. 1, the intake fan 31 is provided along the long side on the Y minus side of the housing 99. In a preferred example, the intake fan 31 is an axial fan that draws external air into the housing 99. The air outside the housing 99 is also referred to as outside air. The intake fan 31 is driven by a fan drive unit 31d. The fan drive unit 31d is a drive signal generation circuit including a DA converter, and supplies a drive signal having a duty ratio based on a control signal from the control unit 10 to the intake fan 31 by PWM (Pulse Width Modulation) control.

[0024] A temperature detection unit 35 is provided next to the intake fan 31. The temperature detection unit 35 includes a thermistor as a temperature sensor and an interface circuit including an AD converter. The temperature detection unit 35 detects the outside air temperature at a predetermined sampling period and transmits the detected data to the control unit 10.

[0025] The cooling fan 32 is provided near the liquid crystal light valve 22 inside the housing 99. In a preferred example, the cooling fan 32 is a sirocco fan that blows outside air drawn in by the intake fan 31 onto heat-generating parts around the liquid crystal light valve 22 to cool it. The heat-generating parts may include the light source unit 21. Although not shown, an air flow path is provided between the intake fan 31 and the cooling fan 32, allowing for efficient blowing of outside air. The cooling fan 32 is driven by a fan drive unit 32d. The fan drive unit 32d is a drive signal generation circuit similar to the fan drive unit 31d, and supplies the cooling fan 32 with a drive signal having a duty ratio based on a control signal from the control unit 10.

[0026] A vibration sensor 37 is attached to the cooling fan 32. In a preferred example, the vibration sensor 37 is an acceleration sensor that detects acceleration along three axes. However, the vibration sensor 37 is not limited to a triaxial acceleration sensor, and any vibration sensor that can detect vibrations including resonant vibrations in the cooling fan 32 will do. For example, the vibration sensor 37 may be an angular velocity sensor that detects angular velocity around three axes, or may be an inertial sensor equipped with a triaxial acceleration sensor and a triaxial angular velocity sensor. A vibration detection circuit 37c is provided between the vibration sensor 37 and the control unit 10. The vibration detection circuit 37c is an interface circuit including an AD converter, detects vibrations using the vibration sensor 37, and transmits the detected data to the control unit 10.

[0027] A temperature detection unit 36 ​​is provided near the liquid crystal light valve 22. The temperature detection unit 36 ​​includes a thermistor as a temperature sensor and an interface circuit including an AD converter. The temperature detection unit 36 ​​detects the temperature near the liquid crystal light valve 22 at a predetermined sampling period and transmits the detected data to the control unit 10.

[0028] The exhaust fan 33 is provided next to the projection optical system 23. In a preferred example, the exhaust fan 33 is an axial fan that cools heat-generating parts including the liquid crystal light valve 22 and expels the exhaust air that has absorbed the heat to the outside of the housing 99. The exhaust fan 33 is driven by a fan drive unit 33d. The fan drive unit 33d is a drive signal generation circuit similar to the fan drive unit 31d, and supplies the exhaust fan 33 with a drive signal having a duty ratio based on a control signal from the control unit 10. In other words, the projector 100 comprises a light source unit 21 as a light source, a liquid crystal light valve 22 as a light modulation device, a projection optical system 23 as a projection unit, a cooling fan 32 as a fan, a control unit 10, and a housing 99, and a vibration sensor 37 is attached to the cooling fan 32.

[0029] As described above, projector 100 is equipped with three cooling fans: intake fan 31, cooling fan 32, and exhaust fan 33. The number of cooling fans is not limited to three, and may be any number that ensures the cooling capacity to maintain the interior of housing 99 within the rated temperature range. For ease of understanding, the following description will focus on cooling fan 32, which is closest to projection optical system 23 and has the greatest impact on resonant vibration in housing 99, to explain the method for measuring the resonance range and the method for driving cooling fan 32. However, the same may be applied to intake fan 31 and exhaust fan 33.

[0030] ***Method of measuring the resonance range*** FIG. 3 is a flowchart showing the flow of measurement of the resonance range. Here, the resonance range measurement method will be described mainly with reference to FIG. 3 and with other figures as appropriate. The following steps are performed by the control unit 10 executing the resonance range measurement program stored in the storage unit 11 to control various components, including the fan drive unit 32d and the cooling fan 32. In a preferred example, the resonance range measurement is performed as part of the initial setup when the projector 100 is installed in a new environment. For example, the measurement is performed by operating the menu key on the remote control 3, selecting resonance range measurement from the initialization menu, and pressing the enter key. Note that the light path shift unit 25 is assumed to be operating. In other words, the resonance range is detected based on vibrations occurring when the light path shift unit 25, which serves as a drive mechanism, is driven. The intake fan 31 and the exhaust fan 33 are driven at constant speeds.

[0031] In step S10, the duty ratio is changed by the fan drive unit 32d to drive the cooling fan 32. A drive signal with the minimum duty ratio at which the fan can be driven is applied to the cooling fan 32.

[0032] In step S11, it is confirmed whether the duty ratio of the drive signal applied in step S10 has reached 100%. If it has reached 100%, measurement ends. If it has not reached 100%, the process proceeds to step S12.

[0033] In step S12, the vibration sensor 37 detects the vibration value of the cooling fan 32 in the driving state.

[0034] In step S13, it is determined whether the vibration value detected in step S12 exceeds a threshold value. If it exceeds the threshold value, the process proceeds to step S14. If it is less than the threshold value, the process returns to step S10, and a duty ratio one step higher is set. The threshold value is a vibration value of resonance that may cause flickering in the projected image, and is stored in advance in storage unit 11. Resonance occurs when the driving vibrations of the three fans, including cooling fan 32, resonate with housing 99.

[0035] In step S14, the duty ratio of the drive signal is stored in the storage unit 11. The duty ratio is stored as a resonance duty ratio corresponding to the resonance range in the storage unit 11. In other words, the vibration sensor 37 detects the resonance range in which the vibration in the housing 99 resonates. In this way, the resonance range that may cause flickering of the projected image around the optical device 28 is measured for the projector 100 installed in a new environment. Because the resonance changes due to disturbances such as temperature and air pressure in the installation environment, it is preferable to measure the resonance range each time the installation environment changes. In other words, the resonance range is acquired in advance in the environment in which the housing 99 is installed, and is stored as a resonance duty ratio in the storage unit 11. For example, in one example installation environment, the resonance duty ratio is stored as a range from 50% to 70%.

[0036] Furthermore, in the above description, the intake fan 31 and the exhaust fan 33 are driven at a constant speed, but the drive speed may be changed. Alternatively, only the cooling fan 32 may be operated and the speed may be determined by calculation. Furthermore, in the above description, the light path shift unit 25 is in a driven state, but this is not limitative. If there is no concern that the drive vibration of the light path shift unit 25 will affect the resonant vibration or if the effect is minor, the drive may be stopped.

[0037] ***Cooling fan operation method*** Fig. 4 is a flow chart showing the flow of driving the cooling fan. Fig. 5 is a graph showing the duty ratio of the drive signal, with the horizontal axis representing time and the vertical axis representing the duty ratio (%). Next, a method for driving cooling fan 32 will be described mainly with reference to Fig. 4, and with reference to other figures as appropriate. The following steps are performed by control unit 10 executing a fan drive program stored in storage unit 11 to control each unit including fan drive unit 32d and cooling fan 32.

[0038] In step S20, the cooling fan 32 is driven by a drive signal with an initial duty ratio. In a preferred example, a drive signal with a duty ratio set the previous time the cooling fan 32 was driven is used. The previous setting is a duty ratio that does not match the resonant duty ratio.

[0039] In step S21, the duty ratio of the drive signal for the cooling fan 32 is calculated based on the temperature detected by the temperature detection unit 36. The calculation formula is pre-stored in the storage unit 11. The calculation may also take into account the temperature detected by the temperature detection unit 35.

[0040] In step S22, it is determined whether the duty ratio calculated in step S21 matches the resonant duty ratio in the storage unit 11. If the duty ratio matches the resonant duty ratio, the process proceeds to step S24. If the duty ratio does not match the resonant duty ratio, the process proceeds to step S23.

[0041] In step S23, the cooling fan 32 is driven by a drive signal having the duty ratio calculated in step S21.

[0042] In step S24, it is determined whether or not a power-off operation has been performed. If a power-off operation has been performed, the operation of the projector 100 is terminated. If a power-off operation has not been performed, the process proceeds to step S25.

[0043] In step S25, the vibration sensor 37 detects the vibration value of the cooling fan 32 in the driven state, and the process proceeds to step S26.

[0044] In step S26, it is determined whether the vibration value detected in step S25 exceeds a threshold value. If it exceeds the threshold value, the process proceeds to step S27. If it is less than the threshold value, the process returns to step S21.

[0045] In step S27, the matched duty ratio is incremented by one step, and the process returns to step S21. In step S21, the duty ratio obtained by incrementing the matched duty ratio by one step is calculated. For example, in the example of graph 8 in FIG. 5, since the resonant duty ratio Rr is in the range of 50% to 70%, if the calculated duty ratio is 50%, a match determination is performed again at 51%, which is an increment of 1%. The increments and match determination are repeated in 1% increments throughout the resonant range. When the resonant duty ratio reaches 71%, the process proceeds to step S23, and the fan is driven. Note that one increment is not limited to 1% and may be set appropriately according to the design specifications. In other words, the control unit 10 drives the cooling fan 32 with a drive signal having a duty ratio that avoids the resonant duty ratio Rr corresponding to the resonant range.

[0046] Steps S25 to S27 are a processing routine designed to prevent resonance when disturbances occur in the installation environment, thereby preventing flickering of the projected image even when the resonance range changes due to the influence of disturbances.

[0047] Furthermore, the above describes the processing flow when increasing the rotation speed of the cooling fan 32, as shown in the rising portion of graph 8 in Fig. 5, but the same can be applied when decreasing the rotation speed. When decreasing the rotation speed of the cooling fan 32, as shown in the falling portion of graph 8 in Fig. 5, it is sufficient to subtract one step from the matched duty ratio in step S27. The other processing is the same.

[0048] As described above, the projector 100 of this embodiment can provide the following effects. Projector 100 as a projection device comprises light source section 21 as a light source, liquid crystal light valve 22 as a light modulation device, projection optical system 23 as a projection section, cooling fan 32 as a fan, control section 10, and housing 99. Cooling fan 32 is equipped with vibration sensor 37, which detects the resonance range in which vibrations resonate in housing 99. Control section 10 drives cooling fan 32 with a drive signal having a duty ratio that avoids resonance duty ratio Rr corresponding to the resonance range in setting the duty ratio of the drive signal that drives cooling fan 32.

[0049] This allows the cooling fan 32 to be driven with a drive signal having a duty ratio that avoids the resonance duty ratio corresponding to the resonance range, thereby suppressing resonance vibration and preventing flickering of the projected image. Furthermore, this configuration is simple and does not require a dedicated actuator as in conventional technology. Therefore, it is possible to provide the projector 100 as a projection device with a simple configuration and with little flicker in the projected image.

[0050] The control unit 10 is also provided with a storage unit 11, and the resonance range is acquired in advance in the environment in which the housing 99 is installed, and is stored in the storage unit 11 as a resonance duty ratio. This makes it possible to drive the cooling fan 32 in a way that does not cause resonance in the installation environment, and makes it possible to provide a projector 100 that produces a projected image with little flicker.

[0051] The projection optical system 23 also includes an optical path shift unit 25 as a drive mechanism that drives the liquid crystal light valve 22 as a light modulation device in a direction perpendicular to the optical axis of the light incident thereon. This makes it possible to suppress resonant vibrations and prevent flickering of the projected image, even if the projector 100 includes the light path shift section 25 that is susceptible to vibrations.

[0052] The resonance range is detected including vibrations occurring when the optical path shifter 25 serving as the drive mechanism is driven. According to this, the resonance duty ratio corresponding to the resonance range is measured in a state where the drive vibration of the light path shift section 25 is taken into account, so that the resonance vibration can be more reliably suppressed.

[0053] Embodiment 2 ***Earthquake Alert Display*** This will be explained using Figure 1. In the above embodiment, the vibration sensor 37 is described as being used to measure the resonance range, but this is not limited to this, and for example, the vibration sensor 37 may be used to detect earthquakes. Hereinafter, the same parts as in the above embodiment will be assigned the same reference numerals, and duplicated explanations will be omitted.

[0054] In this embodiment, when the control unit 10 determines that a change in the vibration detection value of the vibration sensor 37 is due to an earthquake, the control unit 10 causes the OSD processing unit 15 to superimpose earthquake alert information and display it on the projected image. Earthquake waveform patterns are pre-stored in the memory unit 11 and can be collated. The OSD memory of the OSD processing unit 15 stores alert information such as, "Emergency! An earthquake has just occurred. Please ensure your safety." In other words, when the detection signal of the vibration sensor 37 contains an earthquake waveform, the control unit 10 projects an alert image.

[0055] As described above, according to the projector 100 of this embodiment, in addition to the effects of the above-described embodiment, the following effects can be obtained. When the detection signal from the vibration sensor 37 contains an earthquake waveform, the control unit 10 of the projector 100 projects an alert image. This makes it possible to provide the projector 100 as a projection device capable of projecting earthquake alert information when an earthquake occurs.

[0056] ***Summary of this disclosure*** The following is a summary of this disclosure. (Appendix 1) The projector includes a light source, a light modulation device, a projection unit, a fan, a control unit, and a housing. The fan is equipped with a vibration sensor, The vibration sensor detects a resonance range in which vibration resonates in the housing; The control unit sets a duty ratio of a drive signal that drives the fan by: The fan is driven by the drive signal having a duty ratio that avoids a resonance duty ratio that corresponds to the resonance range. Projection equipment.

[0057] This allows the fan to be driven with a drive signal with a duty ratio that avoids the resonance duty ratio corresponding to the resonance range, thereby suppressing resonance vibration and preventing flickering in the projected image. Furthermore, unlike conventional technology, this is a simple configuration that does not require a dedicated actuator. Therefore, it is possible to provide a projection device with a simple configuration and with little flicker in the projected image.

[0058] (Appendix 2) The control unit is provided with a memory unit, The resonance range is acquired in advance in an environment in which the housing is installed and is stored in the storage unit as a resonance duty ratio. 2. The projection device of claim 1.

[0059] This makes it possible to drive the fan in a way that does not cause resonance in the installation environment, and provides a projection device with less flickering in the projected image.

[0060] (Appendix 3) the projection unit includes a drive mechanism that drives the light in a direction perpendicular to the optical axis of the light entering the light modulation device; 3. The projection device according to claim 1 or 2.

[0061] This makes it possible to suppress resonant vibrations and prevent flickering of the projected image, even if the projection device is equipped with a light path shift device that is susceptible to vibrations.

[0062] (Appendix 4) The resonance range is detected to include vibrations occurring when the drive mechanism is driven. 4. The projection device according to any one of claims 1 to 3.

[0063] According to this, the resonance duty ratio corresponding to the resonance range is measured in a state where the drive vibration of the light path shift device is taken into account, so that the resonance vibration can be more reliably suppressed.

[0064] (Appendix 5) The control unit When the detection signal of the vibration sensor includes a seismic waveform, Project an alert image, A projection device according to any one of Supplementary Notes 1 to 4.

[0065] This makes it possible to provide a projection device that can project earthquake alert information when an earthquake occurs.

[0066] (Appendix 6) A control method for a projection device including a light source, a light modulation device, a projection unit, a fan, and a housing, comprising: The fan is equipped with a vibration sensor, measuring a resonance range in which vibration resonates in the housing; and driving the fan by a drive signal having a duty ratio that avoids a resonance duty ratio corresponding to the resonance range, in setting a duty ratio of the drive signal that drives the fan. A method for controlling a projection device.

[0067] This control method drives the fan with a drive signal with a duty ratio that avoids the resonance duty ratio corresponding to the resonance range, thereby suppressing resonance vibration and preventing flickering in the projected image. Furthermore, the projection device does not require a dedicated actuator as in conventional technology, and has a simple configuration. Therefore, it is possible to provide a method for controlling a projection device that reduces flicker in the projected image. [Explanation of symbols]

[0068] 8...Graph, 10...Control unit, 11...Memory unit, 12...IF unit, 13...Image information input unit, 14...Image information processing unit, 15...OSD processing unit, 17...Operation signal receiving unit, 18...Operation unit, 21...Light source unit, 22...Liquid crystal light valve, 22R...Liquid crystal light valve, 22G...Liquid crystal light valve, 22B...Liquid crystal light valve, 23...Projection optical system, 24...Light valve driving unit, 25...Light path shift unit, 28...Optical device , 31...intake fan, 31d...fan drive unit, 32...cooling fan, 32d...fan drive unit, 33...exhaust fan, 33d...fan drive unit, 35...temperature detection unit, 36...temperature detection unit, 37...vibration sensor, 37c...vibration detection circuit, 99...housing, 100...projector, F1...first direction, F2...second direction, P1...image display position, P2...image display position, P3...image display position, P4...image display position.

Claims

1. The projector includes a light source, a light modulation device, a projection unit, a fan, a control unit, and a housing. The fan is equipped with a vibration sensor, The vibration sensor detects a resonance range in which vibration resonates in the housing; The control unit sets a duty ratio of a drive signal that drives the fan by: driving the fan with the drive signal having a duty ratio that avoids a resonance duty ratio corresponding to the resonance range; Projection equipment.

2. The control unit is provided with a memory unit, The resonance range is acquired in advance in an environment in which the housing is installed and is stored in the storage unit as a resonance duty ratio.

2. The projection device according to claim 1.

3. the projection unit includes a drive mechanism that drives the light in a direction perpendicular to the optical axis of the light entering the light modulation device; 3. The projection device according to claim 2.

4. The resonance range is detected to include vibrations occurring when the drive mechanism is driven.

4. The projection device according to claim 3.

5. The control unit When the detection signal of the vibration sensor includes a seismic waveform, Project an alert image, 3. The projection device according to claim 2.

6. A control method for a projection device including a light source, a light modulation device, a projection unit, a fan, and a housing, comprising: The fan is equipped with a vibration sensor, measuring a resonance range in which vibration resonates in the housing; and driving the fan by a drive signal having a duty ratio that avoids a resonance duty ratio corresponding to the resonance range, in setting a duty ratio of the drive signal that drives the fan. A method for controlling a projection device.

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