JPH0315394B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving device that receives and displays a teletext signal transmitted superimposed on a television signal, in which the received character signal is stored in a disk memory or the like for many screens. , the object of the present invention is to provide a device that can select, read out, and display a desired screen from among them, and can display stable and easy-to-read characters during storage recording and playback. It is.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment thereof.

First, FIG. 1 shows the general structure of the system, and FIG. 2 shows the teletext signal multiplexed with the television signal.

In FIG. 1, 1 is a tuner, 2 is a VIF circuit, 3 is a video detection circuit, 4 is a synchronization separation circuit, and 5 is a color subcarrier (f _SC ) regeneration circuit and a sampling clock regeneration circuit. 6 is a circuit that generates a gate pulse for extracting the teletext signal superimposed on the 20th H of the television signal as shown in Figure 2, and 7 is a circuit that shapes the waveform of the video detection output to convert the teletext signal into a predetermined signal. This is a circuit that creates a binary signal waveform. In general, the transmission bandwidth of television signals is about 3.5MHz for video signals, and on the transmission side, the CRI (clock line) signal shown in Figure 2B, FC
(Frasing code) Even if it is a square wave as shown in the signal, the high frequency component is lost and the waveform becomes dull. This dull waveform is the CRI signal in Figure 2B,
A waveform shaping circuit 7 performs waveform processing to restore the waveform to that shown in the FC signal. This circuit 7 is
This is a commonly required circuit for teletext receivers, for example, National Technical Report Vo1.21, No.2
April 1975), Section 228, left column, lines 3 to 9, page 224
Shown in Fig5. 8 is a circuit that samples the output teletext signal using a sampling clock; 9 is a circuit that detects a framing record (FC) signal in the character signal shown in FIG. 2 from the output and performs frame synchronization; Reference numeral 10 denotes a circuit that detects and discriminates the identification signal SI/IN, line numbers LN ₁ , LN _2, etc. as shown in FIG. 2B, and controls the recording and reproduction of character signals as described later.

In this device, when a teletext signal is received, it is first stored in the buffer memory 11 for 1H each time it is received in order from the first line signal (page control packet PCP) of each character screen, and then written in the multi-field memory 12 in order. The multi-field memory 12 is a magnetic disc-shaped multi-track memory with horizontal servo, and uses a magnetic disk memory or the like. For example, it is possible to use a magnetic disk (or sheet) in a still image receiver announced for receiving NHK still image broadcast B system. The output of multitrack memory is also limited in bandwidth and the wide area is lost, so
Similar to the video detection output, waveform shaping is required.

Reading from the multi-field memory 12 is carried out by selecting and extracting a desired screen from the teletext screens (programs) read out from the memory 12 using the selection switch 13,
Write to field digital memory 16. This field memory 16 is similar to the main memory in a normal teletext receiver. Then, data is read out from this field memory 16 in synchronization with the operation of a display circuit 17 such as a CRT, and a character screen is displayed. Here, the multi-field memory 12 shown in FIG. 1, the PCP detection circuit 14 for reading, and the AND
A gate 15 is a part added to a normal teletext receiver.

The operation will be described in detail below with reference to FIGS. 2 and 3. In addition, here, we will explain the part generally known as a teletext receiver and the NHK still image broadcasting B.
A part known as a system receiver will be omitted. first,
At the 20th H, the received signal of the teletext signal as shown in FIG. 2A is sampled by the sampling circuit 8.
Then, as shown in Figure 2C, the 8th part of the FC signal
At the bit, the FC detection output is taken out from the FC detection circuit 9, and this is added to the _fSC regeneration/sampling clock regeneration circuit 5 for frame synchronization of the sampling clock, and then added to the 1H buffer memory 11 for FC detection. Thereafter, it enters the writing state and stores 1H worth of received character signals.

The write control circuit 10 is composed of a microcomputer or the like, and judges the last three bytes after the control signal shown in FIG. 2B. Here, we will consider the case where the format of the teletext signal to be transmitted is the method described in the 1974 Electrical Engineering Examination Report. In this method, first, the identification signal SI/IN is used to determine whether or not the character signal superimposed on the 20th H in the VBL period is a character pattern signal, and only if it is a character pattern signal, a 1H buffer memory is used. 8 bits after identification signal SI/IN to 11 x 3 + 248 bits =
Write the 272-bit received signal. Then the 21st H
After the line number signals LN ₁ and LN ₂ are determined by the write control circuit 10, if the number is not 11111111, which indicates that it is a page control packet PCP, the contents of the buffer memory 11 are ignored, and the multi-field It is not written to the memory 12 either.When the page control packet PCP signal is transmitted,
Of these, the program code signal and page code signal are stored in a part of the work RAM in the write control circuit 10 to create a table, and the predetermined CRI signal and FC signal are assigned to the 272-bit signal of the PCP. It is added and written to the 38th recording position of the first track of the multi-field memory 12. Thereafter, the character pattern signals of each line of the character screen transmitted following the PCP are sequentially received, and the signal of the first line is
Transfer the second line signal to the 40th recording position at the 39th recording position.
The data is sequentially written to the first track of the multi-field memory at the first recording position, and so on.

The case where the multi-field memory 12 of the H servo is a magnetic disk memory will be explained with reference to FIG. In FIG. 3, reference numeral 18 denotes a rotation shaft 21' for rotating the magnetic disk 21 in synchronization with the horizontal synchronization signal output from the synchronization separation circuit 4.
22 is a write/read head that moves in the direction of the arrow in the figure; 19 is a circuit that controls the position of the head 22 to select a track for writing/reading;
A circuit 20 supplies a write signal to be recorded to the head 22, and also receives a reproduction signal read out by the head 22 and converts it to an appropriate level.

Therefore, when the write control circuit 10 specifies the position of the head 22, that is, the number of the recording track, the head position control circuit 19 controls the position of the head 22 and moves it to a predetermined recording track position. Then, when the magnetic disk 21 is rotated to a writing position on the recording track, a read control signal is transmitted to the buffer memory 11, and the received signal temporarily stored there is read out. The output is amplified by the W circuit 20 (level exchanged if necessary), transmitted to the head 22, and written to a predetermined H position on a predetermined track of the magnetic disk 27. If you repeat the above operation for one character screen, that is, 204H, you will get
Character signals for one screen of characters are stored on magnetic disk 2.
It will be written to 1.

When the writing of one screen is completed, the transmission of the next PCP is waited, and when the program number of the screen (telecasting program) that has not yet been written to the magnetic disk 21 is detected, the character signal for one screen that follows from that PCP is sent. is written to the next track on the magnetic disk 21.

In normal teletext broadcasting (pattern transmission), the number of programs of character signals that are repeatedly sent continuously is about 10 to 20, and if it is transmitted using another 1H period in addition to the 20th H during the VBL period. However, there are no more than 40 types. On the other hand, since the magnetic disk 21 can easily have about 50 tracks, the recording capacity is sufficient.

Next, a predetermined value is applied to the output of the 1H buffer memory 11.
We will explain how to add CRI signals and FC signals. FIG. 4 is a block diagram of an example of the circuit, and FIG. 5 is a time chart thereof.

First, assuming that the H servo drive control circuit 18 is synchronized with the received synchronization signal from the synchronization separation circuit 4, the pulse of the H servo is delayed by the delay circuit 19DP, and the pulses as shown in φ ₃ and φ ₅ in FIG. A pulse is formed and supplied to AND gates 30 and 31. these
The clock from the _fSC /clock recovery circuit 5 is also added to the AND gates 30 and 31, and the output of the AND gate 30 becomes _φ6 , and the output of the AND gate 3
The output of 1 will be something like _φ4 . On the other hand, the write control circuit 10 receives line number signals LN ₁ and LN _2.
The writing position of data in the 1H buffer memory 11 (assumed to be the nth line) is determined, and the data is written in a predetermined period.
A high level signal is output for 1H period, and the delay circuit (19DP), AND gate 27, and inverter 2
Add to 9.

Here, if the 38th H recording position of the magnetic disk 21 is made to correspond to the recording position for the 1st line, the 39th H is made to correspond to the recording position for the 2nd line, etc., then as a result, the n1Hth recording The position is the (n ₁ −
38) Line character signal is 1H buffer memory 11
It will be read from and written to. That is, n=n ₁ -38.

Therefore, as shown in FIG. 5, the ROM 24 is first clocked by the clock _φ4 , and 24 bits of the CRI signal and FC signal as shown by _φ2 are read out.
It is supplied to the R/W circuit 19 via the OR gate 25. This part, as shown in Figure 2B,
Since each field is the same, there is no need to write it to the 1H buffer memory 10. As the 1H buffer memory, a 256-bit memory and two 8-bit memories can be used, simplifying the circuit configuration.
Next, 1H buffer memory 1 is activated by clock _φ6 .
The 272-bit signal after the SI/IN signal with the content of 1 is read out and transmitted to the R/W circuit 20, and the (n ₁
-38) The character signal of the line is written to the _n1Hth recording position of the magnetic disk 21. From then on, repeat this process and store the information in Figure 2 A in the 1H buffer memory 11.
Even when only the 272-bit signal after the SI/IN signal is stored, it is written to the magnetic disk 21 in the form of a regular character signal to which the CRI signal and FC signal are added. Since the write control circuit 10 and the ROM 24 are read with the same phase lock, the output of the OR gate 25 becomes a continuous 296-bit signal. Also,
The CRI signal and FC signal are present at the beginning of the teletext signal and are necessary for normal operation of the teletext receiver. In other words, the CRI signal and FC signal are not recorded in the multitrack memory (multifield memory 12), the recording amount is reduced, and the
By adding CRI and FC, the tuner 1 can receive radio waves and operate a teletext receiver in the same way as when receiving a television signal on which teletext is superimposed.

When character signals for one screen are written on one recording track of the magnetic disk 21, character signals for one screen of the next program are then written on the next recording track. Thereafter, this process is repeated, and character signals for a plurality of screens are sequentially recorded on the magnetic disk 21.

Next, reading from the magnetic disk 21 will be described. Note that the magnetic disk 21 is a field memory and has a speed of 3600 rpm. At the time of reading, first, the signals recorded at the 38th recording position of each recording track are sequentially read out, and the contents specified by the selection switch 13 (program code signal PR ₁ and
8 bits of PR ₂ ) and the character signal of each track read from the multi-field memory 12.
Compare the PR ₁ signal and PR ₂ signal, and if they match, start the next track on the matching recording track.
The outputs read from the 39th and subsequent recording positions are sequentially sampled and written into the field memory 16 in the same manner as when receiving character signals. The AND gate 15 becomes conductive only when the output of the PCP detection circuit 14 matches the result of the program comparison and becomes high level, and the detection output of the PCP detection circuit 14 is maintained for one field. If the output of the selection switch 13 and the output of the multi-field memory 12 do not match, move the head 22, read from the next recording track, and read the 38th H PCP signal.
Repeat the operation of checking PR ₁ and PR ₂ . Assuming that the number of recording tracks on the magnetic disk 21 is 60, it is possible to check the character signal programs of all tracks in one second, and one screen's worth of character signals of matching programs PR ₁ and PR ₂ can be checked in one field. It can be transferred to memory 16. This 1 field memory 16
is a digital memory such as RAM, and a normal teletext receiver receives and writes character signals for one line in one field, but in this device, the 204 lines of one screen are stored in the multi-field memory. Read and write from 12.

With the above configuration, the screen of a desired teletext program can be stored in one field memory 16 within one second of waiting time.
It can be written to and displayed on a CRT or the like of the display circuit 17.
Write a character pattern signal on the magnetic disk 21,
If you read it out as it is, the vertical lines may be slightly curved due to the effect of jitter, making it difficult to see. However, if you resample and write to the 1-field memory 16, the character pattern signal read from the 1-field memory 16 will be free from the effects of jitters, etc.

Although the input sampling circuit of the 1-field memory 16 can be shared with the circuits 5, 7, and 8 in FIG. 1, it is sufficient to simply configure it as shown in FIG. 6. That is, the output of the AND gate 15 is shaped by the waveform shaping circuit 32, the clock regeneration circuit 34 forms a sampling clock from the CRI signal by a ringing circuit for more than 1H, and the output of the waveform shaping circuit 32 is shaped by the sampling circuit 33. sample. From the output, the FC detection circuit 35 detects FC.
Detects the signal and synchronizes the clock frame. After the clock of the clock regeneration circuit 34 is frame-synchronized, the line number signals LN ₁ and LN ₂ being output from the sampling circuit 33 are stored in the line detection circuit 36, and the horizontal synchronization signal output from the synchronization separation circuit 4 is outputted by the line counter 37. Compare with the output obtained by counting. The line counter 37 sets the 38th H to 1" and generates a count output as an 8-bit binary signal. The output is compared with the output of the line detection circuit 36 by the comparison circuit 38, and if the two match, the output is becomes high level and makes AND gate 39 conductive.

Note that the memory 16M is written here to include a memory for one screen and a write/read control circuit. The output signal of AND gate 39 is written to a predetermined location in memory 16M, similar to the general operation of a character receiver. Note that reading from the memory 16M is exactly the same as in the case of a normal teletext receiver.

As described in detail above, according to the present invention, a large number of character signal screens are stored in a disk-shaped multi-field memory such as a magnetic disk, and can be immediately read out and displayed as needed. Furthermore, the character signals that are multiplexed and transmitted during the vertical blanking period of the television signal are identified by program code, the character signals that make up the same page of the same program are waveform-shaped, and the character signals that are multiplexed and transmitted during the vertical blanking period of the television signal are waveform-shaped and stored in the magnetic disk memory with horizontal servo control. Since each line is written in accordance with the line number code that makes up the still screen, even if the character signals sent are not in line order, they are written to the magnetic disk memory in line order, and when reading, the magnetic The output of the disk can be written to the pattern memory for one field in the same order and displayed. Furthermore, when displaying, the signal read from the magnetic disk can be waveform-shaped, sampled in the same order, and written to the pattern memory for one field. For this part, the circuit corresponding to the pattern-type character multiplex receiver can be used as is, and there is no need to judge the line number, and when displaying, the character screen is displayed in the correct order from top to bottom from the beginning. can be displayed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a teletext receiving device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of a transmitted character signal and an FC detection signal, and FIGS. 3, 4, and 6 are diagrams of the same device. A concrete block diagram of a part of the 5th
The figure is a waveform diagram explaining the operation. 1... Tuner, 2... VIF circuit, 3... Detection circuit, 4... Synchronization separation circuit, 5... f _SC /clock regeneration circuit, 6... Gate pulse generation circuit, 7...
...Waveform shaping circuit, 8...Sampling circuit, 9...
...FC detection circuit, 10...Write control circuit, 11...
...1H buffer memory, 12...Multi field memory, 13...Selection switch, 14...
PCP detection circuit, 15...AND gate, 16...
1 field memory, 17...display circuit, 18...
...H servo drive control circuit, 19... Head position control circuit, 20... R/W circuit, 21... Magnetic disk, 21'... Rotating shaft, 22... Head, 23
……motor.

Claims (1)

[Claims] 1 Equipped with a magnetic disc type multi-track memory that can follow and synchronize with a horizontal synchronization signal, and receives character signals that are superimposed on the vertical retrace period of a television signal and are transmitted in units of one line with a line number code attached. Then, the character signal waveform, which has been slowed down due to band limitation, is shaped into a rectangular pulse waveform, and the character signals for one line of the same screen of the same program are received in the order in which they are received, excluding the first CRI signal and FC signal, 272 bits. The character signal is written in the recording position corresponding to the line number code of the character signal in the multitrack memory for each minute to record multiple screens, and from the recorded screen, the characters of the desired screen can be selected using selection means such as a selection button or switch. The signal is read out in 272 bits for each line, the readout waveform is shaped into a rectangular pulse waveform, and the early CRI signal and FC signal are added.
In addition to writing to the pattern memory for the screen, the added CRI signal and FC signal are used to form a sampling clock, stabilizing the writing to the pattern memory, and reading the vertical and vertical signals of the television signal from this pattern memory. A teletext receiving device characterized in that it reads and displays data in synchronization with horizontal scanning.