Source: https://patents.google.com/patent/JP3746173B2/en
Timestamp: 2020-01-19 08:00:34
Document Index: 799741007

Matched Legal Cases: ['art 400', 'art.11', 'art 4', 'art 5', 'art 4', 'art 5', 'art 4', 'art 5', 'art 4', 'art 4', 'art\n5', 'art\n5', 'art\n12', 'art\n45', 'art\n45']

JP3746173B2 - Surface illumination device and portable terminal device using the same - Google Patents
Surface illumination device and portable terminal device using the same Download PDF
JP3746173B2
JP3746173B2 JP28651999A JP28651999A JP3746173B2 JP 3746173 B2 JP3746173 B2 JP 3746173B2 JP 28651999 A JP28651999 A JP 28651999A JP 28651999 A JP28651999 A JP 28651999A JP 3746173 B2 JP3746173 B2 JP 3746173B2
JP28651999A
JP2000331523A (en
忍 上鶴
一幸 中島
高広 大森
純生 楯
晴二 真鍋
健生 福田
1999-03-12 Priority to JP11-66415 priority Critical
1999-03-12 Priority to JP6641599 priority
1999-10-07 Application filed by 松下電器産業株式会社 filed Critical 松下電器産業株式会社
1999-10-07 Priority to JP28651999A priority patent/JP3746173B2/en
2000-03-13 Priority claimed from US09/524,587 external-priority patent/US7088333B1/en
2000-11-30 Publication of JP2000331523A publication Critical patent/JP2000331523A/en
2006-02-15 Publication of JP3746173B2 publication Critical patent/JP3746173B2/en
2019-10-07 Anticipated expiration legal-status Critical
The present invention relates to a surface illumination device that illuminates a liquid crystal display device from the back, and more particularly to a surface illumination device that illuminates a light source such as a light emitting diode and a portable terminal device using the same.
2. Description of the Related Art A surface illumination device used as a surface illumination device for a liquid crystal display device such as a mobile phone or a personal handyphone system has a light source using a chip-shaped light emitting diode because of its small size and low power consumption. In recent years, the surface illumination device has also been used for display units of portable devices such as various portable information terminals, digital cameras, video cameras, etc., to reduce the size, extend the battery life, and improve the impact resistance. It is moving from the one used to the light emitting diode light source.
There are various configurations for conventional surface illumination devices using these light-emitting diode light sources. For example, as described in Japanese Examined Patent Publication No. 3-32075, a light emitting diode light source that emits a top surface is disposed on the back side of a liquid crystal display body, and light is irradiated directly toward the back surface of the liquid crystal display body for illumination. However, due to the thinning of the device and the problems in installing electronic circuits on the back of the liquid crystal display element, the surface illumination device for liquid crystal display devices such as mobile phones is directly connected to the back side of the liquid crystal display. The number of light emitting diode light sources arranged is small. On the other hand, as a surface illumination device for a liquid crystal display device such as a mobile phone, a method of arranging a light emitting diode light source outside the display surface of a liquid crystal display element is often used. As described, a light emitting diode light source that emits light from the top surface is arranged outside the display surface of the liquid crystal unit, and illumination is performed by guiding light below the liquid crystal display unit using a reflective surface and a resin plate. Are known.
An example in which the light emitting diode light source is arranged outside the display surface of the liquid crystal display element will be described as a conventional surface illumination device with reference to FIGS. 11 and 12. 11 is a plan view of a conventional surface illumination device, FIG. 12 is a side view of the conventional surface illumination device, 100 is a light source such as a light emitting diode, 200 is a light guide plate, 300 is a light guide portion of the light guide plate 200, 300a. Is an incident surface of the light guide unit 300, 400 is a light emitting unit of the light guide plate 200, 500 is a scattering unit formed on the lower surface of the light emitting unit 400, 500a is a scattering dot printed on the scattering unit 500 with milky white to white ink. , 600 is a holder for holding the light guide plate 200, and 700 is a reflecting surface formed on the holder 600. Here, the light emitted from the light source 100 is reflected by the reflecting surface 700 and then enters the light guide plate 200 from the incident surface 300 a of the light guide unit 300. A part of the light incident on the inside of the light guide plate 200 is diffusely reflected by the scattering unit 500 and emitted from the light emitting unit 400.
However, in the above-described conventional surface illumination device or the like, if the light source 100 is only one in the center of FIG. 11, the luminance distribution that is unevenness of the brightness of the light emitting part 400 becomes large, and the vicinity of the A part in FIG. , B vicinity tends to be dark. In particular, this luminance distribution becomes prominent as the area to be illuminated increases. When such a luminance distribution occurs, when used as a surface illumination device such as a liquid crystal display element, display characters and the like are difficult to see, and furthermore, a display portion that is dark and cannot be recognized is generated. In order to solve this problem, there has conventionally been a means of improving the luminance distribution of the surface illumination device by increasing the number of light sources 100 used and reducing the arrangement interval of the light sources 100.
However, in a liquid crystal display device of a portable device such as a mobile phone, if the number of light sources used in the surface illumination device is increased, there is a problem that not only the power consumption is increased, but also the complexity related to the mounting of the light source and the manufacturing cost are increased. there were.
When a plurality of light sources are used, a difference in wavelength of light emitted from each light source becomes a problem. That is, the wavelength of the light emitted from each light source is usually different by about several nm due to individual differences. However, even with a deviation of about several nanometers, when viewed by the human eye, the color illumination device causes large color unevenness when comparing the irradiation range of each light source and the vicinity of its boundary. Therefore, in order to eliminate color unevenness, the light source is caused to emit light one by one, the wavelength is measured, and the same wavelength is collected so as to eliminate variations in the wavelength of the light source for each surface illumination device. It was necessary to be. However, this operation is very troublesome because all of the light sources must be inspected, and as a result, is one of the factors that reduce the productivity of the surface lighting device.
Moreover, the individual difference of the brightness | luminance of the light source used has also become a cause of the brightness nonuniformity of a surface illuminating device.
Further, as a method for improving color unevenness and luminance distribution, there is a method in which a single light source is used to elongate the light guide portion of the light guide plate and the light is emitted from the light emitting portion after the light is sufficiently diffused. However, there is a problem that downsizing of the entire apparatus is limited.
Therefore, the present invention provides a small surface illumination device that uses a single light source such as a light-emitting diode and has a good luminance distribution and high visibility even when the length of the light guide is short. For the purpose.
In order to solve the above problems, the surface illumination device of the present invention is:One light source and the light emitted from the light sourceAn incident surface, a light guide for guiding light incident from the incident surface, and a light emitting unit for emitting light propagating through the light guideWith a light guide memberThe light guide member has a pair of outer peripheral surfaces and an incident surface is disposed between the pair of outer peripheral surfaces, and the distance between the pair of outer peripheral surfaces is closer to the incident surface side,It is set as the structure provided with the partition which suppresses that the light radiate | emitted from the light source directly injects into a light guide member.
The length of the light guide portion in the short direction is 8 (mm) or less, and the area of the light emitting portion is 500 (mm).2) A surface illumination device including the above light guide member, configured to be capable of selecting any one of a plurality of light sources that emit light according to a situation, wherein the light source emits light at one time. For any of the light sources, the ratio of the maximum luminance portion to the minimum luminance portion of the light emitting portion is 0.3 or more, and the average luminance is 1 (cd / m2) 200 (cd / m)2) Hereinafter, the change value of the luminance of the light emitting unit per unit length is (average luminance) × 100 (cd / m)Three) The configuration is as follows.
Furthermore, display means, conversion means for converting at least one of a data signal or an audio signal into a transmission signal or converting a reception signal into at least one of a data signal or an audio signal, and an antenna for transmitting and receiving the transmission signal and the reception signal And a portable terminal device provided with a control means for controlling each part, wherein the above-described surface illumination device is used below the display means.
The invention described in claim 1One light source and the light emitted from the light sourceAn incident surface for incident light, a light guide portion for guiding light incident from the incident surface, and a light emitting portion for emitting light propagated through the light guide portionWith a light guide memberThe light guide member has a pair of outer peripheral surfaces and the incident surface is disposed between the pair of outer peripheral surfaces, and the distance between the pair of outer peripheral surfaces is closer to the incident surface side,Provided with a partition that prevents light emitted from the light source from directly entering the light guide memberBySince light emitted from the light source can be prevented from entering the light guide member, the vicinity of the light source in the light emitting part is prevented from becoming extremely bright.it can.
Claim2In the invention described in (1), since the light source side surface of the partition wall has a reflecting action, light absorption in the partition wall can be almost eliminated and the light utilization efficiency can be improved.
Claim3In the invention described in item 1, a part of the light reflected by the partition wall is reflected by the outer peripheral surface of the light guide part and enters the light emitting part, so that the light use efficiency can be improved.
Claim4The invention described in (1) includes a storage member for storing the light guide member, and the partition wall is integrally formed with the storage member, so that mass productivity can be improved and the partition wall and the light from the light source can be improved. It is possible to eliminate steps such as alignment between the partition, alignment between the partition wall and the storage member, joining, etc., so that the productivity of the surface lighting device can be improved and the yield can be further improved. .
Claim5The invention described in 1 includes a reflecting member that reflects light emitted from the light source in the direction of the outer peripheral surface of the light guide unit, so that most of the traveling direction of the light emitted upward from the light source is Since it can be converted to the direction of the outer peripheral surface and most of the light emitted from the light source can be guided to the light guide member, the light use efficiency can be improved and the light emitting portion of the light guide member Since the distribution of the light incident on can be made more uniform, it is possible to realize a surface illumination device with small luminance unevenness and high visibility.
Claim6The invention described in (2) includes a storage member that stores the light guide member, and the partition wall and the reflection member are integrally formed on the storage member, so that mass productivity can be improved, and the partition wall and the reflection member Since it is possible to eliminate the alignment between the light from the light source, the alignment between the partition wall and the reflecting member and the storage member, the step of joining, etc., the productivity of the surface lighting device can be improved, Furthermore, the yield can be improved.
Claim7In the invention described in, since the scattering portion is formed on the lower surface of the light guide member opposite to the light emitting portion, the light quantity distribution in the light emitting portion can be made more uniform.
Claim8In the invention described in (2), since the scattering member is provided on the light emitting portion of the light guide member, the traveling direction of the transmitted light is converted into various directions, and the luminance unevenness of the surface illumination device is further reduced. be able to.
Claim9In the invention described in (2), since the reflection plate is provided below the scattering member, the light transmitted through the scattering member can be incident again on the light guide member, so that the light use efficiency can be improved. it can.
Claim10According to the invention described in (2), since the half-value width of the light emission wavelength of the light source is 50 (nm) or less, a beautifully colored screen can be realized with high efficiency. be able to.
Claim11The surface illuminating device using a light emitting diode as a light source, wherein the light emitting diode includes a light emitting element and a cylindrical lens on which light emitted from the light emitting element is incident. The light once hitting the surrounding members among the light emitted from the light can be reduced, and the absorption loss of light energy due to reflection and absorption there can be reduced, so that the light utilization efficiency can be further enhanced.
Claim12The invention according to claim 1 includes display means, conversion means for converting at least one of a data signal or an audio signal into a transmission signal or converting a reception signal into at least one of a data signal or an audio signal, the transmission signal and the reception signal. A portable terminal device comprising an antenna for transmitting and receiving a signal and a control means for controlling each part.11By using any one of the surface illumination devices, luminance unevenness can be reduced in the display unit of the mobile terminal device, so that a mobile terminal device with high visibility and therefore less misperception can be realized. Moreover, since only one light source is used, a portable terminal device with extremely low power consumption can be realized.
An embodiment of the present invention will be described with reference to FIGS. 1 is a plan view of a surface illumination device according to an embodiment of the present invention, FIG. 2 is a side view of the surface illumination device according to an embodiment of the present invention, and FIG. 3 is a light guide plate according to an embodiment of the present invention. 4 is a perspective view of a holder according to an embodiment of the present invention, FIG. 5 is a cross-sectional view of the vicinity of a partition wall of the surface illumination device according to the embodiment of the present invention, and shows a cross section D in FIG. . In the figure, reference numeral 1 denotes a light source, and the light source 1 may be a miniature light bulb, an oval ball, a light-emitting diode, or the like.2The thickness is about 2 mm or less, especially the light emission area is 2.8 mm.2A light emitting surface (point light source) having a light emission surface of about or less than that is preferable, and it is particularly preferable to use a highly efficient light emitting diode because a more uniform luminance distribution can be realized and an easy-to-view surface illumination device can be realized. . Especially when used for a small mobile phone or a portable information terminal, a very small and thin one is required.ThreeThe following are preferably used. In this case, the fact that the light source 1 can be mounted on the substrate can be easily attached to the substrate, so that productivity is improved.
Moreover, since the power consumption in a surface illumination device can be reduced by making the number of the light sources 1 in a surface illumination device one, it can be set as a surface illumination device suitable for a portable apparatus etc. In addition, there is no color unevenness or brightness unevenness caused by variations in the light emission wavelength or light emission efficiency of multiple light sources, so there is no need to select the light source and the productivity of the surface illumination device As well as the cost of the surface illumination device can be significantly reduced.
Furthermore, the structure of the preferable light source 1 is demonstrated using figures. FIG. 16 is a perspective view of the light source of the surface illumination device in one embodiment of the present invention, and FIG. 17 is a light emission intensity distribution diagram of the light source of the surface illumination device in one embodiment of the present invention. Here, the light source 1 is a light emitting diode. In FIG. 16, 1a is a light emitting element that actually emits light, 1b is a lens formed so as to surround the light emitting element 1a, and 1c is mounted with the light emitting element 1a. It is a base substrate. The material of the lens 1b is high in light transparency, and is preferably an epoxy resin that can withstand the high temperature of the later soldering process, and its shape is cylindrical as shown in FIG. When the lens 1b has such a shape, the light source 1 has a light emission intensity distribution as shown in FIG. That is, when viewed from the G direction in FIG. 16, a sharp light emission distribution having a peak immediately above the light emitting element 1a is obtained due to the curved surface of the lens 1b. Further, when viewed from the H direction in FIG. 16, the light emission distribution becomes gentle. If this light source 1 is disposed in the surface illumination device, light emitted from the light source 1 can be reduced once against the surrounding members, and light energy absorption loss due to reflection and absorption is reduced. The utilization efficiency can be further increased.
At this time, the light utilization efficiency can be improved as the angle formed between the cylindrical axial direction and the X direction in FIGS. 1 and 2 is closer to 90 degrees, and if the angle is approximately orthogonal, the light utilization efficiency is maximized. Therefore, it is preferable.
In the present embodiment, only one light source having one light emitting element is mounted per surface illumination device, but one light source having a plurality of light emitting elements having different light emission wavelengths is used, and each light emitting element is used. By controlling the current to flow, the surface illumination device can emit light not only with the number of colors of the light emitting elements but also with the intermediate colors.
FIG. 18 is a perspective view of a light source according to an embodiment of the present invention, showing a light source 20 on which three light emitting elements 20a, 20b, and 20c having different emission wavelengths are mounted. The light emitting element 20a is mounted on the substrate 20d and emits light substantially in blue. The light emitting element 20b is mounted on the substrate 20d and emits light substantially in green. The light emitting element 20c is mounted on the substrate 20d and emits light substantially in red.
As a material constituting the substrate 20d, it is preferable to use a material having high insulation and a high thermal conductivity so that the light emitting element is not damaged by heat.
Furthermore, power supply lines 20f, 20g, and 20h for supplying power to the light emitting elements 20a, 20b, and 20c are formed on the substrate 20d, and a control unit that controls the power that flows through the power supply lines 20f, 20g, and 20h ( It is possible to arbitrarily change the color of the surface illumination device by changing the amount of light emitted from each of the light emitting elements 20a, 20b, and 20c.
The power supply lines 20f, 20g, and 20h are extended to at least one of the side surface and the back surface of the substrate, and serve as connection terminals used when mounted on the wiring substrate. By configuring the feeder lines 20f, 20g, and 20h with electrodes formed of a thin film or a thick film in this way, the light source 20 can be mounted on the wiring board and productivity can be improved, which is preferable. .
Reference numeral 20i denotes a wire, and the wire 20i connects the power supply lines 20f, 20g, and 20h to electrodes (not shown) formed on the light emitting elements 20a, 20b, and 20c, and is usually connected by wire bonding. The
A translucent member 20e is provided on the substrate 20d so as to cover the light emitting elements 20a, 20b, and 20c. The translucent member 20e can prevent the light emitting elements 20a, 20b, and 20c from being deteriorated by direct contact with the outside air, and can also be connected to the light emitting element due to vibration during use or manufacturing (for example, wire bonding). Etc.) can be prevented from being cut or detached. Moreover, since a plurality of light sources are not used, the illumination color can be changed without increasing the power consumption so much. In addition, as a manufacturing method of the translucent member 20e, it is preferable to form the resin material by transfer molding or injection molding from the viewpoint of the degree of freedom in shape and high molding accuracy. Note that glass may be used as the material, which can greatly reduce changes in material and shape due to aging, so that reliability can be improved.
In addition, it is preferable that the translucent member 20e has an action of condensing light emitted from the light emitting elements 20a, 20b, and 20c from the viewpoint of improving the light use efficiency. In particular, it is possible to have a sufficient light spread in the direction that is required to spread more widely and to make the light spread very small in the direction that is required to have a small spread. In particular, light can be guided very efficiently to a thin surface illumination device.
The chromaticity of the emission color of the light emitting element 20a is in the vicinity of (x, y) = (0.14, 0.04), and the chromaticity of the emission color of the light emitting element 20b is (x, y) = (0.12, 0. 76) Since the chromaticity of the emission color of the light emitting element 20c is in the vicinity of (x, y) = (0.72, 0.27), if the currents flowing through the light emitting elements 20a, 20b, and 20c are respectively controlled, In the CIExy chromaticity diagram shown in FIG. 19 (the CIExy chromaticity diagram in one embodiment of the present invention), the color of the area Q can be emitted.
In FIG. 18, the light emitting elements 20a, 20b, and 20c included in the light source 20 have substantially the same shape. However, when the shapes are different or the center of the outer diameter shape is different from the light emission center, the light emission is performed. Arrangement is made so that the line connecting the light emission centers of the elements 20a, 20b, and 20c and the major axis direction of the translucent member 20e substantially coincide with each other, so that light from any of the light emitting elements 20a, 20b, and 20c Since it can be used with substantially uniform efficiency, it is easy to secure the light quantity and the degree of freedom of color.
Here, the light emitting elements 20a, 20b, and 20c have substantially the same shape. However, when the shapes are different, or when the outer shapes are the same but the light emitting point positions are different, the respective optical elements 20a, 20b, and 20c. The light emission points (or light emission centers) of the light emitting elements 20a, 20b, and 20c can be made uniform in the incident condition to the light guide plate 2 to be described later. Accordingly, it is possible to minimize the amount of incident light and the variation of the incident optical axis between the light emitting elements 20a, 20b, and 20c to the light guide plate 2, and to obtain a surface illumination device having sufficient brightness and excellent color tone. Therefore, it is preferable.
In addition, it is preferable to reduce the distance between the light emitting element 20a and the light emitting element 20b and the distance between the light emitting element 20b and the light emitting element 20c because luminance unevenness and color unevenness can be further suppressed. Specifically, the thickness is preferably 0.3 to 1.0 mm. If the distance is less than 0.3 mm, it is difficult to form a power feeding means for a light emitting element such as a bonding wire, and the frequency of occurrence of a short circuit between terminals increases, resulting in a decrease in yield. When the thickness is 1.0 mm or more, it is difficult to suppress the occurrence of uneven luminance and uneven color due to the difference in the light emission position between the light emitting elements. Furthermore, as a preferable range, 0.4 to 0.8 mm can reduce the occurrence of color unevenness and luminance unevenness while minimizing the thermal influence on adjacent elements.
By mounting a light source including two or more light emitting elements having different wavelengths as described above, a user can arbitrarily select a light emitting element to be used or mechanically (by a control means), for example, By changing the light emission wavelength of the light emitting element or changing the amount of light, the light emission color of the surface illumination device can be changed. It is also conceivable to use a plurality of light emitting elements as spares when one light emitting element is broken.
Furthermore, by making the emission wavelengths of a plurality of light emitting elements provided in one light source 1 different from each other and causing at least two or more light emitting elements to emit light simultaneously, a color that cannot be expressed by the wavelength of the originally provided light emitting elements is expressed. Will be able to. Also, in this case, the light-emitting element spacing can be made narrower compared to the case where a plurality of light sources having different wavelengths are provided apart from each other to emit light at the same time. It is done. Further, a more uniform color mixture can be obtained, and a beautiful surface illumination device with almost no color unevenness can be obtained.
In the following description, the light source 20 can be applied to what is described as the light source 1 unless otherwise specified.
A light guide plate 2 made of a transparent material has a function of guiding light from the light source 1 and emitting it from a predetermined position to the outside. As the material, a highly transparent material such as methacrylic resin or polycarbonate resin, specifically, a material having a transmittance of 95% or more per 1 mm thickness and a material of 98% or more when the length is 30 mm or more is used. This is preferable because a decrease in the amount of light can be minimized and the luminance can be increased. As such a material, an organic material or glass is suitable. In particular, it is preferable to use a resin having a high degree of freedom in shape and mass productivity by injection molding using a mold. In this embodiment, a methacrylic resin having a high light transmittance is used among the resins. Further, if the refractive index of the light guide plate 2 is 1.3 or more, preferably 1.4 or more, total reflection easily occurs between the air (refractive index of about 1) layer and leakage from the light guide plate 2 occurs. The amount of light to be emitted can be suppressed, and loss due to the radiation of the light incident on the light guide plate 2 can be suppressed to the minimum, so that the light use efficiency can be improved and the power consumption of the surface illumination device can be suppressed. .
Reference numeral 3 denotes a light guide portion of the light guide plate 2, and the light guide portion 3 is an area having a function of spreading light from the light source 1 in the width direction of the light guide plate 2 through the incident surface 3a and the reflection surface 3b. It is preferable that the length of the light guide unit 3 is as short as possible because the width and length of the surface illumination device and the electronic device on which the surface illumination device is mounted can be reduced. Specifically, there is a request from the industry that the length of the light guide 3 is desired to be 8 mm or less.
The incident surface 3 a is a portion where light from the light source 1 enters the light guide portion 3 of the light guide plate 2. Here, the incident surface 3 a is formed non-perpendicular to the upper surface 2 a of the light guide plate 2. With such a configuration, it is possible to effectively suppress the light from the light source 1 from passing through the plate thickness of the light guide unit 3, and to guide more light from the light source 1 to the light guide plate 2. Is preferable.
The reflecting surface 3 b is a side surface of the light guide plate 2 where most of the light incident from the incident surface 3 a is reflected first, and is inclined with respect to the side surface portion 2 b of the light guide plate 2. In particular, by increasing the inclination (inclination of a straight line connecting both ends in the case of a curved surface), specifically 45 ° or more, even when the light guide plate 2 is wider, it reaches every corner. Light can be incident. At present, in a mobile terminal device or the like, since the display unit is larger and the device itself tends to be downsized, the light guide unit 3 is short and the light emitting unit 4 is large so that the light emitting unit 4 is large. More preferably, the above is used. In addition, the angle between the reflecting surfaces 3b constituted by planes, that is, the angle representing the spreading direction of the light guide 3 is 90 ° or more, more preferably 130 ° or more, so that the width (W2) of the light emitting unit 4 is increased. ) Is 20 mm, the length (W1) of the light guide unit 3 can be 8 mm or less, and the width of the light emitting unit 4 can be increased while shortening the length of the light guide unit 3. It is preferable because it is possible.
The shape of the reflecting surface 3b may be flat or curved, and an optimal luminance distribution can be realized in the light guide plate 2 in consideration of the luminance distribution of the light source 1, the shape of the light guide plate 2, and the like. To be determined. By providing the reflecting surface 3b, the distribution of light incident on the light emitting portion 4 of the light guide plate 2 can be made more uniform even if the length of the light guide portion 3 is shortened. A small and highly visible surface illumination device can be realized.
In particular, when the light source 20 is applied in place of the light source 1, as shown in FIG. 23 (conceptual diagram showing the arrangement of a light source having a plurality of light emitting elements and a light guide portion in an embodiment of the present invention). By making the lengths of the axial lines from the light emitting elements 20a, 20b, 20c included in the light source 20 to the incident surface 3a of the light guide unit 3 substantially equal to each other, incidence on each of the two incident surfaces 3a across the light source 20 Due to the difference in the amount of light, it is possible to suppress the inconvenience that the amount of incident light is different for each light emitting element to the light guide unit 3, and the light distribution can be made more uniform. A high surface illumination device can be realized.
Here, the axis is defined as a straight line connecting or approximating points where the intensity distribution of light propagating in space is the strongest. If the light intensity distribution is different from the shape of the Gaussian distribution, and the intensity distribution is divided in multiple directions, it may be defined by a straight line perpendicular to the light emitting surface of the light emitting element, and the axis line represents the light emitting surface. If it does not pass, a straight line corrected to pass may be considered as an axis. This definition applies to all the terms “axis” herein.
The light emitting portion 4 is a portion on the upper surface of the light guide plate 2 where light incident on the light guide plate 2 is emitted from the light guide plate 2. Since the surface roughness of the light emitting portion 4 is 1 μm or less in average roughness, light emitted with an appropriate luminance distribution is hardly disturbed at the boundary surface. Can be realized.
Reference numeral 5 denotes a scattering portion. The scattering portion 5 is formed on a surface 2c opposite to the upper surface 2a of the light guide plate 2, and has a function of reflecting or transmitting light incident on this portion in various directions. 5a is a scattering dot formed so that the area ratio increases as the distance from the light source 1 increases. The scattering dot 5a is often formed from milky white to white ink and has a scattering action in the scattering unit 5. The formation of the scattering dots 5a on the scattering portion 5 is often performed by printing, and it is preferable to use screen printing or pad printing among the printing because mass productivity can be improved. In particular, the use of pad printing is preferable because the scattering dots 5a can be printed evenly even when the light guide plate has a convex shape.
Further, it is preferable to form the scattering dots 5a from milky white to white ink because good scattering can be obtained and light absorption by the scattering dots 5a can be suppressed to a minimum. Thus, by changing the printing area of the scattering dots 5a, the luminance distribution of the light emitting portion 4 can be made uniform. As the milky white to white ink, those in which white fine particles such as titanium oxide are dispersed in a medium which is a transparent ink are particularly suitable. Also, it is not always necessary to mix colored particles, and the same effect can be obtained by using glass beads having a refractive index higher than that of the ink or using air bubbles having a refractive index lower than that of the ink. It is done. In addition, by forming a large number of minute protrusions or depressions directly on the scattering portion 5 using a mold or the like, it is possible to provide a scattering action and substitute for the scattering dots 5a.
Reference numeral 6 denotes a reflection sheet, and the reflection sheet 6 is a member having a high reflectance placed on the lower surface of the scattering portion 5, and part of the light transmitted through the scattering portion 5 and exiting from the light guide plate 2 is again guided to the light guide plate. It works to return to the inside of 2. This reflective sheet 6 is often composed of a PET (polyethylene terephthalate) sheet or the like, and it is particularly preferable to use a microfoamed PET sheet among the PET sheets because the reflectance is improved. The reflection sheet 6 may be provided as a separate member with respect to the light guide plate 2 or may be directly formed in advance on the light guide plate 2 by a method such as printing or vapor deposition. When formed directly, the manufacturing process of the surface lighting device can be simplified, the productivity of the surface lighting device can be improved, the manufacturing cost of the surface lighting device can be reduced, and the surface lighting device can be reduced. This is a preferable structure because the lighting device can be thinned. Furthermore, when forming directly, the reflection sheet 6 may be formed on the scattering dot 5a, and it may not be formed in the place where the scattering dot 5a is not provided. With this configuration, the light that passes through the scattering dots 5a can be reliably reflected by the reflection sheet 6, and the light can be reliably reflected by total reflection at the light guide plate 2 at portions where the scattering dots 5a are not provided.
Further, in the case where it is constituted by another member, by utilizing an air layer between the reflection sheet 6 and the light guide plate 2, both the total reflection on the light guide plate 2 and the reflection on the reflection sheet 6 can be utilized. Therefore, it is preferable because the light use efficiency can be improved as a whole. Further, the reflection sheet 6 and the light guide plate 2 may be partially joined in a predetermined positional relationship. This is preferable because the assembly process of the surface illumination device can be simplified.
The reflection sheet 6 may be configured to be bonded in advance to a second recess 8c of the holder 8 described later. In this case, at the time of assembling the surface lighting device, the position of the light guide plate 2 and the reflection sheet 6 that are bonded in advance is displaced, so that it is not possible to store the reflection sheet 6 in the second recess 8c. And the yield of the surface lighting device can be improved.
Reference numeral 7 denotes a diffusion sheet. The diffusion sheet 7 is disposed on the upper surface of the light emitting portion 4. When the light passes through the diffusion sheet 7, the diffusion sheet 7 has a function of converting the traveling direction of the transmitted light into various directions. The diffusion sheet 7 is often composed of a satin-treated PET sheet or the like, and may be provided as a separate member with respect to the light guide plate 2 or directly on the light guide plate 2 in advance by printing or a mold. It may be formed. When directly formed, the manufacturing process of the surface lighting device can be simplified, the number of parts can be reduced, the productivity of the surface lighting device can be improved, and the manufacturing cost of the surface lighting device can be reduced. This is a preferable configuration because the surface illumination device can be made thinner.
In the case of using another member, light can be guided to every corner of the light guide plate 2 by total reflection on the upper surface 2a of the light guide plate 2, and the deviation of the light amount can be reduced. Further, in the case where the light emitting unit 4 is constituted by another member, the diffusion sheet 7 and the light guide plate 2 may be joined in a predetermined positional relationship in advance. This is preferable because the assembly process of the surface illumination device can be simplified.
Reference numeral 8 denotes a holder. The holder 8 stores the light guide plate 2, the reflection sheet 6, and the diffusion sheet 7 at desired positions. As the material of the holder 8, various metal materials such as stainless steel, iron, and aluminum, and resin materials are conceivable, but it is particularly preferable to use a resin material that has good shape flexibility and mass productivity and also leads to weight reduction. . In particular, the type of resin is preferably ABS (acrylonitrile, butadiene, styrene), polycarbonate, or the like, and the color of the resin is to return light emitted from the light guide plate 2 to the inside of the light guide plate 2 from other than the light emitting portion 4 efficiently. A color having a high reflectance such as white is preferable, and in particular, using a material having a reflectance of 80% or more with respect to the wavelength of the light emitted from the light source 1 improves the light utilization efficiency and reduces the power consumption. Therefore, it is preferable because necessary luminance can be secured. In the present embodiment, the light from the light guide plate 2 is reflected by the inner surface of the holder 8, but a reflective surface may be separately formed on the inner surface by a metal material or dielectric material having a higher reflectance.
Further, since the holder 8 has a configuration for storing the light guide plate 2, the reflection sheet 6, and the diffusion sheet 7 at predetermined positions, this will be described.
The holder 8 is molded with a first recess 8a, a partition wall 8b, a second recess 8c, a rib portion 8d, a gap portion 8e, a partition wall 8g, a space 8i, and the like.
The first recessed portion 8a is a portion that houses the light guide plate 2, and the outer peripheral shape thereof is such that at least a part thereof is fitted to the outer periphery of the light guide plate 2, and positioning of the light guide plate 2 with respect to the holder 8 is performed. Is going. The height h of the side surface portion of the first concave portion 8a is higher than the thickness of the light guide plate 2, and the light leaking from the side surface of the light guide plate 2 is reflected by the side surface of the first concave portion 8a and again the light guide plate. Since the light utilization efficiency is improved and the luminance of the surface illumination device is improved, it is preferable.
The second concave portion 8c is a portion that houses the reflection sheet 6, and the second concave portion 8c is molded into a shape in which at least a part of the lower surface of the first concave portion 8a is further dug down. The height of the side surface portion of the second recess 8c is higher than the thickness of the reflection sheet 6 to be stored.
8b and 8g are partition walls, and the partition wall 8b is disposed in the thickness direction of the light guide plate 2 between the gap 8e and the first recess 8a, and most of the light from the light source 1 is directly directed to the light guide plate 2, particularly the light source 1. This prevents the light from entering the vicinity of the central portion of the light guide plate 2 adjacent to. By providing this partition wall 8b, it is possible to suppress the light from the light source 1 from directly entering the light guide plate 2, so that the luminance of the light emitting part (C part) close to the light source 1 is extremely bright compared to other parts. It can suppress becoming. Therefore, a surface illumination device with a flatter luminance distribution and high visibility can be realized. In addition, it is preferable that the partition wall 8b is molded integrally with the holder 8. This can improve the mass productivity, align the partition wall 8b with the light from the light source 1, and partition the partition wall 8b and the holder 8. Therefore, the productivity of the surface illumination device can be improved, and the yield can be improved. In this embodiment, the partition wall 8b is made of a shielding plate. However, the partitioning wall 8b may not be a plate having a complete shielding action, and a device having a large number of minute openings or slits can be used. .
The partition wall 8b is formed integrally with the holder 8 in consideration of mass productivity, but it is not always necessary to integrate it.
The partition wall 8g is provided substantially in parallel to the in-plane direction of the light guide plate 2 from the top of the partition wall 8b on the light emission surface 4 side to the top of the rib portion 8d adjacent to the light source 1 on the light emission portion 4 side. It has a function of reflecting light emitted from the light source 1 and emitted upward, and causing most of the light emitted upward to finally enter the light guide plate 2. In the present embodiment, the partition wall 8g is integrally formed with the holder 8 together with the partition wall 8b.
By providing the partition wall 8g, the light emitted above the light source 1 can be efficiently guided to the light guide plate 2, and the light emitted above the light source 1 directly goes out of the surface illumination device. It is possible to prevent light from leaking from a portion that is emitted and should not emit light.
Further, the width of the partition wall 8g is made substantially the same as the distance between the opposing incident surfaces 3a of the light guide portion 3 of the light guide plate 2, and the gap 10 between the partition wall 8g and the light guide plate 2 is almost eliminated. As a result, the amount of light leaking from here can be minimized.
In addition, the inner surface of the partition wall 8b and the partition wall 8g on the light source 1 side is configured as a flat surface in the present embodiment. However, if the shape is convex toward the light source 1, the light can be reflected in the diffusion direction. The light can be guided to the light guide plate 2 more efficiently.
The rib portion 8d reinforces the holder 8 and increases the mechanical strength of the holder 8. Furthermore, it has a function of reflecting at least a part of the light diffusing from the light source 1 on its side surface, and reflects a part of the light that is not directly guided from the light source 1 to the light guide unit 3, thereby guiding the light guide unit. 3 can be indirectly incident. With this configuration, the utilization efficiency of the light emitted from the light source 1 can be improved, so that a surface illumination device with less power consumption and sufficient luminance can be realized.
In addition, ribs can be used to prevent light from being scattered by dust or the like in the gap 8e through which light traveling from the light source 1 toward the incident surface 3a of the light guide 3 passes, and to reduce the amount of light guided to the light guide 3. It is preferable that the height of the portion 8d is substantially the same, and the top surface 8f is configured along a substrate (not shown) disposed thereunder. With such a configuration, the amount of dust entering the gap 8e can be reduced, so that the amount of light scattered by the dust and not incident on the light guide 3 can be reduced. It is preferable because the utilization efficiency of the can be improved.
Reference numeral 8i denotes a space for avoiding interference with a mounting component mounted on a substrate (not shown). Since this space is provided, the effective mounting area of the substrate can be increased.
By adopting a configuration in which the light guide plate 2 and the reflection sheet 6 are accommodated in the holder 8 in this way, the surface lighting device can be thinned, and the surface that can meet the user's request for thinning the device. It can be set as a lighting device.
Next, for the assembly procedure of the light guide plate 2, the reflection sheet 6 and the diffusion sheet 7 for the holder 8, various methods can be considered.
1. A method of incorporating the light guide plate 2, the reflection sheet 6 and the diffusion sheet 7 in the holder 8 in a state where the light guide plate 2 and the diffusion sheet 7 are bonded in a predetermined positional relationship in advance.
2. A method in which the reflection sheet 6 and the diffusion sheet 7 are formed in advance on the surface of the light guide plate 2 by a method such as printing or vapor deposition, and the light guide plate 2 is assembled in the holder 8.
3. The reflection sheet 6 accommodated in the second recess 8c is used as a separate member, and after the reflection sheet 6 is accommodated in the second recess of the holder 8, the light guide plate 2 on which the diffusion sheet 7 is bonded or formed in advance is used as the holder 8 How to incorporate
4). The light guide plate 2, the reflection sheet 6 and the diffusion sheet 7 are separate members, and the reflection sheet 6 is housed in the second recess 8 c of the holder 8, and then the light guide plate 2 is assembled in the first recess 8 a of the holder 8, Then, the method of joining the diffusion sheet 7 to the predetermined position of the light-guide plate 2 etc. can be considered. 1. According to this method, the assembly process of the light guide plate 2, the reflection sheet 6 and the diffusion sheet 7 and the assembly process of the surface lighting device can be performed in parallel in separate processes until the assembly to the holder 8. The assembly process of the lighting device can be simplified and productivity can be improved.
Also, 2. According to this method, the number of parts can be reduced efficiently, and the number of assembly steps and the number of lines can be reduced, so that the productivity of the surface lighting device can be further improved.
Furthermore, 3. According to this method, since the reflection sheet 6 can be reliably stored in the second recess 8c, it is possible to suppress the occurrence of defective products due to the positional deviation between the reflection sheet 6 and the second recess 8c. And the yield of the surface illumination device can be improved.
Next, the operation of the surface illumination device in the first embodiment will be described. Of the light emitted from the light source 1, the light that has reached the partition wall 8 b of the holder 8 is blocked by the partition wall 8 b and is not directly incident on the light guide 3 but is reflected by the partition wall 8 b. The light that has reached the partition wall 8g is blocked by the partition wall 8g and is not directly emitted to the outside of the surface illumination device, but is reflected by the partition wall 8g. A part of the light reflected by the partition walls 8b and 8g enters the light guide portion 3 of the light guide plate 2 from the incident surface 3a, and is further reflected by the reflection surface 3b, from the light emitting portion 4 of the light guide plate 2. The light is emitted directly or indirectly through the scattering portion 5 and the reflection sheet 6.
On the other hand, most of the light emitted from the light source 1 that does not hit the partition walls 8 b and 8 g enters the light guide plate 2 from the incident surface 3 a of the light guide unit 3. The incident light travels inside the light guide 3 and strikes the reflecting surface 3b. The light hitting the reflecting surface 3b is reflected toward the light emitting part 4 and the scattering part 5, and part of the light is emitted directly from the light emitting part 4, or part of the light is reflected by the scattering dots 5a of the scattering part 5. The part is irregularly reflected and emitted from the light emitting part 4, and part of the light is transmitted through the scattering part 5, reflected by the reflection sheet 6, returned to the light guide plate 2, and emitted from the light emitting part 4.
Thereafter, the light emitted from the light emitting portion 4 passes through the diffusion sheet 7. At that time, the traveling direction is converted into various directions. Without the diffusion sheet 7, there is a disadvantage that the pattern of the scattering dots 5 a is clearly recognized by the human eye, but by disposing the diffusion sheet 7, the pattern of the scattering dots 5 a is recognized to a level where there is no problem. become unable.
As described above, by providing the partition wall 8b and changing the distribution of light from the light source 1, it is possible to prevent the luminance of the C portion in the vicinity of the light source 1 of the light emitting unit 4 from being extremely increased, and the luminance is uniform. Can be achieved.
Next, even when the number of light sources such as light-emitting diodes is one and the length of the light guide 3 is short, the luminance distribution is good and a high-visibility, that is, a small surface illumination device with little misidentification is realized. In order to do this, a plurality of samples of the surface illumination device with various conditions changed were manufactured, and the visibility of each sample was actually investigated.
As a result, the surface illumination device using one light source has a light emission area of 500 (mm) per light source.2If the ratio of the maximum luminance part to the minimum luminance part of the light emitting part is 0.3 or more when the distance from the light source 1 to the light emitting part 4 is 8 (mm) or less, there is almost no unevenness. It could be seen that the surface lighting device was clean and easy to see, and if it was 0.4 or more, it was possible to obtain a clean and easy to see surface lighting device with almost no unevenness. Therefore, in the surface illumination device, by setting the ratio of the maximum luminance portion and the minimum luminance portion of the light emitting portion to 0.3 or more, preferably 0.4 or more, a dark portion and a bright portion that are clearly visible to the human being in the surface illumination device. Therefore, a surface illumination device that is highly efficient and has no problem in visibility when the liquid crystal is placed thereon can be obtained.
Next, in the same manner, regarding the relationship between the average luminance of the light emitting unit 4 and the visibility, the surface illumination device uses one light source, and the light emitting area per light source is 500 (mm).2) In the above, and in the case where the distance from the light source 1 to the light emitting portion 4 is 8 (mm) or less, the examination was performed by changing the average luminance of the light emitting portion 4.
As a result, the average luminance of the light emitting portion 4 is 1 (cd / m2), It feels very dark, whereas 1 (cd / m2) Above, the display content can be recognized sufficiently in a dark place, and 3 (cd / m2) Above, you can feel the brightness is easy to see. Conversely, the average luminance of the light emitting portion 4 is 200 (cd / m2) Is too bright and difficult to see. Therefore, the average luminance of the light emitting portion 4 is 1 (cd / m2) 200 (cd / m)2) By using the following range, a surface lighting device that is not too bright or dark when viewed by humans, is easy on the eyes, is highly efficient, and has no problem with visibility when the liquid crystal is placed on top. Obtainable.
Next, the relationship between the ratio of the change in the luminance of light in the surface illumination device and the ratio recognized as luminance unevenness when viewed by a person was examined.
A surface illumination device using one light source, and the light emission area per light source is 500 (mm)2) In the above, and in the case where the distance from the light source 1 to the light emitting portion 4 is 8 (mm) or less, the rate of change in luminance was changed, and the extent to which luminance unevenness was recognized was examined.
As a result, the change value of the luminance of the light emitting unit 4 per unit length is (average luminance) × 100 (cd / mThree) If it is below, it can be recognized that the surface illumination device is not very uneven, and (average luminance) × 80 (cd / m)Three) If it is below, it can be recognized that it is a clean and easy to see surface illumination device with almost no unevenness. Therefore, in the surface illumination device, the change value of the luminance of the light emitting unit 4 per unit length is (average luminance) × 100 (cd / mThree) Or less, preferably (average luminance) × 80 (cd / mThree) By making the following, the surface lighting device is not formed with clear dark and bright parts to the human eye, so that it is possible to obtain a surface lighting device with high efficiency and inconspicuous brightness unevenness, and clean. It is possible to provide an easy-to-see surface illumination device.
Next, the relationship between the half-value width of the light emission wavelength of the light source in the surface illumination device and the sharpness of the screen was examined.
A surface illumination device using a light source as a light source, and a light emission area per light source is 500 mm2) As described above, and the distance from the light source 1 to the light emitting portion 4 is 8 (mm) or less, when the half-value width of the light emission wavelength of the light source 1 is 50 (nm) or more, the screen is not much. In contrast to a surface illumination device that does not look clear and looks totally blurred, if the half-value width of the light emission wavelength of the light source 1 is 50 (nm) or less, the screen can be recognized as being quite clear, and the light source If the half-value width of the emission wavelength is 40 (nm) or less, it can be recognized that the surface illumination device has a clear screen and beautiful color development. Therefore, in the surface illumination device, by setting the half-value width of the light emission wavelength of the light source 1 to 50 (nm) or less, preferably 40 (nm) or less, it is possible to provide a surface illumination device with a clear screen to human eyes. Therefore, when used in an electronic device such as a portable terminal device equipped with this, the outline of the character is clear and can be surely grasped without making a mistake in information.
Next, when the light source 1 was a light emitting diode in the surface illumination device, the light emission efficiency of the light intensity of the light emitting diode on the axis was examined.
A surface illumination device using one light source, and the light emission area per light source is 500 (mm)2) As a result of examining the light emission efficiency and the visibility of the screen when the distance from the light source 1 to the light emitting portion 4 is 8 (mm) or less, the light emission efficiency of the on-axis luminous intensity of the light emitting diode is If it is 1.0 (cd / A) or more, the average luminance is 1 (cd / m).2) The above can be realized, which can greatly contribute to power saving of portable information devices.
Furthermore, by combining a plurality of these five factors into a surface lighting device that satisfies them, it is possible to provide a surface lighting device that is small, has low power consumption, is easier to see, and is beautiful to the eyes.
In addition, when a plurality of light sources are provided, it is configured to satisfy these five factors for any of them, and even when any of the light sources emits light, it is small and has low power consumption. It is possible to provide a surface illumination device that is easier to see and more beautiful for the eyes.
An embodiment of the present invention will be described with reference to FIGS. 6 is a perspective view of the holder of the surface illumination device according to the embodiment of the present invention, and FIG. 7 is a cross-sectional view of the vicinity of the partition wall 8g of the surface illumination device according to the embodiment of the present invention, which is indicated by a dotted line in FIG. A section E of the part is shown. In FIG. 7, 8 h is a reflecting surface, and the reflecting surface 8 h is an inner surface of the partition wall 8 g on the light source 1 side, which is formed of a substantially V-shaped wall, and most of the light emitted upward from the light source 1 proceeds. It has a function of converting the direction into the direction of the reflecting surface 3 b of the light guide plate 2. Since most of the light emitted from the light source 1 can be guided to the light guide plate 2 by the reflecting surface 8h, the light use efficiency can be improved. Further, compared with the case where the light from the light source 1 is directly introduced into the light guide plate 2, the light can be made sufficiently incident before entering the light emitting portion 4 of the light guide plate 2. The light distribution can be made more uniform, and the luminance unevenness of the light emitted from the light emitting unit 4 can be minimized.
When the intensity distribution of the light source 1 is symmetric, the vertex or the top line of the substantially V-shaped wall of the reflecting surface 8h is disposed so as to be on the extension line of the axis of the light source 1. Since the amount of light reflected by the reflecting surface 8h can be made substantially equal on the left and right, a surface illumination device with a small luminance distribution at the light emitting section 4 and easy to see can be realized.
In particular, when a plurality of light emitting elements 20a, 20b, and 20c are provided in a straight line as in the light source 20 shown in FIG. 18, a straight line that approximates the light emission centers of the respective light emitting elements 20a, 20b, and 20c or an approximation thereof. By making the angle between the straight line (hereinafter abbreviated as the light source center line) and the top line of the substantially V-shaped wall of the reflecting surface 8h ± 10 degrees or less, preferably approximately 0 degrees, It can be suppressed that the balance of the wavelength of the light reflected by the reflecting surface 8h and guided to the reflecting surface 3b is broken left and right (or up and down) and the luminance distribution is deteriorated due to the difference in the light emitting position. In addition, when two or more light emitting elements are caused to emit light at the same time, it is possible to suppress the occurrence of uneven color that is slightly different in color in the vertical and horizontal directions when viewing the liquid crystal.
Further, the axial lengths from the light emitting elements 20a, 20b, and 20c included in the light source 20 to the reflecting surface 8h are made substantially equal to each other, thereby causing the light guide plate 2 to move to the light guide plate 2 due to a deviation in the reflecting direction on the reflecting surface 8h. The inconvenience that the amount of incident light is different for each light emitting element can be suppressed, and the light distribution can be made more uniform, so that it is possible to realize a surface illumination device with low luminance unevenness and color unevenness and high visibility. .
Note that this is not the case in the case of a display device (for example, a rainbow-colored display device) that positively uses such a shift in the wavelength balance of light.
Further, when the intensity distribution of the light source 1 is asymmetric, it is reflected by the reflecting surface 8h by changing the area of the surface forming the V-shaped wall forming the reflecting surface 8h according to the asymmetry. Therefore, it is possible to realize an easy-to-see surface illumination device with a small luminance distribution at the light emitting portion. Furthermore, it is possible to intentionally vary the area of the surface constituting the reflecting surface 8 h so that the amount of light varies between the light emitting surfaces 4 of the light guide plate 2.
In addition, the incident surface 3 a is provided to be inclined toward the light source 1 and the reflecting surface 8 h, so that light that is directly incident on the light guide unit 3 of the light guide plate 2 among the light emitted from the light source 1. In addition, both of the light incident through the reflecting surface 8h can be efficiently incident on the light guide plate 2.
Further, the V-shaped angle of the reflecting surface 8h is determined in consideration of the distance from the light source 1 to the reflecting surface 8h, the distance from the reflecting surface 8h to the incident surface 3a of the light guide unit 3, the thickness of the light guide plate 2, and the like. However, it is preferable because the light utilization efficiency can be further improved. The other components are substantially the same as those in the first embodiment.
In the present embodiment, the substantially V-shaped reflecting surface 8h is formed on the partition wall 8g. However, a similar substantially V-shaped reflecting surface may be formed on the inner surface of the partition wall 8b on the light source 1 side. As a result, the amount of light incident on the light guide plate 2 can be further increased. The cross-sectional shape of the reflecting surface 8h may be U-shaped or other shapes, and is preferably optimized so that more light can be incident on the incident surface 3a.
Next, the operation of the surface illumination device will be described. Light emitted from the light source 1 in the direction of the partition wall 8g (Z direction in FIGS. 1 and 2) hardly enters the light guide unit 3 and most of the light reaches the reflecting surface 8h. Most of the light whose traveling direction is converted to a direction different from the Z direction (represented by the Y direction in the drawing) by the reflecting surface 8h is incident on the incident surface 3a of the light guide unit 3. On the other hand, light emitted from the light source 1 to the side enters the light guide plate 2 directly from the incident surface 3 a of the light guide 3. The light incident on the light guide plate 2 in this way is reflected by the reflecting surface 3b in the direction represented by the X direction in the figure, and then emitted from the light emitting unit 4. In this way, a reflection surface 8h formed of a substantially V-shaped wall is provided, and the light emitted in the Z direction is reflected and spread in the Y direction and then travels in the X direction, that is, on the XZ plane. By adopting a configuration in which light is once spread in a direction not included (Y direction) and then traveled in the X direction, the light source 1 that has been used almost indirectly in the first embodiment (above the partition 8g direction) is used. Since the light emitted to the light can be efficiently guided to the light guide section 3, the light use efficiency can be greatly improved, and a high-efficiency surface illumination device with low power consumption can be realized. At the same time, since the distribution of light incident on the light emitting portion 4 of the light guide plate 2 can be made more uniform, it is possible to realize a surface illumination device with small luminance unevenness and high visibility. Here, the axis of light emitted from the light source 1 or the light source 20 often travels substantially along the XYZ axes.
The reflection surface 8h may be configured as shown in FIG. FIG. 8 shows a cross-sectional view of the vicinity of the partition wall 8g of the surface illumination device according to one embodiment of the present invention. The reflecting surface 8h shown in FIG. 7 has a substantially V-shaped wall formed in a planar shape, but in FIG. 8, the surface of the reflecting surface 8h formed of a substantially V-shaped wall is recessed. It has a configuration that can be used. Due to the recess in the surface, the reflecting surface 8h can not only reflect the diffused light from the light source 1 that hits this surface, but also can reduce the diffusion angle. Therefore, it has the function of changing the traveling direction while collecting incident light. Thus, by making the shape of the V-shaped wall of the reflecting surface 8h concave, the light source 3 emits light emitted from the light source 1 more efficiently than the surface illumination device shown in the second embodiment. Therefore, the surface illumination device can be further improved in efficiency.
Further, the reflection surface 8h may be configured as shown in FIG. FIG. 9 shows a cross-sectional view of the vicinity of the partition wall of the surface illumination device according to one embodiment of the present invention. The apex or top line portion of the reflecting surface 8h shown in FIGS. 7 and 8 has a very acute angle, and it is very likely to break if it touches something. Doing so may cause injury. Further, since the luminance is extremely high immediately above the light source 1 with respect to the peripheral portion, if the relative positional relationship between the light source 1 and the reflecting surface 8h is shifted due to manufacturing variations of the surface lighting device, the difference in the amount of light hitting the two reflecting surfaces 8h May increase and uneven luminance may occur on the light emitting surface 4. On the other hand, in the reflection surface 8h shown in FIG. 9, the shape of the apex (or top line) of the V-shaped wall is a shape that is not a sharp edge or a rounded shape. As a result, the light directly above the light source 1 with extremely high luminance can be prevented from directly hitting the inclined portion of the reflecting surface 8h, so that the light emitting portion 4 can be obtained without significantly reducing the light utilization efficiency as a whole. The luminance unevenness in can be minimized.
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a plan view of the surface illumination device according to the third embodiment. As shown in FIG. 10, in the present embodiment, the shape of the reflecting surface 3b is a concave curved surface, and the shape of the fitting portion 8j of the holder 8 is a convex curved surface in accordance with this. In such a configuration, light emitted from the light source 1 is incident on the inside of the light guide plate 2 directly or indirectly from the incident surface 3a of the light guide unit 3 through the partition wall 8b, the reflecting surface 8h, or the like. The incident light travels through the light guide 3 and hits the reflecting surface 3b. The light hitting the reflection surface 3b is diffused in the in-plane direction of the light guide 3 because the shape of the reflection surface 3b is a concave curved surface, and is reflected and diffused by the inner side surface of the holder 8, etc. Proceed toward 5. Since the concave curved surface of the reflecting surface 3b diffuses light in this way, the luminance of the light emitting portion 4 can be made uniform. At this time, it is preferable that the curvature of the reflecting surface 3b is changed in accordance with the intensity distribution of the light emitted from the light source 1 and incident on the reflecting surface 3b. That is, in the portion where the intensity is high, the curvature of the recess is reduced to diffuse light more, and in the portion where the intensity is low, the curvature of the recess is increased so that light diffusion does not occur so much. However, this is a preferable configuration since the luminance of the light emitting portion 4 can be made uniform.
20 is a front view of a surface illumination device according to an embodiment of the present invention, FIG. 21 is a cross-sectional view of the surface illumination device according to an embodiment of the present invention, and shows a cross section taken along a diagonal line ab in FIG. FIG. 22 is a front view of a light guide plate in an embodiment of the present invention.
In the figure, 41 is a light source, 42 is a light guide plate, and the light guide plate 42 is composed of a light guide portion 43 and a light emitting portion 44. As the light source 41, the light source 1 or the light source 20 described in the first to third embodiments can be used.
In FIG. 22, a straight line indicated by a dotted line indicates an outline of the boundary between the light guide portion 43 and the light emitting portion 44, and m, q, p, and l indicate predetermined corner portions of the light guide plate 42, respectively. ing. The light guide 43 has an incident surface 43 a for introducing the light of the light source 41 into the light guide 43 and a reflection surface 43 b for reflecting the light introduced from the incident surface 43 a toward the light emitting portion 44. The light guide portion 43 is formed so as to spread in a V shape from the end portions q and m of the light guide plate 42 toward the opposite corner portions p and l. The light emitting portion 44 is a portion where light incident on the light guide plate 42 is emitted from the light guide plate 42 on the upper surface of the light guide plate 42.
Reference numeral 45 denotes a scattering portion. The scattering portion 45 is formed on the lower surface of the light guide plate 42 and has a function of reflecting or transmitting incident light to this portion in various directions. Reference numeral 45a denotes scattering dots formed so that the area ratio increases as the distance from the light source 41 increases. In this embodiment, the scattering dots 45a are formed of milky white to white ink by screen printing.
Reference numeral 46 denotes a reflection sheet, and the reflection sheet 46 is a member having a high reflectance placed on the lower surface of the scattering portion 45, and a part of the light transmitted through the scattering portion 45 and exiting from the light guide plate 42 is again transmitted to the light guide plate. 42 to return to the inside.
Reference numeral 47 denotes a diffusion sheet. The diffusion sheet 47 is disposed on the upper surface of the light emitting portion 44. When light passes through the diffusion sheet 47, the diffusion sheet 47 functions to change the traveling direction of the transmitted light into various directions. The diffusion sheet 47 was made of a satin-treated PET sheet.
Reference numeral 48 denotes a holder, and the holder 48 accommodates the light guide plate 42, the reflection sheet 46, and the diffusion sheet 47 at desired positions. As a material for the holder 48, white ABS (acrylonitrile, butadiene, styrene) resin having high reflectivity was used.
The operation of the surface illumination device in the present embodiment configured as described above will be described. First, the light from the light source 41 enters from the incident surface of the light introducing portion 43 and is reflected by the reflecting surface 43b, and most of the light has an angle component that satisfies the total reflection condition that occurs at the interface between the resin and air. The light guide plate 42 is guided in the in-plane direction. A part of the light incident on the light guide plate 42 is reflected by the light guide unit 43 and guided toward the light emitting unit 44 of the light guide plate 42, and a part of the light is directly guided to the light emitting unit 44. In the light emitting portion 44, the light introduced from the light guide portion 43 is efficiently confined by total reflection, but the light hitting the scattering dots 45a on the lower surface is reflected or transmitted in various directions, and is totally reflected. Only light with a critical angle or less exits the light guide plate 42. Of these, the light that reaches the light emitting portion 44 is emitted, but the light that hits the reflection sheet 49 and the holder 48 is reflected and returns to the inside of the light guide plate 2 again. In this way, most of the light guided into the light guide plate 42 is emitted from the light emitting portion 44 except for light absorbed on the way, and surface illumination is performed.
In the configuration in which the light source 41 is provided at the corner portion of the light guide plate 42 as described above, only the portion having a large intensity distribution among the light from the light source 41 can be guided to the light guide plate 42. Therefore, FIG. Such a dark portion is unlikely to occur, the light emission characteristics can be made uniform, the distance from the light source 41 to the light emitting portion 44 can be shortened, and the surface illumination device can be further miniaturized.
Next, the arrangement of the light source 41 with respect to the light guide plate 42 when the light source 20 having the plurality of light emitting elements 20a, 20b, and 20c described in Embodiment 1 is used as the light source 41 will be described with reference to the drawings. FIG. 24 is a conceptual diagram showing the arrangement of a light source having a plurality of light emitting elements and a light guide plate in one embodiment of the present invention, and FIG. 25 is a sectional view of the vicinity of the light source in one embodiment of the present invention. The ab cross section in is shown.
In the figure, the light source center line of the light emitting elements 41a, 41b, 41c is preferably approximately 90 so that the angle formed by the light source plate 41 with respect to the diagonal line ab (longest hand direction viewed from the light source) approaches 90 degrees. The light source 41 is arranged so as to have a degree. With such a configuration, the lengths of the axes from the light emitting elements 41a, 41b, and 41c to the incident surface 43a or the reflecting surface 43b of the light guide plate 42 can be made substantially equal, and thus the respective light emitting elements 41a and 41b. , 41c can be uniformized.
In particular, by providing the light source center line so as to be orthogonal to the diagonal direction of the light guide plate 42, luminance unevenness can be most effectively suppressed. When the light emitting surface of the surface illumination device is rectangular, for example, and has a longitudinal direction and a short direction, the angle formed by the light source center line of the light source 41 and the longitudinal direction should be larger than the angle formed by the short direction. Thus, the above effect can be obtained. When the light emitting surface 44 is formed in a shape in which it is difficult to define a diagonal line, a longitudinal direction, or a short direction, the point of the light emitting surface 44 farthest from the light source 41 and the light emitting point (or light emitting center) of the light source 41 are used. The light source 41 is arranged so that the straight line connecting the light source 41 and the light source center line of the light source 41 are substantially orthogonal, or the light emission surface 44 is substantially equally divided by the straight line substantially orthogonal to the light source center line. The above-described effect can be obtained by arranging 41.
In the present embodiment, the light source center line direction and the diagonal direction are substantially orthogonal so that the lengths of the axes from the light emitting elements 41a, 41b, 41c included in the light source 41 to the reflecting surface 43b of the light guide member 42 are equal. However, the height of 41a, 41b, 41c is changed (for example, a step may be provided like a terraced field, the installation surface of the light emitting element may be inclined, or the light emitting element itself) The angles of incidence or axes of light emitted from the light emitting elements 41a, 41b, 41c on the reflecting surface 43b may be equalized. According to this configuration, restrictions on the arrangement relationship between the light source 41 and the light guide member 42 are reduced, and the degree of freedom in design is improved.
Next, as an example in which the surface illumination device described in any of Embodiments 1 to 4 is used in an electronic device, a mobile terminal device that is particularly frequently used will be described as an example.
13 and 14 are a perspective view and a block diagram, respectively, showing a portable terminal device according to an embodiment of the present invention. 13 and 14, reference numeral 29 denotes a microphone that converts sound into a sound signal, 30 denotes a speaker that converts sound signals into sound, 31 denotes an operation unit including dial buttons and the like, 32 denotes a display unit, and 32 denotes a display unit 32. Displays a character such as a telephone number or the name of the other party according to incoming call information, outgoing call information, search information, etc., and is composed of a liquid crystal display device, below which is the surface illumination device shown in the first to fourth embodiments. It is installed. Reference numeral 33 denotes an antenna, and 34 denotes a transmission unit that demodulates a voice signal from the microphone 29 and converts it into a transmission signal. The transmission signal produced by the transmission unit 34 is emitted to the outside through the antenna. Reference numeral 35 denotes a receiving unit that converts a received signal received by the antenna into an audio signal. The audio signal created by the receiving unit 35 is converted into audio by the speaker 30. A control unit 36 controls the transmission unit 34, the reception unit 35, the operation unit 31, and the display unit 32.
An example of the operation will be described below.
First, when there is an incoming call, an incoming signal is sent from the receiving unit 35 to the control unit 36, and the control unit 36 causes the display unit 32 to emit a predetermined light while causing the surface illumination device 13 to emit light based on the incoming signal. When a character or the like is displayed and a button for receiving an incoming call from the operation unit 31 is pressed, a signal is sent to the control unit 36, and the control unit 36 sets each unit to the incoming mode. That is, the signal received by the antenna 33 is converted into an audio signal by the receiving unit 35, and the audio signal is output as audio from the speaker 30, and the audio input from the microphone 29 is converted into an audio signal and transmitted by the transmitting unit 34. Through the antenna 33 and sent to the outside.
Next, the case of making a call will be described.
First, when making a call, a signal indicating that the call is sent from the operation unit 31 is input to the control unit 36. Subsequently, when a signal corresponding to the telephone number is sent from the operation unit 31 to the control unit 36, the control unit 36 sends a signal corresponding to the telephone number from the antenna 33 via the transmission unit 34. The signal input at this time is often displayed on the display unit 32 while causing the surface illumination device 13 to emit light. When communication with the other party is established by the transmission signal, when a signal to that effect is sent to the control unit 36 through the reception unit 35 via the antenna 33, the control unit 36 sets each unit to the transmission mode. That is, the signal received by the antenna 33 is converted into an audio signal by the receiving unit 35, and the audio signal is output as audio from the speaker 30, and the audio input from the microphone 29 is converted into an audio signal and transmitted by the transmitting unit 34. Through the antenna 33 and sent to the outside.
In the present embodiment, an example in which voice is transmitted and received has been described. However, the same effect is obtained not only for voice but also for an electronic device that transmits and / or receives data other than voice, such as character data. be able to.
Next, the configuration in the vicinity of the display unit 32 will be described in detail with reference to FIG. FIG. 15 is a partial cross-sectional view of the mobile terminal device according to the embodiment of the present invention, and shows a cross section taken along the line AA in FIG. In the figure, 11 is a casing which is an exterior material of the mobile terminal device, 12 is a liquid crystal display element for displaying some information of the mobile terminal device, and 13 is any surface described in the first to fourth embodiments. An illumination device 14 indicates a substrate on which the surface illumination device 13 is mounted and an electronic circuit or the like is mounted. By using this surface illumination device 13, the luminance unevenness can be reduced in the display unit of the mobile terminal device, so that it is possible to realize a mobile terminal device with high visibility and therefore less misidentification. Moreover, since only one light source is used, a portable terminal device with extremely low power consumption can be realized.
If the light source 20 on which a plurality of light emitting elements having different emission wavelengths are mounted as described in other embodiments is used as the light source of the surface illumination device 13, the following can be achieved.
1. The emission color of the surface illumination device is changed according to the preference of the mobile terminal user.
2. Separately, a time detection means is provided, and the wavelength to be emitted is switched according to the illumination time. For example, when the surroundings are bright, the peak of human visibility is near 555 nm, and when the surroundings are dark, the peak of human visibility shifts to the short wavelength side. When a green light-emitting element is made to emit light and a blue light-emitting element is made to emit light in the nighttime when the surroundings are dark, a surface illumination device that is bright and easy to see at any time can be realized. Furthermore, by incorporating a calendar or the like and changing the time for switching according to the season, the light source of the surface illumination device can be switched at the optimal time of the year. Further, a configuration may be adopted in which means for detecting external brightness is provided and the color of the light source is changed according to the output.
3. When the incoming call is received, the light emission color of the surface illumination device 13 is changed for each caller in accordance with the telephone directory stored in advance in the information system terminal.
As is clear from the above description, the surface illumination device of the present invention isOne light source and the light emitted from the light sourceAn incident surface for incident light, a light guide portion for guiding light incident from the incident surface, and a light emitting portion for emitting light propagated through the light guide portionWith a light guide memberThe light guide member has a pair of outer peripheral surfaces and the incident surface is disposed between the pair of outer peripheral surfaces, and the distance between the pair of outer peripheral surfaces is closer to the incident surface side,Provided with a partition that prevents light emitted from the light source from directly entering the light guide memberThis configuration eliminates the formation of dark areas and bright areas that are clearly visible to humans in the surface lighting device, so it is highly efficient and has no problem with visibility when the liquid crystal is placed on top. A surface illumination device that is not too bright and not too dark when viewed can be obtained. Further, since the occurrence of color unevenness is eliminated, a clean and highly visible surface illumination device can be obtained.
MaTaichiOne surface light source that sometimes emits light, and one of a plurality of light sources that emit light according to the situation can be selected.AndAs a result, even if any light source is turned on, a clear dark part and bright part are not formed on the surface illumination device to human eyes, so it is highly efficient and visually recognized when the liquid crystal is placed on top. It is possible to obtain a surface illumination device that has no problem in terms of quality and that is not too bright or too dark when viewed by a person and that is clean and easy to see. Further, since the occurrence of color unevenness is almost eliminated, it is possible to obtain a clean and highly visible surface illumination device.
Furthermore, display means, conversion means for converting at least one of a data signal or an audio signal into a transmission signal or converting a reception signal into at least one of a data signal or an audio signal, and an antenna for transmitting and receiving the transmission signal and the reception signal In addition, since the above-described surface illumination device is used below the display unit, the luminance unevenness can be reduced in the display unit of the portable terminal device. Therefore, it is possible to realize a mobile terminal device with high visibility and therefore less misunderstanding. Moreover, since only one light source is used, a portable terminal device with extremely low power consumption can be realized.
FIG. 1 is a plan view of a surface illumination device according to an embodiment of the present invention.
FIG. 2 is a side view of a surface illumination device according to an embodiment of the present invention.
FIG. 3 is a perspective view of a light guide plate in an embodiment of the present invention.
FIG. 4 is a perspective view of a holder according to an embodiment of the present invention.
FIG. 5 is a cross-sectional view of the vicinity of the partition wall of the surface illumination device according to the embodiment of the present invention.
FIG. 6 is a perspective view of a holder of a surface illumination device according to an embodiment of the present invention.
FIG. 7 is a cross-sectional view of the vicinity of the partition wall of the surface illumination device according to the embodiment of the present invention.
FIG. 8 is a cross-sectional view of the vicinity of the partition wall of the surface illumination device according to the embodiment of the present invention.
FIG. 9 is a cross-sectional view of the vicinity of the partition wall of the surface illumination device according to the embodiment of the present invention.
FIG. 10 is a plan view of a surface illumination device according to an embodiment of the present invention.
FIG. 11 is a plan view of a conventional surface illumination device.
FIG. 12 is a side view of a conventional surface illumination device.
FIG. 13 is a perspective view showing a portable terminal device according to an embodiment of the present invention.
FIG. 14 is a block diagram showing a mobile terminal device according to an embodiment of the present invention.
FIG. 15 is a partial cross-sectional view of a mobile terminal device according to an embodiment of the present invention.
FIG. 16 is a perspective view of a light source of the surface illumination device in one embodiment of the present invention.
FIG. 17 is a light emission intensity distribution diagram of a light source of a surface illumination device according to an embodiment of the present invention.
FIG. 18 is a perspective view of a light source according to an embodiment of the present invention.
FIG. 19 is a CIExy chromaticity diagram according to one embodiment of the present invention.
FIG. 20 is a front view of a surface illumination device according to an embodiment of the present invention.
FIG. 21 is a cross-sectional view of a surface illumination device according to an embodiment of the present invention.
FIG. 22 is a front view of a light guide plate according to an embodiment of the present invention.
FIG. 23 is a conceptual diagram showing an arrangement of a light source having a plurality of light emitting elements and a light guide unit in an embodiment of the present invention.
FIG. 24 is a conceptual diagram showing the arrangement of a light source and a light guide plate having a plurality of light emitting elements in an embodiment of the invention.
FIG. 25 is a sectional view of the vicinity of a light source in one embodiment of the present invention.
2 Light guide plate
3 Light guide
3a Incident surface
3b Reflective surface
4 Light emission part
5 Scattering part
5a Scattered dots
6 Reflective sheet
7 Diffusion sheet
8 Holder
8a First recess
8b Bulkhead
8c Second recess
8d rib
8e gap
8f top surface
8g Bulkhead
8h reflective surface
8i space
8j Fitting part
12 Liquid crystal display elements
13 surface lighting device
14 Substrate
20 Light source
20a, 20b, 20c Light emitting element
20d board
20e Translucent member
30 Speaker
31 Operation unit
32 Display section
33 Antenna
34 Transmitter
35 Receiver
36 Control unit
41 Light source
42 Light guide plate
43 Light guide
43a Incident surface
43b Reflective surface
44 Light emission part
45 Scattering part
45a scattering dots
46 Reflective sheet
47 Diffusion sheet
48 holder
One light source, an incident surface on which light emitted from the light source is incident, a light guide unit that guides light incident from the incident surface, and a light emission unit that emits light propagated through the light guide unit The light guide member has a pair of outer peripheral surfaces, the incident surface is disposed between the pair of outer peripheral surfaces, and the interval between the pair of outer peripheral surfaces is on the incident surface side. A surface illumination device comprising a partition wall that becomes narrower as it is closer and prevents light emitted from a light source from directly entering a light guide member.
Surface lighting device according to claim 1, wherein the light source-side surface of the partition wall and having a reflecting action.
3. The surface illumination device according to claim 2, wherein a part of the light reflected by the partition wall is reflected by the outer peripheral surface of the light guide part and enters the light emitting part.
Comprising a housing member for housing the light guide member, the partition wall in the housing member surface lighting device according to claim 1, characterized by being integrally molded.
Surface lighting device according to claim 1, characterized in that a reflecting member for reflecting the light emitted from the light source to the outer circumferential surface direction of the light guide.
6. The surface illumination device according to claim 5 , further comprising a storage member for storing the light guide member, wherein a partition wall and a reflection member are integrally formed on the storage member.
Light emitting portion opposite to the surface illumination device that scattering portion is formed on the lower surface of claim 1, wherein 6 or 1, wherein the light guide member.
Surface lighting device that claims 1 to 7 or 1, wherein the scattering member on the light emitting portion is provided in the light guide member.
Surface lighting device according to claim 1 to 8 or 1, wherein the reflector plate is provided below the scattering member.
The surface illumination device according to any one of claims 1 to 9, wherein a half width of an emission wavelength of the light source is 50 (nm) or less.
A surface lighting device using a light emitting diode as a light source, said light emitting diodes, one of claims 1-10 in which the light emitted from the light emitting element and the light emitting element is characterized in that a cylindrical lens incident The surface illumination device according to claim 1.
Display means; conversion means for converting at least one of a data signal or an audio signal into a transmission signal or converting a reception signal into at least one of a data signal or an audio signal; an antenna for transmitting and receiving the transmission signal and the reception signal; a portable terminal apparatus having a control means for controlling each section, a portable terminal device characterized by using the surface lighting device as claimed in any one claims 1 to 11 under the display unit.
JP28651999A 1999-03-12 1999-10-07 Surface illumination device and portable terminal device using the same Expired - Fee Related JP3746173B2 (en)
JP11-66415 1999-03-12
JP6641599 1999-03-12
JP28651999A JP3746173B2 (en) 1999-03-12 1999-10-07 Surface illumination device and portable terminal device using the same
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JP2000331523A JP2000331523A (en) 2000-11-30
JP3746173B2 true JP3746173B2 (en) 2006-02-15
ID=26407618
JP28651999A Expired - Fee Related JP3746173B2 (en) 1999-03-12 1999-10-07 Surface illumination device and portable terminal device using the same
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