1. Technical Field
The disclosure relates to LED display devices, and particularly to an LED display device with high light extracting efficiency.
2. Description of the Related Art
Light emitting diodes (LEDs) have many advantages, such as high luminosity, low operational voltage, low power consumption, compatibility with integrated circuits, easy driving, and environmental friendliness. Such advantages have promoted the wide use of LEDs as a light source. Now, LEDs are commonly applied in display devices.
A conventional LED display device includes a printed circuit board with a plurality of LEDs mounted thereon, a transparent cover mounted on a front side of the printed circuit board and a back plate mounted on a rear side of the printed circuit board. The printed circuit board includes a plurality of opaque circuit layers stacked together. The back plate connects the transparent cover for sealing the printed circuit board and the LEDs therebetween, thereby protecting the LEDs from dust and dirty. However, due to the printed circuit board is opaque, a portion of light emitted from the LEDs incident on the printed circuit board needs to be reflected many times before emitting out of the LED display device and another portion of light emitted from the LEDs incident on the printed circuit board can be absorbed by the printed circuit board, such that a light extracting efficiency of the LED display device is adversely affected.
What is desired, therefore, is an LED display device which can overcome the above-described shortcomings.
Embodiments of an LED display device as disclosed are described in detail here with reference to the drawings.
Referring to
The first transparent substrate 11 is substantially rectangular, and includes a main plate 110 and a connecting interface 112 at one periphery side of the main plate 110. The first transparent plate 11 is made of transparent material, such as glass or plastic. Referring also to
The LED light source 13 includes a plurality of LEDs 131 arranged in a matrix and mounted on the top surface of the main plate 110. The circuit wires 113 of the circuit structure 111 are electrically connected between the connecting interface 112 and the LEDs 131. The circuit wires 113 are parallel to each other. Referring to
The first ends 114 of the circuit wires 113 are equally spaced from each other along the connecting interface 112. A distance between each two neighboring second ends 115 is larger than that of each two neighboring first ends 114, and the distances between each two neighboring second ends 115 are gradually increased along a direction away from the connecting interface 112. With such a configuration, an impedance of the second ends 115 of the circuit wires 111 which are located far away from the connecting interface 112 can be substantially equal to that of the second ends 115 which are located adjacent to the connecting interface 112. Thus, an intensity of light emitted from a portion of the LEDs 131 which are located far away from the connecting interface 112 can be substantially the same as an intensity of light emitted from the other portion of the LEDs 131 which are located adjacent to the connecting interface 112. In other words, intensity of light emitted from each of the LEDs 131 is substantially equal to each other.
The second transparent substrate 12 is similar to the first transparent substrate 11. The second transparent substrate 12 is substantially rectangular, and made of transparent material, such as glass or plastic. The second transparent substrate 12 is different from the first transparent substrate 11 in that the second transparent substrate 12 has no circuit structure 111 formed thereon. The second transparent substrate 12 covers the LEDs 131.
The affixing layer 14 is interconnected between the first transparent substrate 11 and the second transparent substrate 12. The affixing layer 14 is made of polyvinyl butyral resin or ethylene-vinyl acetate copolymer. The affixing layer 14 is configured to fill in an air clearance defined between the first and the second transparent substrates 11, 12 when the first and the second transparent substrates 11, 12 are connected together.
The diver unit 15 includes a plurality of flexible printed circuit boards 151 with diver circuit formed therein. The diver unit 15 is mounted on the connecting interface 112 of the first transparent substrate 11, and the diver circuit electrically connects with the circuit structure 111 of the first transparent substrate 11.
The control unit 16 is electrically connected with the drive unit 15. The control unit 16 is configured to receive a signal containing displaying message and output the signal to the drive unit 16, such that the LEDs 131 can emit light in a controlled manner for showing the message thereby. The control unit 16 receives the signal via wireless transmission, such as general packet radio service, wireless fidelity, blue tooth, etc. Alternatively, the control unit 16 can include an SD card for storing multiple displaying programs therein.
The AC-DC convertor 17 is electrically connected between an outer power source and the control unit 16. The AC-DC convertor 17 is used to convert an AC voltage obtained from the outer power source to a DC voltage and then supply the DC voltage to the control unit 16.
The fixing frame 18 includes a first fixing plate 181, a second fixing plate 182 and a plurality of fastening elements 186. Each of the first fixing plate 181 and the second fixing plate 182 is elongated, and has a generally L-shaped cross-section. The first fixing plate 181 includes a top wall 180, a side wall 183 extending downward from a long side of the top wall 180, and a first connecting wall 184 extending outward from another long side of the top wall 180. The top wall 180 defines a first engaging groove 185 at a top surface along a lengthwise direction thereof. The second fixing plate 182 includes a bottom wall 187 and a second connecting wall 188 extending outward from a long side of the bottom wall 187. The bottom wall 187 defines a second engaging groove 189 at a bottom surface along a lengthwise direction thereof.
Each of the fastening elements 186 is about U-shaped, and includes two engaging plates 1861 formed at two opposite distal ends thereof. When the fixing frame 18 is assembled, the top wall 180 of the first fixing plate 181 is parallel to and spaced from the bottom wall 187 of the second fixing plate 182, and a bottom of the side wall 183 of the first fixing plate 181 connects with the bottom wall 187. The first fixing plate 181 and the second fixing plate 182 cooperatively define a rectangular receiving room 19 receiving the AC-DC convertor 17, the control unit 16 and the drive unit 15 therein. The first engaging groove 185 and the second engaging groove 189 are aligned with each other. Each of the fastening elements 16 connects the first fixing plate 181 with one of the engaging plates 1861 engaged in the first engaging groove 185, and connects the second fixing plate 182 with the other engaging plate 1861 engaged in the second engaging groove 189. The first connecting wall 184 and the second connecting wall 188 are parallel to and spaced from each other. A distance between the first connecting wall 184 and the second connecting wall 188 is substantially equal to a sum of thicknesses of the first and second transparent substrates 11, 12.
In assembling, the first connecting wall 184 and the second connecting wall 188 abut a top surface of the second transparent substrate 182 and a bottom surface of the first transparent substrate 181, respectively; then screws 20 are extended through the first connecting wall 184, the second transparent substrate 182, the first transparent substrate 11 and the second connecting wall 12 in sequence to thereby connect the first transparent substrate 11, the second transparent substrate 12 and the fixing frame 18 together.
Due to the first transparent substrate 11 and the second transparent substrate 12 which sandwich the LEDs 131 therebetween are both made of transparent material, light emitted from the LEDs 131 incident on the first transparent substrate 11 and the second transparent substrate 12 can directly transmit through the first transparent substrate 11 and the second transparent substrate 12 without multi-reflection, respectively, such that the LED display device 10 has a high light extracting efficiency. In addition, the first transparent substrate 11 and the second transparent substrate 12 both allow light to pass therethrough, such that the LED display device 10 in whole is luminous to have better visual effects.
A method of manufacturing the LED display device 10 includes following steps:
The first step is to provide the first transparent substrate 11 with the circuit structure 111 formed thereon. The circuit structure 111 includes a plurality of circuit wires 113 which are formed on the first transparent substrate 11 by screen printing of conductive silver paste.
The second step is to mount the LEDs 131 on the first transparent substrate 11 in a matrix.
The third step is to provide the second transparent substrate 12 covered on the LEDs 131 via the affixing layer 14.
The fourth step is to provide the drive unit 15, the control unit 16, the AC-DC convertor 17 and the fixing frame 18. The drive unit 15, the control unit 16 and the AC-DC convertor 17 are connected to the first transparent substrate 11 and the second transparent substrate 12 via the fixing frame 18.
Referring to
It is to be further understood that even though numerous characteristics and advantages have been set forth in the foregoing description of embodiments, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Number | Date | Country | Kind |
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100116594 | May 2011 | TW | national |