EP1794631A1 - Illuminated light box with light-emitting diodes - Google Patents

Illuminated light box with light-emitting diodes

Info

Publication number
EP1794631A1
EP1794631A1 EP05794596A EP05794596A EP1794631A1 EP 1794631 A1 EP1794631 A1 EP 1794631A1 EP 05794596 A EP05794596 A EP 05794596A EP 05794596 A EP05794596 A EP 05794596A EP 1794631 A1 EP1794631 A1 EP 1794631A1
Authority
EP
European Patent Office
Prior art keywords
light
guide
rows
led
characterized
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP05794596A
Other languages
German (de)
French (fr)
Inventor
Bertrand Morbieu
David Chaillou
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thales SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to FR0410270A priority Critical patent/FR2875993B1/en
Application filed by Thales SA filed Critical Thales SA
Priority to PCT/EP2005/054378 priority patent/WO2006034943A1/en
Publication of EP1794631A1 publication Critical patent/EP1794631A1/en
Application status is Ceased legal-status Critical

Links

Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
    • H05B33/00Electroluminescent light sources
    • H05B33/02Details
    • H05B33/08Circuit arrangements not adapted to a particular application
    • H05B33/0803Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials
    • H05B33/0842Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials with control
    • H05B33/0857Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials with control of the color point of the light
    • H05B33/0866Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials with control of the color point of the light involving load characteristic sensing means
    • H05B33/0869Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials with control of the color point of the light involving load characteristic sensing means optical sensing means
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336Illuminating devices
    • G02F1/133602Direct backlight
    • G02F1/133603Direct backlight with LEDs
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
    • H05B33/00Electroluminescent light sources
    • H05B33/02Details
    • H05B33/08Circuit arrangements not adapted to a particular application
    • H05B33/0803Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials
    • H05B33/0842Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials with control
    • H05B33/0857Circuit arrangements not adapted to a particular application for light emitting diodes [LEDs] comprising only inorganic semiconductor materials with control of the color point of the light

Abstract

The invention concerns an illuminated light box designed in particular for backlighting liquid crystal displays, the box comprising: a light guide (62) in the form of a thin plate having two opposite main faces (64, 66) and at least two edges (B1, B4), the guide having on one of its faces a light-diffusing optical structure (70); light-emitting diodes (Lnm) arranged linearly along at least one of the edges of the light guide, the light emitted by the light-emitting diodes, illuminating the guide through the edge, being diffused through the face of the guide comprising the optical structure. The light-emitting diodes arranged along each of the edges of the guide are organized into at least two rows (Rb1 to Rb8) such that one light-emitting diode (Lnm) of a row powered by an electric power source (S1 to S8) is immediately followed by a light-emitting diode (L(n+1)m) of the other row powered by another electric power source.

Description

BOX LIGHT EMITTING DIODES

The invention relates to a light box, intended in particular for liquid crystal display backlight.

The backlight of liquid crystal displays for avionics is usually performed by light boxes with fluorescent tubes. These displays produce luminosities of the order of 1000 cd / m 2 required for day vision, sometimes in bright sunlight. In addition the illumination of the light box must be adjusted so as to greatly reduce its brightness during night flight for example to levels of the order of 0.1 Cd / m 2.

Figures 1a, 1b and 1c show various views of a light box of the prior art, fluorescent tubes.

1a shows a sectional view of a light box of the prior art, fluorescent tubes. The box of Figure 1a, of rectangular shape, comprises a housing 10 having a bottom 12 and an opening 14 facing the bottom 12 in the backlight of a liquid crystal display 16. The bottom 12 of housing 10 includes a reflector 20 and an array of fluorescent tubes 22 arranged parallel to the bottom of the housing and, at the opening 14, a light diffuser 24. the reflector 20 is of known form such as r light rays emitted by the fluorescent tubes are directed towards the light diffuser 24 illuminating the LCD screen in a uniform manner.

The light box further comprises a waveguide 30 shaped plate having two parallel faces 32, 34 and edges 36. The face 32 directed towards the opening 14 of the box has a diffusing structure 38 of the light generated by a lateral fluorescent tube 40 illuminating one edge of the light guide.

Figure 1 b shows a top view of the box of Figure 1a showing the arrangement of the fluorescent tube side 40 of the wafer 36 of the light guide 30 having the diffusing structure 38 on the face 32 directed toward the liquid crystal display . Figure 1c is a partial view of an edge of the light guide illuminated by the fluorescent tube 40 side, showing the path of the light rays scattered by the I face 32 of the guide having the diffusing structure 38. When the ambient light is strong , e.g., day, the network fluorescent tubes 22 is on producing a high level of illumination of the LCD screen. During the night lighting should be much lower. The network of fluorescent tubes is then turned off and the single lateral fluorescent tube 40 is turned on creating a low light diffused by the light guide (or waveguide) 30 through the diffuser 24 toward the liquid crystal display 16.

In addition, the range of variation of the light intensity of the light box can be enlarged by a control of the supply power of the tubes. For this purpose the supply voltage fluorescent tubes is shaped frequency slots of a few dozen to a few hundred Hertz. tube feeding power can be adjusted by varying the cyclic ratio of slots.

The fluorescent light boxes have light performance sufficient for illuminating liquid crystal displays intended especially for avionics, however, they have a large volume and require regular maintenance related to the life of the tubes fluorescent.

It is now known to use light-emitting diodes, or LED "Light Emitted Diodes" in English instead of fluorescent tubes for making light boxes. Progress on the LEDs allow to make LED lights boxes less bulky than fluorescent tube and at a lower cost while getting closer yields and light intensities obtained with fluorescent tubes.

Figure 2a shows a lighting device of a light guide 40 having light emitting diodes.

The device of Figure 2a comprises two rows Ra1, wired LED Lnm ​​of Rb2 on a printed circuit 42. Each row Ra1, Ra2 has seven LEDs connected in series (n being the row number, 1 or 2, and m is the number of the LEDs in each row, 1-7). The LED rows are aligned, one after the other along one of the edges B1 of the light guide 40 in the form of thin plate, having two opposite major faces and four edges B1, B2, B3, B4 ( or slices) delimiting the plate. As in the light box of FIG 1a, the light guide 40 has on one side 44 an optical structure 50 of diffusing light propagating in the guide.

The light guide 40 transmits the light generated by the rows of Ra1, Ra2 emitting diode L11, L17 and L21 .... .... A27, B1 applied to its edge which is propagating in the guide is broadcast its optical structure 50 through the entire face 44 of homogeneously guide as already described above.

Each row Ra1, Ra2 emitting diodes is connected to a power source S1 respectively for Ra1 and S2 row, to the row Ra2.

Figure 2b shows the electrical diagram of connection of the rows of diodes Ra 1 and Ra 2 of Figure 2a, at respective sources S1 and S2 power.

Light boxes of the prior art of Figures 2a and 2b with a light source emitting diodes however have the drawback, in case of failure of a diode or a power source, to cause a loss of homogeneity of the brightness of the illuminated surface.

In fact a breakdown of one of the sources S1 supply, S2 or the cleavage of one of the diodes of a row of light emitting diodes leads to the disappearance of illuminating a half-edge (B1) of the guide light of the box, and a variation in the brightness according to the portion illuminated screen. A variation of the brightness of the light box and consequently of the liquid crystal display illuminated by it may impair the readability of aircraft flight instruments, which can be very inconvenient for the driver.

At the end of overcoming the disadvantages of LED light boxes of the prior art, the invention provides a light box, intended especially for LCD screen backlight, the box comprising: - a light guide shaped thin plate having two opposite main faces and at least two portions, the guide having on one side an optical structure diffusing light;

- light emitting diodes linearly arranged along at least one of the wafers of the light guide, the light emitted by the LEDs, illuminating the guide by the wafer, being scattered by the face of the guide having the optical structure; characterized in that the light emitting diodes arranged along each of the slices of the guide are arranged in at least two rows and so that a light emitting diode of a row powered by a power source is immediately followed by a diode emitting of the other row powered by another power source.

In a first variant, the light box according to the invention comprises at least one photodetector providing a light intensity signal of the light emitted by the box. The light intensity information output from the photodetector is transmitted to a control system or servo of the luminance of the light box.

In a second variant of the light box according to the invention, the LED of at least one of the branches (or rows) emit a light spectrum different from that of the other branches.

In a third variant, the light box according to the invention comprises three photosensors with color filters for sensing the light radiation from the light box in the colors red, green and blue to produce signals for making a color balancing rows of light emitting diodes.

In a preferred embodiment, the light box according to the invention comprises a rectangular light guide having four units, eight rows of light emitting diodes, a pair of rows of diodes illuminating a respective portion of the light guide.

A main objective of this invention is to minimize the variation in the homogeneity of the illumination of a light box in case of failure of one or more rows of LEDs or LED power sources.

Another object of the invention is to maintain a sufficient brightness of illumination of the liquid crystal display in particular in case of failure of one or more row of light emitting diodes of the light box.

The invention will be better understood with the aid of examples of embodiments of light boxes according to the invention, with reference to FIGS above drawings, wherein:

- Figures 1a, 1b and 1c, already described, show various views of a light box of the prior art, fluorescent tubes;

- Figure 2a shows a lighting device of a light guide having light emitting diodes; - Figure 2b shows the electrical connection scheme of the rows of diodes Ra 1 and Ra 2 of Figure 2a, at respective sources S1 and S2 power;

- Figures 3a and 3b respectively show a sectional view and a top view of a light box according to the invention; - Figure 3c shows electrical schematics LED connections of the light box of figures 3b;

- Figure 4 shows a first variant of the light box according to the invention;

- fig 5 shows a block diagram of a servo of a light box having the same structure as that described in Figure 4 comprising a photoelectric sensor;

- Figure 6 shows a block diagram of a feedback control of the light emitted by a light box according to the invention comprising three photoelectric sensors; - Figures 7a, 7b and 7c show partial views of light boxes of embodiments of the invention compatible with night vision;

- Figure 8 shows as an example a light box comprising a stack of two stages of LEDs and light guides. Figures 3a and 3b respectively show a sectional view and a top view of a light box according to the invention. The light box figs 3a and 3b comprises a casing 50 having a bottom 52 and an opening 54 facing the bottom casing 52 for backlighting of a liquid crystal display 56, the side of the bottom of the housing 50, a printed circuit 60, parallel to the bottom of the housing, a light guide 62 having on one side 64 directed toward the bottom of housing 52 an optical structure 70 of the diffusing light propagating in the guide.

The printed circuit 60 comprises on one of its faces 72, on the side of the light guide, a reflector 74 for reflecting towards the opening 54 (RF radiation), the scattered light (rd radiation) by the optical structure 70 of the guide.

The light box of Figure 3a further comprises on the side of the opening 54 of the diffuser 75 a box-shaped plate parallel to the bottom of the casing covering the whole of the box.

The printed circuit of the light box of FIG 3, according to the invention comprises eight rows Rb1, Rb2, .... Rb8, seven LED Lnm ​​in series, aligned two by two respectively on each of the edges B1, B2 , B3, B4 of the light guide 60, the Rb1 and Rb2 rows illuminating the edge B1, the Rb3 and Rb4 rows illuminating the edge B2 the Rb5 and Rb6 rows B3 illuminating board and RB7 and Rb8 rows illuminating the edge B4. Each of the LEDs is indicated by Lnm, n being the row number of 1 to 8, and m is the number of the LED in each row, 1-7 in this embodiment, either L1 1, L12 ..... L17 for the row R1; L21, L22 L27 ..... for row R2 and so on to the LED L81, L82 L87 ..... for row R8. Each of the rows of LED Rb1, Rb2, ... R8 is respectively fed by an independent power source S1, S2, S8 and according to a main feature of the invention, for a determined edge of the light guide, a light emitting diode lnm a Rbn row powered by a power source is immediately followed by a light emitting diode L (n + 1) m of the other row Rb (n + 1) supplied by a different power source. For example, the rows of LED Rb 1 and Rb2 are interleaved such a way that the LED L1 1 of the Rb1 row is immediately followed by the LED L21 of Rb2 row and the latter by the LED L12 of Rb1 row and so on until the last LED in the row R2 L28 ending illumination of the edge B1 of the guide. The other edges B2, B3 and B4 have the LEDs of the other branches respectively Rb3, Rb4; Rb5, Rb6 and RB7, Rb8, in the same configuration. Figure 3c shows electrical schematics of Lnm LED connections of the light box of Figures 3b and with the respective power sources S1 to S8.

When the size of the light box is large, the edge of the guide may comprise more than one row of aligned diodes.

4 shows a first variant of the light box of figure 3a according to the invention.

The light box of FIG 4 includes the housing 50 having a bottom 52 and an opening 54 facing the bottom 52 in the backlight of the LCD 56 and the side of the bottom of the housing 50, a printed circuit 90, parallel the bottom of the drill housing with a central hole 92, the light guide 62 having on one side 64 directed toward the bottom of housing 52 an optical structure 70 of the diffusing light propagating in the guide.

The printed circuit board 90 is coated on one of its faces 72, the side of the light guide 62, a translucent white film 94 and an opaque coating 96 having a diffusing coating hole 98 coaxial with the axis of hole central 92 of the printed circuit 90. A diffuser 75 comes to cover all over the light guide.

As in the structure of the light box of Figures 3a and 3b, the printed circuit 90 includes eight rows Rb1, Rb2, .... Rb8, seven LED

Lnm in series, respectively aligned with each of the edges B1, B2, B3, B4 of the light guide 62. Each row being driven by its respective power source S1 to S8.

The light box of the embodiments of Figures 3a, 3b and 4 has a dimension of 2.3 inch by 2.3, the waveguide has a thickness of 1 mm. The central hole 92 of the printed circuit 90 of Figure 4 has a diameter of 3 mm.

The light box of figure 4 further comprises a circuit 104 having a photoelectric 106 light receiving sensor (cp rays) scattered by the optical structure diffuser 70 of the light guide through the coating of the hole 98 opaque and the central bore 92 the printed circuit.

In this variant of Figure 4, the photoelectric sensor (or photodetector) provides electrical information Up function of the light intensity of illumination of the light box. Up this information can be used to detect a failure or a decrease illumination of the light box, but also to perform an automatic control of the light intensity provided by the light box.

Fig 5 shows a block diagram of such a servo light 110 of the same structure box as described in Figure 4 including the photoelectric sensor 106.

The electrical information output Up photoelectric sensor 106 is transmitted, after digitization, to a microprocessor mP 112 connected to a CdS 114 of the power control device supplied by the sources S1 to S8 rows Rb1 to Rb8 of the transmission LED light. Up The information output of the photoelectric sensor is used by the microprocessor 112 to act on the control device CdS 114 so as to maintain the light intensity in the light box, and this within a certain range of possibilities of variation of illumination LEDs. For example, the LED array of the light box are supplied with a periodic signal in the form of pulses, control of the illumination of the LEDs is accomplished by varying the duty cycle of power supply pulses report LED such as described above.

In a variant of the light box according to the invention, at least one row of diodes emit a different light spectrum from that emitted by the other rows.

In an exemplary embodiment, a light box according to the invention, the same structure as that of the embodiment of Figure 4, comprises two rows Rb 1 and Rb4 LED emitting a different color spectrum of other rows Rb2, Rb3, LED Rb8 to Rb5. For example the two rows Rb 1 and Rb4 emit red color in the vicinity of 615 nm.

6 shows a block diagram of a servo light emitted from a light box 119 having three photoelectric sensors 120, 121, 122 each having a respective red color filter 130, green 131 and blue 132. The sensors receiving by the coating of hole 98 and the circuit board 92 of the light box, the light diffused by the light guide.

The electrical information Upv, Upr, Upb output of the three photodetectors corresponding to the respective levels of red green and blue colors of the spectrum emitted by the light box attack after digitizing the input of a microprocessor mP 134 connected to a DoS control device 136 of the power delivered by the sources S1 to S8 rows Rb1 to Rb8 LED of the light box of each row of LEDs, some of the rows emitting different color spectrum of the other.

The microprocessor mP is configured by a memory M 138 to ensure a control of the different rows of LEDs such that the spectrum of output light of the box is the closest to a desired color for example white color and intensity determined light.

In a variant of the embodiments of Figures 3a, 3b and following, the light box according to the invention is compatible with night vision. Light boxes especially for mobile or military aircraft must meet certain radiation characteristics in the near infrared. The LEDs used in light boxes radiate in the near infrared and shall for this purpose be filtered using optical filters.

7a, 7b and 7c show partial views of light boxes of embodiments of the invention compatible with night vision.

In a first embodiment, the light box of Figure 7a comprises, on the side of the opening 54 of the box an optical filter 150 in the form of parallel plate into the housing covering the whole of the box and thus the entire filter light radiation emitted by the box. The liquid crystal display receives a filtered luminous radiation of the near infrared spectrum.

In a second embodiment of Figure 7b, the rows of LEDs themselves are covered by an optical filter 152 near infrared form of, for example, a cover over the entire length of LED branches. Another solution would be to make a molding of LED rows with a filter material near infrared radiation having, for example, the shape of cover 152.

In a third embodiment of Figure 7c, the LEDs are wired on the printed circuit 90 so as to emit light radiation perpendicular to the faces of the light guide 62, the rows of diodes being enclosed in a small housing 156, the length of rows, closed at its upper part by a longitudinal optical filter 158 of the near infrared. A mirror 160 over the entire length of the arms, inclined at 45 ° relative to the faces of the light guide deflects the filtered light emitted by the LED arrays towards the respective edges B1, B2, B3 and B4 of the light guide.

The light box according to the invention may be associated with a liquid having pixels arranged in matrix crystal structure called "quad" or four pixels, red, green, blue and white.

In case it is necessary to have a greater light intensity than that emitted by a single light box, the light box comprises a stack of branches of light emitting diodes and waveguides associated with each set branches of the same plane. 8 shows as an example a light box comprising a stack of two stages of LEDs and light guides.

A first stage E1 having first branches Rb1 to Rb8 wired LED on a first printed circuit 170 including a reflector 172 and its associated first light guide 174 and a second stage E2 having second branches Rb '1 to cable Rb'8 on a second printed circuit board 176 opened on the entire surface of the first guide 174 for passing all of the light of the two stages reflected by the reflector 172 of the first E stage and a second light guide 178 associated with the second branches Rb ' 1 to Rb'8.

The various light boxes according to the invention provide improved availability and readability of the screens to which they are intended. In addition the possibility of illuminance servo ensures retention time characteristic of light output and colorimetry of the emitted light.

Claims

1. A light box, in particular for backlighting liquid crystal displays, the box comprising:
- a light guide (30, 54, 62, 174, 176) in the form of thin plate having two main faces (32, 34, 64, 66) opposite and at least two groups (B1, B2, B3, B4), the guide having on one face a diffusing optical structure (38, 60, 70) of light; - light emitting diodes (Lnm) linearly disposed along at least one of the wafers of the light guide, the light emitted by the LEDs, illuminating the guide by the wafer, being scattered by the face of the guide having the optical structure; characterized in that the light emitting diodes arranged along each of the slices of the guide are arranged in at least two rows (Rb1 to Rb8) and such that a light emitting diode (Lnm) of one row driven by a source of power supply (S1-S8) is immediately followed by a light emitting diode (L (n + 1) m) of the other row powered by another power source.
2. A light box according to claim 1, characterized in that it comprises at least one photodetector (106, 120, 121, 122) providing a light intensity signal (Up, Upv, Upr, Upb) of the emitted light by the box.
3. A light box according to claim 2, characterized in that the light intensity information output from the photodetector is transmitted to a control system or servo of the luminance of the light box.
4. Light Box according to one of claims 1 to 3, characterized in that the LED of at least one of the branches (or rows) (Rb1 to Rb8) emit a light spectrum different from that of the other branches.
5. A light box according to claim 4, characterized in that it comprises three photodetectors (120, 121, 122) respectively provided with color filters (130, 131, 132) for sensing the light radiation from the light box in red, green and blue to produce signals allowing making a balancing color rows of LEDs.
6. Light Box according to claim 4, characterized in that it comprises a light guide (62) of rectangular shape having four units B1, B2, B3, B4, eight rows of light emitting diodes (Rb1 to Rb8) a pair rows of diodes illuminating a respective slices of the light guide.
7. A light box according to one of claims 1 to 6, characterized in that it comprises a housing (50) having a bottom (52) and an opening (54) facing the bottom (52) housing particular for backlight of a liquid crystal display (56), the side of the housing bottom (50), a printed circuit (60), parallel to the bottom of the housing, a light guide (62) having on one of the faces (64) directed toward the bottom of the housing (52) an optical structure diffusing (70) of the light propagating in the guide, the printed circuit (60) having on one of its faces (72), on the side of the light guide, a reflector (74) for reflecting towards the opening (54) (RF-rays), the scattered light (rd radiation) by the optical structure (70) of the guide, the circuit board of the light box with eight rows Rb1, Rb2, .... Rb8, seven LED Lnm ​​in series, n being the row number of 1 to 8, and m is the number of the LED in each row, the rows etan t aligned in pairs respectively on each of the edges B1, B2, B3, B4 of the light guide (60), the Rb1 and Rb2 rows illuminating the edge B1, the Rb3 rows and Rb4 illuminating B2 edge the Rb5 rows and Rb6 illuminating the edge B3 and RB7 and Rb8 rows illuminating the edge B4.
8. A light box according to claim 7, characterized in that each of the rows of LED Rb1, Rb2, ... R8 is respectively fed by an independent power source S1, S2, S8 and in that, for an edge determined the light guide, a light emitting diode Lnm a Rbn row powered by a power source is immediately followed by a light emitting diode L (n + 1) m of the other row Rb (n + 1) supplied by another power source, thus the LED of Rb1 and Rb2 rows are interleaved such a way that the LED L11 of the row Rb1 is immediately followed by the LED L21 of the row Rb2 and the latter by the LED L12 of row Rb1 and so on until the last LED in the row R2 L28 ending illumination of the edge B1 of the guide, the other edges B2, B3 and B4 having the LED of the other branches respectively Rb3, Rb4; Rb5, Rb6 and RB7, Rb8, in the same configuration.
9. Light Box according to one of claims 1 to 8, characterized in that it comprises, from the bottom side of the housing (50), a printed circuit (90) parallel to the bottom of the housing with a central hole (92), the light guide (62) having on one of the faces (64) directed toward the bottom of the housing (52) an optical structure diffusing (70) of the light propagating in the guide, the printed circuit (90) being coated on one of its faces (72), on the side of the light guide (62), a translucent white film (94) and with an opaque coating (96) comprising a diffusing coating hole (98) coaxial with the axis of the central hole (92) of the printed circuit (90).
10. A light box according to one of claims 7 to 9, characterized in that it comprises a printed circuit (104) having a photoelectric sensor (106) receiving light (cp rays) scattered by the optical diffusing structure (70 ) of the light guide through the coating of the hole (98) opaque and the central hole (92) of the printed circuit, the photoelectric sensor providing an electrical information up function of the light intensity of illumination of the light box.
11. A light box according to claim 10, characterized in that the electrical information output Up photoelectric sensor (106) is transmitted, after digitization, to a microprocessor (112) connected to a control device (114) of the power issued by the sources S1 to S8 of rows Rb1 to Rb8 LED of the light box, the information up the output of the photoelectric sensor 106 is used by the microprocessor to act on the control device so as to maintain the light intensity in the light box, and this within a certain range of LED lighting opportunities.
12. A light box according to one of claims 1 to 11, characterized in that the rows of LEDs being fed by a periodic signal in the form of pulses, control of the illumination of the LEDs is carried out by varying the cyclic slots report.
13. A light box according to one of claims 7 to 9, characterized in that it comprises three photo electric sensors (120, 121, 122) each having a respective color filter of red (130), green (131) and blue (132), the receiving sensors by coating of holes (98) and the printed circuit (92) of the light box, the light diffused by the light guide.
14. A light box according to claim 12, characterized in that the electric information (Upr, Upv, Upb) at the output of the three photodetectors corresponding to the respective levels of red, green and blue of the spectrum emitted by the light box attack after digitizing the input of a microprocessor (134) connected to a control device (136) of the power delivered by the sources S1 to S8 rows Rb1 to Rb8 LED of the light box of each row of LED emitting a different color spectrum, the microprocessor configured by a memory (134) for providing control of the various rows of LEDs such that the spectrum of output light of the box is the closest to a desired color e.g. white color and a desired light intensity.
15. A light box according to one of claims 1 to 14, characterized in that the rows of LEDs themselves are covered by an optical filter (152) near infrared, in the form of a cover, over the entire length of LED branches.
16. A light box according to one of claims 1 to 14, characterized in that one carries out a molding LED rows with a filter material near infrared radiation.
17. A light box according to one of Claims 7 to 14, characterized in that the LEDs are wired on the printed circuit (90) so as to emit light radiation perpendicular to the faces of the light guide (62), the rows the diodes being enclosed in a small package (156) of the length of the rows closed at its upper part by a longitudinal optical filter (158) of the near infrared, a mirror (160), over the entire length of the legs, inclined at 45 ° relative to the faces of the guide deflecting the filtered light from LEDs of rows to the respective edges B1, B2, B3 and B4 of the light guide.
18. A light box according to one of claims 1 to 14, characterized in that it comprises a stack of branches of light emitting diodes and waveguides associated with each set of branches of a same plane.
19. A light box according to claim 18, characterized in that it comprises a first stage E1 having first branches Rb1 to Rb8 wired LED on a first printed circuit (170) having a reflector (172) and the first guide associated light (174) and a second stage E2 having second branches Rb '1 to Rb'8 cable on a second printed circuit (176) open on the entire surface of the first guide (174) for passing all of the light of the two stages reflected by the reflector (172) of the first E1 and second light guide (178) associated with the second branches Rb'1 to Rb'8.
EP05794596A 2004-09-28 2005-09-06 Illuminated light box with light-emitting diodes Ceased EP1794631A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
FR0410270A FR2875993B1 (en) 2004-09-28 2004-09-28 Boite a light emitting diode
PCT/EP2005/054378 WO2006034943A1 (en) 2004-09-28 2005-09-06 Illuminated light box with light-emitting diodes

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RU2007116159A (en) 2008-11-10
FR2875993A1 (en) 2006-03-31
BRPI0516198A (en) 2008-08-26
CA2581593A1 (en) 2006-04-06
US8215818B2 (en) 2012-07-10
RU2416811C2 (en) 2011-04-20
WO2006034943A1 (en) 2006-04-06
CA2581593C (en) 2014-07-08
US20080062116A1 (en) 2008-03-13
FR2875993B1 (en) 2006-12-08

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