JP3211558B2 - Character display circuit, character display method, and recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a character data to video signal
By superimposing data relates to a character display circuit and method having a function of displaying a character, a particular function of generating a character display timing signal referenced to vertical / horizontal synchronizing signal of the video signal, one of the character display timing signal As a part, VBI (Video) used for performing closed caption broadcasting with character data carried during a blanking period of a video signal
Blanking Interval) A sentence that matches the code format
The present invention relates to a character display circuit having a function of generating character data , a method thereof, and a recording / reproducing apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, a character display circuit for generating a character display timing signal based on a vertical / horizontal synchronization signal of a video signal and displaying a character pattern on a television screen, and a VBI character used for subtitle broadcasting. It was configured as a separate circuit from the encoding circuit.

As a character display circuit, for example, M35040 manufactured by Mitsubishi Electric is commercially available. On the other hand, as in the case of the teletext signal, as a character encoding circuit using the vertical blanking period, there is CX-7907A manufactured by Sony or the like.

As a technique using teletext, Japanese Patent Laid-Open No.
One example is known from JP-A-91875.

Some commercial VTRs include a character display circuit and V
In some cases, a BI character encoding circuit is provided separately, and a caption signal is superimposed on a blanking period of an image signal when recording is performed by a VTR. By doing so, a closed caption decoder (hereinafter referred to as a CCD) is provided on the TV.
(Abbreviated as “abbreviated”), the subtitle can be reproduced on the TV side from the signal reproduced by the VTR. For example,
If the recording date is superimposed on the video signal, the recording date and time of the video can be confirmed on the TV screen at any time, and subtitles can be erased as necessary. Therefore, unlike the case where the display characters are directly superimposed on the image data, the recording screen is not damaged.

In addition, a VBI character encoding circuit provided in a VTR is used to superimpose digital data generated accompanying a recording screen such as an absolute address on a tape and an edit control mark.

[0007]

However, since the character display circuit and the VBI character encoding circuit are configured as separate circuits, there has been a problem that the circuit configuration becomes complicated.

An object of the present invention, in order to significantly simplify the circuit configuration, new character display circuit and method which in addition to fulfilling also the function of a VBI character coder functions of the conventional character display circuit, and these An object of the present invention is to provide a recording / reproducing apparatus used .

[0009]

The object of the present invention is to provide a character pattern.
Storage means for storing the character pattern and the character pattern.
Generating means for generating character data, and a video signal
Outputting the character data in synchronization with a direct / horizontal synchronization signal
Output means for outputting the output character data to the video signal.
Superimposing means for superimposing on characters, clocks and data
Teletext broadcasting characters composed of "0" and data "1"
Converting means for converting the character pattern
Indicates the display pattern and the clock, data “0”, data
And a coding pattern corresponding to the data "1".
Means for converting the character data into a blank of the video signal.
When superimposed on the switching period,
The character is converted to a character code, and the generating means outputs the character code.
Encoding pattern extracted from the storage means based on the code
Is achieved by generating character data composed of
You.

[0010]

The normal character display function is realized by replacing the original video signal with a character display timing signal generated inside the character display circuit. Text / caption broadcasting is also realized by replacing a specific horizontal synchronization signal with a coded text timing signal. Therefore, the dot frequency of the font ROM data for generating the character pattern is set to the clock of the character / caption broadcast, data “0”, data “1”.
Is defined to be an integral multiple of the frequency of Then, the ROM data corresponding to the display characters is arranged in a predetermined horizontal synchronization signal. The correspondence is shown in FIG. 1 and FIG. Figure 1 shows closed caption broadcasting standard EI in the United States
It shows an encoded part of teletext based on A-608. The teletext data is superimposed on the 21st H of the horizontal synchronizing signal, and is encoded by the 503 kHz NRZ method. A two-character code is entered in the 16-bit data part. FIG.
A-2D shows a character pattern string for generating teletext data according to the present invention. In this example, one character is 8 × 8
The frequency of one dot is an example of 503 kHz × 8 of 4.02 MHz.

If the frequency of one character constituting the character pattern is configured to be equal to the clock frequency of the teletext, one character becomes one bit of the teletext data and control is simplest.

If the ratio of the frequency of one character constituting the character pattern to the clock frequency of the teletext is in an integer relationship, it is possible to represent a plurality of bits by one character or one bit by a plurality of characters. Become. Therefore, even if the character display function is restricted as described above, the number of display characters per line can be set to some extent.

[0013]

FIG. 2 shows an example of a character pattern design in the case where the 1-bit length (D = 1 / 503,488 Hz) of a teletext based on the EIA-608 in the United States is equal to the period of one character of a character display circuit. In this case, the font of one character is composed of 8 dots × 8 lines as shown in FIGS. That is, in this case, one bit of the teletext is composed of 8 dots. Therefore, the dot frequency (YD) of the character display circuit needs to be eight times the clock frequency of the character broadcast, that is, 1 / D × 8 = 4.024 MHz. Figure 2 shows the character pattern of the clock part.
It is shown in (B). By arranging seven of them on the same line, the clock signal for teletext shown in FIG. 1 can be created.
Data "0" is shown in FIG. 2C, and data "1" is shown in FIG. By arranging these on the same line in accordance with the teletext data sequence, a teletext signal can be generated.

FIG. 3 shows a design example of a character pattern when the 4-bit length (4D) of the teletext is equal to three characters of the character display circuit. The structure of one character is 8 dots x as in FIG.
Assuming eight lines, D is composed of 6 dots, and the dot frequency needs to be 1 / D × 6 = 3.018 MHz. Ten types of character patterns to be prepared are required as shown in FIGS. By arranging them on the same line according to the teletext data sequence, a teletext signal can be generated.

As a circuit for displaying a character signal on a display, a known circuit can be used.

A processing procedure for encoding a subtitle signal using a character display circuit will be described in detail with reference to FIGS. 1
Indicates the entire character display circuit. A character pattern as shown in FIG. 5 is prepared in the character font ROM 2. The hexadecimal code attached to the upper left is the character code stored in the display data memory 3. Code "2D", "2E", "2F"
Is a pattern according to the present invention specially prepared for encoding a caption signal.

In this embodiment, since each character is composed of 12 dots, the dot frequency is equal to the 12
That is, 1 / D × 12 = 6.042 MHz.

As a video signal source for superimposing a subtitle signal, a video camera 17 and a VCR (Video
Cassete Recoder 18, Laser disc player (LD
P) 19 mag. The character display circuit 1 processes the video signals input from these video signal sources in the video signal processing unit 10, and the display control circuit 7 sets the character display timing signal based on the vertical / horizontal synchronization signal generated by the synchronization separation circuit 9. Is output. The display position control circuit 6 loads a character code to be displayed from the display data memory 3,
The corresponding character font ROM data is set at the display position determined based on the points specified by the vertical position register 4 and the horizontal position register 5. The ROM data is output as character dot data by the shift register 8 and is superimposed on the video signal by the mixing circuit 11.

The display character control unit 12 includes a display data memory 3
Is a part that performs data generation and communication. The display position control unit 13 is a part that performs data generation and communication of the vertical position register 4 and the horizontal position register 5. The character signal coded data generation unit 15 specifies a character to be superimposed during a blanking period of a video signal, and generates the data. The character display data input unit 16 generates a character display timing signal based on a vertical / horizontal synchronization signal of a video signal. The character display timing signal is character data that can be recognized as a character by a human if displayed on a TV screen without decoding. The display data encoding unit 14 has a conversion table that assigns a code “2D” to the clock of the caption code, “2E” to the data “1”, and “2F” to the data “0”. This is a part that converts data generated by the encoded data generation unit 15 and the character display data input unit 16 into a display data code inside the character display circuit 1.

The display character control unit 12, display position control unit 13, and display data coding unit 14 may be configured as a part of a microcomputer.

The coding control procedure will be described below with reference to FIG. Steps 51-54 correspond to the display data coding unit 14.
It is done in.

Step 51: The character to be encoded in the caption signal is converted into a binary number. For example, in the case of 'AB', 01
Converted to 000001 01000010. (FIG. 7 (4)) Step 52: STOP 2Bit START 1Bit is added. (FIG. 7B) Step 53: 7-bit clock is added. (FIG. 7 (C)) Step 54: Encode into the corresponding character font using the conversion table. In this example, the clock is '2D',
1 is converted to '2E' and 0 is converted to '2F'.

Step 55: The display position controller 13 sets a predetermined value in the horizontal position register 5 and the vertical position register 4. For subtitle signals in the United States, the horizontal position is 10.5
The μs vertical position is set to 21H.

Step 56: A total of 26 bytes of data coded in step 54 are transferred by the display character controller 12 to the display data memory 3. (FIG. 7 (D)) Step 57: The sync separation circuit 9 detects a vertical sync signal separated from the video signal on which the caption signal is to be superimposed. The display position control circuit 6 counts the horizontal synchronizing signal from the vertical synchronizing signal, and outputs a character at the 21st hour.

Step 58: The encoded data output as the character display timing signal is superimposed on the video signal by the mixing circuit 11.

Step 59: It waits until the 21st hour has passed. twenty one
After the Hth eye, the superimposition of the subtitle signal is completed.

As an embodiment of the present invention, a case where the recording date and time is recorded as subtitle broadcast data on a VCR will be described. By doing so, the recording date and time can be displayed only when necessary at the time of reproduction, and there is a merit that the screen is not disturbed during normal video viewing.

FIG. 8 shows an internal block diagram of the VCR. The video signal processing unit 31 performs signal processing relating to recording and reproduction of a video signal. The video signal recorded on the magnetic tape is captioned at the video output 21H of the tuner 21.
The code is superimposed and recorded.

The caption code output from the character display circuit 22 according to the present invention is superimposed on the video signal by the adder 29 with the switch circuit 23 on the A side.

FIG. 9B is a flowchart at the time of reproduction.

At the time of reproduction, the 21st H of the reproduced video signal is detected by counting the vertical / horizontal synchronizing signal output by the caption code decoder 24 (step 71), decoded, and passed to the controller 25 (step 72). controller
25 outputs the decoded result as a character code to the character display circuit 22 (step 73). The character display circuit 22 generates a character display timing signal which is a conventional character pattern according to the input character code (step 74). The generated character display timing signal passes through the B side of the switch circuit 23 and is superimposed on the reproduced video signal by the adder 30 (step 7).
5) The signal is output to the TV via the RF converter 31 (step 76).

The encoded data at the time of recording the caption code, for example, date / time data is created from the output data of the clock circuit 27. Selection of whether to display caption code data at the time of reproduction is performed by a display ON / OFF switch 28.

Caption Code Encoding An OS font is composed of 8 dots per character. An example in which 1 bit of caption code is composed of 6 dots will be described below.

Specifically, the procedure for encoding date / time data into a caption code will be described with reference to FIGS.
This will be described using (A) and 10 (B).

In step 61, when the recording is started, the timer 27
Is converted to ASCII hexadecimal code. For example, the character "0" becomes "30" (0011 0000) in hexadecimal.

At step 62, the controller 25 adds a control code. In the example of FIG. 10A, a code of “1460” is added to the fifteenth line to display in white characters. FIG.
As shown in (B), it is repeated twice as promised with the decoding side.

In step 63, the hexadecimal code is stored in the controller
At 25, the character string is converted into an OSD (On Screen Display) character font string as shown in FIG. This font string is, for example, E
It is determined by a standard such as IA-608. In EIA-608, 7 bits of clock, 2 bits of STOP and 1 bit of START are always added before 16 bits of data per 1 H. The font patterns (G), (H), and (I) in FIG. In the example of FIG. 10B, 4-bit data is created with three OSD font characters.
(O) to (F) and CLOCK, STOP, START
FIG. 12 shows combinations of character fonts. The value in parentheses in Fig. 12 is 16
It is a hexadecimal display. Thus, for example, in the case of date / time data as shown in FIG.
OSD font data indicated in the font column is prepared.

In step 64, in order to record this data in the 21H odd field, the character display circuit 22 outputs one line of the OSD font line in synchronization with the vertical synchronizing signal (frame).

While the recording is continued in step 65, the above encoding processing in steps 61 to 64 is performed while updating the date / time data.

According to the above procedure, the recording date and time can be recorded on a video tape as a subtitle broadcast code.
For the operation during playback, refer to Nikkei Electronics 1991.9.30 (no.539) pages 149-158 and MOT
OROL SEMICONDUCTOR TECHN
Please refer to ICAL DATA MC144143 for details.

[0041]

According to the present invention, an encoding function for teletext broadcasting is provided.
Can be realized as a part of the character display circuit, so that the circuit configuration can be significantly simplified.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a teletext code format in the United States.

FIG. 2 is a diagram illustrating an example of a character pattern design in the case where the 1-bit length of teletext is equal to the timing of one character in a character display circuit.

FIG. 3 is a diagram illustrating a design example of a character pattern when the 4-bit length of teletext is equal to three characters of a character display circuit.

FIG. 4 is a block diagram of a character display circuit according to the present invention.

FIG. 5 is a diagram showing a character pattern stored in a character font ROM.

FIG. 6 is a flowchart illustrating a processing procedure for encoding a subtitle signal.

FIG. 7 is a diagram illustrating an example of encoded characters.

FIG. 8 is a block diagram of a VCR using the character display circuit of the present invention.

9 is a flowchart showing an encoding procedure in the VCR of FIG. 8, and a flowchart showing a reproducing procedure.

FIG. 10 is a diagram showing a TV screen display example of data to be encoded and its encoded data.

FIG. 11 is a diagram showing an example of an OSD (On Screen Display) character font string.

FIG. 12 is a diagram showing the correspondence between OSD character font patterns used in FIG. 10 and encoded data.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Character display circuit, 2 ... Character font ROM, 3 ... Display data memory, 4 ... Vertical position register, 5 ... Horizontal position register, 6 ... Display position control circuit, 7 ... Display control circuit, 8 ... Shift register, 9 ... Sync separation circuit, 10: Video signal processing unit, 11: Mixing circuit, 12: Display character control unit, 13: Display position control unit, 14: Display data coding unit, 15: Character signal coded data generation unit, 16 ... Character display data input unit, 17: video camera, 18: video cassette recorder (VCR), 19: laser disk player (LDP).

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁷ Identification code FI H04N 7/03 7/035

Claims (7)

(57) [Claims] A storage means for storing a character pattern;
Generating means for generating character data composed of character patterns ; output means for outputting the character data in synchronization with a vertical / horizontal synchronization signal of a video signal; and the output sentence
A superimposing means for superimposing character data on the video signal, the character display circuit comprising a clock, data "0", and data "1".
Conversion means for converting to character codes of
The storage means stores a display pattern as the character pattern.
And the clock, data “0” and data “1”.
And a corresponding encoding pattern, and the superimposing means converts the character data to the video signal.
When superimposed on the blanking period, the conversion means
The desired character is converted to a character code.
Encoding extracted from the storage means based on the character code
Generates character data composed of patterns
Character display circuit. 2. A character display circuit according to claim 1, wherein the character pattern is configured such that the frequency of the dots constituting one character is an integral multiple of the clock frequency of the teletext system. 3. A step of reading a character pattern from a memory, a step of generating character data composed of the character pattern, and a step of outputting the character data in synchronization with a vertical / horizontal synchronization signal of a video signal. And a superimposing step of superimposing the output character data on the video signal, wherein the character broadcast is composed of a clock, data "0", and data "1". The character pattern includes a display pattern, and an encoding pattern corresponding to the clock, data “0”, and data “1”. When character data is superimposed on a blanking period of a video signal, a desired character is converted into a character code in the conversion step, and Character display method characterized by generating a character code configured by the coding pattern read from the memory based on the character code in generating step. 4. A character display method according to claim 3, wherein the character pattern is configured such that the frequency of the dots forming one character is an integral multiple of the clock frequency of the teletext system. 5. A recording / reproducing means for recording a video signal on a recording medium or reproducing a video signal from the recording medium, a storage means for storing a character pattern, and extracting a predetermined character pattern from the storage means, and extracting the extracted character. Generating means for generating character data composed of patterns; output means for outputting the character data in synchronization with a vertical / horizontal synchronization signal of the video signal; and superimposing means for superimposing the output character data on the video signal. And converting means for converting a character into a character code of a teletext system composed of a clock, data “0”, and data “1”, wherein the storage means includes a display pattern as the character pattern; The clock, data "0", and an encoding pattern corresponding to data "1". When the video signal superimposed on the ranking period and the character data is superimposed is recorded on a recording medium by the recording and reproducing unit, a desired character is converted into a character code by the conversion unit, and the character code is converted by the generation unit. A recording / reproducing apparatus for generating character data composed of an encoded pattern extracted based on the character data. 6. A video signal processing means for recording / reproducing a video signal on / from a recording medium, a clock means for generating date / time data, a clock / data "0", a data "1" for the date / time data. Converting means for converting into a character code of a teletext system, storage means for storing a character pattern, extracting a predetermined character pattern from the storage means, and generating character data composed of the extracted character pattern. Generating means for outputting the character data in synchronization with a vertical / horizontal synchronization signal of a video signal; and superimposing means for superimposing the output character data on the video signal. Includes, as the character pattern, a display pattern and an encoding pattern corresponding to the clock, data “0”, and data “1”. When the character data is superimposed on a blanking period of the video signal and the video signal on which the character data is superimposed is recorded on a recording medium by the video signal processing means, the date / time data is converted by the conversion means. A recording / reproducing apparatus which converts a character code into character codes and generates character data constituted by an encoding pattern extracted based on the character codes by the generation means. 7. The character pattern according to claim 5 or 6, wherein the frequency of the dots constituting one character is an integral multiple of the clock frequency of the teletext system. Recording and playback device.