TW201706685A - Switchable lighting device and use thereof - Google Patents

Abstract

The invention relates to a lighting device (1) which can be operated in at least two operating modes (B1) for a free viewing mode and (B2) for a restricted viewing mode. It comprises a backlighting system (2) extended in a planar fashion, which emits light into a restricted angular range in the operating mode (B2); a plate-shaped optical element (3) located in front of the backlighting system (2) in the viewing direction; and illuminants (4) arranged laterally on the optical element (3). The optical element (3) is embodied as an optical waveguide consisting of a matrix plastic A and scattering particles composed of a polymer B distributed homogeneously therein. The optical waveguide is at least 80% transparent to the light emerging from the backlighting system (2). The light incident laterally in the optical element (3) from the illuminants (4) is emitted for a free field of view, wherein in the operating mode (B2) the backlighting system (2) is switched on and the illuminants (4) are switched off, and wherein in the operating mode (B1) the illuminants (4) are switched on and the backlighting system (2) is switched off. In interaction with a transmissive imaging system (5) in front of the lighting device (1), a screen can thus be designed for optional free or restricted viewing.

Description

Switchable lighting device and its use

In recent years, great progress has been made in increasing the viewing angle on LCDs. However, there are often situations where the great field of view of the screen is more harmful. Increasingly, information such as bank data or other personal information and sensitive information is stored on mobile devices such as laptops and tablets. Accordingly, one needs to control who has the right to view such sensitive material and can choose another perspective to share the information on the display with others, for example, while viewing a travel photo or for advertising purposes. In addition, a smaller viewing angle is required when it is intended to perform confidential processing on the screen information.

Additional films based on microflakes have been applied to mobile displays for visual data protection. However, these films cannot be switched and must always be applied by hand and removed. In addition, when such films are not required, they must be transported separately from the display. Another major disadvantage of using such a foil film is that it causes light loss.

US 6,765,550 describes such an anti-spying effect achieved by microflakes. The main disadvantages of this case are the mechanical removal and mechanical installation of the privacy film, as well as the loss of light in the protection mode.

No. 5,993,940 describes the use of a film having a evenly arranged stringer on its surface in order to achieve an anti-spy mode. Its R&D and manufacturing costs are high.

WO 2012/033583 is based on the so-called "color ketone" The liquid crystal between the layers of (chromonisch/chromonics) is controlled to switch between free viewing and limited viewing. The case will result in higher light loss and cost.

US 2009/0067156 discloses various concepts for designing lighting systems and screen devices. The scheme shown in Figures 3A and 3B of the present invention uses two backlight members (so-called "backlights") composed of wedge-shaped light guides and an LCD panel, wherein the backlight 3 is forced to be larger. The illumination angle of the front backlight 38 forces a smaller illumination angle. However, the case does not indicate how the backlight 38 produces a smaller illumination angle without substantially causing light from the backlight 40 having a greater illumination angle to be substantially converted to have when passing through the backlight 38. Light with a small illumination angle.

In the design shown in Figure 5 of US 2009/0067156, both of the light guides 46 and 48 produce "narrow light", i.e., light having a smaller illumination angle. The light of the light guide body 48 is converted into "wide light" by means of a split mirror 50 provided with a complicated 稜鏡 structure, that is, light having a large illumination angle. Such an improvement has a severe effect on the light intensity, since the first light that is emitted as the only available light at a smaller illumination angle will then spread out to a larger illumination angle, typically a half space. In this case, the brightness is reduced by 5 or more orders of magnitude (depending on the illumination density) depending on the specific parameters. Therefore, the case proposes a design that is actually difficult to implement.

In the design shown in Figure 7 of US 2009/0067156, a phosphor layer must be provided to convert ultraviolet light into visible light. This is costly, and if it is necessary to generate light sufficient to illuminate the LCD panel by its backlight, it is necessary to apply a very large ultraviolet light intensity. Therefore, the scheme is relatively expensive and complicated, and it is not feasible to shield the necessary ultraviolet radiation alone.

US 2012/0235891 describes a relatively complex backlight that is on the screen. As shown in Figures 1 and 15, the case not only uses multiple light guides, but also makes More complex optical components, such as microlenses 40 and germanium structures 50, are used to direct light from the backlight to the front light. This is more expensive and complicated, and the light loss is also higher. In the scheme shown in Fig. 17 of US 2012/0235891, the two light sources 4R and 18 generate light having a small illumination angle, wherein only a complicated scheme can be used to convert the light originating from the rear light source 18 into a lighter Large illumination angle of light. As mentioned earlier, this complex improvement significantly reduces brightness.

JP 2007-155783 uses a special optical surface that is difficult to calculate and manufacture, which deflects light to different narrower or wider regions depending on the specific angle of incidence of light. These structures are similar to Fresnel lenses. In addition, there are interference edges that deflect light to undesired directions. Therefore, it is not clear whether a favorable light distribution can be achieved.

In general, the same disadvantages of the foregoing methods and arrangements are: significantly reducing the brightness of the basic screen, and/or the need to add active optical components for mode switching, and/or the manufacturing process is complicated and the manufacturing cost is high. And/or, reduce the resolution of the free viewing mode.

In view of the above, it is an object of the present invention to provide a switchable illumination device that implements at least two illumination modes, wherein one mode illuminates only with a limited solid angle and the other mode has a solid angle that is as large as possible Lighting. Therefore, when the lighting device is used with the screen, the information can be reliably presented by the optional limited viewing angle, wherein in the second mode, the viewing is as unrestricted as possible in terms of viewing angle. . This illuminating device can be realized inexpensively with a simple component. Both modes achieve the highest possible resolution, and the original resolution of the screen used is particularly well achieved. Furthermore, the solution of the invention only results in very little light loss.

The solution to achieve the above object of the present invention is a lighting device that can operate in at least two modes of operation, a free viewing mode B1 and a limited viewing mode B2, including: a face-extending backlight that is limited in viewing. The mode of operation B2 emits light in a limited angular range, wherein at least one of the maximum light intensity is at least 10% in a direction that forms an angle greater than 45 degrees with the surface normal of the backlight, and is emitted from the backlight. Light; a plate-shaped optical element located upstream of the backlight in a viewing direction; and a plurality of lighting fixtures laterally disposed on a narrow side of the optical element; wherein: the optical element is constructed as a light guide , which is composed of a matrix plastic A and scattering particles composed of a polymer B uniformly distributed therein; the ratio of the scattering particles composed of the polymer B to the matrix plastic A is 0.01 to 3 weight percent; polymerization The refractive index nD(B) of the substance B is higher than the refractive index nD(A) of the matrix plastic A by at least 0.01 unit; moreover, the light guide body is transparent to at least 80% of the light system originating from the backlight, so that the mold is In the free field of view of B1, light that is incident laterally from the illumination device to the optical element is emitted at least 20% of the maximum light intensity in a direction that forms an angle greater than 45 degrees with the surface normal of the backlight. Wherein, in the operation mode B2, the backlight is turned on, and the lighting fixtures are turned off, and wherein, in the operation mode B1, the lighting fixtures are turned on, and the backlight is turned off.

The matrix plastic A is preferably incompatible with the polymer B.

The plate-shaped optical element is composed of two large surfaces that are opposite each other and are parallel to each other. In particular, the wedge structure is excluded. The two large surfaces are surrounded by four narrow sides that can be used to input light emitted by the lighting fixtures into the optical element. The scattering particles are uniformly distributed, so that the optical element does not have an uneven optical structure.

The optical component is configured by a matrix plastic and polymer scattering particles uniformly distributed therein, and thus, in the optical component and the entire illumination device, light emitted from the backlight and originally emitted in a limited angular range is not It may be converted to light emitted at an unrestricted angular range, at least to a negligible extent.

In the operational state B2, light originating from the backlight is emitted at a maximum of 10% of the maximum light intensity in at least one direction which forms an angle greater than 45 degrees with its surface normal. The direction of projection onto its surface may, for example, be in a horizontal line as far as the observer is concerned, in which case it is preferably limited to emission in a horizontal plane. In the vertical line perpendicular to the horizontal line, it is not necessary to transmit in a limited manner, and the opposite design can also be employed. Switching between a restricted range of emissions and an unrestricted range of emissions, either sustainably or discretely. According to a preferred embodiment, which is easy to implement, in operation mode B2, in all directions which form an angle greater than 45 degrees with the surface normal of the backlight, i.e., outside the 45 degree cone, with a limited angular range , transmitting at a maximum of 10% of the maximum light intensity, thereby maximizing the visibility of the protected information as much as possible.

In other words, such an illumination device 1 capable of operating in at least two modes of operation B1, B2, ..., comprising: a face-extending backlight, emits light having a certain emission characteristic, such that, in conjunction with the backlight The surface normal is formed in a direction greater than 45 degrees, and is emitted at a maximum of 10% of the maximum light intensity; An optical element, located upstream of the backlight in the viewing direction, is at least 80% transparent to the light source from the backlight, and is incident laterally from the plurality of lighting fixtures at an angle greater than 80 degrees from the surface normal. Light, deflected at an angular extent as large as possible, such that at least 20% of the maximum light intensity is emitted in a direction that forms an angle greater than 45 degrees with the surface normal of the backlight; wherein, as a light guide The optical component adopts the foregoing design; and wherein, in the operation mode B2, the backlight is replaced by the lighting fixtures, and wherein, in the operation mode B1, the lighting fixtures are not the backlight The piece is turned on.

In principle, the above parameters can be varied within certain limits and the performance of the design of the invention remains unchanged. For example, such an illumination device can emit light having a certain emission characteristic such that it is performed at a maximum of 0 to 20% of the maximum light intensity in a direction forming an angle larger than 10 to 45 degrees from the surface normal of the backlight. emission.

According to another embodiment independent of the above, the optical element located upstream of the backlight in the viewing direction is transparent to at least 80% (or less than 80%, such as 70% or even only 50%) of the light system originating from the backlight. Light incident from a plurality of lighting fixtures laterally at an angle greater than 80 degrees from their surface normal, deflected at an angular extent as large as possible, such that greater than 10 to 70 are formed on the surface normal to the backlight In the direction of the angle, the emission is performed at least 10 to 70% of the maximum light intensity.

In addition, it should be noted that in the free field of view (ie, mode B1), lateral incidence is emitted from the illumination devices at least 20% of the maximum light intensity in a direction that forms an angle greater than 45 degrees with the surface normal of the backlight. The light to the optical element, of course, can also emit or output a large portion of the light at an angle of less than 45 degrees from the surface normal of the backlight, thereby illuminating a large angular range as a whole, in the best case , Approximately half of the space in front of the optical element is illuminated.

The scattering particles form a corresponding light output coupling structure in the optical element, i.e., the light guide.

The backlight can preferably be constructed as sidelights, edge lights, direct-lit LED backlights, edge LED backlights, OLEDs or other surface emitters. The backlight can also be a dark field illumination.

For example, the backlight is a common backlight (edge lamp, direct-lit LED backlight, etc., etc.), which is plated with a continuous viewing protection film, also known as a privacy film (such as Vikuiti of 3M ^TM) . ^TM ) in order to reduce its light emission characteristics in such a way that light is emitted substantially only at a limited solid angle.

More preferably, the backlight comprises at least one optical layer for light collimation at the position of the continuous privacy film to achieve an angularly limited emission characteristic of the light output by the backlight. Here, for example, it may refer to two intersecting layers of "Optical Lighting Film" (OLF) of Model 2301 of 3M ^TM Company.

The invention also relates to the use of the aforementioned illumination device, wherein a transmissive imager, such as an LCD panel, is arranged in front of the illumination device such that it is present on the imager in mode B1, ie in a free viewing mode The image can be substantially seen from each direction that forms a maximum angle of 90 degrees with the imager, and in mode B2, ie, in the limited viewing mode, the image presented on the imager is substantially It can only be seen in a direction that forms a maximum angle of 45 degrees with the imager.

As mentioned above, the above angle values may vary depending on the design of the corresponding component. In some cases, a certain amount of residual light is allowed to be present at a large angle, such as at an angle of more than 45 degrees from the perpendicular of the imager. The lighting fixtures can be, for example, LEDs or laser diodes. Other designs are also available.

Finally, there may be more modes of operation, such as mode of operation B3, in which both components, ie, the backlight and the lighting fixtures, are turned "on". When the illumination device in mode B3 is used with an imager, a particularly bright image is produced which gradually darkens towards the edge. There may also be more modes of operation, such as an operating mode in which the illumination value of the backlight or lighting fixture is dimmed. In addition, it is also possible to perform switching or reverse switching between a plurality of operating modes, for example, between modes B1 and B2, for example, in a small period, such as one to two seconds. Inside, adjust the brightness of the backlight to zero, and at the same time, adjust the brightness of the lighting fixture to the maximum value or a certain value, and vice versa. When the present invention is used with an imager, a convenient switch between the free viewing mode and the limited viewing mode is performed. In view of this, according to a preferred embodiment, such a lighting device comprises an electronic control device which progressively controls the switching or reverse switching between the operating modes B1 and B2 accordingly.

The invention can also adopt the following preferred embodiment: The light guide body constituting the optical element can be composed, for example, of Evonik LD12 8N or Evonik PLEXIGLAS ^® LED Folie 15950/99/1-3.

Furthermore, the light input coupling is effected by the laterally arranged lighting fixtures from at least two sides, preferably from opposite sides of each other.

The light efficiency can be improved overall by the partial mapping of the optical element on the side facing the backlight, as this redirects the light output towards the backlight back in the direction of the useful light.

According to a preferred embodiment, the optical component is partially mapped on its side facing the backlight, wherein the intensity of the mapping is changed over the entire area so that in the operating mode B1, ie, in the free viewing mode, The optical component loses The difference in brightness of the emitted light is compensated for in the area. The reason for this difference in brightness is uneven illumination, which is associated with lighting fixtures that are only placed on one side of the device: the content presented in the center of the area is closer to the edge of one of the lighting fixtures. Darker. Changes can be implemented in different ways. One way is to be able to choose the intensity of its mapping, ie the ratio of reflection to transmission, in a continuously changing manner, thus achieving a maximum degree of mapping where the brightness of the emitted light is minimal. Alternatively, a brightness limit value of a relative maximum brightness may be preset, and partial mapping, that is, plating on the optical element, is performed only for the area where the brightness (in the case where the mapping is not considered) is lower than the preset limit value. A layer that is transparent in one direction. This solution is less expensive.

In addition, partial mapping on the back side of the transmissive imager also facilitates homogenization of light efficiency from the optical elements. Such partial mapping can also be similar to the partial mapping of optical components, with varying designs or only partial plating to compensate for luminance differences.

The light efficiency can be further improved by the optical element for achieving better output coupling and by laser structured by a plurality of grooves, wherein the grooves are no more than 250 μm, So that: a) is invisible, and b) light from the angle limit of the backlight is not scattered. Wherein the grooves can be arranged on the optical element in an unequal area or in a gradient manner.

As an alternative or in addition, the optical component may be a plate-shaped light guide body having a plurality of built-in turns, wherein on a surface, a plurality of micro-couples coupling the light output are embedded in the light guide body, and the micro- The crucibles are all tapered.

Preferably, the backlight used as the collimation design can also be used as a backlight, that is, the light source is designed such that the light is emitted only within a certain limited angular range. Shoot. According to another preferred embodiment, the same source is always used in both modes, such as a plurality of laterally arranged lighting fixtures. In this case, in order to switch between the two operating modes B1 and B2, for example, through an optoelectronic or optomechanical switch, the light is alternately input into the optical element and the backlight. For example, a light shield or a mechanical switching device (eg, a reversible mirror) can be used as the switch. The lighting fixtures can also be arranged in two rows, wherein only the desired or corresponding rows are connected. The latter solution is particularly advantageous if the lighting device also has the aforementioned third mode of operation B3.

Further, in the limited viewing mode B2, the desired or allowed emission direction can be defined and implemented in a manner independent of each other for the horizontal direction and the vertical direction. For example, cash machines need to be viewed by people of different heights, and side views should be strictly limited, so a larger angle in the vertical direction is more advantageous than the horizontal direction.

According to a further advantageous refinement, the illumination device comprises a control means for transmitting the area of the light output from the optical element in the free viewing mode B1 by means of a complementary pair of brightness differences. The image content on the imager is controlled to compensate for the difference in brightness, thereby presenting a substantially uniform image in terms of brightness on the transmissive imager. In other words: if there is a difference in brightness during the output coupling of the optical element (eg, in the horizontal direction for the viewer, or in multiple directions such as horizontal and vertical, or obliquely, there is a gradient ) or bright spots, dim the rendered image. After the difference in luminance is measured, for example, a reciprocal value normalized by a fixed factor can be obtained, that is, a normalized luminance value whose maximum relative luminance is equal to 1, multiplied by the luminance value at the corresponding position in the image. Take such reciprocal values. This will not dim the darkest position and the darkest position to the greatest extent.

It will be understood that within the scope of the present invention, the above and the following will be described. The features may be combined not only in the manner given in the present application, but also in combination or in separate applications.

1‧‧‧Lighting device

2‧‧‧Backlights

3‧‧‧Optical components

4‧‧‧Lighting equipment

5‧‧‧ Imager

A‧‧‧ matrix plastic

B‧‧‧Polymer

B1‧‧‧ (first) mode of operation; (free viewing) mode

B2‧‧‧ (second) mode of operation; (restricted viewing) mode

B3‧‧‧ (third) mode of operation; (free viewing) mode

X‧‧‧ horizontal axis; (horizontal) location; location

1 is a schematic diagram of the principle that the light of the lateral input optical element is output at the maximum solid angle; FIG. 2 is a schematic diagram of the light from the backlight passing through the optical element; FIG. 3 is the first operation mode of the illumination device in the free viewing mode. A schematic diagram of the principle in B1, in which the solid angle of the largest possible angle is illuminated, wherein the illumination device is used with the imager; FIG. 4 is the illumination device in the second mode of operation B2 of the restricted viewing mode. Schematic diagram of illuminating a restricted solid angle in the second mode of operation, wherein the illumination device is used with an imager; Figure 5 is a line diagram of the relative brightness of light output from the optical element; A line graph of the correction values for the brightness of the image to be presented, as shown in FIG.

The invention will be described in detail below with reference to the accompanying drawings which illustrate the nature of the invention.

The figures are not to scale and are merely illustrative of the principles.

FIG. 1 is a schematic diagram showing the principle of outputting light from the side of the illumination device 4 to the input optical element 3 (here, only a partial cross-sectional view) at a maximum solid angle. Many of the smaller dots represent scattering particles as scattering centers of light input laterally from the lighting fixture 4. Due to total reflection, the input coupled beam of light returns to the light guide on the outer wall, straight At the end, a scattering particle is hit to perform the desired output coupling. For the sake of clarity, the view of Fig. 1 is shown schematically; in fact, a large number of optical paths are provided in the optical element 3.

2 is a schematic diagram showing the principle of light from the backlight 2 passing through the optical element 3. Among them, the effect of the scattering particles is negligible because the light source is derived from the backlight 2 and is not deflected by or substantially back and forth by the total reflection in the light guide.

3 is a schematic illustration of the principle of the illumination device 1 in a first mode of operation B1 (free viewing mode) in which the solid angle of illumination is as large as possible, wherein the illumination device 1 is used with the imager 5. Figure 4 is a schematic illustration of the principle of the illumination device 1 in a second mode of operation B2 in which the viewing mode is limited, in which only the restricted solid angle is illuminated.

Such a lighting device 1 operable in at least two operating modes B1, B2, ... comprises: a face-extending backlight 2 which emits light at a limited angular extent in an operating mode B2 which limits the viewing mode Wherein, in at least one direction which forms an angle greater than 45 degrees with the surface normal of the backlight 2, the light originating from the backlight 2 is emitted at a maximum of 10% of the maximum light intensity; the plate-shaped optical element 3, It is located upstream of the backlight 2 in the viewing direction; and a plurality of lighting fixtures 4 are laterally disposed on the narrow side of the optical component 3; wherein: the optical component 3 is constructed as a light guide, which is comprised of a matrix plastic A And a scattering particle composed of the polymer B uniformly distributed therein; the ratio of the scattering particles composed of the polymer B to the matrix plastic A is 0.01 to 3 weight percent; The refractive index nD(B) of the polymer B is higher than the refractive index nD(A) of the matrix plastic A by at least 0.01 unit; moreover, the light guide is transparent to at least 80% of the light system originating from the backlight 2, so that the operation is performed In the free field of view in mode B1, light that is incident laterally from the illumination fixture 4 to the optical element 3 is emitted at least 20% of the maximum light intensity in a direction that forms an angle greater than 45 degrees with the surface normal of the backlight 2. Wherein, in the second operation mode B2, the backlight 2 is turned on, and the lighting fixtures are turned off by 4, and wherein, in the first operation mode B1, the lighting fixtures 4 are turned on, and the backlights are turned on 2 disconnected.

The optical element 3 is configured by a matrix plastic and polymer scattering particles uniformly distributed therein, and thus, in the optical element 3 and the entire illumination device 1, light originating from the backlight 2 and originally emitted at a limited angular range It is not, or at least only, negligible to be converted into light that is emitted in an unrestricted angular range.

It should be noted here that, in terms of the free field of view in the operation mode B1, at least 20% of the maximum light intensity is emitted from the side of the lighting fixture in a direction forming an angle greater than 45 degrees with the surface normal of the backlight 2. The light incident on the optical element 3, of course, can also emit or output a large part of the light at an angle of less than 45 degrees with the surface normal of the backlight 2, thereby illuminating the entire angular range as a whole, In the best case, approximately half of the space in front of the optical element 3 is illuminated.

In this way, the first operating mode B1 for the free field of view can sense the image on the imager 5, such as the LCD panel, with as large a solid angle as possible and a full resolution. In the second mode of operation B2 for limiting the field of view, the image can be equally resolved on the imager 5, but only with a limited solid angle, thereby implementing a private viewing mode (so-called viewing). Protection mode or peep mode formula). In this way, the visible range of the image presented by the imager 5 can be restrictedly sensed according to the solid angle, in particular depending on the design of the parameters of the illumination angle. In the third operation mode B3 not shown, the backlight 2 and the lighting fixture 4 can be turned on to present an image that is as bright as possible.

This illumination device 1 can be modified in a number of ways to achieve the desired effect.

The backlight 2 can preferably be constructed as a sidelight, an edge light, a direct-lit LED backlight, an edge LED backlight, an OLED or other surface emitter. The backlight 2 can also be a dark field illumination. More preferably, the backlight 2 is a common backlight, that is, for example, based on edge lamps, direct-lit LED backlights, and the like, and the like, on which a continuous anti-slip film (such as Vikuiti ^{TM of} 3M ^TM) is installed. ) in order to reduce the emission characteristics of the light in such a way that the light is emitted substantially only at a limited solid angle.

In some cases, a certain amount of residual light is allowed to occur when squinting is performed at a large angle, such as an angle of 45 degrees or more with the perpendicular of the imager 5. The lighting fixture 4 can for example be an LED or a laser diode. Other designs are also available.

In the first mode of operation B1 of free viewing, preferably, the area of the light output from the optical element 3 is controlled by the image content presented on the transmissive imager 5 in a complementary manner to the difference in luminance. In order to compensate for the difference in luminance, a substantially uniform image in terms of brightness is exhibited on the transmissive imager 5. In other words: if a difference in brightness (eg, a gradient exists in one or more directions) or a bright spot occurs during the output coupling of the optical element 3, the rendered image is dimmed. After the difference in luminance is measured, for example, a reciprocal value normalized by a fixed factor can be obtained, that is, a normalized luminance value whose maximum relative luminance is equal to 1, multiplied by the luminance value at the corresponding position in the image. Take such reciprocal values. This will not dim the darkest position and the darkest position to the maximum extent.

In view of this, FIG. 5 is a line diagram of the relative luminance of light output from the optical element 3, and FIG. 6 is a line diagram of correction values for the luminance of the image to be presented based on the situation shown in FIG. 5.

As shown in FIG. 5, the relative brightness is generally obtained by dividing the locally measured value by its maximum value, including "cd/m ² " or "nit (nit)", usually the illumination density. The horizontal axis is indicated by "X", which corresponds to the horizontal direction of the optical element 3. In this case, the rows of LEDs for optical coupling are arranged, for example, on the two perpendicular narrow sides of the optical element 3 in order to obtain the luminance distribution in FIG.

Find the reciprocal of the relative brightness in Figure 5, and multiply by a fixed factor (the factor here is, for example, 0.5), thereby obtaining the value of the same (relative) position X in the horizontal direction shown in Figure 6, but this The time is the value on the transmissive imager 5. This factor is used to normalize the reciprocal, and the luminance value of the image presented on the imager 5 is not allowed to be multiplied by a factor greater than one because the imager 5 itself cannot increase the brightness. This factor is usually the minimum relative brightness value, and in some cases other options may be used to further dim the entire image.

After multiplying the luminance values of the images presented on the imager 5 by the aforementioned normalized reciprocal values of the relative luminances at the positions X, the brightness of the entire image is substantially uniform in the mode B1 because, in the image content The brightness value in this illumination device has been compensated by the optical element 3.

The foregoing lighting device is suitable for any occasion where it is necessary to display and/or input confidential information, for example, at the time of PIN input, or for displaying data on a cash machine or a payment terminal, or for inputting a password, or reading on a mobile device. When getting mail.

The illumination device is switchable and implements at least two illumination modes, wherein one mode is illuminated only with a limited solid angle and the other mode is as far as possible Large solid angles for illumination.

Therefore, when the lighting device is used with the screen, the information can be reliably presented by the optional limited viewing angle, wherein in the second mode, the viewing is as unrestricted as possible in terms of viewing angle. . This illuminating device can be realized inexpensively with a simple component. Both modes B1 and B2 can achieve the full original resolution of the screen used. Furthermore, the present invention maintains light loss at as low a level as possible.

Unlike the prior art, there is no need to use a strong ultraviolet light source, and it is laborious to convert the angle-limited light distribution into an unrestricted light distribution (this will significantly reduce the brightness), and it is also necessary to set a complicated 稜鏡 structure. Or microlens structure.

3‧‧‧Optical components

Claims (12)

A lighting device (1) operable in at least two modes of operation, a free viewing mode B1 and a limited viewing mode B2, comprising: a face-extending backlight (2) in an operating mode B2 that limits viewing mode The light is emitted in a limited angular range, wherein at least one of the maximum light intensity is at least 10% in a direction that forms an angle greater than 45 degrees with the surface normal of the backlight (2), and the backlight is emitted from the backlight ( 2) light; a plate-shaped optical element (3) located upstream of the backlight (2) in the viewing direction; and a plurality of lighting fixtures (4) laterally arranged in the narrowness of the optical element (3) On the side; wherein: the optical element (3) is constructed as a light guide body, the light guiding system is composed of a matrix plastic A and scattering particles composed of a polymer B uniformly distributed therein; the polymer B The ratio of the scattering particles to the matrix plastic A is 0.01 to 3 weight percent; the refractive index nD (B) of the polymer B is higher than the refractive index nD (A) of the matrix plastic A by at least 0.01 units; The light guide is transparent to at least 80% of the light system originating from the backlight (2) such that The free field of view in the operation mode B1 is emitted from the side of the lighting fixture (4) at least 20% of the maximum light intensity in a direction forming an angle greater than 45 degrees with the surface normal of the backlight (2). To the light incident on the optical element (3); wherein, in the operation mode B2, the backlight (2) is turned on, and the lighting fixtures (4) are turned off, and wherein, in the operation mode B1 The lighting fixtures (4) are turned on and the backlight (2) is turned off. The lighting device (1) of claim 1, wherein the lighting fixtures (4) are LEDs or Laser diode. A lighting device (1) according to claim 1 or 2, wherein the backlight (2) comprises at least one optical layer for light collimation. A lighting device (1) according to any one of claims 1 to 3, wherein the backlight (2) is constructed as a sidelight, an edge light, a direct-lit LED backlight, an edge LED backlight, an OLED or the like Surface emitter. A lighting device (1) according to any one of claims 1 to 4, wherein the backlight (2) is a backlight, such as an edge light or a direct-lit LED backlight, the backlight is plated with Continuous anti-slip film. The illumination device (1) of claim 1, wherein the third operation mode B3 for a particularly bright viewing mode can also be operated, wherein in the operation mode B3, the backlight (2) and the same The lighting fixtures (4) are all switched on. A lighting device (1) operable in at least two modes of operation, a free viewing mode B3 and a limited viewing mode B2, comprising: a face-extending backlight (2) in an operating mode B2 that limits viewing mode The light is emitted in a limited angular range, wherein at least one of the maximum light intensity is at least 10% in a direction that forms an angle greater than 45 degrees with the surface normal of the backlight (2), and the backlight is emitted from the backlight ( 2) light; a plate-shaped optical element (3) located upstream of the backlight (2) in the viewing direction; and a plurality of lighting fixtures (4) laterally arranged in the narrowness of the optical element (3) On the side; wherein: the optical element (3) is constructed as a light guide body, the light guiding system is composed of a matrix plastic A and scattering particles composed of a polymer B uniformly distributed therein; the polymer B The ratio of the scattering particles formed to the matrix plastic A The refractive index nD (B) of the polymer B is higher than the refractive index nD (A) of the matrix plastic A by at least 0.01 unit; and the light guide body is derived from the backlight (2) At least 80% of the light system is transparent such that, in the free field of view in operation mode B1, at least 20 of the maximum light intensity is formed in a direction greater than 45 degrees from the surface normal of the backlight (2) %, emitting light from the lighting fixture (4) laterally incident on the optical element (3); wherein, in the operating mode B2, the backlight (2) is turned on, and the lighting fixtures (4) It is disconnected, and wherein, in operation mode B3, the lighting fixtures (4) and the backlight (2) are both turned on. A lighting device (1) according to any one of claims 1 to 7, further comprising: an electronic control device for progressively controlling the switching or reverse switching between the operating modes B1 or B3 and B2, such that During a certain period, the brightness of the backlight (2) is adjusted to zero, and at the same time, the brightness of the lighting fixtures (4) is adjusted to a maximum value or a certain value, and vice versa. The illuminating device (1) according to any one of claims 1 to 8, wherein the optical element (3) is partially mapped on its side facing the backlight (2), wherein, for the operation mode B1 Or the brightness difference in B3 is compensated, the intensity of the mapping is changed over the entire area of the light output from the optical element (3), or wherein only the brightness is lower than a preset limit without considering the mapping The area of the value, the square is partially mapped. A lighting device (1) according to any one of claims 1 to 9, wherein a transmissive imager (5), such as an LCD panel, is arranged in front of the lighting device (1). The illumination device (1) of claim 10, comprising: control means, in the operation mode B1 or B3, the area of the light outputted from the optical element (3) is borrowed The image content presented on the transmissive imager (5) is controlled in a manner complementary to the difference in luminance to compensate for the luminance difference, thereby presenting on the transmissive imager (5) in terms of brightness A substantially uniform image. A use of a lighting device (1) according to any one of claims 10 or 11 for inputting or displaying confidential information, such as a PIN key, an email, an SMS or a password, on a cash machine, payment terminal or mobile device.