JP7354779B2 - image projection device - Google Patents

Description

The present invention relates to an image projection device.

DLP (Digital Light Processing) projector devices are known today. This DLP projector device irradiates light emitted from a light source onto a color wheel, and the color wheel is formed by arranging several types of filters that transmit specific wavelengths along the circumferential direction of the disk. The light transmitted through each filter of such a color wheel, which is driven to rotate at a high distance on the optical path of the light from the light source, is irradiated onto the light modulation element through the light tunnel. The light modulation element forms an image for projection based on the light that has passed through each filter of the color wheel. This projection image is projected onto a screen or the like via a projection optical system.

As the light modulation element, for example, a DMD (Digital Micromirror Device) is used. The DMD generates an image in synchronization with the rotation of a color wheel based on image data input from an external device such as a personal computer device. That is, the DMD generates an image while synchronizing the color modulation of the signal by driving the image conversion element in synchronization with a rotation reference position signal obtained based on the rotation reference position of the color wheel.

In addition, color light other than one color emitted from the projection lens is detected by a color light detector, and the rotation timing of the color wheel or color modulation is adjusted so that the output of this color light detector becomes minimum or zero (<0>). Projection projection devices that control synchronization timing are also known.

Patent Document 1 (Japanese Unexamined Patent Publication No. 2012-137558) discloses a color wheel unit that detects a rotation reference position of a color wheel using a marker tape. This color wheel unit detects the light reflected by the annular marker tape that rotates together with the color wheel using a position sensor arranged to face the marker tape. Thereby, the rotation reference position of the color wheel can be detected.

However, in the color wheel unit of Patent Document 1, the marker tape is glued to the color wheel motor. Therefore, if the marker tape peels off, there is a problem in that normal image projection becomes difficult.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image projection device that is capable of continuing normal image projection even when a marker peels off.

In order to solve the above-mentioned problems and achieve the objects, the present invention provides a color wheel in which a plurality of color filter groups in which color filters of a plurality of colors are arranged in a predetermined manner are consecutively provided along the rotation direction. , includes a rotating body that is coaxial with the rotation axis of the color wheel and rotates in synchronization with the color wheel, and a plurality of markers provided on the rotating body, and the markers correspond to the reference positions of each color filter group. A color wheel unit installed at each position of the rotating body, a light source unit that irradiates the color wheel with light, a rotation detection sensor that detects the rotation position of the color wheel based on the marker, and a rotation detection sensor that detects the rotation position of the color wheel based on the marker. an image forming unit that forms and projects an image from light from a light source unit via each color filter of the color wheel, and a marker detected by a rotation detection sensor in synchronization with the rotational position of the color wheel. The number of pulses obtained by comparing the number of markers provided on the color wheel, which is indicated by the reference pulse number information, is compared, and the number of pulses of the marker detected by the rotation detection sensor is determined by the reference pulse number information. and a notification unit that performs a predetermined notification operation when the number of markers is smaller than the number of markers shown.

According to the present invention, even if the marker peels off, normal image projection can be continued.

FIG. 1 is a perspective view showing the appearance of a projector according to an embodiment. FIG. 2 is a perspective view of the optical engine of the projector according to the embodiment. FIG. 3 is a perspective view of the illumination optical system unit of the projector according to the embodiment. FIG. 4 is a diagram for explaining the configuration of a color wheel provided in the projector of the embodiment. FIG. 5 is a hardware configuration diagram of the projector according to the embodiment. FIG. 6 is a functional block diagram of the projector according to the embodiment. FIG. 7 is a timing chart showing the timing of each part when the rotation of the color wheel is normally detected by the first marker provided on the rotating body of the color wheel unit. FIG. 8 is a timing chart of various parts showing a state where one marker attached to the color wheel peels off and only the other marker is detected.

Hereinafter, a projector that is an embodiment of a color wheel unit and an image projection device will be described with reference to the accompanying drawings.

(Configuration of projector device)
FIG. 1 is a perspective view showing a projection state of a projector 1 according to an embodiment. FIG. 2 is a perspective view of the optical engine of the projector 1 according to the embodiment. FIG. 3 is a perspective view of the illumination optical system unit of the projector 1 according to the embodiment.

First, a projector 1, which is an example of an image projection device, has an exit window 3 and an external interface (external I/F) 9, as shown in FIG. Further, inside the projector 1, an optical engine that generates a projected image is provided. In the projector 1, an optical engine generates a projection image based on image data transmitted from a personal computer device (PC) or a digital camera connected to an external I/F 9, and an exit window 3 as shown in FIG. An image is projected onto the screen S from. Note that the X1X2 direction shown in FIG. 1 indicates the width direction of the projector 1, the Y1Y2 direction indicates the depth direction of the projector 1, and the Z1Z2 direction indicates the height direction of the projector 1.

(Optical engine configuration)
The optical engine 15 provided in the projector 1 of the embodiment includes a light source 30, an illumination optical system unit 40, an image display unit 50, and a projection optical system unit 60, as shown in FIG.

The light source 30 is provided on the side surface of the illumination optical system unit 40 and irradiates light in the X2 direction. The illumination optical system unit 40 guides the light emitted from the light source 30 to an image display unit 50 provided below. The image display unit 50 generates a projected image using the light guided by the illumination optical system unit 40. The projection optical system unit 60 is provided above the illumination optical system unit 40 and projects the projection image generated by the image display unit 50 to the outside of the projector 1.

Although the optical engine 15 according to the present embodiment is configured to project an image upward using light emitted from the light source 30, it may also be configured to project an image in other directions such as the horizontal direction. good.

(Configuration of illumination optical system unit)
As shown in FIG. 3, the illumination optical system unit 40 provided in the projector 1 of the embodiment includes a color wheel unit 430, a light tunnel 402, relay lenses 403, 404, a cylinder mirror 405, and a concave mirror 406. ing.

The color wheel unit 430 includes, for example, a disc-shaped color wheel 401 in which filters of R (red), G (green), and B (blue) are provided at different parts in the circumferential direction. The color wheel 401 is rotated at high speed and converts the light emitted from the light source 30 into RGB color light in a time-division manner.

The light tunnel 402 is formed into a rectangular tube shape by laminating sheets of glass, for example. The light tunnel 402 multiple-reflects the RGB light that has passed through the color wheel 401 on its inner surface, thereby making the luminance distribution uniform and guiding the light to the relay lenses 403 and 404. The relay lenses 403 and 404 collect the light emitted from the light tunnel 402 while correcting the axial chromatic aberration.

The cylinder mirror 405 and the concave mirror 406 reflect the light emitted from the relay lenses 403 and 404 to a DMD (Digital Micromirror Device) 551 provided in the image display unit 50. The DMD 551 modulates the reflected light from the concave mirror 406 to generate a projected image.

(Color wheel unit configuration)
FIG. 4 is a diagram for explaining the configuration of the color wheel unit 430. Of these, FIG. 4(a) is a right side view of the color wheel unit 430. FIG. 4B is a front view of the color wheel unit 430 (viewed from the light incident side). FIG. 4(b) is a perspective view of the color wheel unit 430 viewed diagonally from above and to the right.

As shown in FIGS. 4(a) to 4(c), the color wheel unit 430 includes a color wheel 401, a rotating body 450, and a rotation detection sensor 400.

The color wheel 401 serves as a color dividing element of the projector 1 and includes RGB color filters (segments) colored based on several colors of glass having different wavelengths. Further, the color wheel 401 has a total of two sets of color filters, one set of RGB color filters. That is, color filters are provided on the color wheel 401 in the order of R→B→G→R→B→G. The color wheel 401 is driven to rotate at high speed by a motor. As a result, light from the light source (numeral 301 in FIG. 5) passes through the RGB color filters in sequence.

A cylindrical rotating body 450 that rotates together with the color filter is provided on the rotating shaft of the motor. Markers 700 are pasted on the outer peripheral surface of this rotating body 450 at the starting positions (reference positions) of the B color filter. That is, the markers 700 are affixed to a total of two locations on the outer circumferential surface of the rotating body 450 that are opposite to each other (positions 180 degrees apart).

Note that the "starting position of the B color filter" is the position where the color of the light passing through the color filter changes from R to B (or from G to B) depending on the rotation direction of the color wheel 401. border). By matching the start position of the color of the color filter as the end positioning reference when pasting the marker 700, the positional accuracy of the pasting position of the marker 700 can be improved. Further, the size of each marker 700 may be the same, or may be different.

The marker 700 is formed by applying black processing to a member based on an aluminum (AL) film. On the other hand, the rotating body 450 is made of an iron member, and has a certain luster due to the surface being plated with zinc or subjected to a corrosion treatment after electrolytic polishing. . Therefore, in the rotating body 450, the amount of light reflected differs between the portion to which the marker 700 is attached and the portion to which the marker 700 is not attached. That is, the portion to which the marker 700 is attached absorbs light, and the portion to which the marker 700 is not attached reflects light.

The rotation detection sensor 400 irradiates the rotating body 450 with light and receives the light reflected by the rotating body 450. Since the portion of the rotating body 450 to which the marker 700 is not attached is glossy, much light is reflected, and the amount of light received by the rotation detection sensor 400 increases. On the other hand, in the portion of the rotating body 450 to which the marker 700 is attached, the amount of reflected light is reduced, and the amount of light received by the rotation detection sensor 400 is also reduced. The rotation detection sensor 400 detects the position of the marker 700 based on such a difference in the amount of received light.

(Hardware configuration)
FIG. 5 is a hardware configuration diagram of the projector 1. As shown in FIG. As shown in FIG. 5, the projector 1 includes a control unit 10 and an optical engine 15.

(Control unit configuration)
The control unit 10 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, an SDRAM (Synchronous Dynamic Random Access Memory) 103, and an NVRAM (Non Volatile Random Access Memory). The control unit 10 also includes a fan 105, an operation section 106, a remote controller receiving section (remote control receiving section) 107, an external I/F 108, a network I/F 109, a media I/F 110, and a power supply unit 4. These units 101 to 110 and the power supply unit 4 are interconnected via a bus line 111.

CPU 101 controls the overall operation of projector 1 . The ROM 102 stores various programs executed by the CPU 101. For example, the ROM 102 stores a rotation control program for the color wheel 401. By executing this rotation control program, the CPU 101 realizes each function described later with reference to FIG. SDRAM 103 is used as a work area for CPU 101.

The operation unit 106 is provided with various keys, buttons, light emitting units (LEDs), and the like. By operating the operation unit 106, the user can perform instruction operations such as adjusting the size of the image to be projected, adjusting the color tone, adjusting the focus, adjusting the keystone, changing the power mode, and changing the image projection mode. etc. The contents of these operations are notified (output) to the CPU 101.

The remote control receiving section 107 has a receiving section that receives commands from the remote control. The remote control receiving unit 107 receives instruction operations from the remote controller, such as adjusting the size of the projected image, adjusting the color tone, adjusting the focus, adjusting the keystone, changing the power mode, and changing the image projection mode. The CPU 101 is notified (output) of the operation details.

The fan 105 rotates or stops based on a control signal from the CPU 101 to exhaust the inside of the projector 1 and cool the inside of the projector 1 . The media I/F 110 controls reading and writing (storage) of data from, for example, a recording medium such as a flash memory. The bus line is an address bus, data bus, etc. for electrically connecting each component.

The network I/F 109 is an interface for data communication using a communication network such as the Internet, for example. External equipment such as a personal computer device is connected to the external I/F 108. Control signals or image data from the personal computer device are acquired via this external I/F 108.

(Optical engine configuration)
The optical engine 15 forms a projected image based on image data input to the projector 1 under the control of the CPU 101. The optical engine 15 includes a light source unit 30, an illumination unit 40, an image display unit 50, and a projection optical system unit 60.

The light source unit 30 includes a light source 301 such as a light emitting diode (LED), and irradiates the illumination unit 40 with light under the control of the CPU 101. Note that the light source 301 may be other than an LED, such as a mercury high-pressure lamp or a xenon lamp.

The lighting unit 40 includes, for example, a color wheel 401, a rotation detection sensor 400, a light tunnel 402, relay lenses 403 and 404, a cylinder mirror 405, a reflection mirror 406, and the like. The illumination unit 40 guides the light emitted from the light source unit 30 to the image display unit 50.

The color wheel 401 has a disk shape in which a plurality of segments (RGB transmission areas) that transmit only light in a specific wavelength range are arranged in order in the rotation direction. Light emitted from the light source 301 is converted into light of each color by the segments through which the rotating color wheel 401 passes. Moreover, the light whose colors of RGB are repeated every unit time by passing through the color wheel 401 is emitted toward the light tunnel 402 .

The light tunnel 402 is formed, for example, from plate glass laminated into a polygonal cylinder shape. The inner surface of the light tunnel 402 is coated with a silver or dielectric multilayer film to reflect light. The light tunnel 402 makes the illuminance uniform and guides the light emitted from the color wheel 401 to the relay lenses 403 and 404.

Relay lenses 403 and 404 are formed by a combination of two lenses. The relay lenses 403 and 404 correct the axial chromatic aberration of the light emitted from the light tunnel 402 and collect the light. The light that has passed through the relay lenses 403 and 404 enters a light modulation element (display element) that is an image generation section of the image display unit 50 via a cylinder mirror 405 and a reflection mirror 406.

The image display unit is controlled by the CPU 101 and modulates the light guided by the lighting unit 40 to generate a display image. Although this is an example, a micromirror (DMD (Digital Micromirror Device)) 551 can be used as the display element. The DMD 551 is turned on and off by the CPU 101 in accordance with image data, thereby modulating the input light. Note that, as the display element, other than the DMD 551, for example, a liquid crystal panel or the like can be used.

The projection optical system unit 60 includes a projection mirror 601 and a projection lens. The projection optical system unit 60 magnifies the display image formed by the DMD 551 of the image display unit 50 with a projection lens, and projects the projection image onto the screen S. There may be a plurality of projection lenses, and an optical element such as a mirror may be provided in addition to the projection lens.

Here, at the timing when the DMD 551 is irradiated with the light of each color of RGB that has passed through the color wheel 401 and is emitted, the DMD 551 needs to perform a modulation operation corresponding to the light of that color. Therefore, it is necessary to synchronize the output timing of the drive signal for causing the DMD 551 to perform the modulation operation and the rotation timing of the color wheel 401.

In order to achieve this synchronization, the color wheel 401 of the lighting unit 40 is provided with the above-mentioned marker 700 for detecting the rotational position. Further, the illumination unit 40 is provided with a rotation detection sensor 400 for detecting a marker 700 provided at a rotation reference position of the color wheel 401.

When the marker 700 reaches a position facing the rotation detection sensor 400, the rotation detection sensor 400 outputs a position detection signal indicating that the marker 700 has reached the rotation reference position. The above-mentioned synchronization control is performed based on this position detection signal.

When powered by the power supply unit 4 and started, the CPU 101 controls the lighting of the light source 301 of the light source unit 30 based on the rotation control program stored in advance in the ROM 102, and also controls the fan 105 at a predetermined rotation speed. Control rotation. In the projector 1, when supply of power is started, the optical engine 15 enters a state capable of displaying an image, and power is further supplied from the power supply unit 4 to various other components.

Further, in the projector 1, when the power switch is turned off, a power off signal is supplied to the CPU 101. When the CPU 101 detects the power OFF signal, the CPU 101 turns off the light source 301. Thereafter, when a predetermined period of time has elapsed, the CPU 101 controls the fan 105 to stop, and ends the control process.

(Functional configuration)
FIG. 6 is a functional block diagram of the projector 1. By executing the rotation control program stored in the ROM 102, the CPU 101 of the projector 1 controls the operation reception section 250, data reception section 251, fan control section 252, position signal acquisition section 253, display control section 254, and optical engine control. Each function of the section 255 and the storage control section 259 is realized. The optical engine control section 255 includes an image generation section 256, a light source control section 257, and a synchronization control section 258.

The operation reception unit 250 performs processing of the CPU 101 and the operation unit 106 or the CPU 101 and the remote control reception unit 107, and receives various inputs from the user. The display control unit 254 displays various information regarding the projector 1 to the user, for example, by performing display processing on the CPU 101 and the operation unit 106. For example, if the operation unit 106 has a lamp, the display control unit 254 controls the lighting and extinguishing of the lamp, and if it is a touch panel, controls the display on the touch panel.

The data reception unit 251 processes the CPU 101 and the external I/F 108, and receives various data such as image data input from an external device such as a personal computer device. Further, the data reception unit 251 processes the CPU 101 and the network I/F 109, and receives various data such as image data input via a predetermined network such as a LAN (Local Area Network) or the Internet.

The fan control unit 252 performs rotation control and stop control of the fan 105. The position signal acquisition unit 253 is realized by processing of the rotation detection sensor 400, detects a signal indicating the rotation position of the color wheel 401, and notifies the optical engine control unit 255 of the signal.

The optical engine control section 255 includes a light source control section 257, an image generation section 256, and a synchronization control section 258, and controls the entire optical engine 15. The light source control unit 257 controls the output of the light source 301. The light source control unit controls the output of the light source 301 by controlling the power supplied to the light source 301, for example.

The image generation unit 256 controls the DMD 551 provided in the image display unit 50 of the optical engine 15 based on input image data or superimposed image (OSD) data such as menu information, and generates an image to be projected on the screen S. generate.

The synchronization control unit 258 generates a synchronization signal to the light source 301, color wheel 401, and DMD 551 based on the rotational position signal from the position signal acquisition unit 253, and synchronizes their movements. For example, the period in which the DMD 551 is displaced and the period in which the color wheel 401 is rotated are synchronously controlled, and images of each color are generated in a synchronously controlled time-sharing manner.

The storage control unit 259 controls the CPU 101 to store various data in a storage unit such as the SDRAM 103 or NVRAM 104, or controls the reading of various data from the storage unit. Further, a position signal indicating the number of rotation detection pulses detected by the rotation detection sensor 400 is stored in advance in the storage unit. As will be described later, the display control unit 254 calculates the number of pulses detected by the rotation detection sensor 400 during one rotation of the color wheel 401 and the number of pulses indicated by the position signal stored in the storage unit. compare. Then, if the number of pulses detected by the rotation detection sensor 400 is smaller than the number of pulses indicated by the position signal, the display control unit 254 performs a warning operation such as displaying a message urging repair etc. .

In this example, the operation reception unit 250 to storage control unit 259 are realized by software, but some or all of them may also be realized by hardware such as an IC (Integrated Circuit). good.

Further, the rotation control program may be provided as an installable or executable file recorded on a computer readable recording medium such as a CD-ROM or a flexible disk (FD). Further, the rotation control program may be provided by being recorded on a computer readable recording medium such as a CD-R, a DVD (Digital Versatile Disk), a Blu-ray Disc (registered trademark), or a semiconductor memory. Furthermore, the rotation control program may be provided by being installed via a network such as the Internet, or may be provided by being pre-installed in a ROM or the like within the device.

(Rotation detection operation)
Next, the rotation detection operation of the color wheel 401 in the projector 1 of the embodiment will be described. First, FIG. 7 is a timing chart showing the timing of each part when the rotation of the color wheel 401 is normally detected by the marker 700 provided on the rotating body 450 of the color wheel 401. Among them, FIG. 7A shows the timing at which light of each color is sequentially formed by the light from the light source 301 entering each RGB segment of the rotating color wheel 401. FIG. 7B shows the timing of rotation detection pulses obtained when the rotation detection sensor 400 detects each marker 700 attached to the rotating body 450 of the rotating color wheel 401. FIG. 7(c) shows the drive timing of the DMD 551.

As can be seen from FIGS. 7(a) to 7(c), when each marker 700 is normally detected by the rotation detection sensor 400, each time the color wheel 401 rotates once, the At the timing when the light of the color is formed (FIG. 7(a)), the rotation detection sensor 400 detects each marker 700 (FIG. 7(b)).As a result, as shown in FIG. 7(c), The DMDs 551 can be driven in accurate synchronization.

Note that, as described above, the amount of reflected light obtained from marker 700 is smaller than the amount of reflected light from other parts. Therefore, the rotation detection pulse of the marker 700 shown in FIG. 7(b) usually becomes a rotation detection pulse of negative polarity. FIG. 7B is an example in which the rotation detection pulse of the marker 700 is illustrated as a positive polarity pulse by inverting the polarity of the entire rotation detection pulse.

Next, one of the markers 700 attached to the color wheel 401 may peel off. FIG. 8 is a timing chart showing the timing of each part of the color wheel 401 immediately after the marker 700 is peeled off from the rotating body 450. Among them, FIG. 8A shows the timing at which light of each color is sequentially formed by the light from the light source 301 entering each RGB segment of the rotating color wheel 401. FIG. 8B shows the timing of a rotation detection pulse obtained when the rotation detection sensor 400 detects one marker 700 attached to the rotating body 450 of the rotating color wheel 401. FIG. 8(c) shows the drive timing of the DMD 551.

As shown in FIGS. 8(a) and 8(b), when one marker 700 peels off, the rotation detection sensor 400 cannot output a rotation detection pulse at the timing of one marker 700, but when the next marker 700 The other marker 700 can be detected at the timing of the B color filter and a rotation detection pulse can be output.

That is, as described above, the two sets of color filters are arranged in the same order of RBG, and the marker 700 is also provided at the starting position of the B color filter 180 degrees apart. Therefore, even if one of the markers 700 peels off from the rotating body 450, a rotation detection pulse can be generated at the timing of the start position of the color filter B, and this rotation detection pulse can be used to generate the rotation detection pulse as shown in FIG. 8(c). , the DMD 551 can be driven with accurate timing. Therefore, for example, even if one marker 700 peels off during projection, normal image projection can be continued using the other marker 700.

(warning action)
Next, the display control unit 254 shown in FIG. 6 calculates the number of pulses detected by the rotation detection sensor 400 during one rotation of the color wheel 401 and the number of pulses indicated by the position signal stored in the storage unit. compare. In this example, the number of pulses detected by the rotation detection sensor 400 during one rotation of the color wheel 401 is "2". Further, the number of pulses indicated by the position signal is "2".

However, when one marker 700 peels off as described above, the number of pulses detected by the rotation detection sensor 400 during one rotation of the color wheel 401 becomes "1", and the number of pulses detected by the rotation detection sensor 400 becomes "2" as indicated by the position signal. The number of pulses is less than the number of pulses. The fact that the number of pulses detected by the rotation detection sensor 400 is smaller than the number of pulses indicated by the position signal means that a failure in which the marker 700 peels off from the rotating body 450 has occurred.

Therefore, the display control unit 254, which is an example of the notification unit, controls the display unit to display a message urging repair, such as “The marker has come off from the color wheel. Please request repair.” Thereby, the user can recognize a malfunction in which the marker has peeled off, and can promptly request repair.

(Effects of embodiment)
As is clear from the above description, the projector device according to the embodiment provides the color wheel 401 with two or more color filter groups each having the same arrangement of color filters. Furthermore, markers 700 are provided on the rotary body 450 that rotates in synchronization with the color wheel 401 in correspondence with the reference positions of each filter group.

As a result, even if one marker 700 comes off from the rotating body 450 of the color wheel 401, the reference position can be detected using the other marker 700, and projection can be continued based on the other marker 700. .

Furthermore, when the display control unit 254 detects a decrease in the number of rotation detection pulses obtained during one rotation of the color wheel 401, it controls the display unit to display a message urging repair. Thereby, the user can recognize a failure in which the marker 700 has peeled off, and can promptly request repair.

Finally, the embodiments described above are presented as examples and are not intended to limit the scope of the present invention. This new embodiment can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention.

For example, in the embodiment described above, two sets of RGB color filters are provided, and the marker 700 is pasted at the starting position of each B color filter. However, three or more RGB color filter groups may be provided and the marker 700 may be pasted at the starting position of each B color filter. Moreover, the color filter may be a color filter other than RGB, for example, a color filter of other colors such as transparent, cyan, magenta, and yellow. Further, the marker 700 may be attached to a starting position of a color other than B, or may be attached to a position other than the starting position. In either case, effects similar to those described above can be obtained.

Further, the embodiments and modifications of each embodiment are included within the scope and gist of the invention, and are included within the scope of the invention described in the claims and its equivalents.

1 Projector 3 Exit window 9 External interface 10 Control unit 15 Optical engine 30 Light source unit 40 Illumination optical system unit 50 Image display unit 60 Projection optical system unit 253 Position signal acquisition section 254 Display control section 255 Optical engine control section 301 Light source 401 Color wheel 430 Color wheel unit 450 Rotating body 700 Marker

Japanese Patent Application Publication No. 2012-137558

Claims (1)

A color filter group in which color filters of a plurality of colors are arranged in a predetermined manner is synchronized with a color wheel provided in plurality consecutively along the rotation direction, and a color wheel provided coaxially with the rotation axis of the color wheel. and a plurality of markers provided on the rotating body, the markers each being provided at a position on the rotating body corresponding to a reference position of each of the color filter groups. wheel unit and
a light source unit that irradiates light to the color wheel;
a rotation detection sensor that detects the rotational position of the color wheel based on the marker;
an image forming unit that forms and projects an image from light from the light source unit via each color filter of the color wheel in synchronization with the rotational position of the color wheel detected by the rotation detection sensor ;
The number of pulses obtained by detecting the marker detected by the rotation detection sensor is compared with the number of markers provided on the color wheel, which is indicated by reference pulse number information, and the rotation detection is performed. a notification unit that performs a predetermined notification operation when the number of marker pulses detected by the sensor is smaller than the number of markers indicated by the reference pulse number information;
An image projection device having:

Images