JP2011085700A - Illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device which prevents luminance unevenness recognized as stripes from being included in light emitted from a lens array, while using a plurality of light sources. <P>SOLUTION: The illumination device includes a light source body comprising a plurality of light sources, and a lens array having a plurality of lenses corresponding to each of the light sources. The lens array emits light having luminance distribution in which luminance decreases toward the boundary of each lens from the vertex of each lens. A blast plate is provided at a position where the light having the luminance distribution is transmitted. The blast plate comprises a transparent substrate obtained by forming, with uniform frequency, a plurality of blast areas, where light transmittance is reduced, over one surface on which the light emitted from the lens array is made incident, or over the surface opposite to the one surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an illumination device including a light source body including a plurality of light sources and a lens array having a plurality of lenses corresponding to the individual light sources.

  Conventionally, for example, Patent Document 1 proposes a head-up display using a halogen lamp as a light source. Patent Document 2 proposes an illumination device that employs an LED as a light source for a head-up display.

  In the head-up display described in Patent Document 1, light emitted from a halogen lamp is collected by an integrator lens, and the collected light is emitted to a front panel via a light receiving display element. The reflected light is emitted to the viewer (observer).

  In the head-up display described in Patent Document 2, light emitted from a light source body in which a plurality of LEDs are arranged is collected by a lens array, and the collected light is front panel via a liquid crystal display panel. The light reflected on the front panel and reflected by the front panel is irradiated to the user (observer).

Japanese Patent Laid-Open No. 5-104979 JP 2005-228606 A

  Incidentally, as described above, the head-up display described in Patent Document 1 employs a halogen lamp as a light source. Since the halogen lamp emits light by heat radiation, the light includes infrared rays (heat rays) in addition to visible light. Therefore, infrared light is irradiated on the light receiving display element together with visible light, which may cause the light receiving display element to generate heat and be damaged.

  In order to solve the above-described problem, Patent Document 2 employs an LED as a light source. Since the LED emits light having a wavelength corresponding to the energy gap of the semiconductor (a value unique to the semiconductor), when visible light is selected as the LED light, infrared light is not included in the light emitted from the LED. Therefore, heat generation of the liquid crystal display panel (light receiving display element) due to light emitted from the light source is suppressed.

  By the way, when LED is employ | adopted as a light source of a head-up display, since the brightness | luminance of LED is lower than a halogen lamp, it is necessary to prepare several LED. In this case, an optical system that collects light emitted from each LED in one direction is required. In Patent Document 2, the lens array described above is employed as an optical system that performs such a function.

  The lens array disclosed in Patent Document 2 includes a plurality of convex lenses that collect light emitted from one LED. The surface facing the LED in the lens array has a planar shape, and the back surface of the facing surface has a shape in which a plurality of curved surfaces (convex lenses) that are convex on the back surface side are connected (FIG. 3 of Patent Document 2). And FIG. 4). The optical axis of the LED coincides with the apex of the convex lens corresponding to the LED, and the light collected by the convex lens forms a luminance distribution having the peak at the apex of the convex lens. Light having such a luminance distribution is emitted from each convex lens and irradiated to the observer through the liquid crystal display panel and the front panel.

  The light luminance distribution varies depending on the observation direction of the observer. Hereinafter, the light luminance distribution when the direction perpendicular to the light emitting surface of the LED is set as the observation direction will be described.

  The luminance distribution of light emitted from one convex lens has the highest luminance at the apex of the convex lens, and from that apex to the boundary line formed between one convex lens (curved surface) and the adjacent convex lens (curved surface). As it goes, the brightness decreases. As described above, when the luminance changes abruptly between the apex of one convex lens and the boundary line described above, the luminance difference of light becomes remarkable. Furthermore, in the lens array shown in Patent Document 2, the shape of the boundary line described above is a linear shape, so the shape of the region with the lowest luminance is also a linear shape. As shown above, when the observer is irradiated with light containing uneven brightness where the difference in brightness of the light is significant and the shape of the region with the lowest brightness is linear, the viewer will see the region with the lowest brightness. It may be recognized as a stripe.

  When light including luminance unevenness recognized by the observer as stripes (hereinafter, such light is referred to as light including stripes for convenience) is irradiated to the observer via the liquid crystal display panel and the front panel, There is a problem that it becomes difficult for the observer to visually recognize the optical information displayed on the front panel.

  In addition, since the luminance distribution of the light irradiated to the observer depends on the observation direction (line-of-sight direction) of the observer, it may be difficult to irradiate the observer with light including fringes in a certain observation direction. However, since the observation direction of the observer is not constant, after all, the observer observes light including fringes, and it is difficult for the observer to visually recognize the light information displayed on the front panel. Problems arise.

  In view of the above problems, an object of the present invention is to provide an illuminating device in which luminance unevenness recognized as stripes is suppressed in emitted light while using a plurality of light sources.

  In order to achieve the above object, an invention according to claim 1 is an illumination device including a light source body including a plurality of light sources, and a lens array having a plurality of lenses corresponding to the individual light sources. The array has a blast plate provided at a position where light having a luminance distribution that decreases in luminance as it goes from the apex of each lens toward the boundary of each lens, and is transmitted through the light having the luminance distribution. The plate is constituted by a transparent substrate in which a plurality of blast regions for reducing light transmittance are formed with a uniform frequency over one surface on which light emitted from the lens array is incident or the entire back surface thereof. It is characterized by being.

  Thus, according to the present invention, the light emitted from the lens array passes through the blast plate. Part of the light that has passed through the blast plate is reduced in transmittance by a blast region formed at a uniform frequency over one surface of the transparent substrate or the entire back surface thereof. , Low brightness areas are included at a uniform frequency. As a result, the local low-brightness region that may be recognized as a stripe included in the light emitted from the lens array overlaps with the low-brightness region that occurs at a uniform frequency, and the local low-brightness region The shape becomes unclear.

  In addition, as described above, since the plurality of blast regions are formed with a uniform frequency over one surface of the transparent substrate or the entire back surface thereof, a low-luminance region that is generated with a uniform frequency is generated from the blast plate. The contained light is emitted. Since humans have the property that light having a luminance distribution including a local low luminance region is easier to recognize than light having a luminance distribution including a low luminance region that occurs at a uniform frequency, Human recognition of the low brightness area formed by the blast plate is suppressed.

  As described in claim 2, the blast regions are arranged in a staggered manner on one surface or the back surface, and the maximum length of the blast region and the maximum length between adjacent blast regions in the direction along the one surface or the back surface. The length is preferably 0.3 mm or less.

  For example, the size of the pixels constituting the television screen is about 0.3 mm. This is because the human resolution limit (the limit of the ability to disassemble and view two adjacent objects) is about 0.3 mm when the distance between the human and the observation object (television) is 1 m away. Because.

  From the blast plate, light whose luminance is reduced by the blast region is emitted. The size of the area in which the luminance is reduced by the blast area is almost the same as that of the blast area. That is, it has a size of 0.3 mm or less, which is a size exceeding the human resolution limit. Thereby, when the observer observes the light emitted from the blast plate enlarged by the optical system, it is suppressed that the low brightness area formed by the blast area is recognized.

  In addition, as a planar shape of a blast area | region, a polygon or a circle | round | yen can be employ | adopted like Claim 3 and Claim 4, for example.

  A configuration having a diffusing plate for diffusing light emitted from the blast plate is preferable. According to this, the brightness difference included in the light emitted from the blast plate can be reduced by the diffusion plate. That is, it is possible to suppress the luminance unevenness recognized as the stripes from being emitted from the diffusion plate.

  In addition, as a lighting device, a head-up display having a liquid crystal display panel that controls light transmittance for each pixel or each segment can be adopted as described in claim 6. In the head-up display described above, the light emitted from the blast plate is applied to the front panel of the vehicle via the liquid crystal display panel, and the light reflected from the front panel is applied to the pupil of the observer who has boarded the vehicle. To be mounted on the vehicle.

It is sectional drawing which shows schematic structure of the head-up display which concerns on 1st Embodiment. It is sectional drawing which shows schematic structure of a backlight. It is a top view for demonstrating a blast area | region. It is a top view which shows the modification of a blast area | region. It is a top view which shows the modification of a blast area | region. It is sectional drawing which shows the modification of a backlight.

Hereinafter, an embodiment in which the lighting device according to the present invention is applied to a vehicle head-up display will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of the head-up display according to the first embodiment. FIG. 2 is a cross-sectional view showing a schematic configuration of the backlight. FIG. 3 is a plan view for explaining the blast region. In the following, the direction in which the plurality of LEDs 12 are arranged along the light emitting surface of the LED 12 is the x direction, the direction along the light emitting surface of the LED 12 is the direction perpendicular to the x direction, the y direction, and the light emitting surface of the LED 12. The perpendicular direction is indicated as z direction.

  As shown in FIG. 1, the head-up display 100 includes a backlight 10, a cylindrical lens 30, and a liquid crystal display panel 50 as main parts. The main components 10, 30, and 50 of the head-up display 100 are arranged side by side in the z direction, and the head-up display 100 is configured such that light emitted from the backlight 10 passes through the cylindrical lens 30 and the liquid crystal display panel 50. The light is irradiated onto the front panel 70 provided on the windshield and is reflected on the front panel 70 so that the light is incident on the observer's pupil. The backlight 10 is disposed on the cylindrical lens 30 side from the focal point 30f of the cylindrical lens 30 on the backlight 10 side.

  As illustrated in FIG. 2, the backlight 10 includes a plurality of LEDs 12 mounted on a circuit board 11, a lens array 14 having a plurality of lenses 13 that focus light emitted from the LEDs 12 in one direction, and the lens array. 14 includes a blast plate 15 that forms a low-brightness region at a uniform frequency in the light emitted from the light 14, and a diffusion plate 16 that diffuses the light emitted from the blast plate 15. An external power supply is electrically connected to the circuit board 11, and the LED 12 emits light by electricity supplied from the circuit board 11. The plurality of LEDs 12 are arranged in the x direction at a predetermined interval, and the plurality of lenses 13 constituting the lens array 14 are also arranged in the x direction corresponding to the LEDs 12. A blast plate 15 and a diffusion plate 16 are sequentially arranged in the z direction immediately above the surface of the lens array 14 from which light is emitted. The LED 12 corresponds to the light source described in the claims, and the circuit board 11 and the LED 12 constitute the light source body described in the claims.

  The lens array 14 is formed by injecting molten translucent resin material such as acrylic into a mold and cooling and solidifying the molten resin. The surface of the lens array 14 facing the LED 12 has a planar shape, and the back surface thereof has a shape in which a plurality of convex surfaces that are convex toward the liquid crystal display panel 50 are connected. And one lens 13 is comprised by one convex surface formed in the back surface side, and the vertex of the convex surface (lens 13) and the optical axis of LED12 correspond. The light collected by the lens 13 has a peak at the apex of the lens 13 and forms a luminance distribution in which the luminance decreases toward the boundary formed between the adjacent lenses 13. As described above, the light emitted from the lens array 14 has a sudden change in luminance between the apex of the lens 13 and the boundary between the adjacent lenses 13, and a low luminance region (hereinafter, low luminance). The shape of the region (shown as a region) includes luminance unevenness depending on the shape of the boundary between the adjacent lenses 13. When light including such brightness unevenness is irradiated to the observer, the observer may recognize the low brightness area as a stripe. In the present embodiment, the blast plate 15 is irradiated with light including luminance unevenness that may be recognized as the stripes. The blast plate 15 is a feature point of the head-up display 100 according to the present embodiment, and will be described in detail later.

  The diffuser plate 16 is formed by spraying fine particles such as glass beads on the entire surface of the transparent substrate so that random irregular shapes are formed on the entire surface of the transparent substrate. Since the light transmitted through the diffusion plate 16 is randomly diffused by the uneven shape described above, luminance unevenness included in the light is reduced. As described above, since the blast plate 15 and the diffusing plate 16 are sequentially arranged in the z direction, luminance unevenness included in the light emitted from the blast plate 15 is reduced by the diffusing plate 16. .

  The cylindrical lens 30 is an optical system that functions to collect light in one direction. The cylindrical lens 30 has a bowl shape that divides a cylinder in half, and the surface facing the backlight 10 has a planar shape, and the back surface has a curved shape that is convex toward the liquid crystal display panel 50 side. . The cylindrical lens 30 is disposed such that the longitudinal direction thereof is along the x direction, and the light emitted from the backlight 10 is condensed in the y direction by the cylindrical lens 30.

  The liquid crystal display panel 50 includes a pair of transparent substrates (not shown) and a liquid crystal layer (not shown) sealed between the pair of transparent substrates. A transparent electrode (not shown) for applying a voltage to the liquid crystal layer is formed on the transparent substrate. By controlling the voltage applied to the transparent substrate, the transmittance of light irradiated to the liquid crystal layer can be increased. Control is performed for each pixel or each segment. Therefore, a luminance difference is formed for each pixel or segment in the light transmitted through the liquid crystal display panel 50, and as a result, vehicle information such as vehicle speed is included in the light transmitted through the liquid crystal display panel 50. Light including this vehicle information is emitted to the front panel 70.

  Next, the operation of the head-up display 100 will be described. When electricity is supplied to the LED 12 from the circuit board 11, the LED 12 emits light, and light is emitted from the LED 12. The light emitted from the LED 12 is condensed in the z direction by the lens 13, and a low luminance region is formed at a uniform frequency by the blast plate 15 in the condensed light. The light having the low luminance region formed at a uniform frequency is diffused by the diffusion plate 16, and the diffused light is condensed in the y direction by the cylindrical lens 30. The light condensed in the y direction is incident on the front panel 70 via the liquid crystal display panel 50, and a part of the light incident on the front panel 70 is reflected by the front panel 70. This reflected light enters the observer's pupil. As described above, the light transmitted through the liquid crystal display panel 50 includes vehicle information. Therefore, the light including the vehicle information is irradiated to the observer who is on board through the front panel 70, so that the observer visually recognizes the vehicle information.

  In the present embodiment, as described above, the backlight 10 is disposed closer to the cylindrical lens 30 than the focal point 30f. Therefore, the light emitted from the virtual image 10a whose apparent size is larger than that of the backlight 10 is incident on the observer. As described above, when the apparent light emitting area is enlarged, luminance unevenness included in the light incident on the observer is reduced.

  Next, the blast plate 15 that is a characteristic point of the head-up display 100 according to the present embodiment will be described. The blast plate 15 includes a transparent substrate 18 in which a plurality of blast regions 17 are formed on the surface facing the lens array 14 at a uniform frequency over the entire surface. The blast plate 15 is formed, for example, by forming a mask having an opening only in a region where the blast region 17 is to be formed on one surface of the transparent substrate 18 and spraying fine particles such as glass beads on the surface exposed from the mask. By forming a random concavo-convex shape, a blast region 17 with reduced light transmittance is formed, and then the mask is removed. Or, after forming the above-mentioned mask on a part of the inner wall surface, spray fine particles such as glass beads on the part exposed from the mask, and in a mold having a random uneven shape formed on a part of the inner wall surface Alternatively, the blast plate 15 may be formed by injecting a translucent resin material such as melted acrylic and cooling and solidifying the melted resin. As described above, the blast region 17 corresponds to a region where a random uneven shape is formed, and light incident on the blast region 17 is randomly diffusely reflected on the blast region 17, and thus light incident on the blast region 17. The transmittance is reduced.

  As shown in FIG. 3, the planar shape of the blast area | region 17 along the surface of the transparent substrate 18 is circular, The diameter is set to 0.3 mm or less. Further, the plurality of blast regions 17 are arranged in a zigzag pattern on the one surface of the transparent substrate 18 at a uniform frequency, and the distance between the four blast regions 17 adjacent to each other is also 0.3 mm. It is set as follows. This size of 0.3 mm corresponds to the human resolution limit (the limit of the ability to disassemble and view two adjacent objects) when the distance between the human and the observation object is 1 m away.

  Next, functions and effects of the head-up display 100 according to the present embodiment will be described. As described above, the lens array 14 emits light that may recognize the low-luminance region as a stripe, and this light is applied to the blast plate 15. Since a part of the light irradiated to the blast plate 15 is reduced in transmittance by the blast region 17, the light emitted from the blast plate 15 is recognized as a fringe included in the light emitted from the lens array 14. In addition to the local low-brightness region that may be generated, the low-brightness region having a uniform frequency with the transmittance reduced by the blast region 17 is included. Thus, in the light emitted from the blast plate 15, a low luminance region depending on the shape and arrangement of the blast region 17 is formed around the local low luminance region. As a result, light and dark are formed in the vicinity of the local low-brightness region, and the shape of the local low-brightness region becomes unclear.

  Further, as described above, since the plurality of blast regions 17 are formed with a uniform frequency on the entire surface of the transparent substrate 18, light including the low luminance region is uniformly transmitted from the blast plate 15. Emitted. Since humans have the property that light including a local low-intensity region is more easily recognized than light including a low-intensity region having a uniform frequency, it is formed by the blast region 17. It is suppressed that a human recognizes the low-luminance area | region performed.

  As described above, light including luminance unevenness that the observer may recognize as stripes is irradiated to the observer via the liquid crystal display panel 50 and the front panel 70, and the observer displays the light displayed on the front panel 70. It is suppressed that the malfunction that it becomes difficult to visually recognize information arises.

  Incidentally, the blast plate 15 emits light whose luminance is reduced by the plurality of blast regions 17 at a uniform frequency. The size of the area whose luminance is reduced by the blast area 17 is approximately the same as that of the blast area 17. That is, it has a size of 0.3 mm or less, which is a size exceeding the human resolution limit. Since this light is magnified by the cylindrical lens 30, when the observer observes the light emitted from the blast plate 15, the observer has a uniform frequency in the low luminance region having a size of about 0.3 mm. The light formed by is incident. In this way, by setting the size of the blast region 17 to 0.3 mm or less, the observer is prevented from recognizing the low luminance region formed by the blast plate 15.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment, an example in which the planar shape of the blast region 17 is a circle is shown. However, the planar shape of the blast region 17 is not limited to the above example, and for example, a polygonal shape such as a rhombus or a hexagon can be adopted as shown in FIGS. In this case as well, the maximum length along the surface of the transparent substrate 18 in the blast region 17 and the distance between the blast regions 17 that are closest to itself are set to 0.3 mm or less. 4 and 5 are plan views showing modifications of the blast region.

  Moreover, in this embodiment, as shown in FIG. 2, the example which the blast board 15 and the diffusion plate 16 comprised separately was shown. However, for example, as shown in FIG. 6, one transparent substrate 19 is prepared, and a random uneven shape (blast region) is formed at a uniform frequency on the surface of the transparent substrate 19 facing the lens array 14. A random uneven shape may be formed on the entire back surface. According to this, since the number of parts is reduced, the cost is reduced. FIG. 6 is a cross-sectional view showing a modification of the backlight.

10 ... Backlight 12 ... LED
DESCRIPTION OF SYMBOLS 13 ... Lens 14 ... Lens array 15 ... Blast board 16 ... Diffuser 30 ... Cylindrical lens 50 ... Liquid crystal display panel 100 ... Head-up display

Claims (6)

A lighting device comprising: a light source body composed of a plurality of light sources; and a lens array having a plurality of lenses corresponding to each of the light sources,
From the lens array, light having a luminance distribution in which the luminance decreases from the apex of each lens toward the boundary of each lens, and having a blast plate provided at a position where the light having the luminance distribution is transmitted,
The blast plate is formed by a transparent substrate in which a plurality of blast regions for reducing light transmittance are formed at a uniform frequency over one surface on which light emitted from the lens array is incident or the entire back surface thereof. A lighting device, characterized in that it is configured. The blast region is arranged in a staggered pattern on the one surface or the back surface,
2. The lighting device according to claim 1, wherein a maximum length of the blast region and a maximum length between adjacent blast regions in a direction along the one surface or the back surface are 0.3 mm or less. .   The lighting device according to claim 1, wherein a planar shape of the blast region is a polygon.   The lighting device according to claim 1, wherein a planar shape of the blast region is a circle.   The lighting device according to claim 1, further comprising a diffusion plate that diffuses light emitted from the blast plate. The illuminating device is a head-up display having a liquid crystal display panel for controlling light transmittance for each pixel or each segment,
In the head-up display, the light emitted from the blast plate is irradiated on the front panel of the vehicle via the liquid crystal display panel, and the light reflected on the front panel is reflected by the observer who has boarded the vehicle. The illumination device according to claim 1, wherein the illumination device is mounted on the vehicle so as to irradiate a pupil.

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