JP2002287699A - Led(light emitting diode) display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an extremely excellent video display by reducing the generation of noise and jitter extremely small in an LED display device. SOLUTION: In an LED display device 14 in which an image display signal which is generated in a display signal transmitting part 16 is transmitted to a display part 17 which is provided at a distance away from the transmitting part 16 and each LED of the LED display device 14 constituting the display part 17 are driven by a digital signal, the generation of noise from an outside and jitter is made extremely small when transmitting an image signal by providing a means for converting an analog image signal of AV equipment which is to be inputted to the transmitter 9 of the display signal transmitting part 16 into a digital signal in the transmitter 9 being at the side of the transmitter 16 and by transmitting the image signal to a signal transmission line 34 in the form of the digital signal and, thus, the extremely excellent video display can be obtained in this device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED display device used for an outdoor or indoor panel display, for example. The present invention relates to an LED display device for obtaining a display.

[0002]

2. Description of the Related Art In recent years, in the information display field for indoor and outdoor facilities, full-color compatible using red (R), green (G), and blue (B) light emitting diodes (hereinafter, referred to as "LED"). LED display devices have begun to spread rapidly. In such an LED display device, a television, a VCR, a laser disk player, a video camera, a digital video disk (DV
D) A video signal of the NTSC system such as a player is often used.

In the following description, a device for displaying an NTSC video signal will be described.
The same applies to other video signals such as CAM, HDTV, DV, and personal computer R, G, B signals.

FIG. 5 is a schematic view showing an example of the configuration of a conventional LED display device previously filed (Japanese Patent Application No. 2000-11).
0298).

[0005] As shown in FIG. 5, the LED display device has a configuration roughly divided into a transmission section 16 and a display section 17. The sending unit 16 includes a television tuner 1, a laser disk player 2,
It is provided with AV equipment such as a video deck 3 and a video camera 4, an AV selector 5, an amplifier 6, a monitor 7, a scan converter 8, and an RGB transmitter 31. On the other hand, the display unit 17 includes the RGB receiver 32, the controller 1
1, a speaker 12, a power supply 13, an LED panel display 14, and a housing 15.

[0006] AV equipment such as the television tuner 1, the laser disk player 2, the video deck 3, and the video camera 4 of the transmission unit 16 are connected as inputs of the AV selector 5. The AV selector 5 selects input signals of these AV devices. The output of the AV selector 5 is input to the scan converter 8. The scan converter 8 separates an NTSC video signal into a color signal C and a luminance signal Y, and performs color adjustment of hue, lightness, and saturation. The color signal C is then separated into color difference signals RY (U) and BY (V). These signals are subjected to analog-to-digital conversion, then scaled to an effective display area, converted to digital R, G, and B signals, and finally converted to analog and output as analog RGB signals.

[0007] The RGB transmitter 31 amplifies a signal necessary for transmitting an analog RGB signal to the RGB receiver 32. The signal transmitted to the RGB receiver 32 is R
(Red), G (green), B (blue), H (horizontal synchronization signal), and V (vertical synchronization signal). RGB transmitter 3
The distance between 1 and the RGB receiver 32 is usually about 50 to 200 m, and analog RGB signals are connected via the cable 33.

FIG. 6 shows an example of functional blocks of the RGB receiver 32. The RGB receiver 32 has an R block 32R, G
Block 32G and B block 32B, each of which includes a DC regeneration circuit 18, an analog amplifier circuit 19, and a PLL.
A circuit 21 and an A / D conversion circuit 20 are provided.

The DC reproduction circuit 18 is a circuit for adjusting the black voltage level (ground level) of the RGB color signals to a constant value.

[0010] The PLL circuit 21 of FIG. 6 generates a CLK (clock) from the horizontal synchronizing signal H.

The analog amplifier circuit 19 has a function of amplifying a signal amplitude necessary for inputting an RGB color signal to the A / D conversion circuit 20 and adjusting a gain level. A /
The RGB color signals input to the D conversion circuit 20 are converted into digital signals at the falling edge of the CLK generated by the PLL circuit 21 and output to the controller 11 shown in FIG.

The controller 11 has a gamma conversion table,
It is composed of a multiplier and a display division circuit (both not shown). The output from the RGB receiver 32 is input to the controller 11, and the controller 11 multiplies the input data by a coefficient of a gamma conversion table to perform inverse gamma conversion. Correct the difference. After that, the LE is divided by the display division circuit.
The display is divided into light emitting block units on the D panel display 14 and the signal is converted into a format in which the LED panel display 14 can read the signal.

Although the display section 17 is simply shown in FIG. 5 for clarity, in actuality, a large number of LED panel displays 14 are arranged vertically and horizontally, The display / non-display of the LED is switched. Each light-emitting block of the LED panel display 14 is composed of three primary colors of R, G, and B LEDs. Thus, the LED panel display 14
By turning on / off the R, G, and B LEDs constituting each pixel in accordance with a signal input from the controller 11, a video display can be obtained.

[0014]

However, in the conventional display device shown in FIG. 5, the A / D conversion circuit 20 for converting RGB signals from analog to digital is provided in the RGB receiver 32 on the display unit side. Therefore, there were the following problems. (1) Since the transmission unit 16 and the display unit 17 are connected by the cable 33, external noise is likely to be mixed into the cable 33. (2) The rise and fall characteristics of the signal deteriorate due to the influence of the inductance and the capacitance of the cable 33. (3) The signal loss and delay vary depending on the signal frequency due to the influence of the frequency response characteristics of the cable 33. (4) The GND level of the electric circuit on the sending unit 16 side and the GND level of the electric circuit on the display unit 17 side are different, and the sending unit 16 side and the display unit 17 are different.
Current flows between the electric circuits on the sides, and in the worst case, the driver may be destroyed.

Due to these effects, there is a certain limit to the display image quality, and a phenomenon such as noise or fluctuation due to jitter cannot be avoided.

It is an object of the present invention to obtain an image display with extremely low noise and jitter generation in such an LED display device.

[0017]

According to the present invention, there is provided an LED display device which transmits an image display signal generated by a display signal transmitting means to a display section which is installed separately from the display signal transmitting means via a signal transmission path. L that transmits and drives each LED constituting the LED display of the display unit with a digital signal.
In the ED display device, means for converting an analog image signal from an image source input to the display signal sending means into a digital signal is provided in the display signal sending means, and the image signal is provided in the form of a digital signal on the signal transmission path. Is transmitted.

According to the present invention, the image signal generated by the display signal transmitting means is transmitted to the LED display section in the form of a digital signal via the signal transmission path, so that noise and jitter are significantly reduced. This makes it possible to obtain a much better image display.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, an image display signal generated by a display signal transmitting means is provided with a signal transmission path on a display unit which is installed separately from the display signal transmitting means. L that transmits each of the LEDs constituting the LED display of the display unit with a digital signal.
In the ED display device, means for converting an analog image signal from an image source input to the display signal sending means into a digital signal is provided in the display signal sending means, and the image signal is provided in the form of a digital signal on the signal transmission path. , And the image signal generated by the display signal transmitting means is transmitted through a signal transmission path in the form of a digital signal.
It has the effect of being transmitted to the ED display.

According to a second aspect of the present invention, the display signal transmitting means has a function of converting an input analog display signal into a digital signal, and then multiplexing the digital signal and converting the digital signal into an optical signal. Has a function of converting an optical signal into an electric signal and restoring the same, and the signal transmission path is an optical fiber, and the multiplexed optical signal is transmitted through a single optical fiber to a display signal receiving means. Has the effect of being transmitted to

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

(Embodiment) FIG. 1 is a schematic configuration diagram of an LED display device according to an embodiment of the present invention. In FIG. 1, the same components as those in FIG. 5 showing the conventional configuration are denoted by the same reference numerals, and description thereof will be omitted. The difference from the past is that
This embodiment is different from the first embodiment in that the transmitter and the receiver have different internal configurations, and that the transmitter and the receiver are connected by an optical fiber for transmitting an optical signal.

More specifically, the transmitter 9 of the present invention performs analog-to-digital conversion, signal multiplexing, and conversion into an optical signal. The receiver 10 converts an optical signal into an electric signal and performs restoration. The connection between the transmitter 9 and the receiver 10 is performed by one optical fiber 34.

Hereinafter, the present embodiment will be described for the case where the output from the scan converter 8 is a VGA signal. The concept is the same even when this signal is an XGA signal or any other signal.

FIG. 2 shows an example of a functional block of the transmitter 9. The input signals to the transmitter 9 are analog RGB color signals, H (horizontal synchronization signal), and V (vertical synchronization signal). The transmitter 9 includes a DC reproduction circuit 18, an analog amplifier circuit 19, a PLL circuit 21, an A / D conversion circuit 20, an OSC circuit 22, a timing control circuit 23, a RAM 24, a multiplexing circuit 25, and an E / O conversion circuit 26. You.

The input from the scan converter 8 adjusts the black voltage level (ground level) of the RGB color signal to a constant value by the DC reproduction circuit 18 provided in each of the R block 9R, the G block 9G, and the B block 9B. . This is because the output of the scan converter 8 absorbs the difference in specifications depending on the manufacturer, and because there is a slight level difference between the RGB signals. Therefore, when high-precision conversion is required, adjustment of the DC level and gain of these signals is indispensable.

The PLL circuit 21 outputs a signal from the horizontal synchronizing signal H to CL.
K is generated, and the phase is adjusted at the same time. CLK is A / D
Since this becomes a reference for the conversion timing of the conversion circuit 20, it is necessary to adjust the phase.

The analog amplifier circuit 19 has a function of amplifying a signal amplitude necessary for inputting an RGB color signal to the A / D conversion circuit 20 and adjusting a gain level. A /
The RGB color signals input to the D conversion circuit 20 are converted into 10-bit digital signals for each color at the falling edge of the CLK generated by the PLL circuit 21.

The OSC circuit 22 is a circuit for generating OCLK having a reference transmission frequency for optical transmission. In this embodiment, 32 VGA signals (R, G, B, H, V) are multiplexed, so that 25 MHz × 32 = 800 MHz, and transmission is performed at 1 GHz with a margin.

The timing control circuit 23 controls the storage and reading of the A / D-converted RGB digital signals to and from the RAM 24 and, at the same time, controls the data transfer to the multiplexing circuit 25. The inside of the RAM 24 is composed of two sets, one for odd frames and one for even frames. When writing data to an odd frame, the timing control circuit 23 transmits the data of the even frame to the multiplexing circuit 25 so that the digital RGB write frequency (25M
Hz) and the difference between the read frequency of optical transmission (1 GHz).

The multiplexing circuit 25 converts the RGB digital data, the horizontal synchronizing signal H and the vertical synchronizing signal V into serial data, and generates a serial horizontal synchronizing signal HS and a serial vertical synchronizing signal VS. The E / O conversion circuit 26 converts the serially converted electric signal into an optical signal.

FIG. 3 shows an example of functional blocks of the receiver 10. The input signal to the receiver 10 is an optical signal. The receiver 10 includes a synchronization circuit 27, a clock recovery circuit 28, an O /
It comprises an E conversion circuit 29 and a restoration circuit 30. The received optical signal is converted into an electric signal by the O / E conversion circuit 29. This signal is output to the synchronization circuit 27 and the clock recovery circuit 2
8 and the restoration circuit 30. The clock recovery circuit 28 restores the OCLK signal to 1 GHz from the electric signal. A signal is generated by this circuit so that the frequency and the phase become the same as the timing at the time of transmission. The synchronization circuit 27 extracts a serial vertical synchronization signal VS and a serial horizontal synchronization signal HS from the electric signal. Clock recovery circuit 28
And the synchronization circuit 27, the serial horizontal synchronization signal HS,
The serial vertical synchronization signals VS and OCLK are restored so as to be the same as at the time of transmission. The restoration circuit 30
H, V, CLK and R from K, HS, VS and electric signal
The digital 30-bit data of GB is restored and converted into parallel data.

The operation of the transmitter 9 and the receiver 10 will be described while comparing the timing chart of the present embodiment shown in FIG. 4 with the timing of the conventional RGB receiver shown in FIG. To summarize the characteristics of the conventional timing, the display signal is invalid during the blank period when the vertical synchronizing signal V is "L".
The display signal is valid during the period when the horizontal synchronization signal H and the vertical synchronization signal V are “H”. The effective display data is 640 dots at 1H and 480 lines at 1V.

On the other hand, the timing of the transmitter according to the embodiment of the present invention shown in FIG. 4 can be roughly classified into a data valid period and an invalid period. The vertical synchronization signal V is a combination of “L” of four clocks and “H” of four clocks (the serial vertical synchronization signal VS described above). The period during which the display data is invalid changes from L to H, and the period during which the display data is valid changes from H to L. The horizontal synchronization signal H always changes from L to H by a combination of “H” of two clocks and “L” of two clocks (the serial horizontal synchronization signal HS described above). While the data is valid, display data is sent after the serial horizontal synchronizing signal HS.

Data R0, G0, B0, R of the first dot
Each color of R9, G9, B9 by repeating 1, G1, B1
0-bit data is transmitted and transmitted up to the 640th dot. Further, when these 640 dots of data are transmitted through 480 lines, one frame of display data is transmitted, and the invalid period thereafter.

When the power is turned on, several frames of non-display data are sent. As shown in FIG. 4, in this case, the display data all become "H" in this period and do not change, and the signal changes only in the vertical synchronization and the horizontal synchronization. The receiver 10 can reproduce the start timing of the frame by extracting the change point. Similarly, the clock recovery circuit 28 of the receiver 10 extracts the change point of the horizontal synchronization to obtain the OC.
The frequency and phase of LK can be reproduced. After these synchronization operations are completed, the actual display data is sent.

As described above, the synchronization work is performed at the beginning of the power supply, and after the work is completed, the actual display data is transmitted, so that the RGB, H, and V signals can be transmitted / restored with one optical fiber. Will be possible. In this case, depending on the multiplexing method and the transmission frequency, the transmission distance can be from 1 km to several tens km with one fiber.

On the other hand, when signals are not multiplexed,
For example, in the case of 10 bits for each color, a 30-bit signal is H,
It is necessary to connect a total of 33 signals of V and CLK by the sending means and the receiving means. In addition, since this connection is usually made with a metal cable, only a few hundred meters can be transmitted even in parallel transmission.

Although the above embodiment has been described with reference to the case of transmitting with one signal, it is of course possible to perform transmission with a plurality of signals by changing the transmission method.

Further, by arranging the A / D conversion circuit 20 near the scan converter 8, it is possible to further reduce noise mixed in from the electric wiring.

[0041]

As described above, according to the present invention, the image signal generated by the display signal transmitting means is transmitted in the form of a digital signal to the LED display unit via the signal transmission path. The generation of external noise and jitter during transmission is extremely small, so that a much better image display can be obtained.

Further, after the display signal transmitting means converts the analog display signal into a digital signal, the digital signal is multiplexed, converted into an optical signal, and output to the receiving means, thereby reducing the number of physical cables. It is possible to improve wiring work, maintainability, and reliability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a display device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a transmitter provided in a transmission unit of the LED display device.

FIG. 3 is a configuration diagram of a receiver provided in a display unit of the LED display device.

FIG. 4 is an internal timing diagram of a transmitter.

FIG. 5 is a schematic configuration diagram of a conventional LED display device.

FIG. 6 is a configuration diagram of a transmitter provided in a display unit of a conventional LED display device.

FIG. 7 is an internal timing diagram of the receiver.

[Explanation of symbols]

 Reference Signs List 1 TV tuner 2 Laser disc player 3 Video deck 4 Video camera 5 AV selector 6 Amplifier 7 Monitor 8 Scan converter 9 Transmitter 10 Receiver 11 Controller 12 Speaker 13 Power supply 14 LED panel display 15 Housing 16 Sending unit 17 Display unit 18 DC playback Circuit 19 Analog amplifier circuit 20 A / D conversion circuit 21 PLL circuit 22 OSC circuit 23 Timing control circuit 24 RAM 25 Multiplex circuit 26 E / O conversion circuit 27 Synchronization circuit 28 Clock recovery circuit 29 O / E conversion circuit 30 Restoration circuit 31 RGB transmitter 32 RGB receiver 33 Cable 34 Optical fiber

Claims (2)

[Claims] 1. An image display signal generated by a display signal transmitting means is transmitted to a display unit provided at a distance from the display signal transmitting means via a signal transmission path to constitute an LED display of the display unit. In an LED display device that drives each LED with a digital signal, a means for converting an analog image signal from an image source input to the display signal sending means into a digital signal is provided in the display signal sending means,
An LED display device configured to transmit an image signal in the form of a digital signal to the signal transmission path. 2. The display signal transmitting means has a function of converting an input analog display signal into a digital signal, multiplexing the digital signal and converting the digital signal into an optical signal, and the display signal receiving means converting the optical signal into an electric signal. Has the function of converting to and restoring,
2. The LE according to claim 1, wherein the signal transmission path is an optical fiber.
D display device.