Projector

Abstract

To provide a projector that can efficiently drive a fan to maintain cooling performance, while preventing shaking of a projection image.SOLUTION: A projector of the present invention comprises: a light source device; an image forming device that modulates light from the light source device to form image light; a projection optical device that projects the image light; an external housing; a fan that cools the inside of the external housing or a heat source; and a control unit that drives the fan under pulse-width modulation control on the basis of a drive parameter regulating the relationship between a duty ratio of pulse-width modulation and the number of rotations. The projector has a characteristic frequency, and the control unit drives the fan to remove a duty ratio that overlaps a resonance band corresponding to the characteristic frequency.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a projector. [Background technology]

[0002] In recent years, there has been a demand for projectors with higher brightness due to the trend toward higher image quality and larger screens for projection mapping, etc. As a result, the temperatures of heat sources such as image forming devices including panels, light sources, and power supplies in projectors become higher, making it necessary to improve the cooling performance of fans used as cooling devices.

[0003] On the other hand, vibrations caused by the operation of the cooling device fan are transmitted to the projection lens, causing vibrations in the projected image and leading to a deterioration in image quality. For example, in the projector disclosed in Patent Document 1 below, in order to suppress vibrations in the projected image, the fan is driven at a rotation speed that avoids resonating with the natural frequency of the projector. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-211492 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above projectors, the range of rotation speeds at which the fan is driven is limited, making it difficult to fully utilize the cooling performance of the fan. Therefore, there is a need for a new technology that can maintain cooling performance by efficiently driving the fan while suppressing shaking of the projected image. [Means for solving the problem]

[0006] In order to solve the above problems, according to one aspect of the present invention, there is provided a projector including a light source device, an image forming device that modulates light from the light source device to form image light, a projection optical device that projects the image light, an exterior housing, a fan that cools the inside of the exterior housing or a heat source, and a control device that drives the fan by pulse width modulation control based on drive parameters defining the relationship between the duty ratio and the rotation speed of pulse width modulation. The projector has a natural frequency, and the control device drives the fan so as to exclude the duty ratio overlapping a resonance band corresponding to the natural frequency.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each of the following drawings, for ease of viewing each component, the scale of the dimensions may be shown differently depending on the component.

[0009] (First Embodiment) FIG. 1 is a diagram showing the configuration of the projector of the present embodiment. The projector 1 of the present embodiment modulates the illumination light emitted from the light source device 2 to generate image light corresponding to the image information, and enlarges and projects the formed image light onto a projection surface such as a screen. As shown in FIG. 1, the projector 1 includes a light source device 2, an image forming device 3, a projection optical device 4, an exterior housing 5, a cooling device 6, and a power supply device 14.

[0010] In the following description, an XYZ orthogonal coordinate system is used as necessary. In each drawing, the X-axis is an axis along the optical axis AX1 of the illumination light WL emitted from the light source device 2 toward the image forming device 3. The Y-axis is orthogonal to the X-axis and is the direction in which the projection optical device 4 projects the image light, that is, an axis along the optical axis AX2 of the projection optical device 4. The Z-axis is an axis orthogonal to the optical axis AX1 and the optical axis AX2. Also, in the present embodiment, the direction along the Z-axis is referred to as the "vertical direction Z", +Z is referred to as the "upper side", -Z is referred to as the "lower side", the direction along the X-axis is referred to as the "left-right direction X", +X is referred to as the "right side", -X is referred to as the "left side", and the direction along the Y-axis is referred to as the "front-rear direction Y", +Y is referred to as the "front side", and -Y is referred to as the "rear side" for explanation. Note that the vertical direction Z, the left-right direction X, and the front-rear direction Y are merely names for explaining the arrangement relationship of the respective components of the projector 1, and do not define the actual installation posture or direction in the projector 1.

[0011] The light source device 2 supplies white illumination light WL to the image forming unit 3A of the image forming device 3. The light source device 2 is connected to a light source connection portion 10a provided in the case 10.

[0012] The light source connection part 10a is composed of, for example, a window part having translucency. Note that the light source connection part 10a may be an opening formed in the case 10 as long as it can seal the inside of the case 10 when the light source device 2 is connected. Based on such a configuration, the image forming apparatus 3 of the present embodiment can make the illumination light WL from the light source device 2 enter the light modulation panels 32R, 32G, and 32B through the light source connection part 10a of the case 10.

[0013] The image forming apparatus 3 is configured by accommodating at least the image forming part 3A, the heat exchanger 7 for panel heat absorption, and the panel fan 16 in a sealed state in a case 10 having a sealed structure. The case 10 accommodates the image forming part 3A, the heat exchanger 7 for panel heat absorption, and the panel fan 16 while holding them in predetermined positions. The image forming apparatus 3 is configured by arranging and accommodating the image forming part 3A, the heat exchanger 7 for panel heat absorption, and the panel fan 16 in the case 10 in order from the front side (+Y side) to the rear side (-Y side).

[0014] The heat exchanger 7 for panel heat absorption is arranged in the case 10 of the image forming apparatus 3 so as to partition the accommodation space that is the accommodation part of the image forming part 3A and the accommodation space that is the accommodation part of the panel fan 16. In the case of the present embodiment, the heat exchanger 7 for panel heat absorption is arranged along the left - right direction so as to divide the space inside the case 10 into two in the front - rear direction Y along the optical axis AX2.

[0015] Inside the case 10 of the image forming apparatus 3, the image forming part 3A, the heat exchanger 7 for panel heat absorption, and the panel fan 16 are arranged in the front - rear direction Y, and the heat exchanger 8 for panel heat radiation extends along the front - rear direction Y.

[0016] The image forming part 3A includes the light modulation panels 32R, 32G, 32B and the cross - dichroic prism 34. Each of the light modulation panels 32R, 32G, 32B modulates the incident color light according to the image information to form image light. Each of the light modulation panels 32R, 32G, 32B is composed of a light - transmissive liquid crystal panel.

[0017] The light modulation panel 32R is a liquid crystal panel for red corresponding to the red light LR, the light modulation panel 32G is a liquid crystal panel for green corresponding to the green light LG, and the light modulation panel 32B is a liquid crystal panel for blue corresponding to the blue light LB.

[0018] The cross-dichroic prism 34 synthesizes the respective image lights emitted from the light modulation panels 32R, 32G, and 32B. The cross-dichroic prism 34 has a substantially square shape in plan view formed by bonding four right-angled prisms, and a dielectric multilayer film is provided on a substantially X-shaped interface where the right-angled prisms are bonded to each other. Based on such a configuration, the image forming unit 3A of the present embodiment generates full-color image light by synthesizing the image lights of each color.

[0019] In the present embodiment, field lenses 33R, 33G, and 33B are provided on the light incident sides of the light modulation panels 32R, 32G, and 32B, respectively. Although not shown, an incident-side polarizing plate is disposed between each of the light modulation panels 32R, 32G, and 32B and each of the field lenses 33R, 33G, and 33B, and an emission-side polarizing plate is disposed between each of the light modulation panels 32R, 32G, and 32B and the cross-dichroic prism 34.

[0020] In the present embodiment, the image forming apparatus 3 further includes a uniform illumination optical system 30 and a color separation light guiding optical system 31 housed in the case 10. The case 10 houses the uniform illumination optical system 30 and the color separation light guiding optical system 31 while holding them in predetermined positions.

[0021] The illumination light WL emitted from the light source device 2 enters the uniform illumination optical system 30. The uniform illumination optical system 30 includes a first lens array 301, a second lens array 302, a polarization conversion element 303, and a superposition lens 304.

[0022] The first lens array 301 includes a plurality of first small lenses for dividing the illumination light WL from the light source device 2 into a plurality of partial light beams. The plurality of first small lenses are arranged in a matrix in a plane orthogonal to the optical axis AX1 of the illumination light WL.

[0023] The second lens array 302 includes a plurality of second small lenses corresponding to the plurality of first small lenses of the first lens array 301. The plurality of second small lenses are arranged in a matrix in a plane orthogonal to the optical axis AX1.

[0024] The second lens array 302, together with the superimposing lens 304, forms an image of each first small lens of the first lens array 301 near the image formation regions of the light modulation panels 32R, 32G, and 32B, respectively.

[0025] The polarization conversion element 303 converts the light emitted from the second lens array 302 into one linearly polarized light. The polarization conversion element 303 has, for example, a polarization separation film and a retardation plate (not shown).

[0026] The superimposing lens 304 condenses each partial light beam emitted from the polarization conversion element 303 and superimposes them near the image formation regions of the light modulation panels 32R, 32G, and 32B, respectively.

[0027] The color separation light guiding optical system 31 separates the illumination light WL that has passed through the uniform illumination optical system 30 into red light LR, green light LG, and blue light LB, and guides them to the respective light modulation panels 32R, 32G, and 32B. The color separation light guiding optical system 31 includes a first dichroic mirror 311, a second dichroic mirror 312, a first reflection mirror 313, a second reflection mirror 314, a third reflection mirror 315, a first relay lens 316, and a second relay lens 317.

[0028] The first dichroic mirror 311 reflects the red light LR and transmits the green light LG and the blue light LB. The second dichroic mirror 312 reflects the green light LG out of the green light LG and the blue light LB that have passed through the first dichroic mirror 311 and transmits the blue light LB. The first reflecting mirror 313 reflects the red light LR. The second reflecting mirror 314 and the third reflecting mirror 315 reflect the blue light LB. The first relay lens 316 is disposed between the second dichroic mirror 312 and the second reflecting mirror 314, and the second relay lens 317 is disposed between the second reflecting mirror 314 and the third reflecting mirror 315.

[0029] The projection optical device 4 is detachably connected to a projection connection portion 10b provided in the case 10. The projection optical device 4 is composed of a projection lens group, and light from each of the light modulation panels 32R, 32G, and 32B of the image forming unit 3A is incident through the projection connection portion 10b of the case 10.

[0030] The projection connection portion 10b is constituted by, for example, a window portion having translucency. Note that the projection connection portion 10b may be an opening formed in the case 10 as long as it is configured to be able to seal the inside of the case 10 when the projection optical device 4 is connected. Further, the projection connection portion 10b may be provided with a lens shift mechanism that shifts the optical axis AX2 of the projection optical device 4.

[0031] Based on such a configuration, the image forming apparatus 3 of the present embodiment can enlarge and project the image light generated by the image forming apparatus 3 toward a projection surface such as a screen through the projection connection portion 10b of the case 10. As a result, an enlarged color image is displayed on the screen.

[0032] The exterior housing 5 houses the light source device 2, the image forming device 3, the cooling device 6, and the power supply device 14 inside and constitutes the exterior of the projector 1.

[0033] In the projector 1 of this embodiment, a plurality of heat sources are arranged inside the exterior housing 5. For example, the first heat source is the light modulation panels 32R, 32G, and 32B in the image forming device 3, and the second heat source is the light source device 2. The projector 1 of this embodiment includes a cooling device 6 for cooling the heat generated by the above heat sources.

[0034] The cooling device 6 of this embodiment includes a light source heat absorption heat exchanger 25 that absorbs the heat generated by the light source device 2, a panel heat absorption heat exchanger 7 that absorbs the heat generated by the light modulation panels 32R, 32G, and 32B, a light source heat dissipation heat exchanger 9 that dissipates the heat transmitted from the light source heat absorption heat exchanger 25, a panel heat dissipation heat exchanger 8 that dissipates the heat transmitted from the panel heat absorption heat exchanger 7, and a plurality of fans F inside the exterior housing 5 or for cooling the heat sources. The plurality of fans F include a panel fan 16, a heat exchanger fan 17 that sends an air flow to the panel heat dissipation heat exchanger 8 and the light source heat dissipation heat exchanger 9, and an exhaust heat fan 13. In this embodiment, the panel fan 16 corresponds to the "first fan" described in the claims, and the heat exchanger fan 17 corresponds to the "second fan" described in the claims.

[0035] In the projector 1 of this embodiment, the light modulation panels 32R, 32G, and 32B that generate heat are cooled by sending an air flow using the panel fan 16. In this embodiment, a plurality of panel fans 16 are provided inside the case 10. The plurality of panel fans 16 include three fans 16a, 16b, and 16c. The fan 16a sends an air flow to the light modulation panel 32R, the fan 16b sends an air flow to the light modulation panel 32G, and the fan 16c sends an air flow to the light modulation panel 32B.

[0036] Each of the fans 16a, 16b, and 16c that constitute the panel fan 16 is arranged in a plurality in the left - right direction X along the panel heat absorption heat exchanger 7. The air flow of each of the fans 16a, 16b, and 16c flows to the light modulation panels 32R, 32G, and 32B of the image forming unit 3A through a duct (not shown) provided between the panel heat absorption heat exchanger 7 and the image forming unit 3A and the exterior housing 5.

[0037] In this embodiment, each of the fans 16a, 16b, and 16c is arranged on the rear side (-Y) of the panel heat-absorbing heat exchanger 7. Therefore, the airflow heated by cooling the light modulation panels 32R, 32G, and 32B passes through the panel heat-absorbing heat exchanger 7 and is suctioned again by each of the fans 16a, 16b, and 16c. The panel heat-absorbing heat exchanger 7 absorbs heat from the airflow heated by the light modulation panels 32R, 32G, and 32B.

[0038] The panel heat-absorbing heat exchanger 7 is composed of a radiator. The panel heat-absorbing heat exchanger 7 is a heat exchanger that absorbs heat from the airflow by exchanging heat between the heat exchange liquid flowing into the interior and the airflow. The heat exchange liquid flowing through the radiator heated by absorbing heat from the airflow is supplied to the panel heat-radiating heat exchanger 8 via a cooling flow path (not shown).

[0039] The panel heat-radiating heat exchanger 8 radiates heat from the heat exchange liquid supplied from the panel heat-absorbing heat exchanger 7. In this embodiment, the panel heat-radiating heat exchanger 8 is composed of a radiator. The panel heat-radiating heat exchanger 8 is a heat exchanger that radiates heat from the heat exchange liquid by exchanging heat between the airflow K and the heat exchange liquid flowing into the interior. The heat exchange liquid cooled by the panel heat-radiating heat exchanger 8 is supplied again to the panel heat-absorbing heat exchanger 7 via the cooling flow path and is used for heat exchange with the airflow heated by the light modulation panels 32R, 32G, and 32B.

[0040] Thus, according to the image forming apparatus 3 of this embodiment, when circulating the airflow K to the light modulation panels 32R, 32G, and 32B housed in the sealed space, by reducing the temperature of the airflow via the panel heat-absorbing heat exchanger 7, the light modulation panels 32R, 32G, and 32B can be efficiently cooled. Further, the image forming apparatus 3 of this embodiment can suppress the occurrence of problems such as a decrease in display quality due to adhesion of dust, foreign matter, etc. by housing the light modulation panels 32R, 32G, and 32B in the sealed space.

[0041] In the projector 1 of the present embodiment, the light source device 2 includes, for example, a solid light source that emits blue laser light as excitation light, and a wavelength conversion element that converts at least a part of the blue light emitted from the solid light source into fluorescence including green light and red light. The solid light source that emits laser light becomes hot. Therefore, in the light source device 2 of the present embodiment, the light source device 2 is cooled by providing a heat exchanger 25 for light source heat absorption to absorb heat from the solid light source.

[0042] The heat exchange liquid flowing in the radiator heated by absorbing heat from the solid light source of the light source device 2 is supplied to the heat exchanger 9 for light source heat dissipation through a cooling flow path (not shown). The heat exchanger 9 for light source heat dissipation reduces the temperature of the heat exchange liquid by dissipating the heat absorbed by the heat exchanger 25 for light source heat absorption. In the present embodiment, the heat exchanger 9 for light source heat dissipation is constituted by a radiator. The heat exchanger 9 for light source heat dissipation is a heat exchanger that absorbs heat from the air flow by exchanging heat with the air flow through the heat exchange liquid flowing into the interior. The heat exchange liquid whose temperature has been lowered by being cooled by the heat exchanger 9 for light source heat dissipation is supplied again to the heat exchanger 25 for light source heat absorption through the cooling flow path.

[0043] According to the projector 1 of the present embodiment, by circulating the heat exchange liquid between the heat exchanger 25 for light source heat absorption and the heat exchanger 9 for light source heat dissipation, the cooling efficiency in the heat exchanger 25 for light source heat absorption can be enhanced. Therefore, the light source device 2 can be cooled stably and efficiently.

[0044] In the cooling device 6, the heat exchanger 8 for panel heat dissipation and the heat exchanger 9 for light source heat dissipation overlap in the flow direction of the air flow K, and the air flow K flows from the heat exchanger 8 for panel heat dissipation toward the heat exchanger 9 for light source heat dissipation.

[0045] In the projector 1 of the present embodiment, the temperature of the heat generated by the light source device 2 is higher than the temperature of the heat generated by the image forming device 3. In the case of the present embodiment, since the air flow K flows through the heat exchanger 8 for panel heat dissipation first, the cooling efficiency of each of the light modulation panels 32R, 32G, and 32B can be improved.

[0046] The exterior housing 5 includes a front surface portion 51, a rear surface portion 52, a left side surface portion 53, a right side surface portion 54, a top surface portion 55, and a bottom surface portion 56. The exterior housing 5 is formed, for example, in a substantially rectangular parallelepiped shape. In FIG. 1, in order to show the internal structure of the exterior housing 5, the top surface portion 55 is illustrated as a transparent member.

[0047] The front surface portion 51 is located on the front side (+Y) in the front-rear direction Y and is a plate-like portion along the XZ plane. The rear surface portion 52 is located on the rear side (-Y) in the front-rear direction Y and is a plate-like portion along the XZ plane. The left side surface portion 53 is located on the left side (-X) in the left-right direction X and is a plate-like portion along the YZ plane. The right side surface portion 54 is located on the right side (+X) in the left-right direction X and is a plate-like portion along the YZ plane. The top surface portion 55 connects the upper side (+Z) ends of the front surface portion 51, the rear surface portion 52, the left side surface portion 53, and the right side surface portion 54 to each other and is a plate-like portion along the XY plane. The bottom surface portion 56 connects the lower side (-Z) ends of the front surface portion 51, the rear surface portion 52, the left side surface portion 53, and the right side surface portion 54 to each other and is a plate-like portion along the XY plane.

[0048] The front surface portion 51 has an opening 51a provided substantially at the center. The projection optical device 4 is inserted into the exterior housing 5 through the opening 51a and is connected to the image forming device 3. In the case of this embodiment, the front end portion of the projection optical device 4 protrudes outside the exterior housing 5 through the opening 51a, but the front end portion of the projection optical device 4 may be located inside the exterior housing 5 rather than the opening 51a.

[0049] In this embodiment, the image forming device 3, the heat exchanger 8 for panel heat dissipation, and the heat exchanger 9 for light source heat dissipation are arranged in one direction along the X axis so as to overlap each other.

[0050] The bottom surface portion 56 of the exterior housing 5 includes an air inlet 56a and an air inlet 56b. The intake port 56a is provided on the bottom surface portion 56 at a position facing the space between the panel heat exchanger 8 located on the image forming apparatus 3 side among the panel heat exchanger 8 and the light source heat exchanger 9 and the image forming apparatus 3, and takes in outside air into the exterior housing 5. The intake port 56b is provided on the bottom surface portion 56 at a position facing the space between the panel heat exchanger 8 and the light source heat exchanger 9, and takes in outside air into the exterior housing 5. Note that the intake port 56b may be integrally formed with the intake port 56a. That is, a part of the intake port 56a may extend to a position facing the space between the panel heat exchanger 8 and the light source heat exchanger 9.

[0051] The rear surface portion 52 of the exterior housing 5 includes an intake port 52a. The intake port 52a is provided at a position facing the space between the panel heat exchanger 8 and the image forming apparatus 3, similar to the intake port 56a, and takes in outside air as an air flow K into the exterior housing 5. In the case of this embodiment, the intake port 52a extends to a position facing the space between the panel heat exchanger 8 and the light source heat exchanger 9.

[0052] The front surface portion 51 of the exterior housing 5 further includes an intake port 51b. The intake port 51b is provided at a position facing the space between the panel heat exchanger 8 and the image forming apparatus 3, similar to the intake ports 56a and 52a, and takes in outside air as an air flow K into the exterior housing 5. In the case of this embodiment, the intake port 51b extends to a position facing the space between the panel heat exchanger 8 and the light source heat exchanger 9.

[0053] Based on such a configuration, the heat exchanger fan 17 can efficiently take in the air flow K into the exterior housing 5 through the intake port 51b, the intake port 52a, the intake port 56a, and the intake port 56b. Note that a filter for collecting dust contained in the air flow K may be provided for each of the intake ports 51b, 52a, 56a, and 56b.

[0054] The fans 17 for the heat exchanger are arranged in parallel in the Y-axis direction between the heat exchanger 8 for panel heat dissipation and the left side surface 53 of the exterior housing 5. The left side surface 53 has an exhaust port 53a provided at a position facing the heat exchanger 8 for panel heat dissipation. The exhaust port 53a discharges the exhaust air inside the exterior housing 5 by the fans 17 for the heat exchanger to the outside.

[0055] In the case of this embodiment, since the heat exchanger 9 for light source heat dissipation is arranged between the left side surface 53 and the heat exchanger 8 for panel heat dissipation, the air flow K sucked from the intake ports 52a and 56a by the fans 17 for the heat exchanger flows to the exhaust port 53a through the heat exchanger 8 for panel heat dissipation and the heat exchanger 9 for light source heat dissipation.

[0056] The right side surface 54 has an intake port 54a and an exhaust port 54b. The intake port 54a is provided at a position facing the light source device 2 and takes in outside air at a predetermined position of the light source device 2. A filter for collecting dust contained in the air passing through the intake port 54a may be provided. The exhaust port 54b is provided at a position facing the exhaust fan 13 for heat removal. The exhaust fan 13 for heat removal discharges heat from inside the exterior housing 5 to the outside through the exhaust port 54b, thereby cooling the inside of the exterior housing 5.

[0057] Here, the layout of each member housed inside the exterior housing 5 will be described. The light source device 2 is arranged inside the exterior housing 5 on the right side (+X side), which is one side in the left-right direction X intersecting the optical axis AX2 of the projection optical device 4, with respect to the image forming device 3. The heat exchanger 8 for panel heat dissipation is arranged inside the exterior housing 5 on the left side (-X), which is the other side in the left-right direction X, with respect to the image forming device 3. The heat exchanger 8 for panel heat dissipation extends along the front-rear direction Y.

[0058] The heat exchanger 9 for heat dissipation of the light source is arranged on the left side (-X side) in the left-right direction X with respect to the image forming apparatus 3 within the exterior housing 5. The heat exchanger 9 for heat dissipation of the light source extends along the front-back direction Y. That is, in the present embodiment, the heat exchanger 8 for panel heat dissipation and the heat exchanger 9 for heat dissipation of the light source are arranged on the left side (-X side) of the image forming apparatus 3 within the exterior housing 5.

[0059] The power supply device 14 is arranged on the right side (+X) with respect to the case 10 of the image forming apparatus 3 within the exterior housing 5. The power supply device 14 supplies power to the light source device 2 and the image forming unit 3A. The power supply device 14 is arranged within the exterior housing 5 so as to overlap at least a part of the light source device 2 in the up-down direction Z that intersects the front-back direction Y and the left-right direction X along the optical axis AX2. In the case of the present embodiment, the power supply device 14 is arranged below (-Z) the light source device 2.

[0060] According to the projector 1 of the present embodiment, within the exterior housing 5, by arranging the power supply device 14 and the light source device 2 so as to overlap in the up-down direction Z, compared to the layout in which the power supply device 14 and the light source device 2 are arranged side by side in the left-right direction X or the front-back direction Y, the size of the exterior housing 5 when viewed in plan from the up-down direction Z can be reduced. That is, according to the layout of the present embodiment, the footprint of the projector 1 can be reduced.

[0061] Subsequently, the electrical configuration of the projector 1 will be described. FIG. 2 is a block diagram showing the electrical configuration of the projector 1 of the present embodiment. As shown in FIG. 2, the projector 1 of the present embodiment further includes a control device 100 that controls the operation of the projector 1. The control device 100 includes a control unit 101, a storage unit 102, and a drive unit 103.

[0062] The control unit 101 is constituted by a processor such as a CPU (Central Processing Unit), for example. Note that part or all of the functions of the control unit 101 may be constituted by circuits such as a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and an FPGA (Field Programmable Gate Array).

[0063] The control unit 101 performs signal processing on signals input from the outside and acquires information necessary for controlling the light source device 2, the cooling device 6, and the image forming device 3. For example, the control unit 101 outputs control signals for each device required for image generation based on an image signal input from an external device.

[0064] The storage unit 102 includes an HDD (Hard Disk Drive), an SSD (Solid State Drive), an EEPROM (Electrically Erasable Programmable Read Only Memory), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The storage unit 102 stores, for example, various programs, various commands, various information, etc. that the projector 1 processes during operation. The control unit 101 reads predetermined information from the storage unit 102 and outputs control signals for each device to the drive unit 103. The drive unit 103 generates drive signals for each of the light source device 2, the cooling device 6, and the image forming device 3 based on the control signals output from the control unit 101.

[0065] In the projector 1 of the present embodiment, the control device 100 controls the driving of the plurality of fans F of the cooling device 6 by PWM control using pulse width modulation (PWM). As each fan F, for example, a centrifugal fan or a sirocco fan can be used, but the type of fan is not limited to this.

[0066] Incidentally, the vibration of the fan F is transmitted to the outer housing 5 and the like. Since the rotational speed of the fan F changes according to the situation during driving, there is a possibility that the vibration frequency caused by the fan F overlaps with the natural frequency of the projector 1. Then, the entire projector 1 may vibrate due to resonance, and the projection optical device 4 may shake, which may deteriorate the quality of the projected image.

[0067] On the other hand, in the projector 1 of the present embodiment, the control device 100 drives the fan F by PWM control in which the duty ratio overlapping the resonance band resonating with the natural frequency of the projector 1 is removed. In this specification, the PWM control in which the duty ratio overlapping the resonance band is removed can also be paraphrased as PWM control (hereinafter simply referred to as skip control) that skips the duty ratio overlapping the resonance band. In this specification, the case where the duty ratio overlaps the resonance band may also be referred to as "the duty ratio overlaps the prohibited region".

[0068] Thereby, the projector 1 of the present embodiment can suppress the occurrence of a resonance phenomenon between the projector 1 due to the rotation of each fan F, and can suppress a deterioration in quality due to shaking of the projected image caused by resonance vibration. The projector 1 of the present embodiment performs the above-described skip control for each fan F, but the control device 100 only needs to perform the above-described skip control on at least one of the plurality of fans F, and the other fans F may be driven by normal PWM control.

[0069] Hereinafter, taking the panel fan 16 among the plurality of fans F as an example, the control device 100 will explain the outline of the skip control. In the following description, the panel fan 16 may sometimes be simply referred to as the fan 16. FIG. 3 is a graph schematically showing changes in the duty ratio in the skip control. In FIG. 3, the vertical axis represents the duty ratio, and the horizontal axis represents time.

[0070] In FIG. 3, the fan 16 with a duty ratio input that overlaps the prohibited region A will rotate at a rotational frequency that overlaps the resonance band resonating with the natural frequency of the projector 1. That is, the duty ratio that overlaps the prohibited region A resonates the projector 1 due to the rotation of the fan 16, causing the projected image to shake. The first region A1 is a region with a duty ratio lower than that of the prohibited region A and is a region where resonance due to the rotation of the fan 16 does not occur. Also, the second region A2 is a region with a duty ratio higher than that of the prohibited region A and is a region where resonance due to the rotation of the fan 16 does not occur.

[0071] As shown in FIG. 3, the control device 100 drives the fan 16 while gradually increasing the duty ratio input to the fan 16 from the first region A1 based on the drive parameters that define the relationship between the duty ratio and the rotation speed stored in the storage unit 102 shown in FIG. 2. In the first region A1, the control device 100 drives the fan 16 using normal PWM control, not skip control.

[0072] The duty ratio will eventually reach the lower limit of the prohibited region A. At this time, the control device 100 holds the duty ratio at the boundary value on the lower limit side of the prohibited region A that does not overlap the prohibited region A until the duty ratio required for driving the fan 16 exceeds the prohibited region A. That is, during the prohibited region A, the control device 100 drives the fan 16 with a value lower than the duty ratio required to drive the fan 16. When the duty ratio required to drive the fan 16 exceeds the prohibited region A and reaches the second region A2, the control device 100 drives the fan 16 with the duty ratio at the boundary value on the upper limit side of the prohibited region A that does not overlap the prohibited region A. That is, the control device 100 drives the fan 16 with a duty ratio that skips the prohibited region A.

[0073] Note that when the duty ratio required to drive the fan 16 reaches the lower boundary value of the prohibited region A, the control device 100 skips the duty ratio to the upper boundary value of the prohibited region A that does not overlap with the prohibited region A, and then maintains the duty ratio at the upper boundary value of the prohibited region A until the duty ratio required to drive the fan 16 exceeds the upper boundary value of the prohibited region A. Skip control shown by the dashed line in FIG. 3 may be performed.

[0074] That is, when the input duty ratio overlaps with the prohibited region A, the control device 100 changes the input duty ratio to an input duty ratio that exceeds the prohibited region A, and drives the fan 16 at the changed input duty ratio for a predetermined period. According to this configuration, since the duty ratio is held at a value that skips the prohibited region A, it is possible to reliably prevent a duty ratio that overlaps with the prohibited region A from being input to the fan 16.

[0075] When the input duty ratio input to the fan 16 overlaps with the prohibited region A, the control device 100 holds the input duty ratio at the upper boundary value of the prohibited region A. According to this configuration, since the fan 16 is driven at a value higher than the duty ratio actually required for driving, the cooling capacity of the fan 16 can be increased. Therefore, control of the projector 1 that prioritizes the cooling performance of the cooling device 6 can be realized. Then, the fan 16 is driven by normal PWM control that gradually increases to the target rotational speed in the second region A2.

[0076] Further, for example, when the temperature of the heat source drops and the target rotational speed is set in the first region A1, the control device 100 gradually decreases the rotational speed of the fan 16 while gradually decreasing the duty ratio toward the first region A1 along the drive parameter. That is, in the second region A2, the control device 100 drives the fan 16 by normal PWM control, not skip control.

[0077] The duty ratio will eventually reach the upper limit of the prohibited region A. At this time, the control device 100 maintains the duty ratio at the boundary value on the upper limit side of the prohibited region A that does not overlap with the prohibited region A until the duty ratio required for driving the fan 16 exceeds the prohibited region A. That is, during the prohibited region A, the control device 100 drives the fan 16 at a value higher than the duty ratio required to drive the fan 16. When the duty ratio required to drive the fan 16 reaches the first region A1 beyond the prohibited region A, the control device 100 drives the fan 16 at the duty ratio from the boundary value on the upper limit side of the prohibited region A to the boundary value on the lower limit side of the prohibited region A that does not overlap with the prohibited region A. That is, the control device 100 drives the fan 16 at a duty ratio that skips the prohibited region A. Then, the fan 16 is driven by normal PWM control up to the target rotation speed in the first region A1.

[0078] Note that when the duty ratio required to drive the fan 16 reaches the boundary value on the upper limit side of the prohibited region A, the control device 100 may perform skip control shown by the broken line in FIG. 3, in which the duty ratio is skipped to the boundary value on the lower limit side of the prohibited region A that does not overlap with the prohibited region A, and then the duty ratio is maintained at the boundary value on the lower limit side of the prohibited region A until the duty ratio required to drive the fan 16 exceeds the boundary value on the lower limit side of the prohibited region A.

[0079] One skip control is that when increasing the rotation speed from the first region A1 to the second region A2, when the duty ratio reaches the boundary value on the lower limit side of the prohibited region A, the duty ratio is maintained at the boundary value on the lower limit side of the prohibited region A until the required duty ratio exceeds the prohibited region A, and then the duty ratio is skipped. Thereafter, when decreasing the rotation speed from the second region A2 to the first region A1, when the duty ratio reaches the boundary value on the upper limit side of the prohibited region A, the duty ratio is skipped to the boundary value on the lower limit side of the prohibited region A, and then the duty ratio is maintained at the boundary value on the lower limit side of the prohibited region A until the required duty ratio exceeds the boundary value on the lower limit side of the prohibited region A.

[0080] When increasing the rotational speed from the first region A1 to the second region A2 in other skip controls, when the duty ratio reaches the boundary value on the lower limit side of the prohibited region A, after skipping the duty ratio to the boundary value on the upper limit side of the prohibited region A, the duty ratio is maintained at the boundary value on the upper limit side of the prohibited region A until the required duty ratio exceeds the boundary value on the upper limit side of the prohibited region A. Thereafter, when decreasing the rotational speed from the second region A2 to the first region A1, when the duty ratio reaches the boundary value on the upper limit side of the prohibited region A, it is maintained at the boundary value on the upper limit side of the prohibited region A until the required duty ratio exceeds the boundary value on the lower limit side of the prohibited region A, and then the duty ratio is skipped.

[0081] As described above, when increasing or decreasing the input duty ratio input to the fan 16 based on the drive parameter, when the input duty ratio overlaps with the prohibited region A of the projector 1, the control device 100 of this embodiment maintains the input duty ratio at the boundary value of the prohibited region A until the input duty ratio exceeds the prohibited region A. Therefore, since the control device 100 does not drive the fan 16 at a duty ratio that resonates with the natural frequency of the projector 1, it is possible to suppress the shaking of the projected image.

[0082] Subsequently, the skip control by the control device 100 will be described in detail. Hereinafter, the control in the area surrounded by the reference symbol E in FIG. 3, that is, the case of skipping from the first region A1 to the prohibited region A and reaching the second region A2 when the duty ratio increases will be described.

[0083] FIG. 4 is a diagram showing the operation flow of the fan. As shown in FIG. 4, in step S1, the control device 100 reads out the initial value of the internal duty ratio as a drive parameter used for internal calculation from the storage unit 102 shown in FIG. 2 together with the activation of the projector 1. The control device 100 sets the initial value of the internal duty ratio when driving the fan 16. The drive parameter is selected from activation modes such as, for example, drive parameters in the normal mode, drive parameters in the highland mode, and drive parameters for the silent mode.

[0084] Subsequently, in step S2, the fan 16 is started based on the internal duty ratio set by the drive parameter.

[0085] Subsequently, the control device 100 determines, in step S3, whether the internal duty ratio of the fan 16 overlaps with the prohibited region of the projector 1. If the internal duty ratio of the fan 16 overlaps with the prohibited region, a resonance phenomenon of the projector 1 will occur due to the rotation of the fan 16.

[0086] If the control device 100 determines that the internal duty ratio does not overlap with the prohibited region (when step S3 is NO), it proceeds to step S4. In step S4, the control device 100 detects the actual rotation speed of the fan 16. Hereinafter, the actual rotation speed of the fan 16 is referred to as the actual rotation speed.

[0087] In step S5, the control device 100 reads out the latest target rotation speed of the fan 16. Specifically, the control device 100 acquires the temperature of the optical modulation panel 32R again and calculates the latest target rotation speed of the fan 16.

[0088] In step S6, the control device 100 determines whether the rotation speed of the fan 16 detected in step S4 has reached the target rotation speed. If the control device 100 determines, based on the determination in step S6, that the actual rotation speed of the fan 16 has not reached the target rotation speed (when step S6 is NO), it proceeds to step S7. In step S7, the control device 100 increases the internal duty ratio by a predetermined amount toward the target rotation speed of the fan 16. In the case of this embodiment, the control device 100 increases the internal duty ratio by, for example, 2%. Thereby, the control device 100 increases the rotation speed of the fan 16 and proceeds to step S9. That is, in step S7, the control device 100 adjusts the rotation speed of the fan 16 toward the target rotation speed by increasing the internal duty ratio through internal calculation. In this way, the control device 100 can realize control to bring the rotation speed of the fan 16 close to the target rotation speed by using the internal duty ratio.

[0089] The control device 100 determines, in step S9, whether the internal duty ratio set in step S7 overlaps with the prohibited region. If the control device 100 determines, based on the determination in step S9, that the internal duty ratio does not overlap with the prohibited region (when step S9 is NO), it proceeds to step S10. In step S10, the control device 100 sets the internal duty ratio to the duty ratio actually input to the fan 16 (hereinafter referred to as the actual duty ratio), and drives the fan 16 at the actual duty ratio. Then, the control device 100 proceeds to step S12. In this description, the actual duty ratio corresponds to the "input duty ratio" in the claims.

[0090] That is, in steps S9 and S10, the control device 100 compares the internal duty ratio with the prohibited region, and until the internal duty ratio overlaps with the prohibited region, it sets the internal duty ratio to the input duty ratio and drives the fan 16. Thereby, the control device 100 can increase the rotation speed of the fan 16 by increasing the duty ratio until it overlaps with the prohibited region.

[0091] Subsequently, in step S12, the control device 100 determines whether to stop driving the fan 16 after the process of step S10. As a case where the driving of the fan is stopped, for example, the case where the power of the projector 1 is turned off can be considered. If the control device 100 determines, in step S12, to stop driving the fan 16 (when step S12 is YES), it ends the control of the fan 16.

[0092] On the other hand, if the control device 100 determines, based on the determination in step S12, not to stop driving the fan 16 (when step S12 is NO), it returns to step S3. When returning from step S12 to step S3, the control device 100 reads out the internal duty ratio used for the determination in step S9.

[0093] The control device 100 controls the driving of the fan 16 based on the actual duty ratio reflecting the internal duty ratio while updating the internal duty ratio toward the target rotation speed by repeating each of the above steps, for example, every second. Thereby, the control device 100 increases the rotation speed of the fan 16.

[0094] For example, as the rotation speed of the fan 16 increases, there may be a case where the fan 16 reaches the target rotation speed before the duty ratio overlaps with the prohibited region. At this time, when the control device 100 determines, based on the determination in step S6, that the actual rotation speed of the fan 16 has reached the target rotation speed (when step S6 is YES), the control device 100 proceeds to step S8. In step S8, the control device 100 maintains the internal duty ratio. The control device 100 proceeds from step S9 to step S10, sets the internal duty ratio as the actual duty ratio, and drives the fan 16.

[0095] On the other hand, as the internal duty ratio increases by 2% at a time in step S7, the control device 100 determines, based on the determination in step S9, that the internal duty ratio overlaps with the prohibited region (when step S9 is YES), and proceeds to step S11. In step S11, the control device 100 does not set the internal duty ratio as the actual duty ratio. Therefore, the actual duty ratio of the fan 16 is not updated and remains at a constant value. In the case of this embodiment, when the control device 100 determines that the internal duty ratio of the fan 16 overlaps with the prohibited region, the actual duty ratio is held at the duty ratio before overlapping with the prohibited region.

[0096] When the internal duty ratio overlaps with the prohibited region, in step S3, the control device 100 determines that the internal duty ratio overlaps with the prohibited region (when step S3 is YES), and proceeds to step S13. In step S13, the control device 100 sets the virtual rotation speed corresponding to the internal duty ratio of the fan 16, and proceeds to step S14.

[0097] In step S14, the control device 100 reads the latest target rotation speed of the fan 16. Specifically, the control device 100 acquires the temperature of the optical modulation panel 32R again, calculates the latest target rotation speed of the fan 16, and proceeds to step S15.

[0098] If, based on the determination in step S15, the control device 100 determines that the virtual rotation speed of the fan 16 has not reached the target rotation speed (when step S15 is No), it proceeds to step S16. In step S16, the control device 100 increases the internal duty ratio by a predetermined amount toward the target rotation speed of the fan 16 and proceeds to step S9. In the case of this embodiment, the control device 100 increases the internal duty ratio by 2%. Thereby, the control device 100 increases the rotation speed of the fan 16 and proceeds to step S9.

[0099] Steps S13 to S17 described above are arithmetic processes that the control device 100 performs on the internal duty ratio when the internal duty ratio overlaps the prohibited region. Therefore, the actual duty ratio for actually driving the fan 16 is controlled based on the actual duty ratio held in step S11.

[0100] FIG. 5 shows the drive parameters set when the target rotation speed of the fan 1 is 5000 rpm. The rotation speed of the fan 16 corresponding to the duty ratio in the prohibited region is set to be above 4000 rpm and 6000 rpm. Therefore, the target rotation speed of 5000 rpm overlaps the prohibited region. The initial value of the internal duty ratio at the initial drive of the fan 16 was set to 30%. The actual rotation speed of the fan 16 is 3000 rpm at a duty ratio of 30%, and 1% of the duty ratio corresponds to 100 rpm. Until 5 seconds before the internal duty ratio enters the prohibited region, the control device 100 increases the internal duty ratio by 2% each time, the actual duty ratio also increases by 2% each time, and normal PWM control is executed until the actual rotation speed of the fan 16 reaches 4000 rpm. That is, the control device 100 executes control that repeats steps S3, S4, S5, S6, S7, S9, S10, and S12 shown in FIG. 4. And after 6 seconds, since it enters the prohibited region, the actual rotation speed of the fan 16 is maintained at 4000 rpm, while a virtual rotation speed is set. That is, at 6 seconds, since the internal duty ratio enters the prohibited region, the control device 100 proceeds from step S3 to step S13, and a virtual rotation speed of 4200 rpm corresponding to an internal duty ratio of 42% is set. Thereafter, until 10 seconds, the control device 100 executes control that repeats steps S3, S13, S14, S15, S16, S9, S11, and S12. The internal duty ratio increases by 2% at a time up to 50% corresponding to the target rotation speed, and the virtual rotation speed increases by 200 rpm at a time up to the target rotation speed of 5000 rpm. The actual duty ratio during this period is maintained at 40%. And after 11 seconds, since the virtual rotation speed has reached the target rotation speed, the increase in the internal duty ratio is interrupted and the internal duty ratio is maintained. The internal duty ratio is maintained at 50%, the virtual rotation speed is maintained at 5000 rpm, and the actual duty ratio is maintained at 40%. That is, the control device 100 executes control that repeats steps S3, S13, S14, S15, S17, S9, S11, and S12. Note that the holding of the internal duty ratio continues unless the driving of the fan 16 is stopped or the target rotation speed of the fan 16 is changed.

[0101] Figure 6 shows the drive parameters set when the target rotation speed of the fan 16 is 6600 rpm. That is, it shows the case where the target rotation speed exists outside the prohibited region. The initial values of the prohibited region and the internal duty ratio are set the same as in Figure 5.

[0102] As shown in Figure 6, until 5 seconds before the internal duty ratio enters the prohibited region, the control device 100 increases the internal duty ratio by 2% at a time, also increases the actual duty ratio by 2% at a time, and normal PWM control is executed until the actual rotation speed of the fan 16 reaches 4000 rpm. That is, the control device 100 executes control that repeats steps S3, S4, S5, S6, S7, S9, S10, and S12 shown in Figure 4.

[0103] And since it enters the prohibited region from 6 seconds to 15 seconds, while the actual rotation speed of the fan 16 is maintained at 4000 rpm, a virtual rotation speed is set. That is, at 6 seconds, since the internal duty ratio enters the prohibited region, the control device 100 proceeds from step S3 to step S13, and a virtual rotation speed of 4200 rpm corresponding to an internal duty ratio of 42% is set. Then, until 15 seconds, the control device 100 executes control that repeats steps S3, S13, S14, S15, S16, S9, S11, S12. The internal duty ratio increases by 2% each time, and the virtual rotation speed increases by 200 rpm each time. The actual duty ratio during this period is maintained at 40%.

[0104] And at 16 seconds, it exceeds the prohibited region, and the actual rotation speed of the fan 16 is set to 6200 rpm. While the internal duty ratio overlaps with the prohibited region, the actual rotation speed of the fan 16 is held at the boundary value on the lower limit side of the prohibited region, and when the internal duty ratio exceeds the prohibited region, it is skip-controlled to the boundary value on the upper limit side of the prohibited region. That is, at 16 seconds, the control device 100 proceeds to steps S3, S13, S14, S15, S16. In S16, the internal duty ratio increases by 2% to 62%. In step S9, the internal duty ratio of 62% is set to the actual duty ratio of 62%, the actual rotation speed of the fan 16 is set to 6200 rpm, and it proceeds to step S12.

[0105] And the fan 16 is increased to a target rotation speed of 6600 rpm by normal PWM control. Until it reaches the target rotation speed, the control device 100 executes control that repeats steps S3, S4, S5, S6, S7, S9, S10, S12. When it is determined in step S6 that the rotation speed of the fan 16 has reached the target rotation speed, it proceeds to step S8, and the internal duty ratio is maintained at 66%. Then, it proceeds to steps S9, S10, the actual rotation speed of the fan 16 is maintained at 6600 rpm, and it proceeds to S12. Thereafter, it executes control that repeats steps S3, S4, S5, S6, S8, S9, S10, S12.

[0106] In this way, after the internal duty ratio overlaps with the prohibited region, the control device 100 compares the target rotational speed with the virtual rotational speed of the fan 16 corresponding to the internal duty ratio, adjusts the virtual rotational speed of the fan 16 toward the target rotational speed by increasing the internal duty ratio, and when the target rotational speed and the virtual rotational speed match, the control device 100 sets the internal duty ratio to the input duty ratio and drives the fan 16. Therefore, the control device 100 can suppress the surging phenomenon of the fan 16 described later.

[0107] In the case of this embodiment, as described above, the virtual rotational speed is calculated as a virtual parameter from the internal duty ratio, the virtual rotational speed and the target rotational speed are compared, and the internal duty ratio is maintained as long as the virtual rotational speed does not reach the target rotational speed.

[0108] Here, as a comparative example for the drive parameters in FIG. 5, the case of controlling the drive of the fan 16 without using the virtual rotational speed will be described. FIG. 7 is a table showing an example of the parameters used by the control device of the comparative example when driving the fan. In the comparative example, the target rotational speed of the fan 16 is 5000 rpm, and the rotational speed corresponding to the prohibited region is above 4000 rpm and less than 6000 rpm.

[0109] In the control of the comparative example shown in FIG. 7, when the internal duty ratio reaches the lower limit of the prohibited region, the actual duty ratio of the fan is maintained at the boundary value 40% on the lower limit side of the prohibited region, and the fan 16 rotates at 4000 rpm. In the control of the comparative example, since the step of maintaining the internal duty ratio by comparing the virtual rotational speed and the target rotational speed is not executed, the internal duty ratio continues to increase toward the target rotational speed even after the target rotational speed overlaps with the prohibited region. Eventually, the internal duty ratio reaches the boundary on the upper limit side of the prohibited region in 16 seconds, the actual duty ratio is set to the boundary value 60% on the upper limit side of the prohibited region that does not overlap with the prohibited region, and the fan 16 rotates at 6000 rpm.

[0110] In the case of the control of the comparative example, since the virtual rotation speed is not used, it is determined that the rotation speed of 6000 rpm is higher than the target rotation speed of 5000 rpm. In order to approach the target rotation speed, the internal duty ratio starts to be reduced. Since the internal duty ratio is a value corresponding to the prohibited region, the actual duty ratio is maintained at the boundary value of 60% on the upper limit side of the prohibited region, and the fan 16 is maintained at 6000 rpm. Then, when the internal duty ratio reaches the boundary value on the lower limit side of the prohibited region, the actual duty ratio of the fan 16 is set to the boundary value of 40% on the lower limit side of the prohibited region where it does not overlap with the prohibited region, and the fan 16 rotates at 4000 rpm again.

[0111] When the fan 16 starts to rotate at 4000 rpm, in the control of the comparative example, the internal duty ratio is increased again toward the target rotation speed. Since the internal duty ratio overlaps with the prohibited region, until the internal duty ratio reaches the boundary on the upper limit side of the prohibited region, the actual duty ratio is maintained at the boundary value of 40% on the lower limit side of the prohibited region, and the fan 16 is rotated at 4000 rpm. In this way, in the control of the comparative example, until the duty ratio actually input to the fan 16 exceeds the prohibited region, the rotation speed of the fan 16 alternately switches between 4000 rpm and 6000 rpm, which are the boundary values of the prohibited region. Therefore, an annoying humming sound is generated by the rotation of the fan 16.

[0112] On the other hand, according to the control device 100 of the present embodiment, as described above, the virtual rotation speed calculated from the internal duty ratio is compared with the target rotation speed. After the virtual rotation speed matches the target rotation speed, the internal duty ratio is held, and the held internal duty ratio is set as the actual duty ratio to drive the fan 16. For this reason, while the target rotation speed overlaps with the prohibited region, the internal duty ratio is not set to the boundary value on the upper limit side of the prohibited region. Therefore, unlike the control of the comparative example, there is no annoying humming sound generated by switching the rotation speed of the fan 16 between the upper and lower boundary values of the prohibited region.

[0113] As described above, the projector 1 of the present embodiment includes a light source device 2, an image forming device 3 that modulates the light from the light source device 2 to form image light, a projection optical device 4 that projects the image light, an exterior housing 5, a fan F that cools the inside of the exterior housing 5 or a heat source, and a control device 100 that drives the fan F by pulse width modulation control based on drive parameters defining the relationship between the duty ratio and the rotation speed of the pulse width modulation. The projector 1 has a natural frequency. The control device 100 drives the fan F so as to exclude a duty ratio that overlaps with a resonance band corresponding to the natural frequency.

[0114] According to the projector 1 of the present embodiment, since each fan F is not driven at a duty ratio that resonates with the natural frequency of the projector 1 by the control device 100, it is possible to suppress the shaking of the projected image. Further, in the projector 1 of the present embodiment, since the rotation speed of each fan F can be finely controlled by PWM control, the control of each fan F can be precisely controlled. Therefore, while suppressing the shaking of the projected image, the cooling effect by each fan F can be enhanced.

[0115] In the projector 1 of the present embodiment, the required rotation speeds of the respective fans F differ depending on the installation location and application. For example, it is desirable to set a higher duty ratio for a fan whose heat source to be cooled has a higher temperature than for a fan whose heat source has a lower temperature. In this case, the control device 100 of the present embodiment may control the plurality of fans F based on different drive parameters.

[0116] Specifically, the control device 100 may also be based on drive parameters optimized for each of the panel fan 16, the heat exchanger fan 17, and the exhaust heat fan 13. Here, the optimized drive parameters mean that the upper and lower limit values of the duty ratio overlapping the prohibited region are different for each fan F, and the duty ratio bands skipped by each fan F in the prohibited region are different.

[0117] According to this configuration, when the vibration characteristics of each fan F are different, each fan F is skip-driven in an optimal startup mode, so that the shaking of the projected image due to resonance can be more effectively suppressed.

[0118] (First Modification Example) Subsequently, a first modification example of the projector will be described. The projector of this modification example is different from the projector 1 of the first embodiment in that it controls the fan based on drive parameters corresponding to the startup mode. In the following, the description will mainly focus on the difference in the fan control method, and the components common to the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted or simplified.

[0119] FIG. 8 is a block diagram showing a schematic configuration of the projector 1A of this modification example. As shown in FIG. 8, in the projector 1A of this modification example, the control device 100 drives the fan F based on parameters corresponding to the startup mode of the projector 1A. In the case of this modification example, the control device 100 has drive parameters P10 including a parameter P11 corresponding to the first startup mode, a parameter P12 corresponding to the second startup mode, and a parameter P13 corresponding to the third startup mode.

[0120] The first startup mode corresponds to the normal mode selected when the projector 1A is normally used. The second startup mode is the highland mode selected when the projector 1A is used in a place with a high altitude. The third startup mode is the silent mode selected when suppressing the sound emitted by the projector 1A. The natural frequency of the projector 1A is different for each startup mode.

[0121] The parameter P11 corresponding to the normal mode is set such that, for example, when the rotational speed range of 3400 to 3600 rpm is set as the prohibited region, the upper limit of the duty ratio is 90% and the lower limit is 80%. The parameter P13 corresponding to the silent mode sets the lower limit of the duty ratio lower than that in the normal mode in order to suppress the noise of the fan. For example, when the rotation speed range of 3000 - 3600 rpm is set as the prohibited region, the upper limit of the duty ratio is set to 90% and the lower limit is set to 70%.

[0122] The parameter P12 corresponding to the high altitude mode sets the upper limit of the duty ratio to 85% and the lower limit to 75% when, for example, the rotation speed range of 3400 - 3600 rpm is set as the prohibited region. At high altitudes, the air density decreases due to the low air pressure, reducing the driving load of the fan F and increasing the rotation speed. Therefore, the duty ratio is lower than that in the normal mode. For this reason, the relationship between the duty ratio and the rotation speed in parameter P12 is different from the relationship between the duty ratio and the rotation speed in parameter P11.

[0123] The control device 100 selects parameters P11 - P12 corresponding to the startup mode selected by the user from among the drive parameters P10 and drives the fan F based on the selected parameters.

[0124] Thus, according to the projector 1A of this modification example, even when the natural frequency changes according to the startup mode, the fan F is controlled based on the parameters corresponding to the startup mode. Therefore, the fan F is not driven at a rotation speed that resonates with the natural frequency of the projector 1B, and it is possible to suppress the shaking of the projected image due to resonance.

[0125] (Second Modification Example) Subsequently, a second modification example of the projector will be described. The projector of this modification example differs from the projector 1 of the first embodiment in that it controls the fan based on drive parameters corresponding to the installation posture of the projector. Below, the description will mainly focus on the differences in the fan control method, and the same reference numerals will be given to the components common to the first embodiment, and the description thereof will be omitted or simplified.

[0126] FIG. 9 is a block diagram showing the schematic configuration of the projector 1B of this modification example. As shown in FIG. 9, in the projector 1B of this modified example, the control device 100 drives the fan F based on parameters corresponding to the installation posture of the projector 1B. In the case of this modified example, the control device 100 has a drive parameter P20 including a parameter P21 corresponding to the first posture and a parameter P22 corresponding to the second posture.

[0127] The projector 1B is used in a first posture where it is placed on the floor, a table, etc., or in a second posture where it is suspended from the ceiling or wall using a mounting bracket or the like. The natural frequency of the projector 1B is different in the first posture and the second posture. For this reason, the control device 100 makes the relationship between the duty ratio and the rotation speed in the parameter P21 different from the relationship between the duty ratio and the rotation speed in the parameter P22.

[0128] The control device 100 selects the parameters P21 and P22 corresponding to the posture installed by the user from among the drive parameters P20, and drives the fan F based on the selected parameters.

[0129] Thus, according to the projector 1B of this modified example, even when the natural frequency changes according to the posture at the time of installation, the fan F is controlled based on the parameters corresponding to the posture. For this reason, since the fan F is not driven at a rotation speed that resonates with the natural frequency of the projector 1B, it is possible to suppress the shaking of the projected image due to resonance.

[0130] (Third Modified Example) Subsequently, a third modified example of the projector will be described. The projector of this modified example is different from the projector 1 of the first embodiment in that it has a plurality of natural frequencies. Hereinafter, the description will mainly focus on the difference in the fan control method, and the same reference numerals will be given to the configurations common to the first embodiment, and the description thereof will be omitted or simplified.

[0131] FIG. 10 is a diagram showing a method for controlling the duty ratio in the projector 1C of this modified example. In FIG. 10, the horizontal axis represents time, and the vertical axis represents the duty ratio of the fan. Note that the projector 1C of this modified example has two natural frequencies. Note that the number of natural frequencies is not limited to two, and it may have three or more.

[0132] As shown in FIG. 10, the control device 100 drives the fan so as to skip the duty ratio in each of the first prohibited region AA and the second prohibited region AB corresponding to the two natural frequencies. That is, the control device 100 performs pulse width modulation control to remove the duty ratio overlapping the prohibited regions AA and AB corresponding to the two natural frequencies.

[0133] Thus, according to the projector 1C of this modified example, even when there are a plurality of natural frequencies, since each fan is not driven in the prohibited regions AA and AB corresponding to each natural frequency, it is possible to suppress the shaking of the projected image due to resonance.

[0134] (Second Embodiment) Hereinafter, the projector of the second embodiment will be described. The basic configuration of the projector of the second embodiment is the same as that of the first embodiment, but the configuration of the projection optical device is different from that of the first embodiment. The same reference numerals are given to the configurations and members common to the first embodiment, and the detailed description thereof will be omitted.

[0135] FIG. 11 is a block diagram showing a schematic configuration of the projector 11 of this embodiment. As shown in FIG. 11, the projector 11 of this embodiment includes a projection optical device 40 including a plurality of projection lenses 41. Each of the plurality of projection lenses 41 of the projection optical device 40 is detachably attached to the image forming device 3. The plurality of projection lenses 41 include a first projection lens 41a, a second projection lens 41b, and a third projection lens 41c.

[0136] The projector 11 of the present embodiment has a different first natural frequency when the first projection lens 41a is attached and a different second natural frequency when the second projection lens 41b is attached. In the projector 11 of the present embodiment, the control device 100 has a drive parameter P1 that skips a prohibited band that is a resonance band corresponding to the first natural frequency, and a drive parameter P2 that skips a prohibited band that is a resonance band corresponding to the second natural frequency.

[0137] The control device 100 drives the fan F by pulse width modulation control in which the duty ratio overlapping the resonance band corresponding to the first natural frequency of the projector 11 with the first projection lens 41a attached and the second natural frequency of the projector 11 with the second projection lens 41b attached is removed.

[0138] Further, in the projector 11 of the present embodiment, the third natural frequency when the third projection lens 41c is attached is substantially equal to the first natural frequency when the first projection lens 41a is attached. Note that the substantially equal natural frequencies of the third natural frequency and the first natural frequency means that a frequency difference that does not cause a difference in vibration characteristics during resonance caused by the two natural frequencies is allowed.

[0139] The control device 100 uses the drive parameter P1 that skips the prohibited band corresponding to the first natural frequency as the drive parameter that skips the prohibited band corresponding to the third natural frequency. For this reason, the control device 100 can save the capacity of the internal memory by sharing the drive parameters of lenses having similar vibration characteristics.

[0140] Further, the control device 100 drives the fan F by pulse width modulation control in which the duty ratio overlapping the prohibited band corresponding to the third natural frequency of the projector 11 with the third projection lens 41c attached is removed.

[0141] According to the projector 11 of this embodiment as described above, even when the natural frequency of the projector 11 changes by replacing the plurality of projection lenses 41 including the first projection lens 41a, the second projection lens 41b, and the third projection lens 41c, the fan F is not driven at a rotational speed that resonates with the natural frequency corresponding to the mounted projection lens. Therefore, the shaking of the projected image can be suppressed.

[0142] Note that the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. In addition, the specific configurations such as the number, arrangement, shape, and material of various components constituting the projector and the image forming apparatus are not limited to the above-described embodiment and can be appropriately changed.

[0143] The summary of the present disclosure is appended below. (Appendix 1) A light source device, An image forming apparatus that modulates light from the light source device to form image light, A projection optical device that projects the image light, An exterior housing, A fan that cools the inside of the exterior housing or a heat source, A control device that drives the fan by pulse width modulation control based on a drive parameter that defines the relationship between the duty ratio and the rotational speed of pulse width modulation, and a projector comprising: The projector has a natural frequency, The control device drives the fan so as to exclude the duty ratio that overlaps with the resonance band corresponding to the natural frequency. A projector characterized by the above.

[0144] According to the projector of Supplementary Note 1, since the fan is not driven at a duty ratio that resonates with the natural frequency of the projector by the control device, it is possible to suppress the shaking of the projected image. Further, in the projector having this configuration, since the rotation speed of the fan can be finely controlled by pulse width modulation control, the control of the fan can be precisely controlled. Therefore, while suppressing the shaking of the projected image, the cooling effect by the fan can be enhanced.

[0145] (Supplementary Note 2) including a plurality of the fans, the plurality of fans include a first fan and a second fan, the control device controls the first fan and the second fan based on different drive parameters from each other, The projector according to Supplementary Note 1, characterized in that.

[0146] According to the configuration of Supplementary Note 2, since each fan is driven in an optimal startup mode, it is possible to more effectively suppress the shaking of the projected image due to resonance.

[0147] (Supplementary Note 3) the control device uses an internal duty ratio for calculating a virtual rotation speed of the fan and an input duty ratio for driving the fan, the control device, calculates toward the target rotation speed of the drive parameter using the virtual rotation speed based on the internal duty ratio, During a period when the internal duty ratio does not overlap with the resonance band, the fan is driven using the internal duty ratio as the input duty ratio, During a period when the internal duty ratio overlaps with the resonance band, the internal duty ratio is not reflected in the input duty ratio, and the rotation speed is controlled so as not to overlap with the resonance band, The projector according to Supplementary Note 1 or Supplementary Note 2, characterized in that.

[0148] According to the configuration of Supplementary Note 3, by using the virtual rotation speed based on the internal duty ratio, it is possible to easily perform control that does not overlap with the resonance band of the fan. And it is possible to stably control the fan toward the target rotation speed.

[0149] (Supplementary Note 4) After the internal duty ratio overlaps with the resonance band, the control device compares the target rotation speed with the virtual rotation speed of the fan corresponding to the internal duty ratio, and adjusts the virtual rotation speed of the fan toward the target rotation speed by increasing or decreasing the internal duty ratio. The projector according to Supplementary Note 3, characterized in that.

[0150] According to the configuration of Supplementary Note 4, after the internal duty ratio overlaps with the resonance band, by comparing the virtual rotation speed calculated from the internal duty ratio with the target rotation speed, the rotation speed of the fan can be adjusted toward the target rotation speed.

[0151] (Supplementary Note 5) When the target rotation speed and the virtual rotation speed match, the control device holds the internal duty ratio. The projector according to Supplementary Note 4, characterized in that.

[0152] According to the configuration of Supplementary Note 5, while the target rotation speed overlaps with the resonance band, it does not repeat increasing or decreasing the internal duty ratio between the upper limit and the lower limit within the resonance band. Therefore, it is possible to suppress the generation of a howling sound caused by the rotation speed of the fan switching between the boundary values of the upper limit and the lower limit of the prohibited region.

[0153] (Supplementary Note 6) When increasing or decreasing the input duty ratio input to the fan based on the drive parameter, the control device increases or decreases the internal duty ratio, and when the internal duty ratio overlaps with the resonance band, holds the input duty ratio at the boundary value of the resonance band until the internal duty ratio exceeds the resonance band. The projector according to one of Appendices 3 to 5, characterized in that...

[0154] According to the configuration of Appendix 6, after the internal duty ratio overlaps the resonance band, the fan can be driven at the boundary value of the resonance band until the internal duty ratio exceeds the resonance band. Therefore, it is possible to realize driving of the fan that suppresses shaking of the projected image due to resonance.

[0155] (Appendix 7) When the internal duty ratio overlaps the resonance band, the control device changes the input duty ratio to a value exceeding the resonance band, and drives the fan with the changed input duty ratio until the internal duty ratio exceeds the resonance band. The projector according to one of Appendices 3 to 5, characterized in that...

[0156] According to the configuration of Appendix 7, in order to hold the input duty ratio at a value that skips the resonance band, it is possible to reliably prevent a duty ratio that overlaps the resonance band from being input to the fan.

[0157] (Appendix 8) When the internal duty ratio overlaps the resonance band, the control device holds the input duty ratio at the upper limit side boundary value of the resonance band. The projector according to one of Appendices 3 to 7, characterized in that...

[0158] According to the configuration of Appendix 8, it is possible to realize drive control of the projector that prioritizes the cooling performance by the fan.

[0159] (Appendix 9) The drive parameter includes a parameter corresponding to the first startup mode of the projector and a parameter corresponding to the second startup mode of the projector. The control device drives the fan based on a parameter corresponding to the startup mode of the projector. The projector according to any one of Appendices 1 to 8, characterized in that...

[0160] According to the configuration of Supplementary Note 9, even when the natural frequency changes according to the startup mode, the fan is controlled based on parameters corresponding to the startup mode. Therefore, since the fan is not driven at a rotational speed that resonates with the natural frequency of the projector, it is possible to suppress the shaking of the projected image due to resonance.

[0161] (Supplementary Note 10) The drive parameters include parameters corresponding to the first posture of the projector and parameters corresponding to the second posture of the projector. The control device drives the fan based on parameters corresponding to the posture of the projector. The projector according to any one of Supplementary Notes 1 to 8, characterized in that.

[0162] According to the configuration of Supplementary Note 10, even when the natural frequency changes according to the posture at the time of installation, the fan is controlled based on parameters corresponding to the posture. Therefore, since the fan is not driven at a rotational speed that resonates with the natural frequency of the projector, it is possible to suppress the shaking of the projected image due to resonance.

[0163] (Supplementary Note 11) The projector has a plurality of the natural frequencies. The control device performs pulse width modulation control to exclude the duty ratio overlapping the plurality of resonance bands corresponding to the plurality of the natural frequencies. The projector according to any one of Supplementary Notes 1 to 8, characterized in that.

[0164] According to the configuration of Supplementary Note 11, even when having a plurality of natural frequencies, since each fan is not driven in the resonance band corresponding to each natural frequency, it is possible to suppress the shaking of the projected image due to resonance.

[0165] (Supplementary Note 12) The projection optical device has a plurality of projection lenses including a first projection lens and a second projection lens that are each detachably attached to the image forming device. The control device drives the fan by pulse width modulation control in which the duty ratio overlapping the resonance band corresponding to the first natural frequency of the projector equipped with the first projection lens and a second natural frequency different from the first natural frequency of the projector equipped with the second projection lens is removed. The projector according to any one of Appendices 1 to 8, characterized in that.

[0166] According to the configuration of Appendix 12, even when the natural frequency of the projector changes by replacing a plurality of projection lenses, the fan is not driven at a rotational speed that resonates with the natural frequency corresponding to the attached projection lens, so that shaking of the projected image can be suppressed.

[0167] (Appendix 13) The plurality of projection lenses further includes a third projection lens. At least one of the first natural frequency and the second natural frequency is equal to a third natural frequency of the projector with the third projection lens attached to the exterior housing. The projector according to Appendix 12, characterized in that.

[0168] According to the configuration of Appendix 13, the control device can save the capacity of the internal memory by sharing the drive parameters of lenses having similar vibration characteristics.

Explanation of Signs

[0169] 1, 1A, 1B, 1C, 11… Projector, 2… Light source device, 3… Image forming device, 4, 40… Projection optical device, 5… Exterior housing, 16… Panel fan (first fan), 17… Heat exchange fan (second fan), F… Fan, 41… Projection lens, 41a… First projection lens, 41b… Second projection lens, 41c… Third projection lens, 100… Control device, A… Prohibited region (resonance band), AA… First prohibited region (resonance band), AB… Second prohibited region (resonance band), P1, P2, P10, P20… Drive parameters, P11, P12, P13, P21, P22… Parameters.

Claims

1. A light source device, an image forming device that modulates light from the light source device to form image light, a projection optical device that projects the image light, an exterior housing, a fan that cools within the exterior housing or a heat source, and a control device that drives the fan by pulse width modulation control based on drive parameters defining the relationship between the duty ratio and the rotation speed of pulse width modulation, wherein the projector has a natural frequency, the control device drives the fan so as to exclude the duty ratio that overlaps with the resonance band corresponding to the natural frequency, a projector characterized by this.

2. including a plurality of the fans, the plurality of fans including a first fan and a second fan, the control device controls the first fan and the second fan based on different drive parameters from each other, the projector according to claim 1, characterized by this.

3. the control device uses an internal duty ratio for calculating the virtual rotation speed of the fan and an input duty ratio for driving the fan, the control device, calculates toward the target rotation speed of the drive parameters using the virtual rotation speed by the internal duty ratio, when the period in which the internal duty ratio does not overlap with the resonance band, the control device drives the fan with the internal duty ratio as the input duty ratio, when the internal duty ratio overlaps with the resonance band, the control device does not reflect the internal duty ratio in the input duty ratio and controls the rotation speed so as not to overlap with the resonance band, the projector according to claim 1, characterized by this.

4. after the internal duty ratio overlaps with the resonance band, the control device compares the target rotation speed and the virtual rotation speed of the fan corresponding to the internal duty ratio, and adjusts the virtual rotation speed of the fan toward the target rotation speed by increasing or decreasing the internal duty ratio, the projector according to claim 3, characterized by this.

5. when the target rotation speed and the virtual rotation speed match, the control device holds the internal duty ratio, sets the held internal duty ratio as the input duty ratio, and drives the fan, the projector according to claim 4, characterized by this.

6. When increasing or decreasing the input duty ratio input to the fan based on the drive parameter, the control device increases or decreases the internal duty ratio, and when the internal duty ratio overlaps with the resonance band, the control device holds the input duty ratio at the boundary value of the resonance band until the internal duty ratio exceeds the resonance band. The projector according to any one of claims 3 to 5, characterized in that.

7. When the internal duty ratio overlaps with the resonance band, the control device changes the input duty ratio to a value exceeding the resonance band, and drives the fan with the changed input duty ratio until the internal duty ratio exceeds the resonance band. The projector according to any one of claims 3 to 5, characterized in that.

8. When the input duty ratio overlaps with the resonance band, the control device holds the input duty ratio at the upper limit side boundary value of the resonance band. The projector according to any one of claims 3 to 5, characterized in that.

9. The drive parameter includes a parameter corresponding to the first start mode of the projector and a parameter corresponding to the second start mode of the projector. The control device drives the fan based on the parameter corresponding to the start mode of the projector. The projector according to any one of claims 1 to 5, characterized in that.

10. The drive parameter includes a parameter corresponding to the first posture of the projector and a parameter corresponding to the second posture of the projector. The control device drives the fan based on the parameter corresponding to the posture of the projector. The projector according to any one of claims 1 to 5, characterized in that.

11. The projector has a plurality of the natural frequencies. The control device performs the pulse width modulation control to exclude the duty ratio overlapping with the plurality of resonance bands corresponding to the plurality of the natural frequencies. The projector according to any one of claims 1 to 5, characterized in that.

12. The projection optical device has a plurality of projection lenses including a first projection lens and a second projection lens that are each detachably attached to the image forming device. The control device drives the fan by pulse width modulation control in which a duty ratio overlapping with the resonance band corresponding to a first natural frequency of the projector equipped with the first projection lens and a second natural frequency different from the first natural frequency of the projector equipped with the second projection lens is removed. The projector according to any one of claims 1 to 5, characterized in that.

13. The plurality of projection lenses further includes a third projection lens. At least one of the first natural frequency and the second natural frequency is equal to a third natural frequency of the projector in which the third projection lens is mounted on the exterior housing. The projector according to claim 12, characterized in that.

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