JPS59160386A - Optical picture signal transmitter - Google Patents

Abstract

PURPOSE:To correct automatically a signal level of every color by supreposing a pilot signal for AGC control on the signals of respective transmission systems of the three primary colors. CONSTITUTION:Color signals R, G, and B are supplied to terminals 3, 4, and 5 of a transmission side 1 and supplied to mixers 7, 8, and 9. A synchronizing signal is applied to a terminal 6 and converted by a shaping circuit 13 into a pulse signal which contains none of the color signals as shown in a figure C, and the converted signal is applied to the mixers 7, 8, and 9 respectively. Electrooptic converting circuits 10, 11, and 12 convert electric signals from the mixers into light signals, which are sent out through optical fiber cables 14, 15, and 16. A reception side 2, on the other hand, separates the pulse signals superposed on the transmission side by respective gate circuits and level comparators to control the gains of variable gain amplifying circuits 20, 21, and 22 inserted into respective systems according to the levels of the separated pulse signals.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical image signal transmission device using light as a transmission medium.

Conventional configurations and their problems In recent years, information transmission systems using light as a transmission medium have been increasingly adopted. This is because light is not affected by electromagnetic waves, is resistant to noise, can transmit large amounts of data, and optical fibers are lightweight and have a small volume. However, in conventional display systems using color TV displays, electrical signals are transmitted as they are, but this method is susceptible to noise caused by electromagnetic waves, and when it comes to long-distance transmission, compared to optical fiber cables,
The disadvantage is that the volume and weight of the cable becomes extremely large.

Purpose of the Invention In view of the above-mentioned disadvantages of the conventional technology, the present invention provides a display system using a color television display in which three primary color signals are transmitted using three independent optical transmission paths, and the three primary color signals are An object of the present invention is to provide an optical image transmission device that automatically adjusts the level of the image.

Structure of the Invention The present invention provides an electro-optical conversion circuit that converts three sets of electrical signals corresponding to the three primary colors of R, G, and B of a television signal into optical signals, an optical transmission line that transmits each optical signal, Three sets of independent transmission systems are formed, each including a photoelectric conversion circuit that converts an optical signal from each transmission line into an electrical signal, and an amplifier circuit that amplifies the electrical signal from each photoelectric conversion circuit. A pulse signal of a constant amplitude is superimposed on a part of the non-image display period of the primary color signal, and the level difference between the three sets of transmission systems is detected and compensated for by the level of the pulse signal. An optical image transmission device is provided in which level fluctuations between signals are minimized.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings.
1) is a transmitter, and (2) is a receiver. In the proximal portion (1), +31 <4+ (5) is an input terminal for the three primary color signals of RoG and B of the television signal, respectively, and (6) is a synchronization signal input terminal for the television signal. (7) (8) (9)
is a mixing circuit for each of the three primary color signals and synchronous and superimposed signals, 00α
η(6) is an electro-optical conversion circuit that converts the electric signal output from the mixing circuit into an optical signal, and (to) is a synchronization and superimposition signal shaping circuit. α4) αυα0 is the transmitter (1) and the receiver (2)
) is an optical transmission line (optical fiber) that connects the three primary color signals, and is provided corresponding to each of the three primary color signals. In the receiving section (2), α'7) (181α9) is a photoelectric conversion circuit, (4) C
υ is a variable gain amplifier circuit, (4) is an amplifier circuit, (c) (
C) (C) is a gate circuit, ■ (A) is a level comparison circuit,
□□□ is the gate signal shaping circuit, and ■lυ are R and G, respectively.
.

B is the output terminal for the three primary color electric signals, and No. 6 is the input terminal for the horizontal synchronization signal.

Next, the operation will be explained. First, in the transmitting section (1), a horizontal synchronizing signal (2) of a television signal as shown in FIG. 2 (Al) is supplied from a synchronizing signal input terminal (6) to a shaping circuit (alpha).

In FIG. 2 (Al), (b) is a -horizontal period, (b) is an image display period, and (b) is a non-image display period (retrace line and overscan period). The shaping circuit α rises from the end of the horizontal synchronization signal of the non-image display period (towards the image/display period).
During the period (b) until the start of t, a pulse signal (pilot signal) N shown in Fig. 2 (C) is generated, and when it is superimposed with the horizontal synchronizing pulse, a signal as shown in Fig. 2 (C) is generated. Output. The amplitude of this pulse signal is determined by the mixing circuit (7)' (
8) In the mixed state in (9), the maximum amplitudes of the three primary color signals of RoG and B are held constant so as to match. on the other hand,
Input terminal +31 (4! Mixing circuit (7) from (5)
(8) In (9), the R of the television signal as shown in the example in Figure 2
Three primary color signals of oG and B are supplied. Then, in the mixing circuit <7)L8) (9), the three primary color signals of R8G and H (c) and the synchronization signal) and the pulse signal (to) are mixed to produce a signal as shown in Figure 2 (D). Each of the signals is supplied to the next-stage electro-optical conversion circuit 00α])021. Electro-optical conversion circuit (10Q
l) Q2 modulates the electrical signal into an optical signal (light amplitude, width modulation, etc.) using a light emitting element such as an LED, and sends it to the optical transmission line 04.
Send each to α5106.

In the receiving section (2), the optical signals from the optical transmission lines (14), (g) and 0 are converted into electrical signals using a photoelectric conversion circuit using PIN photodiodes, etc., respectively, and then converted to electrical signals for the next stage. The signal is supplied to the gain type amplifier circuit (E) (2η) and the amplifier circuit (A), each amplifying the signal and transmitting the signal to the next stage gate circuit (2η).
goods) to supply signals to the fourth. On the other hand, the horizontal synchronizing pulse signal generated by the subsequent display (not shown) is input to the horizontal synchronizing signal input terminal (a) and is supplied to the gate signal and signal shaping circuit. The gate signal shaping circuit eAl generates a gate pulse signal ■ to gate and extract the 6-wave portion of the pulse signal as shown in Figure 3 (Al) from the horizontal synchronizing pulse, and the gate circuit (e) (c) ( c) is supplied as a gate signal.

In the gate circuit (23 (c) 4), signals similar to those shown in FIG. At the same time, the gate pulse signal shown in FIG. 3(A) from the gate signal shaping circuit is
Extract only the pilot signal direction corresponding to the pulse signal shown in ). And extracted pilot signal (9
) is supplied from the gate circuit to the level comparison circuit (to), from the gate circuit (c) to the level comparison circuit (a), and from the gate circuit (c) to the level comparison circuit (c) and the output. do. In this way, based on the pilot signal (6) from the gate circuit (c) in one transmission system of the three primary color signals of RlC and B of the television signal, the pilot signal from the gate circuit @ ■ in the other transmission system is 0.
The level comparators (4) (a) compare υ, and if it is larger than the pilot signal from the gate circuit (c), the gain is lowered, and if it is smaller, the gain is increased. (c) From (a) to variable gain amplifier circuit 12
0) @I) and keep the output voltage levels of the three primary color signals of R, G, and B constant. In this way, R, G,
Even if the three primary color B signals are transmitted using independent transmission systems, there are inconveniences such as the amplitude and level of each signal fluctuating and the displayed hue changes, or the accurate hue cannot be transmitted due to variations in the transmission path. is completely eliminated.

Effects of the Invention As is clear from the above description, the optical image signal transmission device of the present invention can realize optical transmission without interference from noise such as electromagnetic waves even in the transmission of image signals from color televisions, etc. R,G.

The three primary color B signals can be transmitted using independent transmission systems, rather than in the form of a TV composite signal that is susceptible to band limitations and non-linear distortion, and furthermore, the amplitude and level fluctuations between the three signals can be automatically compensated for, resulting in extremely high performance. It has many advantages, such as being able to transmit high-quality image signals.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an optical image signal transmission device according to the present invention, and FIG. 2 (Al FB+ (C) (D+,
FIG. 3(c) HBI is a signal waveform diagram for explaining the operation. (7) (8) (9) is a mixed circuit, (jσ (6) (l) is an electro-optical conversion circuit, 841α uniform aQ is an optical transmission line, aηQ
8) Q') is a photoelectric conversion circuit, 翰(2υ) is a variable gain type amplifier circuit, (goods) is an amplifier circuit, 迺(c)(to) is a gate circuit, (4)(a) is a level comparison circuit, The second one is the gate signal shaping circuit.

Claims (1)

[Claims] An electro-optical conversion circuit that converts three sets of electrical signals corresponding to the three primary color signals into optical signals, an optical transmission line that transmits each optical signal, and an opto-electrical circuit that converts the optical signals from each transmission line into electrical signals. Three sets of independent transmission systems are constructed, each equipped with a conversion circuit and an amplifier circuit that amplifies the electrical signal from each opto-electrical conversion circuit. An optical image signal transmission device configured to superimpose pulse signals of 1 to 3 and to detect and compensate for level differences between three sets of transmission systems using the levels of the pulse signals.