JP2597159Y2 - Character position correction circuit on the screen - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correction circuit for correcting a display position of character information on a screen in an image device such as a television receiver capable of displaying character information on a screen of a cathode ray tube. is there.

[0002]

2. Description of the Related Art In a conventional television receiver, various information such as a channel number, a volume and a time are displayed by an operation (on-screen) for displaying character information in addition to a video. These pieces of information are stored in a memory inside the television receiver, and are read out and displayed on-screen. The character information is determined by numerically setting the writing position of a character block area capable of displaying a maximum of 24 characters in the vertical and horizontal directions. The character block is an area in which character information can be displayed, and its vertical position can be determined at any of 128 positions where the horizontal synchronization signal of the television receiver is counted and numerical values are set. Further, the writing position of the character block can be set to any position of 64 steps in the horizontal direction by counting the 4 MHz clock signal generated from the display clock oscillation circuit.

The setting of the character position is performed when the television receiver is shipped from the factory. However, since the quality of electronic components such as capacitors constituting the display clock oscillation circuit varies, the writing position of the character block is set. Does not always appear at a predetermined position where a numerical value is set.

[0004] For example In FIG. 2, the screen (16) if the write start position of the character block (17) on the had from the end as b diagram is numerically set to a position of an H ₁ in the horizontal direction, in fact As shown in FIG. 3A, the writing position of the character block (17) may be delayed in the horizontal direction and may be higher than H ₂ (H ₂ > H ₁ ) or a predetermined position (H ₂ <H ₁ ). In order for the writing position of the character block (17) to appear at a predetermined position (FIG. 2B) where a numerical value is set, it is necessary to manufacture the display clock oscillation circuit with high-accuracy and high-priced parts, and the manufacturing cost There was a problem that becomes high.

An object of the present invention is to form a display clock oscillation circuit by using components having irregularities in provisional performance. Therefore, even if there is an error in the frequency of the display clock, the display position of the character block is automatically moved. , Character information is displayed at a predetermined position where a numerical value is set.

[0006]

A solution for the present invention compares the display position signal of a character block (17) and a horizontal synchronizing signal, detecting circuit for outputting a detection signal V ₂ corresponding to the actual display position
And (5), a reference value circuit for outputting a reference signal V ₁ corresponding to the numerical value setting position of the character block (17) (7), the detection signal V ₂
And a comparison circuit for comparing the magnitude of the reference signal V ₁ (6), the output of the comparator circuit (6), a microcomputer for controlling the change of the character block display position (2), according to the output of the microcomputer (2) And a character position changing circuit (25) for moving the horizontal writing position of the character block on the screen.

[0007]

[Action] Depending on the writing position of the character block of the on-screen, the detection circuit (5) outputs a detection signal V ₂ corresponding to the actual display position. Since the other hand the reference value circuit (7) outputs the reference signal V ₁ corresponding to the numerical value setting position, by comparing the V ₂ V ₁ and either actually appear character block on the screen is in place, or progressed You can detect whether you are out or late.

When the display position is delayed (a in FIG. 2)
(Figure), the microcomputer reduces the set value of the built-in horizontal register, and moves the actual display position in the advancing direction.

Conversely, if the actual display position is ahead of the predetermined position, the microcomputer increases the numerical value of the horizontal register and delays the display position of the character block.

By the above-described correction processing in accordance with the program of the microcomputer, the detection signal V ₂ of the actual display position becomes the reference signal V ₁
, And the writing position of the character block can be displayed at the predetermined position where the numerical value is set.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a television signal received by an antenna and tuned by a tuner (11) is an intermediate picture frequency circuit.
(12), a video signal is passed through the video output circuit (13), and a video is displayed on the cathode ray tube (16). The video output circuit (13)
Furthermore, the synchronization signal counter (22) and the character generator (2
4) supplies a vertical synchronizing signal (V) and a horizontal synchronizing signal (H). The synchronization signal counter (22) outputs a vertical synchronization signal (V).
The horizontal synchronizing signal (H) is counted immediately after the issuance of is output, and the count value is output to the microcomputer (2). Microcomputer
(2) ON / OFF control of the video blanking circuit (14) based on the output of the synchronizing signal counter (22) to set a predetermined range of the horizontal period only for the image portion of the character information corresponding to the numerically set character block The background screen is blanked, the character image is added to the background screen, and the blanking process makes the character information displayed on the screen easier to read. The character image is stored in the memory (4).

[0012] display clock oscillation circuit (3) generates a <br/> pulse at a constant period, the counter (31) after the horizontal synchronizing signal emitted by counting the number of pulses, the next horizontal synchronizing signal It is reset before the issuance is issued and repeats this.

The writing position of the character block is determined by setting a numerical value in the reference value circuit (7). When the count value of the counter (31) reaches the set value indicating the writing position, the microcomputer (2) reads a character block from the memory (4) and outputs a character to be on-screened to the character generator (5). The character generator (24) outputs RGB pulses indicating a character to a set position based on the vertical synchronizing signal (V) and the horizontal synchronizing signal (H),
The signal addition / synthesis circuit (15) adds the image signal to the television image signal and displays the image on the CRT (16).

The above configuration is a known character display device in a television receiver. In the present invention, a character block signal (17) for confirming a display position is read from a memory (4).
Output to the character generator (24) via the microcomputer (2) and output to the detection circuit (5) connected to the microcomputer (2).

The detection circuit (5) has an exclusive OR circuit (51) and an integration and sample hold circuit (52). The exclusive OR circuit (51) receives the horizontal synchronizing signal (H) from the video output circuit (13), and simultaneously receives the character block signal (17) from the microcomputer (2). The sum output is supplied to an integration and sample-and-hold circuit (52).

FIG. 3 shows signals of various parts of the detection circuit (5). One cycle (1H) of the horizontal synchronizing signal (H) represents the width of the screen of the cathode ray tube (16). When the display clock oscillation circuit (3) is in a normal oscillation state, the writing start position when the counter (31) counts the set number of clocks is:
A position time T ₁ elapses is emitted horizontal synchronizing signal (b view).

FIG. 3C shows a display clock oscillation circuit (3).
This is the display state of the character block when the oscillation period of the character block is delayed from the normal state. Counter (31) is, when the writing start position of the character block (17) is determined by counting the number of setting clocks already time T ₂ after the associated horizontal sync signal (H), the character block range of the screen Cannot display a predetermined number of characters.

A determination signal for determining the writing start position of the character block (17) based on the count number of the counter (31) ;
The exclusive OR with the horizontal synchronization signal (H) is shown in FIGS.
It is as represented respectively d view and e views when. Fig. d shows a normal state, and Fig. e shows a shifted state corresponding to Fig. c. When these signals are integrated and sample-and-hold processing is performed, a voltage V ₁ is output in a normal state, but a voltage V ₂ (V ₂ > V ₁ ) in a state shifted in a delaying direction as shown in FIG.
Is output.

The output is subjected to A / D conversion (53), and a comparison circuit (6)
Comparing the reference value signal V ₁ and the magnitude relation of the reference value circuit (7) to the converter (61) In. By this comparison, it is determined whether the writing position of the character block (17) on the screen is actually advanced or delayed with respect to the normal state, and is corrected according to the program shown in FIG. The actual writing start position of the character block is shifted to a normal position.

The program shown in FIG. 4 is executed by an electronic circuit built in the microcomputer (2),
When (6) determines that V ₂ > V ₁ , the terminal A of the microcomputer (2) is set to “H”. When the comparison circuit (6) determines that V ₂ <V ₁ or V ₂ = V ₁ , the terminal A of the microcomputer (2) is set to “L” (8
2).

[0021] or when the terminal A of the microcomputer (2) is H, the stage set small numerical character block display position horizontal register built in the microcomputer stores (83), V ₂ matches the V ₁ Is determined (84). If still V _2> V ₁ At a this determination, the process repeatedly continues until V2 = V _1.

If the writing position of the character block is ahead of the normal state, portA is "L".
The set value stored in the horizontal register built in the microcomputer is increased by one step, and the above processing is repeated until V ₂ = V ₁ .

When V ₂ = V ₁ , the microcomputer outputs to the character position changing circuit (25), and moves the writing position of the character block to a position in a normal state (FIG. 3B) (86). ), Output to the character generator (24), and displayed on the CRT screen via the addition circuit (15) (87).

The description of the above embodiment is for the purpose of explaining the present invention, and should not be construed as limiting the invention described in the claims for utility model registration or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims for utility model registration.

[0025]

According to the present invention, even if the period of the display clock oscillation circuit (3) is slightly different from a predetermined value, the detection circuit (5) can be used.
Since the normal state can be corrected correctly by the software processing in the comparison circuit (6) and the microcomputer, the adjustment operation performed one by one at the time of the conventional factory shipment becomes unnecessary.

In addition, the components of the display clock oscillation circuit (3) do not need to be high-precision and expensive, and inexpensive components having some variation in performance can be used, thereby reducing the manufacturing cost of the product. Can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIGS. 2A and 2B are explanatory diagrams showing positions of character blocks on a screen and a corrected situation. FIGS.

FIG. 3 is a waveform diagram showing a signal waveform of a character block (17) in one horizontal section and a signal waveform of each part in a detection circuit (5).

FIG. 4 is a program for correcting a character block writing position in the microcomputer.

[Explanation of symbols]

 (16) CRT (17) Character block (2) Microcomputer (22) Synchronous signal counter (25) Character position change circuit (3) Display clock oscillation circuit (13) Counter (5) Detection circuit (6) Comparison circuit (7 ) Reference circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. A writing position of a character block (17) on a screen is set in advance by a numerical value, and the counted number is set to a predetermined position in the horizontal direction of the character block by counting a display clock .
When the corresponding predetermined count is reached, start writing characters.
And it outputs a determination signal for deciding, At a display device for displaying characters, based on the count number of the display clock character block (1
Beginning a determination signal for determining the writing 7), and a horizontal synchronizing signal
The size corresponding to the actual display position by exclusive OR of
A detection circuit for outputting a detection signal V ₂ (5), a reference value circuit for outputting a <br/> reference signal V ₁ the size of which corresponds to the numerical value setting position of the character block (17) (7), detection comparator circuit for comparing the magnitude of the signal V ₂ and the reference signal V ₁
And (6), the output of the comparator circuit (6), relative to the horizontal synchronizing signal
When a judgment signal that determines the start of writing a character block appears
A microcomputer (2) for changing the interim position, and a character position changing circuit (2) for moving a horizontal writing position of a character block on the screen in accordance with an output of the microcomputer (2).
5) A character position correcting circuit on a screen, comprising: correcting the writing position of the character block (17) to a predetermined position set by a numerical value.