JP2013068718A - Planar lighting unit and electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar lighting unit having improved visibility of a predetermined display symbol without increasing power consumption of the light source of the lighting unit.SOLUTION: A symbol facing part 26 is disposed at each light scattering pattern 22 formed on a light guide plate as a pattern arrangement part arranged directly below each display symbol 3a at least in plan view. The symbol facing part 26 has first density that is high density. A pattern arrangement part 28 having second density that is dot density lower than the first density is arranged so as to surround the symbol facing part 26. The symbol facing part 26 having the first density distributes necessary light to a minimum required range of the display symbol 3a on a display film 3. The pattern arrangement part having the second density that is dot density lower than the first density, which is a symbol periphery part 28, distributes light to the display symbol 3a on the display film 3 so that the range illuminated by the symbol facing part 26 is rimmed. This allows the whole of the display symbol 3a to be lit up and prevents a partially missing character.

Description

  The present invention relates to a planar illumination device and an electronic device using the same.

2. Description of the Related Art Conventionally, as an input device for an electronic device having a display device such as an LCD (liquid crystal display device) or a CRT, characters, numbers and other symbols (graphics) arranged on the screen of the display device and displayed on the screen , Including pictograms called icons made up of images, etc., including a single symbol made up of a plurality of symbols) from the surface side while seeing through the desired characters, numbers and other symbols ( In the following description, the position of “display symbol”) is touched with a finger or the like, and a device that generates and outputs information corresponding to the symbol position (hereinafter, such an input device is also referred to as a touch panel) is widely used. It is widespread (for example, see Patent Document 1).
For example, in electronic devices such as automated teller machines such as banks and car navigators, touch panel displays have been prevalent, and they are actively used in small electronic devices such as portable information terminals and electronic dictionaries. It has become.

On the other hand, various proposals have been made to realize an input device that does not necessarily include a display device such as an LCD or CRT using a touch panel. For example, the applicant does not require a function as a display device. A keyboard device has been proposed that has a flat input operation surface located on the uppermost surface as in the case of a touch panel display (see, for example, Patent Document 2).
In addition, input devices using a touch panel are not only those having a great variety of operation units such as keyboard devices, but also, for example, operation units of home appliances and home appliances, operation units of portable information terminals, etc. It is widely used so as to replace an input device of a type having a conventional keycap (see, for example, Patent Documents 3 and 4).

JP 2005-317041 A JP 2011-1000025 A JP 2007-208682 A JP 2009-070717 A

  An input device such as a keyboard device described in Patent Document 2, an operation unit such as a home appliance or a home device described in Patent Document 3, and an operation unit of a portable information terminal described in Patent Document 4 is a flat input operation. In realizing the surface, it is possible to detect input with high sensitivity by adopting the capacitive touch sensor, both of which can make the input operation surface flat It becomes easy to clean, dirt becomes difficult to adhere, and the appearance is improved, and a clean state can be maintained, and it has a high degree of functionality and aesthetics.

Further, on the inner side (lower layer) of the input operation surface, as will be described later, a translucent touch panel, a display film on which a predetermined display symbol is printed, and a planar illumination which is a surface emitting layer for illuminating the display film A stack with the device is housed. Then, a predetermined display symbol is clearly raised on the input operation surface by the surface illumination device, and it is possible to further improve functionality and aesthetics.
The planar illumination device includes a light guide plate having one of a pair of main surfaces as a light emission surface for a display film, and a light source disposed adjacent to a side surface of the light guide plate. The light scattering pattern which receives the incident light from the light source and scatters the incident light is formed at a position corresponding to each display symbol of the display film in plan view. Accordingly, the incident light deflected by the light scattering pattern is emitted from the emission surface of the planar illumination device and is irradiated toward the display film, whereby a predetermined display symbol is illuminated.

According to the present invention, in the above-described planar illumination device, a display device incorporating the same, an input device, and other electronic devices, the predetermined display symbols can be further increased without increasing the power consumption of the light source of the planar illumination device. The purpose is to improve visibility.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) A planar illumination device that is disposed on the back side of a display film on which a plurality of display symbols are formed and irradiates light toward the display film,
A light guide plate having one of a pair of main surfaces as a light exit surface for the display film; and a light source disposed adjacent to a side surface of the light guide plate, wherein the light guide plate has a light output from the light source. A light scattering pattern that receives incident light and scatters the incident light is formed at a position corresponding to each of the display symbols at least in a plan view, and a plurality of dots are arranged in each of the light scattering patterns. A first density pattern arrangement portion arranged in a range immediately below the display symbol in at least a plan view of the light scattering pattern, and surrounding the first density pattern arrangement portion A planar illumination device including a second density pattern arrangement portion arranged and having a dot density smaller than the first density.

  The planar illumination device described in this section includes a light guide plate having one of a pair of main surfaces as a light emission surface for the display film, and a light source disposed adjacent to the side surface of the light guide plate. On the light guide plate, a light scattering pattern for receiving incident light from the light source and scattering the incident light is formed at a position corresponding to each display symbol of the display film at least in a plan view. The incident light incident on the light guide plate from the light source is deflected by the light scattering pattern, exits from the exit surface of the planar illumination device, and is irradiated toward the back surface of the display film, whereby a predetermined display symbol is obtained. It is illuminated so that it may be visually recognized from the surface of a display film.

In addition, the planar illumination device described in this section is configured by appropriately adjusting the dot arrangement of a portion configured by arranging a plurality of dots included in the plurality of light scattering patterns formed on the light guide plate. The necessary light distribution is performed within the necessary range of each display symbol of the display film.
In addition, at least the display symbols of the display film are required by the first density pattern arrangement portion that is included in each of the light scattering patterns formed on the light guide plate and is disposed at least in the range immediately below the display symbols in plan view. In this range, necessary light distribution is performed. In addition, the second density pattern arrangement section is arranged so as to surround the first density pattern arrangement section, and the dot density is smaller than the first density, so that the range illuminated by the first density pattern arrangement section is outlined. As a result, light distribution is performed. And, regardless of the relationship between the planar illumination device, each display symbol of the display film, and the user's line of sight, the entire display symbol is illuminated by the planar illumination device to prevent missing characters. Become. Moreover, in the first density pattern arrangement section, the incident light consumption ratio in the second density pattern arrangement section having a dot density lower than the first density is kept low while increasing the consumption ratio of incident light to the light guide plate. As a result, useless consumption of incident light is also reduced. Further, it is possible to improve the uniformity of luminance from the light incident end portion to the opposite end portion of the light guide plate.

(2) A planar illumination device according to (1) above, wherein the plurality of dots are arranged in a grid pattern in plan view.
The planar illumination device described in this section is necessary in the necessary range of each display symbol of the display film by appropriately adjusting the number of rows or columns of a plurality of dots arranged in a grid pattern in plan view. Light distribution.

(3) In the above items (1) and (2), the distance from the center position in the front-rear direction of the display symbol corresponding to each position of the light scattering pattern to the front outer edge of the light scattering pattern is A planar illumination device provided at a position larger than the rear outer edge portion of the light scattering pattern (Claim 3).

The planar illumination device described in this section is a plane of each display symbol of the display film corresponding to each position of the light scattering pattern in a state of being arranged on the back side of the display film on which a plurality of display symbols are formed. The distance from the center position in the front-rear direction to the front outer edge of the light scattering pattern is set at a position larger than the distance to the rear outer edge of the light scattering pattern. With this configuration, each display symbol of the display film is illuminated over a wide range from the center position in the front-rear direction in plan view to the front edge side of the light scattering pattern. The planar illumination device performs light distribution in consideration of the relationship between each display symbol of the display film and the user's line of sight (viewpoint).
That is, in the use state in which the display symbol is visually recognized from the rear with respect to the normal direction at the center position in the front-rear direction in the plan view of the display symbol, The area on the front side is also illuminated by the light emitted from the light guide plate by the light scattering pattern, so that the entire display symbol is illuminated without the front of the display symbol being out of the irradiation range, thereby preventing missing characters. It becomes. In this way, by performing necessary light distribution in a necessary range, the amount of incident light consumed for unnecessary light distribution is also reduced.

(4) The planar illumination device according to (1) to (3), wherein the plurality of light scattering patterns formed on the light guide plate include a rectangular pattern arrangement portion in plan view.
The planar illumination device described in this section is arranged immediately below a position corresponding to each of the display symbols in a plan view, and has a rectangular pattern placement portion in a plan view, so that the minimum of each display symbol of the display film. The necessary light distribution is performed within the limited necessary range.
And it is necessary for the necessary range of each display symbol of the display film by appropriately adjusting the installation range of the rectangular pattern arrangement part included in the plurality of light scattering patterns formed on the light guide plate. Light distribution.

(5) The planar illumination device according to (4), wherein the pattern arrangement portion that is rectangular in the plan view is the first density pattern arrangement portion.
The planar illumination device described in this section is necessary for each display symbol of the display film by appropriately adjusting the installation range of the rectangular pattern arrangement portion constituting the first density pattern arrangement portion in a plan view. The adjustment is made to ensure the necessary and sufficient light distribution for a certain range. On the other hand, the shape of the installation range may be appropriately set for the second density pattern arrangement portion so as to ensure appropriate light distribution.

(6) A display device including the planar illumination device according to any one of (1) to (5) and a display film on which a plurality of display symbols are formed (Claim 6).
The display device described in this section is a display device including the planar illumination device according to any one of (1) to (5) above and a display film on which a plurality of display symbols are formed. The effect corresponding to the term is exhibited.

(7) An input device including the planar illumination device according to any one of (1) to (5) above, a display film on which a plurality of display symbols are formed, and a touch panel (Claim 7).
The input device described in this section is an input device including the planar illumination device according to any one of (1) to (5) above, a display film on which a plurality of display symbols are formed, and a touch panel. The operation corresponding to each of the above items is achieved.

  Since the present invention is configured as described above, in a planar illumination device, a display device incorporating the same, an input device, and other electronic devices, a predetermined display can be performed without increasing the power consumption of the light source of the planar illumination device. It becomes possible to further improve the visibility of the symbols.

It is a schematic diagram which shows the component of the planar illuminating device which concerns on embodiment of this invention, (a) is a top view of a light-guide plate, (b) is a top view of the display film in which the several display symbol was formed. It is. It is a top view which shows the positional relationship of the display symbol of a display film, and the light-scattering pattern of a light guide plate in the state which overlapped the light guide plate and display film shown by FIG. 1, (a) is implementation of this invention (B) relates to a comparative example. (A) is a top view which shows the positional relationship of the display symbol of the display film which concerns on the application example of FIG. 2, and the light-scattering pattern of a light-guide plate, (b) is a display film of a planar illuminating device. It is explanatory drawing about the relationship between a display symbol and a user's eyes | visual_axis. (A) is explanatory drawing which shows typically a mode that the consumption ratio of the incident light in the pattern arrangement | positioning part of the 2nd density in which the dot density is smaller than the 1st density is suppressed low in the example of FIG. 2 (a). (B) is explanatory drawing which shows the mode of consumption of incident light based on the comparative example of FIG.2 (b). BRIEF DESCRIPTION OF THE DRAWINGS The keyboard apparatus which comprises the planar illuminating device which concerns on embodiment of this invention is shown, (a) is a top view, (b) is a front view, (c) is a right side view. FIG. 6 is an A-A ′ cross-sectional enlarged view of FIG. It is a figure which shows typically the cross-section of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, parts that are the same as or correspond to those in the prior art are denoted by the same reference numerals, and detailed description thereof is omitted. Further, the directions of “up” and “down” in the following description mean the vertical direction in a state where the planar illumination device and the input device in this description are placed flat.

The input device shown in FIG. 5 to FIG. 7 is a keyboard device for a personal computer, and includes a shallow square dish-shaped lower case 1 having a horizontally long rectangular shape in plan view and a substantially inverted trapezoidal cross section. The lower case 1 is manufactured by synthetic resin molding, for example, ABS resin molding, and includes a leg portion 1a on the bottom surface. Housed in the lower case 1 is a main part of a keyboard device that performs an input operation by an operator touching a fingertip.
That is, as shown in FIGS. 6 and 7, in the lower case 1, a translucent touch panel 2, a display film 3 on which an arbitrary display symbol 3a (see FIG. 5) is printed, and the display film 3 The laminated body 5 with the planar illumination device 4 which is a surface light emitting layer that illuminates the light is housed. In this case, the touch panel 2 is disposed on the front surface side of the display film 3, the upper surface in the illustrated example, and the planar illumination device 4 is disposed on the rear surface side of the display film 3, on the lower surface in the illustrated example. 1B shows a single plan view of the display film 3, although some of the display symbols 3a are different from those in FIG. 5A.

Further, a translucent cover panel 7 is laminated on the upper surface side of the touch panel 2, in the present embodiment, on the upper surface of the touch panel 2. The cover panel 7 is fitted and fixed to the upper end portion of the inner wall of the lower case 1 so as to cover the upper surface opening of the lower case 1, and is positioned at the uppermost part of the apparatus. That is, the upper surface of the cover panel 7 forms the input operation surface 6 and is a flat surface without unevenness.
The cover panel 7 is formed by laminating a half mirror, a smoke panel, or a translucent plate or sheet (collectively referred to as a translucent panel) and a half mirror. In this embodiment, the translucent panel 8 and the half mirror 9 are laminated | stacked, and the half mirror 9 is arrange | positioned toward the touch panel 2 side. Here, the translucent panel 8 is made of a transparent acrylic plate or a transparent polycarbonate plate, and the half mirror 9 is made of a film-like or film-like half mirror, for example, and is attached to the translucent panel 8 to cover the cover panel 7. It constitutes.

Further, below the components of the cover panel 7, the capacitive touch panel 2, the display film 3, and the planar illumination device 4, there are circuits for driving the keyboard device, that is, a touch panel drive circuit and a backlight device turn-on / off circuit. A substrate (circuit board) 12 and a battery (battery for operating the touch panel drive circuit and the planar illumination device 4) 13 on which (not shown) are mounted are arranged. In FIG. 7, the battery 13 is not shown.
Since the cover panel 7 and the touch panel 2 have translucency as described above, the display symbol 3a printed on the display film 3 on the lower surface of the touch panel 2 can be seen through on the uppermost surface of the apparatus (input operation surface 6). Further, when the cover panel 7 is composed of the translucent panel 8 and the half mirror 9, when the planar illumination device 4 is turned on, an input operation for forming the display symbol 3a printed on the display film 3 on the uppermost surface of the device. The surface 6 can be clearly seen through. When the planar illumination device 4 is turned off, the uppermost surface of the device that forms the input operation surface 6 is in a mirror state, and the effect as a mirror is exhibited.

By the way, the planar illumination device 4 is disposed adjacent to the light guide plate 20 (see FIG. 1A) in which one of the pair of main surfaces is a light exit surface for the display film 3, and the side surface of the light guide plate 20. Light source (not shown). Further, as shown in FIGS. 6 and 7, the planar illumination device 4 is disposed on the rear surface side of the display film 3 and assembled in the light guide plate 20. Are scattered at positions corresponding to the respective display symbols 3a of the display film 3 in plan view.

  Specifically, as shown in FIG. 2A, each of the light scattering patterns 22 formed on the light guide plate 22 has at least a range immediately below the display symbol 3a in plan view, that is, the symbol facing portion 26. The arranged dots 24 are rectangular pattern placement portions 26 (hereinafter also referred to as “symbol facing portions” or “first density pattern placement portions”) as a high-density dot pattern placement. In addition, the second density pattern arrangement is such that the dots 24 arranged so as to surround the first density pattern arrangement section 26 have a rectangular pattern arrangement with a lower dot density than the first density pattern arrangement section 26. The part 28 is used.

In the example of FIG. 2A, the dots 24 of the symbol facing portion 26 arranged immediately below the planar view of the display symbol (“clear”) are arranged in a high density and lattice pattern (the pitch of the dots 24 is constant). By arranging columns with varying pitches on the outer periphery of a 3 × 9 grid, a rectangular dot pattern portion is obtained. It should be noted that, instead of the columns in which the pitches of the dots 24 are changed as appropriate, they may be configured so as to form a 5-row 11-column lattice with the same pitch. Then, on the outer peripheral side of the first density pattern arrangement portion (symbol facing portion) 26, a second density pattern arrangement portion (symbol peripheral portion) 28 in which the density of dots 24 is smaller than that of the first density pattern arrangement portion 26. Is provided. The pitch of the dots 24 in the first density pattern arrangement portion 26 is, for example, 0.8 mm in both the vertical direction and the horizontal direction, whereas the pitch of the dots 24 in the second density pattern arrangement portion 28 is Both the vertical direction and the horizontal direction are 1.0 mm.
2B shows a light scattering pattern 22 ′ including a symbol facing portion 26 and a symbol peripheral portion 28 in which the density of the dots 24 is constant, as a comparative example of FIG. 1A.

Furthermore, as an application example of the present embodiment, a characteristic portion illustrated in FIG. 3A may be used in combination. In the example of FIG. 3A, a rectangular pattern arrangement portion 26 similar to that of FIG. 2A is provided immediately below the display symbol 3a (“clear”) in plan view.
Further, in the plan view, in the periphery of the symbol facing portion 26, there are 3 rows and 15 columns in front of the symbol facing portion 26 (upper side in FIG. 3A, opposite to the side where the user's viewpoint is located). In the arrangement pattern of dots 24 in 1 row and 15 columns behind the facing portion 26 (the lower side of FIG. 3A, the side where the user's viewpoint is located) and 5 rows and 2 columns on the left and right of the symbol facing portion 26, respectively. A symbol peripheral portion 28 is provided.

In the symbol peripheral portion 28 illustrated in FIG. 3A, the front portion composed of the three rows of dots 24 has more dots 24 provided by about two rows than the rear portion composed of the one row of dots 24. It has been. In other words, in plan view, the light scattering pattern 22 is slightly larger than the display symbol 3a in the plan view, and the light scattering pattern 22 including the symbol facing portion 26 and the symbol peripheral portion 28 in the front-rear direction. The center position C22 is positioned about one line ahead of the center position (character center) C3a in the front-rear direction of the display symbol 3a (in the case where the display symbol 3a includes a plurality of characters or the like as the character center C3a). Is a center line that bisects the parallel line that passes through the most forward part and the parallel line that passes through the most rear part.

In other words, the light scattering pattern 22 formed on the light guide plate 20 is such that the distance from the front-rear direction center position C3a of each display symbol 3a in plan view to the front outer edge of the light scattering pattern 22 is light scattering. The pattern 22 is provided at a position larger than the rear outer edge portion.
The symbol facing portion 26 in FIG. 3A is configured as a first density pattern arrangement portion, and the symbol peripheral portion 28 is configured as a second density pattern arrangement portion.

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained.
That is, the planar illumination device 4 employed in the personal computer keyboard device according to the embodiment of the present invention includes a light guide plate 20 having one of a pair of main surfaces as a light exit surface for the display film, and the light guide plate 20. And a light scattering pattern 22 that receives incident light from the light source and scatters the incident light is displayed at least in a plan view. It is formed at a position corresponding to each of the display symbols 3 a of the film 3. The incident light incident on the light guide plate 20 from the light source is deflected by the light scattering pattern 22, exits from the exit surface of the planar illumination device 4, and is irradiated toward the back surface of the display film 3. The display symbol 3 a is illuminated so as to be visually recognized from the surface of the display film 3.

In addition, each of the light scattering patterns 22 formed on the light guide plate 20 has a symbol opposing portion 26 that is a pattern placement portion disposed at least in a range immediately below the display symbol 3a in a plan view as a first high density. The second density pattern arrangement portion 28 having a dot density lower than the first density is arranged so as to surround the symbol facing portion 26 which is the first density pattern arrangement portion.
For this reason, each display of the display film 3 is included in each of the light scattering patterns 22 formed on the light guide plate 20 by the first density symbol facing portion 26 disposed at least in a range immediately below the display symbol in plan view. Necessary light distribution is performed within the minimum necessary range of the symbol 3a. Further, the symbol opposing portion 26 is illuminated by a symbol peripheral portion 28 which is a second density pattern arranging portion having a dot density smaller than the first density and arranged so as to surround the first density symbol opposing portion 26. Light is distributed to each display symbol 3a of the display film 3 so as to border the range. The entire display symbol 3a is illuminated by the planar illumination device 4 regardless of the relationship between the planar illumination device 4, each display symbol 3a of the display film 3, and the user's line of sight VP. It will prevent chipping.

Further, in the first density pattern arrangement 26, the incident light consumption ratio in the second density pattern arrangement section 28 having a dot density lower than the first density while increasing the consumption ratio of incident light incident on the light guide plate 20. It is possible to reduce unnecessary consumption of incident light by keeping the value low.
4A schematically shows the light guide plate 20 according to FIG. 2A. In FIG. 4A, 20a is a light incident portion where a light source is arranged, and 20b is opposed to the light incident portion 20b. At the opposite end, L indicates incident light. On the other hand, FIG. 4B schematically shows the light guide plate 20 ′ according to FIG.

As is clear from FIG. 4A, the dot density of the second density pattern placement portion 28, which is an originally unnecessary portion (auxiliary portion), is compared with that of the first density pattern placement portion 26. Since the first density pattern placement section 26 is relatively small, the second density pattern placement section having a dot density lower than the first density while increasing the consumption ratio of the incident light L to the light guide plate 20. By suppressing the consumption ratio of the incident light L at 28, it is possible to reduce the unnecessary consumption of incident light. Moreover, the uniformity of the brightness from the light incident end 20a to the opposite end 20b of the light guide plate 20 can be improved. On the other hand, in the reference example of FIG. 2B, the incident light L is considerably consumed even in the pattern arrangement portion 28 ′ (in the auxiliary portion of the pattern arrangement portion 28 ′) as shown in FIG. 4B. It will be done.

Furthermore, in the manufacturing process of the present apparatus, even if a positional shift occurs between the light scattering pattern 22 of the light guide plate 20 and the display symbol 3a of the display film 3, the second density having a dot density lower than the first density. Since the pattern placement unit 28 is disposed so as to surround the symbol facing unit 26 which is the first density pattern placement unit, the display symbol 3a can be stably illuminated. Further, even when viewed from an oblique direction, the so-called character missing of the display symbol 3a does not occur.
Therefore, it is possible to further improve the visibility of the predetermined display symbol 3a without increasing the power consumption of the light source of the surface illumination device 4.

  Further, as shown in FIG. 3A, the planar illumination device 4 is disposed at each position of the light scattering pattern 22 in a state where the planar illumination device 4 is disposed on the back side of the display film 3 on which a plurality of display symbols 3a are formed. Corresponding distance Yf from the front-rear direction center position C3a in the plan view of each display symbol 3a of the display film 3 to the front outer edge of the light scattering pattern 22 is more than the distance Yr to the rear outer edge of the light scattering pattern. Alternatively, it may be provided at a larger position. With this configuration, each display symbol 3a of the display film 3 is illuminated over a wide range from the center position C3a in the front-rear direction in the plan view toward the front edge side of the light scattering pattern. And the light distribution which considered the relationship between each display symbol 3a of the display film 3 and a user's eyes | visual_axis will be made by the planar illumination apparatus 4. FIG.

That is, as shown in FIG. 3B, the user's line of sight VP is backward R with respect to the normal N direction at the center position in the front-rear direction (reference C3a in FIG. 3A) in the plan view of the display symbol 3a. In the use state where the display symbol 3a is viewed from the front, the area on the front F side of the display symbol that extends beyond the viewpoint (line of sight) via the display symbol 3a is also emitted from the light guide plate 20 by the light scattering pattern 22. By being illuminated by the light, the entire display symbol 3a is illuminated without the front of the display symbol 3a being out of the irradiation range, and so-called character omission is prevented.
In this way, by performing the necessary light distribution in the necessary range, the amount of incident light consumed for unnecessary light distribution is reduced, and without increasing the power consumption of the light source of the surface illumination device 4, It becomes possible to further improve the visibility of the predetermined display symbol 3a.

In addition, the planar illumination device according to the embodiment of the present invention has a dot arrangement in a portion configured by arranging a plurality of dots 24 included in the plurality of light scattering patterns 22 formed on the light guide plate 20. By appropriately adjusting, necessary light distribution can be performed within a necessary range of each display symbol of the display film.
In addition, by appropriately adjusting the number of rows or columns of the plurality of dots 24 arranged in a grid pattern in plan view, the necessary light distribution is performed in the necessary range of each display symbol 3a of the display film 3. Is possible.

Further, by appropriately adjusting the installation range of the rectangular pattern arrangement portion 26 in a plan view included in the plurality of light scattering patterns 24 formed on the light guide plate, each display symbol 3a of the display film 3 is necessary. The necessary light distribution is performed in the range.
In addition, the minimum of each display symbol 3a of the display film 3 is arranged by a pattern arrangement portion (symbol facing portion) 26 that is rectangular in plan view and is disposed immediately below the position corresponding to each of the display symbols 3a in plan view. Adjustments can be made to ensure the required light distribution for the required range. On the other hand, for the second density pattern arrangement portion (symbol peripheral portion) 28, the shape of the installation range may be appropriately set so as to ensure appropriate light distribution.

Therefore, if the display device including the above-described planar illumination device 4 and the display film 3 on which the plurality of display symbols 3a are formed is configured, the display device has the effects corresponding to the above. It will be a thing.
Further, by configuring an input device including the above-described planar illumination device 4, the display film 3 on which a plurality of display symbols 3a are formed, and the touch panel 2, a personal computer keyboard device illustrated in FIG. In the input device taking the above as an example, the above-described effects can be obtained.

  3: display film, 3a: display symbol, 4: planar illumination device, 20: light guide plate, 22: light scattering pattern, 24: dots, 26: first density pattern arrangement part (symbol facing part), 28: first 2 density pattern arrangement part (symbol peripheral part), C3a: center position in the front-rear direction of the display symbol, C22: center position in the front-rear direction of the light scattering pattern, Yf: center position in the front-rear direction of the display symbol in plan view, Distance to the front outer edge of the light scattering pattern, Yr: Distance from the center position in the front-rear direction of the display symbol in plan view to the rear outer edge of the light scattering pattern

Claims (7)

A planar illumination device that is arranged on the back side of a display film on which a plurality of display symbols are formed and irradiates light toward the display film,
A light guide plate having one of a pair of main surfaces as a light exit surface for the display film, and a light source disposed adjacent to a side surface of the light guide plate,
On the light guide plate, a light scattering pattern that receives incident light emitted from the light source and scatters the incident light is formed at positions corresponding to each of the display symbols at least in plan view, and
Each of the light scattering patterns includes a pattern in which a plurality of dots are arranged, and a first density pattern arrangement unit arranged in a range immediately below the display symbol in at least a plan view of the light scattering pattern; And a second density pattern arrangement section having a dot density lower than the first density and surrounding the first density pattern arrangement section. The planar illumination device according to claim 1, wherein the plurality of dots are arranged in a lattice shape in a plan view. The distance between the display symbol corresponding to each position of the light scattering pattern from the center position in the front-rear direction in plan view and the front outer edge of the light scattering pattern is larger than the rear outer edge of the light scattering pattern. The planar illumination device according to claim 1, wherein the planar illumination device is provided at a position. The planar illumination device according to any one of claims 1 to 3, wherein the plurality of light scattering patterns formed on the light guide plate include a rectangular pattern arrangement portion in a plan view. The planar illumination device according to claim 4, wherein the planar pattern arrangement portion in the plan view is the first density pattern arrangement portion. 6. A display device comprising: the planar illumination device according to claim 1; and a symbol display film on which a plurality of display symbols are formed. An input device comprising: the planar illumination device according to any one of claims 1 to 5, a symbol display film on which a plurality of display symbols are formed, and a touch panel.