The present invention relates to a liquid crystal display device.
Liquid crystal display devices for displaying information as an image are widely used. Such a liquid crystal display device is also used, for example, in a vehicle-mounted head-up display that emits display light for displaying an image from the liquid crystal display device to display a virtual image in front of a viewer. For example, in the head-up display disclosed in Patent Document 1 below, a liquid crystal display panel formed of a thin film transistor (TFT) is held via a packing in a TFT holder together with a hot mirror that protects a front surface of the liquid crystal display panel.
In the configuration of Patent Document 1 described above, the liquid crystal display panel is pressed and held by a rubber surface of the packing, and it is thus difficult to perform control so that a fixing stress applied to the liquid crystal display remains constant, and this results in a problem in that uneven brightness occurs in the liquid crystal display panel due to an influence of the fixing stress. Further, the liquid crystal display panel is held via the packing such as a rubber, and thus, if the positioning accuracy is poor, an image may be affected by the display light.
The present invention has been contrived in view of the above problems, and an object thereof is to provide a liquid crystal display device capable of suppressing uneven brightness.
To achieve the above object, a liquid crystal display device according to the present invention includes
a liquid crystal display panel,
a transmissive panel provided in front of the liquid crystal display panel and configured to transmit light,
a packing configured to support a periphery of the transmissive panel, and
a frame body configured to hold and fix the liquid crystal display panel and the packing.
The frame body includes a first frame body and a second frame body to be coupled in engagement with each other,
the first frame body is provided with a support portion penetrating the packing and being provided in front of the liquid crystal display panel,
the second frame body is provided with an elastic support portion facing the support portion and being provided behind the liquid crystal display panel, and
the liquid crystal display panel is sandwiched between the support portion and the elastic support portion to be held and fixed without abutting against the packing.
According to the present invention, it is possible to suppress uneven brightness.
A liquid crystal display device according to an embodiment of the present invention will be described in detail with reference to the drawings.
A liquid crystal display device 10 according to the present embodiment is used, for example, as a display component of a vehicle-mounted head-up display that that emits display light for displaying an image such as vehicle information to display a virtual image in front of a viewer. The liquid crystal display device 10 emits display light representing an image from the liquid crystal display device 10 toward a windshield of the vehicle. A viewer (mainly a driver of the vehicle) receives the display light reflected by the windshield and visually recognizes a virtual image superimposed on a scenery that the viewer sees through the windshield. Usually, a mirror member such as a concave mirror is arranged in an optical path of the display light from the liquid crystal display device 10 to the windshield.
The liquid crystal display device 10 according to the present invention includes a liquid crystal display panel 11, a transmissive panel 12 provided in front of the liquid crystal display panel 11 and configured to transmit light, a packing 13 serving as a buffer member for supporting a periphery of the transmissive panel 12, and a frame body 20 configured to hold and fix the liquid crystal display panel 11 and the packing 13. The frame body 20 includes a first frame body 21 and a second frame body 31 to be coupled in engagement with each other. The first frame body 21 is provided with a support portion 22 penetrating the packing 13 and being provided in front of the liquid crystal display panel 11. The second frame body 31 is provided with an elastic support portion 32 facing the support portion 22 and being provided behind the liquid crystal display panel 11. The liquid crystal display panel 11 is sandwiched between the support portion 22 and the elastic support portion 32 to be held and fixed without abutting against the packing 13.
Thus, it is possible to suppress uneven brightness due to a force applied to hold and fix the liquid crystal display device 10 and improve the positioning accuracy.
As illustrated in
The liquid crystal display panel 11 is, for example, a color liquid crystal module, and is formed of a dot matrix type TFT module.
The liquid crystal display panel 11 receives light from a backlight unit (not illustrated), forms an image, and emits the image as display light. The liquid crystal display panel 11 includes a liquid crystal cell including a pair of transparent substrates and a liquid crystal layer enclosed between the pair of transparent substrates, and polarizing filters facing each other with the liquid crystal cell interposed therebetween. Transparent electrodes formed of indium tin oxide (ITO) or the like are formed on the transparent substrates. The liquid crystal display panel 11 is connected to a driver and a control unit (not illustrated) for the liquid crystal display panel 11 mounted on a circuit board. In the liquid crystal display panel 11, if a drive voltage is applied to the liquid crystal layer via the transparent electrodes under the control of the control unit, the orientation of the liquid crystal molecules in the liquid crystal layer is controlled, and each of a plurality of pixels included in the liquid crystal display panel 11 is switched to a transmissive/non-transmissive state. With such a combination of the pixels, the liquid crystal display panel 11 forms a predetermined image and emits the image as display light. The control unit acquires vehicle information such as a vehicle speed from an electronic control unit (ECU) of the vehicle, for example, and emits acquired image information as display light.
The hot mirror 12 is provided on a front side (in front) of the liquid crystal display panel 11. The hot mirror 12 includes a multilayer film on a transparent glass, and thus, the hot mirror 12 transmits visible light and reflects infrared light, and therefore, provides protection from a temperature increase in the liquid crystal display panel 11 and the like.
The diffusion plate 14 is provided on a rear side of (behind) the liquid crystal display panel 11. The diffusion plate 14 uniformly diffuses light incident on the liquid crystal display panel 11 from the backlight unit (not illustrated). As illustrated in
The frame body 20 is formed in a rectangular frame shape corresponding to an outer shape of the liquid crystal display panel 11, and the liquid crystal display panel 11 is housed in the frame body 20 to be held and fixed by the frame body 20. The frame body 20 is formed of a resin (for example, polypropylene). The frame body 20 includes the holder 21 having a substantially L-shaped cross-section and the cover 31 having a substantially L-shaped cross section, which are engaged and coupled. The holder 21 and the cover 31 are coupled in engagement with each other to form the frame body 20 having a substantially U-shaped cross section and an opening inside.
The holder 21 is arranged in front of the liquid crystal display panel 11. The holder 21 has a wide upper side and a narrow lower side, and a side surface shape of the holder 21 is formed in a substantially trapezoidal shape.
The cover 31 is arranged behind the liquid crystal display panel 11 and is coupled in engagement with the holder 21.
The cover 31 is formed so that the widths of an upper side, a lower side, and both lateral sides of the cover 31 are constant, and if the cover 31 is vertical in a state where the holder 21 is coupled in engagement with the cover 31, an upper part of the holder 21 protrudes forward and a lower part of the holder 21 is closer to the rear side (see
The liquid crystal display panel 11, the hot mirror 12, the packing 13, and the diffusion plate 14 are housed between the holder 21 and the cover 31.
In the liquid crystal display device 10, the liquid crystal display panel 11 is directly sandwiched between the holder 21 and the cover 31 to be held and fixed without contacting (abutting against) the packing 13.
That is, as illustrated in
As illustrated in
Thus, front and back surfaces of the liquid crystal display panel 11 can be sandwiched from both sides to be held between the elastic support portion 32 of the cover 31 and the support portion 22 of the holder 21 without contacting (abutting against) the packing 13, and thus, a position of a panel surface of the liquid crystal display panel 11 on an X-Y plane is restricted in a Z direction.
Further, as illustrated in
As illustrated in
Therefore, the liquid crystal display panel 11 is guided to be placed against the positioning portions 28 of the holder 21 and is positioned in an up-down direction (Y direction).
The two positioning guide portions 34 are formed on a lateral side portion (left side portion in
Therefore, the position of the liquid crystal display panel 11 is restricted and the liquid crystal display panel 11 is positioned in the X direction, the Y direction, and the Z direction by the support portion 22 and the elastic support portion 32, and by the positioning portions 28 and the positioning guide portions 34 at the upper and lower side portions and the lateral side portions, and thus, the liquid crystal display panel 11 is held and fixed between the holder 21 and the cover 31 without (abutting against) the packing 13.
It is noted that a structure in which the packing 13 does not contact the liquid crystal display panel 11 will be described later.
Further, the holder 21 and the cover 31 are engaged and coupled to be fitted with each other.
That is, two coupling protrusion portions 24 protruding upward are formed on each of an upper side portion and a lower side portion of an outer surface of the holder 21, and the cover 31 is formed with coupling frame portions 36 to engage with the coupling protrusion portions 24 to surround the outside of the coupling protrusion portions 24.
Therefore, the coupling frame portions 36 of the cover 31 are pushed to place over the coupling protrusion portions 24 of the holder 21, and the coupling frame portions 36 are positioned in a state where the coupling frame portions 36 place over the coupling protrusion portions 24, and thus, the holder 21 and the cover 31 can be held in a coupled state.
As illustrated in
Further, a tip end portion of the engaging protrusion portion 37 is formed into a slanted surface having a thin shape so that the insertability into the engaging concave portion 25 can be improved.
It is noted that the position of the holder 21 and the cover 31 being coupled in engagement with each other is restricted in the Z direction by a reaction force acting between the support portion 22 of the holder 21 and the elastic support portion 32 of the cover 31 via the liquid crystal display panel 11.
The hot mirror 12 is held and fixed in the frame body 20 via the packing 13.
As illustrated in
The packing 13 attached to the holder 21 is placed against a rear surface of the hot mirror 12 and pushes the hot mirror 12.
As illustrated in
As illustrated in
The support portion 22 configured to support the front surface of the liquid crystal display panel 11 is defined as a length by which the support portion 22 protrudes from a through hole of the packing 13 to the rear in a state where the packing 13 is supported by the holder 21. Thus, the packing 13 is mounted in the holder 21 without contacting (abutting against) the liquid crystal display panel 11, and the packing 13 contacts the hot mirror 12 to support the hot mirror 12.
The packing 13 is integrally formed with an inclined pressing portion 13a that positions the hot mirror 12.
As illustrated in
The packing 13 is formed of an elastic material such as a rubber or elastomer, or a porous material such as polyurethane foam, and includes a rectangular opening portion 13c corresponding to a display surface of the liquid crystal display panel 11. It is necessary to mount the packing 13 in the holder 21 in a state where the rectangular opening portion 13c is secured even if distortion or the like occurs.
As illustrated in
On the other hand, the pair of positioning portions (locking portions) 28 to be locked to the pair of notch portions 13d are provided in the holder 21 at positions corresponding to the notch portions 13d, and an interval L1 between the pair of positioning portions 28 is set larger than the interval L between the pair of notch portions 13d. It is noted that the positioning portions 28 also serve as the above-described positioning portions 28 configured to position the liquid crystal display panel 11 in the X direction and the Y direction.
Therefore, outer surfaces of the pair of positioning portions 28 are placed against outer surfaces of the pair of notch portions 13d, and thus, each side of the packing 13 can be expanded to both sides, and the opening portion 13c can be secured.
Further, as illustrated in
As illustrated in
Therefore, the four sides of the periphery of the diffusion plate 14 are positioned in the mounting groove 38, and the positioning piece 14a is inserted into the insertion hole 39, and thus, the diffusion plate 14 is positioned and attached in a state where the diffusion plate 14 is embedded in the cover 31. Therefore, the diffusion plate 14 is mounted in the cover 31 in a state where the diffusion plate 14 does not contact the liquid crystal display panel 11 arranged on the front side.
With such a liquid crystal display device 10, the liquid crystal display panel 11, the hot mirror 12, the packing 13, and the diffusion plate 14 are attached and housed in a state where the liquid crystal display panel 11, the hot mirror 12, the packing 13, and the diffusion plate 14 are positioned between the holder 21 and the cover 31. Thus, the liquid crystal display panel 11 is held and fixed by the support portion 22 and the elastic support portion 32 without abutting against the packing 13.
As specifically described above in detail together with the embodiment, the liquid crystal display device 10 according to the present invention includes the liquid crystal display panel 11, the hot mirror (transmissive panel) 12 provided in front of the liquid crystal display panel 11 and configured to transmit light, the packing 13 configured to support the periphery of the hot mirror 12, and the frame body 20 configured to hold and fix the liquid crystal display panel 11 and the packing 13. The frame body 20 includes the holder (first frame body) 21 and the cover (second frame body) 31 to be coupled in engagement with each other. The holder 21 is provided with the support portion 22 penetrating the packing 13 and being provided in front of the liquid crystal display panel 11. The cover 31 is provided with the elastic support portion 32 facing the support portion 22 and being provided behind the liquid crystal display panel 11. The liquid crystal display panel 11 is sandwiched between the support portion 22 and the elastic support portion 32 to be held and fixed without abutting against the packing 13.
With such a configuration, the liquid crystal display panel 11 held by the holder 21 and the cover 31 is supported by the support portion 22 and the elastic support portion 32 without the packing 13 formed of an elastic body such as rubber being interposed, and thus, the liquid crystal display panel 11 can be held uniformly with a constant fixing force, and no biased force is applied to the liquid crystal display panel 11, so that it is possible to suppress occurrence of uneven brightness. Further, the liquid crystal display panel 11 is held and fixed without the packing 13 being interposed, and thus, it is possible to improve positioning accuracy, and emit display light for displaying an image of excellent quality. Further, the liquid crystal display panel 11 is pressed by the support portion 22 and the elastic support portion 32, and thus, a pressing force can be adjusted and controlled to press the liquid crystal display panel 11. Further, a necessary function such as a rigidity of the packing 13 can be freely set independently from the holding of the liquid crystal display panel 11.
According to the liquid crystal display device 10 of the present invention, the positioning portion 28 against which the liquid crystal display panel 11 is placed is provided in any one of the holder 21 and the cover 31, and the positioning guide portion 34 against which the liquid crystal display panel 11 is placed and which guides the liquid crystal display panel 11 toward the positioning portion 28 is provided in the other one of the holder 21 and the cover 31.
With such a configuration, the liquid crystal display panel 11 is guided and pushed toward the positioning portion 28 by the positioning guide portion 34, and thus, it is possible to position the liquid crystal display panel 11 at a predetermined position.
Therefore, the positioning accuracy of the liquid crystal display panel 11 can be improved to improve the image quality.
According to the liquid crystal display device 10 of the present invention, the engaging concave portion 25 for engaging and positioning the holder 21 and the cover 31 is provided in any one of the holder 21 and the cover 31, and the engaging protrusion portion 37 that fits into the engaging concave portion 25 is provided in the other one of the holder 21 and the cover 31.
With such a configuration, the holder 21 and the cover 31 can be positioned at a predetermined position by the engaging concave portion 25 and the engaging protrusion portion 37, and thus, the liquid crystal display panel 11 and the like housed in the holder 21 and the cover 31 can be positioned with high accuracy.
According to the liquid crystal display device 10 of the present invention, the pair of notch portions (locked portions) 13d are formed in the packing 13 with an interval L on each side of the opening portion 13c, and the pair of positioning portions (locking portions) 28 locked to the pair of notch portions 13d are formed in any one of the holder 21 and the cover 31. The interval L1 between the positioning portions 28 is larger than the interval L between the notch portions 13d, and thus, the positioning portions 28 are placed against both outer sides of the notch portions 13d and are locked with the notch portions 13d.
Thus, in the packing 13, the opening portion 13c is pushed and expanded outward by the positioning portions 28 inserted into the notch portions 13d, and thus, it is possible to prevent the opening portion 13c from narrowing due to distortion and the like so that a display range of the liquid crystal display panel 11 is not covered by the packing 13.
According to the liquid crystal display device 10 of the present invention, the hot mirror 12 is positioned by the hot mirror receiving portions (corner support portions) 27 that are provided in the holder 21 of the frame body 20 and restrict the position of the hot mirror 12 at the four corners, and the inclined pressing portion 13a provided in the packing 13 between two of the hot mirror receiving portions 27 and pushes the hot mirror 12 toward the other two hot mirror receiving portions 27.
Therefore, by pressing the hot mirror 12 with the packing 13, one side of the hot mirror 12 is pressed by the inclined surface 13b of the inclined pressing portion 13a of the packing 13 against the hot mirror receiving portions 27 on the other side, and thus, the hot mirror 12 can be positioned.
It is noted that an example where a TFT module is applied for the liquid crystal display panel 11 is described in the embodiment above, however, another liquid crystal display panel may be employed.
Further, in the above-described embodiment, a case where the liquid crystal display device is applied to an on-vehicle head-up display is described for an example. However, the liquid crystal display device is not limited to an on-vehicle application, and the liquid crystal display device may be mounted in a transportation such as an airplane, and a ship.
Further, the present invention is not limited to the above-described embodiment, and can be implemented in various aspects.
For example, the support portion and the elastic support portion configured to support the liquid crystal display panel 11 may be switched with each other for installation in the holder and the cover. Similarly, the positioning portion and the positioning guide portion, and the engaging concave portion and the engaging protrusion portion may also be switched with each other for installation in the holder and the cover, and needless to say, various improvements and design changes can be made without departing from the gist of the present invention.
Number | Date | Country | Kind |
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2018-085141 | Apr 2018 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2019/016782 | 4/19/2019 | WO | 00 |