JPS6156919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image recording device that stores television images for a long time so that they can be read out and displayed at any time. By using memory to store regular television broadcast screens as binary signals, for example, characters and figures such as names and quantities of ingredients in cooking programs and addresses on postcards can be retained for long periods of time. The aim is to provide a device that can

Conventional image recording devices of this kind have used analog memories such as disk memories or large-capacity digital memories, and have been very expensive and had complex peripheral circuits.

The present invention uses digital memory for about one field of a teletext receiver to convert video signals into two simple
The object of the present invention is to provide a simple and low-cost device by converting the signal into a value signal and storing it in this digital memory.

Hereinafter, the present invention will be explained with reference to the drawings. First, FIG. 1 shows a block diagram of this embodiment. Here, the parts marked with symbols 1 to 18 are well-known so-called teletext receivers, and 1 is a tuner for receiving television signals;
2 is a VIF circuit, 3 is a video detection circuit, 4 is an amplifier circuit, 5 is a read signal from the memory 17 and the amplifier circuit 4
6 is a video output circuit, 7 is a cathode ray tube for display, 8 is a synchronization separation circuit, and 9 is a color subcarrier regeneration circuit. Further, 10 is a circuit for waveform shaping a television signal into a binary signal, and 11 is a gate circuit for extracting only the 20th H character signal superimposed section during the vertical blanking period (VBL) in the case of teletext reception. The device is also capable of extracting the 21st to 258th H video signals as described below).
12 is a circuit that counts horizontal pulses and generates gate pulses during the period when the gate circuit 11 extracts the signal;
13 is the basic clock 8sc (≒28MHz)
This is an oscillation circuit that oscillates a signal, and the phase is synchronized with the color subcarrier sc using a PLL circuit or the like. 14
15 is a circuit that samples the output of the gate circuit 11 using the clock pulse output from the clock generation circuit 16, and 15 is a circuit that detects a start signal in the control signal when receiving teletext broadcasting, and the detection output is used to start the clock. The phase of the generator circuit 16 is controlled to properly match the sampling clock to the phase of the received signal. This clock generation circuit 16 is 1/5
A circuit that includes a frequency divider circuit, the basic clock oscillation circuit 1
The basic clock of 8sc from 3 is divided by 1/5 to obtain a phase-synchronized pulse with the same frequency as the bit rate of the received signal, and this is further divided or gated to obtain various necessary clock pulses. 1
Reference numeral 7 denotes a memory for storing received character signals. Assuming that character information is expressed as a pattern signal of 256 bits per line and one screen is composed of 200 lines in total, this memory 17 has a capacity of 51,200 bits. use something Note that if the number of lines on the screen is 256, a 64K bit general-purpose IC memory can be used. The memory control circuit 18 is a circuit that controls writing and reading of signals in the memory 17. Since the operation of the circuit described above is well known as a so-called teletext receiver, a detailed explanation thereof will be omitted.

Next, an outline of the present apparatus, which uses the above-mentioned teletext receiver to store ordinary television broadcast screens, will be described first. Here, it is assumed that characters are extracted from a screen showing ingredients of a cooking program as shown in FIG. 2A and stored. Note that the text portion is closer to the white peak than the other portions. It is often desirable to keep the screen static for a while and take notes on the contents of the screen displayed in such characters, so this device
In such a case, the received video signal is sliced at a predetermined level by a waveform shaping circuit to extract only the characters as shown in Figure 2B, stored in the memory for the teletext receiver, and then continuously reproduced (read). Do it like this. At that time, while the waveform shaping circuit is adjusting the slice level, only the slice output is displayed on a depolarizer tube, etc. to facilitate the adjustment, and after the adjustment is completed, only the readout output from the memory is displayed, or as needed. Accordingly, the image is displayed superimposed on the image receiving screen.

Below, referring to FIG. 3, a circuit for waveform shaping a television screen into a binary signal will be described first. In FIG. 3, 21 is a transistor forming an emitter follower stage, 22 is a capacitor of a clamp circuit, and 23 is a soft clamp circuit for pedestal clamping. Therefore, at the clamp output end (point _P1 ), the color burst is not attenuated, as shown in FIG. 4B. Incidentally, FIG. 4A shows the output waveform or the detection output of the positive polarity of the image. As shown in Figure 4B,
Clamp the pedestal to e.g. OV at _one point P.
Transistor 24 is for buffer amplifier, 25,2
6 is a transistor forming a differential amplifier, 27 is an output load resistance, and when the relay 28 is short-circuited between A and C, the variable resistor 29 is adjusted, and the character information in VBL is shaped into a binary signal. P Take out from ₂ points. On the other hand, when the adjustment knob in the adjustment circuit 19 shown in FIG. 1 is touched, the detection circuit 20 detects this and the flip-flop (FF) 30 is set. The touch detection means may be a calculator key, a television channel key, a local adjustment knob known as a magic line, or the like. The most desirable type is one in which the output of the touch detection circuit 20 appears only while the knob of the adjustment circuit 19 is being touched. Then, turn the knob of the adjustment circuit 19 to quickly adjust so that only the signal of the character portion appears as the output of the slice circuit, as shown in FIG. 2B. Note that when a white peak hits a part of the screen or the level of the text has not reached the white peak, pixels other than text will also appear as white figures in the waveform in Figure 2B, but if the text can be read, the purpose is I can accomplish it. The signal waveform of X-X' in FIG. 2A is shown in FIG. 4A, and the slice output becomes FIG. 4C and is displayed as in FIG. 2B.
31 in FIG. 3 is a circuit that resets the FF 30 by detecting the end of the output of the detection circuit 20 (auto-reset) or by resetting it with a manual switch, and the FF 30 is a high-output type that activates the relay 28. It is FF. The slice output signals of _{the two} points P are converted to a TTL level by the level conversion circuit 32 and applied to the gate circuit 11, and are also converted to the same level as the video signal of _{the three} points P and transmitted to the mixing circuit 5.

While the waveform shaping circuit 10 is adjusting the slice level, the switching/mixing circuit 5 is switched to output only the slice output signal from the level conversion circuit 32 by the Q output of the FF 30, and the cathode ray tube 7 Only the sliced and extracted video is displayed. In this way,
It becomes extremely easy to adjust the slice level to the optimum state while viewing the extracted video, and the best memorization can be achieved.

Furthermore, since the memory 17 is generally a digital memory, reading and writing cannot be performed at the same time.
30), the output of the level shift circuit 32 is transmitted to the cathode ray tube 7 as described above, and the output of the level shift circuit 32 is transmitted to the memory 1.
7, it is suitable to write signals for about 240 lines of each field screen.

Next, writing to the extraction gate 11 and memory 17 will be described. When receiving teletext broadcasting, the extraction gate 11 is used for the character signal superimposed section in VBL, for example
The output of the waveform shaping circuit 10 is passed during 238H from the 21st H to the 258th H.

This part will be described in detail below with reference to FIGS. 5 and 6. In FIG. 5, 8A is a part of the synchronization separation circuit 8, and its output is a composite synchronization signal. 8V is a circuit that integrates the output to obtain a vertical pulse as shown in Figure 6E.For example, as shown in Figure 6F, the pulse falling at the 4th H (267th H) common to the two fields is Output. A flip-flop 8F is set with the output of the integrating circuit 8V, and the output shown in FIG. 6G is obtained. This output G is supplied to the clear terminals of line counters 33A and 33B. For example, the counters 33A and 33B are SN7493.
There is a 4-bit binary counter such as Counters 33A and 33B are enabled to count when G goes low, and count the leading edge of the 5H horizontal pulse (this pulse may be the horizontal flyback pulse of a normal television receiver). Therefore,
The 20th H will be the 16th count. That is, the 16th count from the decoder 34 in FIG.
Obtain a low level output for 1H, invert this and
Supply to AND gate 35. On the other hand, FF36 is the
It is set at the beginning of the 17th count (21st H),
It is reset at the beginning of the 255th count (259th H), and the Q output of the FF 36 is transmitted to the AND gate 37. On the other hand, when the changeover switch 19S is short-circuited between a and b as shown in FIG. th~th
The signal is at a high level for 238H on the 258th H, and is transmitted from the output of the level shift circuit 32 to the sampling circuit 14 via the AND gate 39 for 239H. That is, almost the entire screen of a typical television receiver (including most of the vertical overscan area) can be sampled and stored in memory.

The pulse width of 1 bit in the case of teletext is approximately 175 ns when the clock rate is 5.7 MHz, so a portion of 0.175 x 256 = 44.8 μs in the horizontal direction will be recorded, but if it is insufficient, it will be even longer. All you have to do is increase the capacity of the memory 17. Furthermore, the roughness of the sampling in the horizontal direction is fine enough for practical use. In addition, in Fig. 5, the changeover switch (19-S) is set to b-
Needless to say, when C is short-circuited, the output of the OR gate 38 becomes high level only during the 20th H, and the receiver functions as a known teletext receiver.

As described above, it is possible to sample a normal television screen as points of 238 lines in the vertical direction and 256 bits in the horizontal direction.

Next, writing to the memory 17 may be the same as writing the 20th H teletext signal, but in order to make it easier to understand, how to give an address will be explained with reference to FIG. 7. For simplicity, the horizontal direction is the same as when receiving teletext broadcasting. That is, when sampling and storing the teletext signal, that is, the 20th H
ONLY the AND gate 15A is made conductive, the start signal of the phase information signal in the character signal is detected, the start position is determined, and the horizontal address counter 18A is
make it work. At times other than the 20th H, the AND gate 15B is made conductive, and the counter 15C counts 8sc basic clock pulses from the beginning of the horizontal flyback pulse to generate a condensed start pulse at an appropriate position as the left edge of the screen.
The tarlock generating circuit 16 is driven through the OR gate 150 and the horizontal address of the display and the horizontal address when recording the above-mentioned television screen are determined.

Next, vertical addresses will be described. In the case of teletext broadcasting, a control signal indicating the display position in the vertical direction in the character signal is sent, so this is stored in the latch memory 18M, data is converted so that it can be written to an appropriate position in the memory 17, and the vertical address is set. Preset counter 18C. At this time, since the address selector 18S passes the output of the counter 18C, data is written into the memory 17 as in the case of a normal teletext receiver. For reading, address selector 18S
supplies the outputs of counters 33A and 33B to memory 17. When storing a normal television screen, the selector 18S always transmits the outputs of the counters 33A and 33B to the memory 17. Note that 14 is an 8-bit serial input->parallel output shift register.

To switch between writing and reading the memory 17,
This can be done as shown in FIG. That is, the output of the AND gate 35 is at a high level only at the 20th H when multiple characters are received, and when the write instruction signal is output at a high level from the memory control circuit 18, the output of the AND gate 40 is at a high level. Become. Therefore, NOR
The output of gate 41 goes low and memory 1
7 is in the write state. On the other hand, AND gate 35
When the output of is low level, when FF30 is high level, the output of AND gate 42 is high level,
The output of the NOR gate 41 becomes low level and the memory 17 enters the write state. Therefore, Q of FF30
While the output is at a high level, that is, when the switching adjustment circuit 19 is touched as described above, and the output of the touch detection circuit 20 is at a high level, the video signal is converted into a binary value and the memory 1
7. At this time, the output of the level shift circuit 32 is displayed on the cathode ray tube 7. During writing, the output level may be unstable depending on the type of memory 17, but with this method, during writing,
Since the memory write input signal is displayed, there is no effect of output fluctuations.

As described above, according to the present invention, it is possible to easily store characters, etc. on a normal television screen using the digital memory of a teletext receiver, and read them out and display them at any time later. Moreover, a useful device can be obtained. Furthermore, even if the digital memory is shared in this way, the waveform shaping level in the waveform shaping circuit is adjusted separately for the teletext signal and the television screen video signal.
Regardless of which signal is stored, it can always be independently adjusted to the optimum state. Further, while adjusting the slice level, only the image output from the waveform shaping circuit is displayed, so that the slice state of the television screen, that is, the storage state can be displayed in an easy-to-understand manner, making adjustment easy.

In addition, while adjusting the waveform shaping level of the video signal on the television screen, the waveform shaping output is displayed, so you can clearly see how the memorized signal is and adjust the shaping level. This can be done in a way that makes it easy to do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an image storage display device according to an embodiment of the present invention, FIGS. 2A and B are front views of the display state of the device, and FIG. 3 is a specific circuit diagram of a part of the device. Figure 4 is a waveform diagram of each part, Figure 5 is a specific circuit diagram of a part of the same device, Figure 6 is a waveform diagram of each part, and Figures 7 and 8 are specific circuit diagrams of a part of the same device. It is. 1... tuner, 2... VIF circuit, 3... video detection circuit, 4... amplifier circuit, 5... switching/mixing circuit, 6... video output circuit, 7... cathode ray tube, 8...
... Synchronization separation circuit, 9 ... Color subcarrier regeneration circuit, 1
0... Waveform shaping circuit, 11... Gate circuit, 12
...Gate pulse generation circuit, 13...Basic clock oscillation circuit, 14...Sampling circuit, 15...
...Start signal detection circuit, 16...Clock generation circuit, 17...Memory, 18...Memory control circuit, 19...Switching adjustment circuit, 20...Touch detection circuit.

Claims (1)

[Claims] 1. A teletext signal multiplexed with a television broadcast signal and a video signal of a television broadcast screen transmitted as an analog signal are waveform-shaped at a predetermined level and converted into a binary signal. a waveform shaping circuit for converting; an adjusting means for separately adjusting waveform shaping levels of the teletext signal and video signal; and a signal processing circuit for processing the teletext signal converted into a binary signal by the waveform shaping circuit to generate a character signal. It comprises a teletext receiving circuit for reproducing, a digital memory for storing approximately one field of the character signal and the television broadcast screen signal converted into the binary signal, and a shaping level of the video signal in the waveform shaping circuit. A switching circuit is provided for displaying only the image output from the waveform shaping circuit on the display device during the adjustment period, and displaying only the image read output from the digital memory on the display device when the adjustment is completed. An image storage display device characterized by: 2. The image storage display device according to claim 1, further comprising an output terminal for outputting readout output from the digital memory to other equipment outside the housing. 3. Claims 1 or 2, characterized by comprising a switching means for switching to a waveform shaping level adjustment state when a human body comes into contact with a television screen video signal adjustment element of the waveform shaping circuit. Image storage and display device as described.