JP2009288662A - Image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce electromagnetic interference wave from a harness that connects a plurality of substrate units of a liquid crystal projector. <P>SOLUTION: The image projection apparatus includes: a plurality of substrate units each of which is covered with a shielding case; the harness that connects the plurality of substrate units; a ground connection sheet metal that connects grounds of the respective shielding cases; and an elastic member that presses the harness against the ground connection sheet metal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image projection apparatus using an image modulation element such as a liquid crystal panel, and more particularly to reduction of electromagnetic wave noise in the image projection apparatus.

  In recent years, high-speed digital technology has been introduced for electrical and electronic equipment including liquid crystal projectors, and high-frequency circuits such as switching power supplies and oscillation circuits have been adopted one after another. May be a source. In particular, in a high-frequency circuit using a differential signal such as LVDS, common mode noise of about 100 MHz to 1 GHz is likely to be generated in the ground line due to a noise signal generated in a rectangular signal. In addition, direct radiation noise of the same frequency level that is directly radiated from the IC on the substrate or the pattern on the substrate is also generated. These noises may be emitted from the gap of the shield case, or transferred to the cable coming out of the shield and emitted outside the equipment. If this electromagnetic interference wave interferes with other electric and electronic devices, it causes other electric and electronic devices to malfunction.

Patent Document 1 discloses a configuration in which common mode noise is suppressed by a simple external member.
JP2008-10796

  In order to reduce the influence of electromagnetic interference waves, it is necessary to select an IC that does not generate electromagnetic interference waves or to devise a circuit configuration. Further, in order to prevent the noise generated in the circuit from being released to the outside of the image projection apparatus, it is effective to cover the substrate body with a metal shield case. On the other hand, in the liquid crystal projector, the electric board is divided and installed in various places in the image projection apparatus in order to increase the degree of freedom of the interface layout considering the operability of the user and the layout of the optical system. In particular, in a liquid crystal projector, an electric substrate is often composed of a plurality of substrate units, and an optical system is often disposed between the plurality of substrate units. Each board unit needs to be covered with a shield case. Moreover, it is necessary for each board | substrate unit to arrange | position both the harness for transmitting a control signal, and the harness which supplies power from a power supply board. There is a need to prevent high-frequency noise from the board from riding on these harnesses, and the harness acting as an antenna to be released as it is to the outside of the image projection apparatus.

  The image projection apparatus of the present invention includes a plurality of substrate units each covered with a shield case, a harness connecting between the plurality of substrate units, and a ground connection sheet metal that connects the grounds of the respective shield cases. Here, an elastic member for pressing the harness against the ground connection sheet metal is provided.

  According to the present invention, a liquid crystal projector with reduced electromagnetic interference can be provided.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 3 shows an image projection apparatus of the present invention. FIG. 2 shows the inside of the optical engine unit 6 of the image projection apparatus of the present invention. 1 is a light source lamp, 2 is a lamp holder for holding the lamp 1, 3 is explosion-proof glass, 4 is a glass holder, 6α is an illumination optical system for incident light from the lamp 1, and 6β is incident light from the illumination optical system. The color separation / synthesis optical system includes a liquid crystal panel for three colors of RGB. Reference numeral 5 denotes a projection lens barrel for projecting an image onto a screen (projected surface) (not shown) by receiving light emitted from the color separation / synthesis optical system. The projection lens barrel 5 has a projection lens optical system to be described later. Is housed. Reference numeral 6 denotes an optical box that houses the lamp 1, the illumination optical system α, and the color separation / synthesis optical system β and to which the projection lens 5 is fixed. In FIG. 3, 8 is a power source and 10 is a ballast power source for lighting the lamp 1. The power supply 8 and the ballast power supply 10 are surrounded by a shield case 9 made of, for example, aluminum. An electric exhaust fan 14 exhausts heat generated in the power supply 8 and the ballast substrate 10. On the other hand, the RGB board 11c for driving the liquid crystal panel, the interface board 11b for inputting / outputting signals, the main board 11a for controlling the video signal processing and the lighting of the lamp 1 are placed vertically to minimize the external shape of the projector, Surrounded by a shield case 16. Furthermore, the power supply board 8 and the ballast power supply board 10 are controlled by the main board. Thus, in order to exchange both signals, the control harness 18a and the power harness 18b are provided. Reference numeral 12 denotes a suction cooling fan for an optical system for cooling an optical element such as a liquid crystal panel in the color separation / synthesis optical system β.

  Reference numeral 17 denotes a lamp duct for sending blowing air to the lamp 1 and sending cooling fan cooling air for the light source lamp for cooling the lamp 1 to the lamp. Reference numeral 15 denotes an exhaust fan, and the exhaust fan 18 discharges hot air after passing through the lamp 1 by the lamp cooling fan 14.

  Next, an image projection apparatus equipped with the above-described lamp 1, the illumination optical system 6α, the color separation / synthesis optical system 6β, and the reflective liquid crystal display element (image forming element such as a reflective liquid crystal panel) constituted by the projection lens 5. The optical configuration will be described with reference to FIG.

In FIG. 2, reference numeral 41 denotes an arc tube that emits white light with a continuous spectrum, and reference numeral 42 denotes a reflector that collects light from the arc tube 41 in a predetermined direction, and the arc tube 41 and the reflector 42 form the lamp 1.
Reference numeral 43a denotes a first cylinder array formed of a lens array having a refractive power in the horizontal direction (horizontal direction in the traveling direction of light from the lamp 1 (direction perpendicular to the paper surface)). 43b is a second cylinder array having a lens array corresponding to each lens of the first cylinder array 43a, 44 is an ultraviolet absorbing filter, and 45 is a polarization conversion element for aligning non-polarized light with predetermined polarized light.

  46 is a front compressor composed of a cylindrical lens having a refractive power in the vertical direction, and 47 is a total reflection mirror for converting the optical axis by 88 degrees. Reference numeral 43c denotes a third cylinder array formed of a lens array having a refractive power in the vertical direction (the vertical direction in the traveling direction of light from the lamp 1 (the vertical direction on the paper surface)). 43d is a fourth cylinder array having a lens array corresponding to each lens of the third cylinder array 43c, and 50 is a color filter for returning the color in a specific wavelength range to the lamp in order to adjust the color coordinate to a certain value. It is. 48 is a condenser lens, and 49 is a rear compressor composed of a cylindrical lens having refractive power in the vertical direction. The illumination optical system α is configured as described above.

  58 is a dichroic mirror that reflects light in the blue (B) and red (R) wavelength regions and transmits light in the green (G) wavelength region, and 59 for G in which a polarizing element is attached to a transparent substrate. , Which transmits only P-polarized light. Reference numeral 60 denotes a first polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  Reference numerals 61R, 61G, and 61B are a reflective liquid crystal display element for red, a reflective liquid crystal display element for green, and a reflective liquid crystal display element for blue that reflect incident light and modulate the image, respectively. 62R, 62G, and 62B are a quarter wavelength plate for red, a quarter wavelength plate for green, and a quarter wavelength plate for blue, respectively. A trimming filter 64a returns orange light to the lamp in order to increase the color purity of R, and 64b is an incident-side polarizing plate for RB in which a polarizing element is attached to a transparent substrate, and transmits only P-polarized light. 65 is a color selective phase difference plate that converts the polarization direction of the R light by 90 degrees and does not convert the polarization direction of the B light. Reference numeral 66 denotes a second polarization beam splitter that transmits P-polarized light and reflects S-polarized light, and has a polarization separation surface.

  68B is a B output side polarizing plate (polarizing element), which rectifies only the S polarized light of B, and 68G is a G output side polarizing plate that transmits only the S polarized light. Reference numeral 69 denotes a dichroic prism that transmits RB light and reflects G light.

  The above dichroic mirrors 58 to 69 constitute the color separation / synthesis optical system β.

  Here, if the definitions of P-polarized light and S-polarized light are clarified, 45 polarization conversion elements convert P-polarized light into S-polarized light. Here, P-polarized light and S-polarized light are described with reference to 45 polarization conversion elements. Yes. On the other hand, since the light incident on the dichroic mirror 58 is considered on the basis of the polarization beam splitters 60 and 66, it is assumed that P-polarized light is incident. Although the light emitted from the 45 polarization conversion elements is S-polarized light, the same S-polarized light is defined as light that enters the dichroic mirror 58 as P-polarized light in this embodiment.

Next, the optical action will be described.
Light emitted from the arc tube 41 is collected in a predetermined direction by the reflector 42. The reflector 42 has a paraboloid shape, and light from the focal position of the paraboloid becomes a light beam parallel to the symmetry axis of the paraboloid. However, since the light source from the arc tube 41 is not an ideal point light source but has a finite size, the condensed light flux contains many light components that are not parallel to the symmetry axis of the paraboloid. Yes. These light beams are incident on the first cylinder array 43a. The light beam incident on the first cylinder array 43a is divided into a plurality of light beams corresponding to the respective cylinder lenses and condensed (a plurality of belt-shaped light beams in the vertical direction). Further, a plurality of light beams (a plurality of light beams in a strip shape in the vertical direction) are formed in the vicinity of the polarization conversion element 45 via the ultraviolet absorption filter 44 and the second cylinder array 43b.

  The polarization conversion element 45 includes a polarization separation surface, a reflection surface, and a half-wave plate, and a plurality of light beams are incident on the polarization separation surface corresponding to the column, and are reflected by the transmitted P-polarized component light. The light is divided into polarized light components. The reflected light of the S polarization component is reflected by the reflecting surface and is emitted in the same direction as the P polarization component. On the other hand, the transmitted P-polarized light component is transmitted through the half-wave plate, converted into the same polarized light component as the S-polarized light component, and emitted as light having the same polarization direction. A plurality of light beams that have undergone polarization conversion (a plurality of light beams in a strip shape in the vertical direction) are emitted from the polarization conversion element 45 and then reflected by the reflection mirror 47 through the front compressor 46 by 88 degrees. Further, the light enters the third cylinder array 43c. The light beam incident on the third cylinder array 43c is divided and condensed into a plurality of light beams corresponding to the respective cylinder lenses (a plurality of belt-shaped light beams in the horizontal direction). After passing through the fourth cylinder array 43d, a plurality of light beams (a plurality of light beams in a strip shape in the horizontal direction) are formed and reach the condenser lens 48 and the rear compressor 49.

  Here, due to the optical action of the front compressor 46, the condenser lens 48, and the rear compressor 49, a rectangular uniform illumination area is formed by overlapping the rectangular images of the plurality of light beams. Reflective liquid crystal display elements 61R, 61G, and 61B, which will be described later, are arranged in this illumination area. Next, the light converted to S-polarized light by the polarization conversion element 45 enters the dichroic mirror 58. The dichroic mirror 58 reflects B (430 to 495 nm) and R (590 to 650 nm) light and transmits G (505 to 580 nm) light.

Next, the G optical path will be described.
The G light transmitted through the dichroic mirror 58 enters the incident side polarizing plate 59. The G light is still P-polarized light after being decomposed by the dichroic mirror 58 (S-polarized light in the case of 45 polarization conversion element standard). The G light exits from the incident-side polarizing plate 59, then enters the first polarizing beam splitter 60 as P-polarized light, passes through the polarization splitting surface, and is transmitted to the G reflective liquid crystal display element 61G. And so on. In the reflective liquid crystal display element 61G for G, the G light is image-modulated and reflected. The P-polarized component of the image-modulated G reflected light is transmitted again through the polarization separation surface of the first polarization beam splitter 60, returned to the light source side, and removed from the projection light. On the other hand, the S-polarized component of the image-modulated G reflected light is reflected by the polarization separation surface of the first polarization beam splitter 60 and travels toward the dichroic prism 69 as projection light. At this time, in a state in which all the polarization components are converted to P-polarized light (a state in which black is displayed), ¼ provided between the first polarizing beam splitter 60 and the reflective liquid crystal display element 61G for G. The slow axis of the wave plate 62G is adjusted in a predetermined direction. Thereby, it is possible to suppress the influence of the disturbance of the polarization state generated in the first polarization beam splitter 60 and the G-type reflective liquid crystal display element 61G. The G light emitted from the first polarizing beam splitter 60 enters the third polarizing beam splitter 69 as S-polarized light, reflects the G light on the dichroic film surface of the dichroic prism 69, and enters the projection lens 70. It reaches.

  On the other hand, the R and B lights reflected by the dichroic mirror 58 enter the incident side polarizing plate 64a. The R and B lights are still P-polarized light after being decomposed by the dichroic mirror 58. Then, after the orange light is cut by the trimming filter 64a, the R and B lights are emitted from the incident side polarizing plate 64b and are incident on the color selective phase difference plate 65. The color-selective phase difference plate 65 has an action of rotating the polarization direction of only R light by 90 degrees, whereby the R light becomes S-polarized light and the B light becomes P-polarized light. Is incident on. The R light incident on the second polarization beam splitter 66 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 66 and reaches the R reflective liquid crystal display element 61R. The B light incident on the second polarization beam splitter 66 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 66 and reaches the B-use reflective liquid crystal display element 61B.

  The R light incident on the R reflective liquid crystal display element 61R is image-modulated and reflected. The S-polarized light component of the image-modulated R reflected light is reflected again by the polarization separation surface of the second polarization beam splitter 66, returned to the light source side, and removed from the projection light. On the other hand, the P-polarized light component of the image-modulated R reflected light is transmitted through the polarization separation surface of the second polarization beam splitter 66 and directed to the dichroic prism 69 as projection light.

  The B light incident on the B reflective liquid crystal display element 61B is image-modulated and reflected. The P-polarized component of the image-modulated B reflected light is again transmitted through the polarization separation surface of the second polarization beam splitter 66, returned to the light source side, and removed from the projection light. On the other hand, the S-polarized component of the image-modulated B reflected light is reflected by the polarization separation surface of the second polarizing beam splitter 66 and travels to the dichroic prism 69 as projection light.

  At this time, by adjusting the slow axes of the quarter-wave plates 62R and 62B provided between the second polarizing beam splitter 66 and the reflective liquid crystal display elements 61R and 61B for R and B, G As in the case of, the black display of R and B can be adjusted.

  In this way, B light out of the R and B projection lights emitted from the second polarization beam splitter 66, synthesized into one light beam, is analyzed by the exit-side polarizing plate 68B and enters the dichroic prism 69. The R light passes through the polarizing plate 68B as it is with the P polarization, and enters the 69 dichroic prism.

  Incidentally, the B projection light is generated by passing through the second polarizing beam splitter 66, the B-use reflective liquid crystal display element 61B, and the quarter-wave plate 62B by being analyzed by the exit-side polarizing plate 68B. The light is cut from invalid components.

  The R and B projection light incident on the 69 dichroic prism is transmitted through the dichroic film surface of the 69 dichroic prism, and is combined with the G light reflected on the dichroic film surface to reach the projection lens 5. .

  Then, the combined R, G, B projection light is enlarged and projected onto a projection surface such as a screen by the projection lens 5.

  Since the optical path described above is for the case where the reflective liquid crystal display element displays white, the optical path for the case where the reflective liquid crystal display element displays black will be described below.

  First, the G optical path will be described.

  The P-polarized light of the G light that has passed through the dichroic mirror 58 enters the incident-side polarizing plate 59, and then enters the first polarizing beam splitter 60 and is transmitted through the polarization separation surface. It reaches the element 61G. However, since the reflective liquid crystal display element 61G displays black, the G light is reflected without being image-modulated. Accordingly, since the G light remains P-polarized light after being reflected by the reflective liquid crystal display element 61G, it is transmitted again through the polarization separation surface of the first polarization beam splitter 60 and transmitted through the incident-side polarizing plate 59. Then, it is returned to the light source side and removed from the projection light.

Next, the R and B optical paths will be described.
P-polarized light of R and B light reflected from the dichroic mirror 58 is incident on the incident-side polarizing plate 64b. Then, the R and B lights are emitted from the incident side polarizing plate 64 b and then enter the color selective phase difference plate 65. The color-selective phase difference plate 65 has an action of rotating the polarization direction of only R light by 90 degrees, whereby the R light becomes S-polarized light and the B light becomes P-polarized light. Is incident on. The R light incident on the second polarization beam splitter 66 as S-polarized light is reflected by the polarization separation surface of the second polarization beam splitter 66 and reaches the R reflective liquid crystal display element 61R. The B light incident on the second polarization beam splitter 66 as P-polarized light passes through the polarization separation surface of the second polarization beam splitter 66 and reaches the B-use reflective liquid crystal display element 61B. Here, since the R reflective liquid crystal display element 61R displays black, the R light incident on the R reflective liquid crystal display element 61R is reflected without being image-modulated. Therefore, even after being reflected by the reflective liquid crystal display element 61R for R, the R light remains as S-polarized light, and is reflected again by the polarization separation surface of the first polarizing beam splitter 60, and is incident on the incident side polarizing plate. Since it passes through 64b and is returned to the light source side and is removed from the projection light, a black display is obtained. On the other hand, the B light incident on the B reflective liquid crystal display element 61B is reflected without being image-modulated because the B reflective liquid crystal display element 61B displays black. Accordingly, since the B light remains P-polarized light even after being reflected by the B-type reflective liquid crystal display element 61B, it again passes through the polarization separation surface of the first polarization beam splitter 60. The light is converted into P-polarized light by the color-selective retardation plate 65, passes through the incident-side polarizing plate 64b, returns to the light source side, and is removed from the projection light.

  The above is the optical configuration in the image projection apparatus using the reflective liquid crystal display element (reflective liquid crystal panel).

Next, a method for removing electromagnetic noise from the liquid crystal projector according to the present invention will be described.
FIG. 1 shows a configuration of a ground connection sheet metal 19 that connects a power supply substrate case (shield case) 9 and a main substrate case (shield case) 16. The optical engine 6 is omitted in the figure.

  In general, since the electromagnetic wave generated by the current flowing out from the signal generation source finally returns through the ground, it is preferable that the ground connection sheet metal 19 has a surface area as large as possible as shown in FIG. Further, in order to stabilize the ground, the ground connection sheet metal is directly connected to the ground of the AC power supply line.

  The configuration of FIG. 1 is a configuration in which the harness 18 is arranged at the upper part of the liquid crystal projector, and thus the ground connection sheet metal 19 is arranged at the upper part of the liquid crystal projector, but any of them may be arranged at the lower part of the liquid crystal projector. Also, a plurality of upper and lower portions may be arranged. However, when it is arranged at the top and bottom, it is necessary to pay attention to the ground wiring so that a ground loop does not occur. This is because when a ground loop is formed, common mode noise is generated from the loop.

  When the ground connection sheet metal 19 is formed on the upper part of the liquid crystal projector, the ground connection sheet metal 19 also serves as a shield case for the entire liquid crystal projector and has a shielding action. Therefore, it is preferable that the signal line (harness) 18 is disposed inside the ground connection sheet metal 19, that is, the ground connection sheet metal 19 is disposed outside the harness. Further, if the grounds are not securely coupled, a potential difference is generated between the grounds, and noise currents easily flow. For this reason, it is necessary to devise so that the gaps between the ground connection sheet metal 19, the power supply board case 9 and the main board case 16 do not become slit antennas by increasing the number of screws and narrowing the space between the screws. is there. In particular, it is important to set the distance between the ground connection sheet metal 19, the control harness 18a, and the power harness 18b short.

  FIG. 4 shows a side view of the image projection apparatus. The control harness 18 a and the power supply harness 18 b are arranged along the inner side of the ground connection sheet metal 19. Flexible substrates from the liquid crystal panels 61R, 61B, 61G mounted on the optical engine 6 are mounted on the RGB substrate 11c. Power is supplied to these substrates from the power supply substrate 8. High frequency noise generated in the board unit constituted by the main board 11a, interface board 11b, and RGB board 11c in FIG. 1 moves to the control harness 18a and the power supply harness 18b. Furthermore, there is a possibility that electromagnetic noise may be emitted outside the device using the control harness 18a and the power harness 18b as antennas. In view of this, the control harness 18a and the power harness 18b are pressed against the ground connection sheet metal 19 by the elastic member 20 disposed at the upper portion of the optical engine 6.

  FIG. 5 shows a detailed view of the periphery of the harness 18. A gasket in which an elastic body 20a such as a sponge is wrapped with a conductive cloth 20b is attached to the top of the optical engine 6, and is pressed against the ground connection metal plate 19 in this order: the control harness 18a and the power harness 18b. This is because high-frequency noise generated from the IC on the main board 11a tends to ride on the control harness 18a more easily. The harness 18 is covered with a resin insulator 22 around the core wire 21. When the harness 18 is pressed against the ground connection sheet metal 19, an equivalent circuit as shown on the right side of FIG. The harness insulator 22 acts as a capacitor to form a low-pass filter. Therefore, a high-frequency noise current in the range of 100 MHz to 1 GHz on the cable flows from the harness 18 to the ground connection sheet metal 19.

  With such a configuration, high-frequency noise on the harness 18 can be reduced in units of several dB. Although the example using the gasket as the elastic member has been described, the harness 18 may be pressed against the ground connection sheet metal 19 using, for example, a spring, a swunge, or a mold member. Furthermore, when the ground connection sheet metal 19 becomes an antenna, the antenna component can be removed by the following means. When the length indicated by 19a in FIG. 3 coincides with an integral multiple of the wavelength of the basic clock frequency of the IC on the main board, a plurality of slit holes 19b are provided on the sheet metal 19 to substantially shorten the length of 19a. be able to. The sheet metal lengths 19c and 19d thus formed are configured not to be an integral multiple of the wavelength. Accordingly, the ground connection sheet metal can be configured not to be an antenna that emits high frequency noise.

  In the first embodiment, the configuration in which the control harness 18a and the power supply harness 18b are pressed against the ground connection sheet metal 19 using an elastic member such as a gasket, a spring, a swunge, and a mold member has been described. FIG. 6 shows a side view of the harness. The configuration of FIG. 6 is characterized in that a ferrite core 23 effective for a frequency of about 1000 to 300 MHz is attached to the harness in addition to the configuration of the first embodiment. The elastic member 24 presses both the harness 18 and the ferrite core 23 attached to the harness 18 against the ground connection sheet metal 19. Thereby, the high frequency noise on the harness 18 can be more reliably removed.

  In the first and second embodiments, the control harness 18a and the power harness 18b are pressed against the ground connection sheet metal 19 with elastic members, but the surface of the harness 18 is only covered with the ground connection sheet metal 19. In order to remove noise more reliably, the harness 18 itself may be covered with the shield metal plate 25. Then, a part of the shield sheet metal 25 surrounding the harness 18 is configured by, for example, a leaf spring, and the harness 18 is pressed against the ground connection sheet metal 19 by the leaf spring, thereby obtaining two effects of the shield effect and the capacitor effect at the same time. it can.

  The embodiment of the present invention describes a reflective liquid crystal display device, but may be a transmissive liquid crystal display device.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist.

The perspective view which shows Example 1 of this invention The top view and side view which show the optical system of Example 1 of this invention The top view which shows Example 1 of this invention The side view which shows Example 1 of this invention Sectional drawing which shows Example 1 of this invention Sectional drawing which shows Example 2 of this invention Sectional drawing which shows Example 3 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source lamp 2 Lamp holder 3 Explosion-proof glass 4 Glass holder 5 Projection lens 6 Optical box 8 Power supply 9 Shield case 10 Ballast power supply 11 Circuit board 12 Optical cooling fan 13 RGB duct 14 Power supply exhaust fan 15 Lamp exhaust fan 16 Shield case 17 Lamp cooling Fan and duct 18 Harness 19 Ground connection sheet metal 20 Gasket 21 Core wire 22 Insulator 23 Ferrite core 24 Elastic member 25 Elastic shield member 41 Lamp arc tube (light source)
42 reflector

Claims (4)

  A plurality of board units each covered by a shield case, a harness connecting the plurality of board units, a ground connection sheet metal connecting the grounds of the respective shield cases, and pressing the harness against the ground connection sheet metal An image projection apparatus comprising an elastic member.   The image projection apparatus according to claim 1, wherein the ground connection sheet metal is disposed outside the image projection apparatus with respect to the harness, and has a shielding action with respect to the harness and the substrate unit.   The image projection apparatus according to claim 1, wherein the harness includes a ferrite core, and the elastic member presses the ferrite core against the ground connection sheet metal.   4. The image projection apparatus according to claim 1, further comprising: a shield case that covers the harness, wherein the elastic member is formed in a part of the shield case. 5.

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