JP2007287479A - Illumination device and liquid crystal display device using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device in which the illumination device of a thin type is obtained, a light utilization rate and sufficient brightness can be obtained, and brightness distribution is uniform, and a liquid crystal display device using the device at a low cost. <P>SOLUTION: In a direct illumination device 1 composed of a plurality of linear light sources 7 arranged in parallel, the respective linear light sources 7 are covered in the whole width of the longitudinal direction with a brightness adjustment part 8 composed of a transparent resin, a face opposed to the linear light sources 7 of the brightness adjustment part is constituted of a first recessed part of the same nearly semicircular shape as the linear light source 7 in cross section, and a face opposed to a diffusion plate 5 is constituted of a second recessed part of an inverse-triangular shape in cross section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination device and a liquid crystal display device.

  In recent years, liquid crystal display devices, which are rapidly spreading in place of cathode ray tubes (CRT), are widely used in liquid crystal televisions, monitors, mobile phones, and the like, taking advantage of their energy-saving, thin, and lightweight features. Further, an illuminating device is disposed behind these liquid crystal display devices, and the illuminating devices are mainly classified into an edge light type and a direct type.

  In the edge light type, a light guide plate is provided behind the liquid crystal panel, and a light source is provided at the lateral end. The light emitted from the light source is reflected by the light guide plate and indirectly illuminates the liquid crystal panel indirectly. Due to this structure, the brightness is low, but it is thin and excellent in brightness uniformity, and it is mainly used in small and medium liquid crystal displays such as mobile phones and notebook computers.

  In the direct type, a plurality of linear light sources are arranged in parallel behind the liquid crystal panel to directly irradiate the liquid crystal panel. Therefore, it is easy to obtain high brightness even on a large screen, and is mainly used in large liquid crystal displays of 20 inches or more.

  Here, the lighting device is required to have high efficiency and cost reduction, and as a result, the number of linear light sources has been required to be reduced.

  However, in direct-type illumination devices, the direct light from the linear light source has a particularly high brightness in the immediate vicinity of the light source, so an image of the linear light source (hereinafter referred to as a lamp image) appears on the liquid crystal panel, resulting in uneven brightness. There is a problem of reducing the luminance uniformity of the entire liquid crystal panel. This problem becomes more prominent because the distance between adjacent fluorescent tubes is increased by reducing the number of linear light sources, and the difference in brightness between the immediate brightness of the light sources and the light source intermediate portion is increased.

  Further, even if the number of fluorescent tubes is the same, the difference between light and dark appears significantly by increasing the light emission amount per fluorescent tube.

  Therefore, there is a limit in achieving a reduction in the number of fluorescent tubes and an increase in light emission while avoiding an increase in lamp image.

Conventionally, in order to solve these problems, brightness adjusting means made of polycarbonate resin or the like having light diffusibility is provided on the upper part of each linear light source, and an attempt is made to eliminate the brightness unevenness by adjusting the amount of light incident on the diffusion plate directly above the light source ( Patent Document 1), or a light guide plate that covers the entire plurality of linear light sources arranged in parallel on one surface between the light source and the diffusing plate, and adjusts the optical path from the light source to ensure luminance uniformity (Patent Documents 2 and 3) Have been proposed).
JP 2000-338895 A JP 2004-22344 A JP 2004-302067 A

  However, in the description of Patent Document 1, the brightness adjusting means has a simple shape and is not provided so as to cover the light source, but only provided in a part of the optical path. For this reason, it is only possible to change the optical path of a part of the light emitted from the fluorescent tube and directed upward and a part of the light reflected and passing through the upper part of the fluorescent tube. Therefore, the range in which the luminance unevenness can be adjusted is very limited, and the luminance uniformity of the entire direct illumination device has not been sufficiently ensured.

  In Patent Documents 2 and 3, the light guide plate is provided on one surface so as to cover all of the plurality of light sources, thereby changing the optical path of the upward light of the light emitted from the light sources to reduce unevenness in luminance. be able to. However, since the light other than that is changed in the light guide plate and emitted to the diffuser plate, the entire light guide plate has not yet completely eliminated the luminance unevenness. In addition, there is a concern that light passing through the light guide plate is partially absorbed by the resin constituting the light guide plate and the overall light emission efficiency is reduced.

  In view of the above problems, an object of the present invention is to provide an illumination device having high luminance and excellent luminance uniformity, and a liquid crystal display device using the illumination device at low cost.

    In order to achieve the above object, the configuration of the present invention includes a plurality of linear light sources arranged in parallel, a reflector provided on the back surface of the linear light source, and a diffuser plate provided on the front surface of the linear light source. In the direct type illumination device including the above, each of the linear light sources is covered with a brightness adjusting portion made of a transparent resin so that the entire width in the longitudinal direction is covered, and the brightness adjusting portion faces the linear light source and is emitted from the linear light source. It comprises a light incident surface on which light is directly incident and a light emitting surface from which light incident from the light incident surface faces the diffuser plate, and the light incident surface is located directly above the linear light source. A first concave portion having a substantially semicircular cross section having the same shape as that of the first light source, and the light emitting surface having a second concave portion recessed in an inverted triangular shape in a portion directly above the linear light source. It is a lighting device.

  According to the present invention, in the direct-type illumination device having the above-described configuration, the top of the second recess is on a vertical line that is lowered from the center point of the linear light source to the diffusion plate, and the light incident from the vertical line and the first light source The angle formed by the two concave portions is an angle satisfying the total reflection condition.

  According to the present invention, in the direct illumination device having the above-described configuration, the width of the second recess is larger than the diameter of the linear light source and smaller than the width of the first recess.

  According to the present invention, in the direct illumination device having the above-described configuration, a lower end portion of the light incident surface is positioned lower than a lower surface of the linear light source.

  According to the present invention, in the direct illuminating device having the above-described configuration, the light emitting surface includes a lower reflecting surface that reflects light reflected by the second concave portion downward, and the light incident surface is the lower reflecting surface. It has an upper reflecting surface for reflecting the light reflected downward by the upward direction.

  Further, according to the present invention, in the direct type illumination device having the above-described configuration, the lower reflection surface is a surface facing substantially perpendicular to the second recess, and the upper reflection surface is substantially parallel to the lower reflection surface. It is a surface.

  Further, according to the present invention, in the direct illumination device having the above-described configuration, the width of the light emitting surface is smaller than the width of the intermediate point between the adjacent linear light sources, and the end of the light emitting surface and the end of the light incident surface A curved surface recessed in an arc shape is formed between the first and second portions.

  According to the first configuration of the present invention, the portion facing the linear light source on the light incident surface of the brightness adjusting unit is recessed in a substantially semicircular cross section having the same shape as the linear light source, and thus covers the linear light source. As described above, a luminance adjustment unit can be provided. Further, the light emitted upward from the linear light source enters the brightness adjusting unit from the light incident surface having a substantially semicircular cross section with almost no change in the optical path.

  At this time, light entering the brightness adjusting unit and entering the second recessed portion at an incident angle satisfying the total reflection condition among the light that is to be emitted from the second recessed portion recessed in an inverted triangular shape to the outside of the brightness adjusting unit is The light is totally reflected in the lateral direction without being emitted toward the diffusion plate. Thereby, a part of the light incident on the diffusion plate directly above the linear light source is dispersed in the lateral direction, and the expression of the lamp image can be suppressed. In addition, when the light reflected in the lateral direction is reflected again in the brightness adjusting unit and irradiated near the midpoint of the adjacent linear light source, the brightness uniformity can be improved while ensuring the brightness.

  In addition, the brightness adjustment unit does not cover the entire surface of the backlight, but is provided separately for each linear light source, so that the light utilization efficiency of the entire backlight can be improved by adjusting the light from each linear light source. it can.

  Further, according to the second configuration of the present invention, the light emitted from the linear light source is symmetrically dispersed by positioning the top of the second concave portion on the vertical line that is lowered from the center point of the linear light source to the diffusion plate. This makes it easy to adjust the luminance uniformity.

  In addition, when the angle between the perpendicular and the second recess satisfies the total reflection condition, most of the light emitted upward from the linear light source can be reflected in the lateral direction. Thereby, it becomes possible to further suppress the luminance of the portion immediately above the linear light source, and improve the luminance uniformity.

  Further, according to the third configuration of the present invention, the width of the second concave portion is made larger than the diameter of the linear light source and made smaller than the width of the first concave portion of the light incident surface. It is possible to limit the amount of light reflected and to adjust the luminance in the vicinity of the linear light source appropriately.

  According to the fourth configuration of the present invention, since the lower end portion of the light incident surface is positioned lower than the lower surface of the linear light source, the light path of all the light emitted from the linear light source is changed in the luminance adjusting portion and back. The entire light is dispersedly irradiated. This makes it possible to ensure high brightness uniformity.

  Further, according to the fifth configuration of the present invention, in the brightness adjusting unit, the light reflecting surface is provided with the lower reflecting surface that reflects the light reflected in the lateral direction by the second concave portion downward, and the lower reflecting surface causes the lower direction to be lowered. By providing the light incident surface with an upper reflection surface that reflects the light reflected upward, the light reflected laterally by the second recess reflects the lower reflection surface and the upper reflection surface and changes the optical path upward. . Further, by adjusting the angles of the lower reflecting surface and the upper reflecting surface on the light emitting surface and the light incident surface, it is possible to irradiate light on a portion having a low luminance on the diffusion plate.

  According to the sixth configuration of the present invention, the lower reflection surface is a surface substantially perpendicular to the second recess, and the upper reflection surface is a surface substantially parallel to the lower reflection surface. The light reflected in the lateral direction by the concave portion appropriately reflects the lower reflection surface and the upper reflection surface and changes the optical path upward. Thereby, the brightness | luminance and brightness | luminance uniformity of the whole backlight can be ensured with sufficient balance.

  According to the sixth configuration of the present invention, since the width of the light emitting surface is smaller than the width of the intermediate point between the adjacent linear light sources, the brightness adjustment is performed for each linear light source without being restricted by the adjacent brightness adjusting unit. Can be provided. Further, by forming a curved surface that is recessed in an arc shape between the end portion of the light incident surface and the end portion of the light emitting surface, the light reflected in the lateral direction from the second recess is directly from the curved surface that is recessed in the arc shape. The light is emitted out of the brightness adjustment unit. This light travels to the adjacent brightness adjusting section, enters a curved surface that is recessed in an arc shape, refracts upward, and exits.

  Thereby, the light emitted from the linear light source can be dispersed and emitted in the direction of the diffusion plate, and the luminance uniformity of the entire backlight is ensured.

  Further, according to the seventh configuration of the present invention, it is possible to provide a liquid crystal display device excellent in high luminance and luminance uniformity at low cost by using the illumination device in a liquid crystal display device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig.1 (a) is a schematic front view which shows the liquid crystal display device 1 which is embodiment of this invention. FIGS. 1B and 1C are schematic side views showing the cross section of the liquid crystal display device 1 shown in FIG. 1A from the arrow x direction and the arrow y direction, respectively. A plurality of linear light sources 7 are arranged in parallel behind the liquid crystal panel 3, and a reflecting plate 2 is provided behind the linear light sources 7, and a diffusion plate 5 and various optical sheets 4 are provided in front. In FIG. 1A, the liquid crystal panel 3, the diffusion plate 5, and the optical sheet 4 are not shown.

  Further, the linear light source 7 is covered by a luminance adjusting unit 8 along the longitudinal direction of the linear light source 7, and a backlight unit that irradiates the liquid crystal panel 3 with the linear light source 7, the diffusion plate 5, and the optical sheet 4. (Direct type illumination device). Therefore, the light emitted from the linear light source 7 passes through the brightness adjusting unit 8, and the optical path is changed in the process, enters the diffusion plate 5, passes through the optical sheet 4, and reaches the liquid crystal panel 3.

  Here, both ends of the brightness adjusting member 8 are fixed together with the linear light source 7 by a lamp holder 6 around the backlight unit.

  2A and 2B are enlarged views of the cross-sectional shape of the brightness adjusting unit 8 according to the present invention together with the linear light source 7. FIG. In the brightness adjusting unit 8, a surface that faces the linear light source 7 and directly receives light emitted from the linear light source 7 is a light incident surface 9, and light that is opposed to the diffusion plate 5 and incident from the light incident surface is emitted. The surface to be used is a light emitting surface 10.

  Moreover, the brightness adjusting unit 8 is configured in a symmetrical shape. Thereby, the light emitted from the linear light source is changed in the luminance adjustment unit 8 and the light path is changed in the left-right direction toward the diffusion plate 5, so that it is easy to adjust the luminance uniformity. For simplification of the drawing, a dotted arrow indicating the traveling direction of light represents only light traveling in a certain direction.

  The portion immediately above the linear light source 7 on the light incident surface 9 is formed by a first recess 9 a having the same semicircular cross section as the linear light source 7. As a result, the brightness adjusting unit 8 can be provided close to the linear light source 7, and the light emitted upward from the linear light source 7 is not changed by the first recess 9a without changing the optical path. 8 is incident.

  Further, the portion immediately above the linear light source 7 on the light emitting surface 10 forms a concave second concave portion 10a having an inverted triangular cross section. In addition, the top formed by the second recess 10 a is positioned on a perpendicular line that extends from the center of the linear light source 7 to the diffusion plate 5. As a result, the light emitted above the linear light source 7 and incident into the brightness adjusting unit 8 from the first recess 9a enters the second recess 10a with a predetermined angle.

  At this time, when the incident angle of the light incident on the second recess 10a is smaller than the critical angle at the boundary surface between the brightness adjusting member 8 and the air, the light is emitted to the diffusion plate 5 side. However, when the incident angle of light is larger than the critical angle, the light is not transmitted to the diffusion plate 5 side but is totally reflected.

  Here, it is the magnitude α of the apex angle formed by the second recess 10 a that determines the incident angle of the light incident on the second recess 10 a, and the critical angle is determined based on the base constituting the brightness adjusting unit 8. The refractive index of the material. Therefore, when adjusting the luminance near the linear light source 7, it is necessary to determine the apex angle α while taking into consideration the refractive index of the base material constituting the luminance adjusting unit 8. The critical angle of the acrylic material is 42.15 °, and the critical angle of the polycarbonate material is about 38.9 °.

  Of the light emitted upward from the linear light source 7 and incident on the second recess 10 a, the light having the smallest incident angle is light that travels on a perpendicular line dropped from the center point of the linear light source 7 to the diffusion plate 5. . Therefore, if the incident angle of the light on the second recess 10a is larger than the critical angle, all the light emitted upward from the linear light source 7 and incident on the second recess 10a satisfies the total reflection condition and is totally reflected. It is possible to suppress the luminance near the linear light source.

  In addition, since total reflection is reflection without any energy loss, it is possible to improve luminance uniformity and light utilization efficiency by turning the light totally reflected by the second recess 10a to a portion having low luminance.

  2B, the opening width A of the second recess 10a is preferably larger than the diameter φ of the linear light source 7 and smaller than the opening width C of the first recess 9a. When the opening width A of the second recess 10 a is smaller than the diameter φ of the linear light source 7, the region of light reflected by the second recess 10 a among the light emitted upward from the linear light source 7 becomes small.

  For this reason, in the upper part of the linear light source 7, the luminance is higher at the portion irradiated with the light that is transmitted without being reflected by the second concave portion 10 a, and the luminance is lower at the portion above the second concave portion 10 a because the light is not transmitted. As a result, new luminance unevenness occurs above the linear light source 7 and luminance uniformity is reduced.

  When the opening width A of the second recess 10a is larger than the opening width C of the first recess 9a, the region of light reflected by the second recess 10a out of the light emitted upward from the linear light source 7 becomes larger. .

  For this reason, not only the luminance in the vicinity of the portion directly above the linear light source 7 having a particularly high luminance is suppressed, but also the light to be irradiated to the region where the luminance is not so high is reflected by the second recess 10a. Thereby, the luminance uniformity of the entire backlight is lowered.

  Further, it is desirable that the lower end portion of the light incident surface 9 is positioned lower than the lower surface of the linear light source 7. When the lower end of the light incident surface 9 is positioned higher than the lower surface of the linear light source 7, most of the light emitted from the linear light source 7 in the lateral direction and below does not enter the luminance adjusting unit 8. Therefore, these lights cannot be effectively directed toward the diffusion plate 5, and the brightness adjustment and the brightness uniformity cannot be sufficiently ensured.

  Next, the light reflected by the 2nd recessed part 10a is demonstrated. As described above, since the light totally reflected by the second concave portion 10a has no energy loss due to reflection, if the optical path of this light can be changed upward, it is possible to ensure luminance uniformity while improving the light utilization efficiency. it can.

  As shown in FIG. 2 (a), when the lower reflecting surface 10b facing the second recess 10a at the angle β is formed on the light emitting surface 10, the light reflected in the lateral direction by the second recess 10a is lowered. It can be reflected downward by the reflecting surface 10b.

  At this time, by adjusting the angle β, it is possible to design the lower reflecting surface 10b that can efficiently reflect downward with respect to the second concave portion 10a having the apex angle α.

  Further, when the upper reflection surface 9b having an angle γ with respect to the first concave portion 9a is formed on the light incident surface 9, the light reflected downward from the lower reflection surface 10b can be reflected upward. At this time, by adjusting the angle γ, it is possible to design the upper reflection surface 9b that can efficiently reflect upward. In addition, the brightness uniformity can be further improved by adjusting the angle γ at which the light reflected by the upper reflecting surface 9b is irradiated near the midpoint of the adjacent linear light source.

  Further, as a result of examining the relationship between the angles β and γ and the luminance uniformity, the angle β formed by the inverted triangular surface 10a and the lower reflecting surface 10b is about 90 °, and the lower reflecting surface 10b and the upper reflecting surface 9b are parallel to each other. It is known that the luminance uniformity and light utilization efficiency of the entire backlight are excellent when designed in the above manner.

  FIGS. 3A and 3B are cross-sectional views showing other forms of the brightness adjusting unit 8 used in the direct illumination device of the present invention. Similarly to FIG. 2, the brightness adjusting unit 8 faces the linear light source 7 so that the light incident surface 9 on which the light emitted from the linear light source 7 directly enters and the light incident on the light incident surface 9 facing the diffuser plate are incident. It comprises a light exit surface 10 that exits toward the diffusion plate 5 side. Further, the portion of the light incident surface 9 immediately above the linear light source 7 has a first recess 9a, and the portion of the light emitting surface 10 directly above the linear light source 7 has a second recess 10a.

  Further, the light incident surface 9 is shaped so as to sandwich the linear light source 7 with the same width as that of the first concave portion 9 a and the lower end thereof is positioned lower than the linear light source 7. With this shape, the light emitted from the linear light source 7 in the lateral direction or the downward direction also enters the luminance adjusting unit 8. Then, the light path of the light is changed in the brightness adjusting unit 8 and contributes to improvement of brightness uniformity of the entire backlight.

  Further, it is desirable that the width of the light emitting surface 10 is smaller than the width of the intermediate point between the adjacent linear light sources 7. This is because the brightness adjusting units 8 provided in the adjacent linear light sources 7 can be provided without being restricted by each other.

  The difference from the brightness adjusting unit 8 shown in FIG. 2 is that the end of the light incident surface 10 and the end of the light incident surface 9 form a curved surface 11 that is recessed in an arc shape. As described in the description of FIG. 2 above, the light emitted upward from the linear light source 7 is totally reflected laterally by the second recess 10a. Here, the curved surface 11 reflects part of the light traveling in the lateral direction upward, and transmits the other light to the outside of the brightness adjusting unit 8. The transmitted light travels in the horizontal direction as it is, and then enters the curved surface 11 of the adjacent luminance adjusting unit 8.

  At this time, the light incident on the curved surface 11 spreads the optical path so that the curved surface 11 acts like a concave lens and diverges upward, and travels in the direction of the diffusion plate. Thereby, it is possible to improve luminance uniformity as well as to ensure luminance. In addition to the light reflected laterally in the second recess 10a, the light emitted laterally from the linear light source 7 takes the same optical path.

  Here, the curved surface 11 has a shape that is recessed in an R shape, but if this is a flat surface, the light traveling in the lateral direction is uniformly refracted in this plane, so that the entire backlight is irradiated with diffuse light. Instead, it irradiates only one area above the linear light source 7. Therefore, the luminance uniformity of the entire backlight is not improved so much. (See Fig. 3 (c))

  In addition, when the curved surface 11 has a convex shape instead of a concave shape, the light from the lateral direction serves as a convex lens and is condensed at one point above the linear light source 7. Therefore, when these non-recessed surfaces are formed, the luminance uniformity of the entire backlight cannot be ensured. (See Fig. 3 (d))

  The brightness adjusting unit 8 may be made of a material that is transparent or translucent to the light emitted from the linear light source 7 and incident from the light incident surface 9 and emitted from the light emitting surface 10, specifically, Polycarbonate resin etc. are mentioned. Moreover, since the brightness adjustment part 8 is provided facing the position close | similar to the linear light source 7, it needs to have predetermined heat resistance.

  Moreover, since the brightness uniformity is higher than that of the conventional lighting device by using the lighting device for the liquid crystal display device 1, the use of the optical sheet used for improving the uniformity can be suppressed, and the cost can be reduced uniformly. It is possible to easily provide the liquid crystal display device 1 having high performance.

  The present invention is not limited to the above-described embodiments, and various modifications are possible. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the present invention. Included in the technical scope.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to an Example unless it is contrary to the meaning.

  4 (a), 4 (b), and 4 (c) each show a luminance adjusting unit according to the present invention. Acrylic resin is used for these luminance adjusting members, and the semicircular light incident surface 9a and the inverted triangular light emitting surface 10a have the same dimensions in any luminance adjusting portion, and the inverted triangular opening width A = 4 mm, semicircular aperture width C = 5 mm, and apex angle α = 42.15 on the inverted triangle. Further, a cold cathode tube having a diameter φ = 3 mm was used as the linear light source, and it was arranged so that the pitch p = 28 mm and the diffusion plate distance l = 16 mm.

[Example 1]
FIG. 4A shows a brightness adjusting unit according to the present invention. The brightness adjusting unit has a width w = 10 mm, a brightness adjusting unit height h = 10 mm, and an angle β between the inverted triangular surface 10a and the lower reflecting surface 10b is 90 °. It shape | molded so that it might face. This brightness adjusting unit was provided on four cold cathode tubes, and the brightness of the entire direct type illumination device was measured to evaluate the brightness uniformity.

[Example 2]
FIG. 4B shows a luminance adjusting unit according to the present invention. The luminance adjusting unit has a width w = 20 mm and a luminance adjusting unit height h = 10 mm. A curved surface that is concave in an arc shape diffuses light by a concave lens action. Molded into shape. This brightness adjusting unit was provided on four cold cathode tubes, and the brightness of the entire direct type illumination device was measured to evaluate the brightness uniformity.

[Example 3]
FIG. 4C shows a luminance adjusting unit according to the present invention. The luminance adjusting unit has a width w = 15 mm and a luminance adjusting unit height h = 15 mm, and the light incident surface other than the semicircular shape is not flat but uneven. Formed on the surface. When this brightness adjusting unit is provided in the linear light source, the light emitted upward from the linear light source is totally reflected laterally by the second concave portion and then reflected downward from the second concave portion at an angle β = 90 °. Reflected downward by the surface. This downward light is considered to be incident on the uneven surface and diffusely reflected upward. Further, the lower end of the light incident surface was positioned s = 1.5 mm above the lower surface of the linear light source. This brightness adjusting unit was provided on four cold cathode tubes, and the brightness of the entire direct type illumination device was measured to evaluate the brightness uniformity.

[Comparative Example 1]
Without providing a brightness adjusting section, the brightness of the entire direct type illumination device composed of four cold cathode tubes was measured and evaluated for brightness uniformity.

  The luminance distribution measured using the direct illumination device is shown in FIGS. The luminance distribution in FIG. 8 is a luminance distribution table measured without the luminance adjustment unit, and FIGS. 5, 6, and 7 are direct illuminations evaluated in Example 1, Example 2, and Example 3, respectively. It is a luminance distribution table | surface of an apparatus. The vertical axis represents luminance, and the horizontal axis represents the position in the width direction of the lighting device. The measured luminance is light measured on the diffusion plate, and is not light uniformed by an optical sheet or the like.

  As can be seen from FIG. 8 above, in the direct type illumination device without the brightness adjusting unit, the brightness difference between the intermediate point of the linear light source directly above and the adjacent linear light source is large, so that a lamp image appears. It can be seen that the luminance unevenness reduces the luminance uniformity of the entire direct illumination device.

  Further, as apparent from FIGS. 5 and 6, by providing the linearity light source with the luminance adjusting unit according to the present invention, the luminance of the entire direct lighting device is secured to a predetermined value or more and the luminance unevenness is suppressed. It was found that the luminance uniformity was improved.

  Further, as is apparent from FIGS. 7 and 8, it was found that by providing the linear light source with a luminance adjustment unit, it is possible to suppress the luminance near the linear light source and prevent the display of the lamp image. Therefore, it is considered that the luminance uniformity can be further improved by adjusting the vertex angle of the inverted triangular surface of the luminance adjusting unit shown in FIG.

  Further, as apparent from a comparison between FIGS. 5, 6 and 7, it has been found that the luminance uniformity is further stabilized by positioning the end of the light incident surface below the linear light source. In the luminance adjusting unit shown in FIG. 4C, the light incident surface does not cover the entire linear light source. For this reason, the light emitted from the linear light source in the horizontal direction and the downward direction hardly enters the luminance adjustment unit. Therefore, it is considered that most of the light emitted from the linear light source in the lateral direction and the downward direction does not change the optical path upward, and sufficient brightness adjustment is not performed.

    INDUSTRIAL APPLICABILITY The present invention can be used for lighting devices used for bulletin boards and the like, household and commercial lighting devices, or liquid crystal display devices equipped with lighting devices.

It is the schematic front view and schematic side view which show the liquid crystal display device of embodiment of this invention. It is a cross-sectional view which shows the shape of the brightness | luminance adjustment part which concerns on this invention. It is a cross-sectional view which shows the shape of the brightness | luminance adjustment part which concerns on this invention. It is a cross-sectional view which shows the shape of the brightness | luminance adjustment part which concerns on this invention. It is a luminance distribution table | surface which the direct type illuminating device in Example 1 shows. It is a luminance distribution table | surface which the direct type illuminating device in Example 2 shows. It is a luminance distribution table | surface which the direct type illuminating device in Example 3 shows. It is a luminance distribution table | surface which the direct type illuminating device in the comparative example 1 shows.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Reflector 3 Liquid crystal panel 4 Optical sheet 5 Diffuser 6 Lamp holder 7 Linear light source 8 Brightness adjustment part 9 Light incident surface 9a 1st recessed part 9b Upper reflecting surface 10 Light emitting surface 10a 2nd recessed part 10b Downward reflection Surface 11 Curved surface

Claims (8)

In a direct type illumination device including a plurality of linear light sources arranged in parallel, a reflector provided on the back surface of the linear light source, and a diffuser plate provided on the front surface of the linear light source,
Each of the linear light sources is covered with a full width in the longitudinal direction by a brightness adjusting portion made of a transparent resin,
The brightness adjusting unit faces the linear light source and has a light incident surface on which light emitted from the linear light source is directly incident;
Consists of a light exit surface from which the light incident from the light entrance surface is opposed to the diffuser plate,
The light incident surface has a first recess recessed in a substantially semicircular cross-section of the same shape as the linear light source in a portion directly above the linear light source,
The direct illumination apparatus according to claim 1, wherein the light exit surface has a second recess recessed in an inverted triangular shape in a portion directly above the linear light source.   The top of the second recess is on a perpendicular line from the center point of the linear light source to the diffuser plate, and the angle formed between the light incident from the perpendicular and the second recess is an angle satisfying the total reflection condition. The direct type illumination device according to claim 1, wherein:   3. The direct illumination device according to claim 1, wherein a width of the second concave portion is larger than a diameter of the linear light source and smaller than a width of the first concave portion.   The direct illumination device according to any one of claims 1 to 3, wherein a lower end portion of the light incident surface is positioned lower than a lower surface of the linear light source. The light emitting surface has a lower reflecting surface that reflects light reflected by the second recesses downward;
5. The direct illumination according to claim 1, wherein the light incident surface includes an upper reflection surface that reflects upward the light reflected downward by the lower reflection surface. 6. apparatus.   The said lower reflective surface is a surface which faces a substantially right angle with respect to the said 2nd recessed part, The said upper reflective surface is a surface substantially parallel with respect to the said lower reflective surface, The Claim 6 characterized by the above-mentioned. Direct lighting device. The width of the light exit surface is smaller than the width of the intermediate point between the adjacent linear light sources,
5. The curved surface that is recessed in an arc shape is formed between an end of the light exit surface and an end of the light entrance surface, according to claim 1. Direct lighting device.   A liquid crystal display device comprising the direct illumination device according to any one of claims 1 to 7.

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