JPH0530426A - Character display device - Google Patents

Abstract

PURPOSE:To implement character display with stability and high accuracy by excluding a blur of a character displayed on a digital video image pickup picture. CONSTITUTION:The display device is provided with a device multiplexing a character signal (A), a frame signal (B) and a luminance signal (E) with each other through mixing or insertion, and when a 6-th bit of an output signal C of a decode latch circuit 30 represents the mix mode, after an area level 35B and a frame level 36B are mixed to the luminance signal (E) at an adder 38, a lower limit is limited by a limiter circuit 39, and in the insert mode, the luminance signal (E) is inserted switchingly with a frame level 41B and in the area level, a level 42B is inserted by using an insert switch 41 and an area insert switch 42 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a character display device suitable for use in a video camera or the like.

[0002]

2. Description of the Related Art A conventional character display device of this type is constructed as shown in FIG. 3, and its operation will be described below with reference to FIG.

That is, in FIG. 3, when displaying a camera number or a title, a framing pulse (B) and an area pulse (C) output from a character generator 12 controlled by a microcomputer (hereinafter referred to as a microcomputer) 11 are used. , The changeover switches 14A and 14B are driven to switch between the luminance signal (A), the framing level α and the area level β.

That is, while the edging pulse (B) is active, the changeover switch 14A is in contact with the edging level α side, and while the area pulse (C) is active, the changeover switch 14 (B) is in the area. It contacts the level β side.

Further, for example, in the lens iris control, when it is desired to designate the display of the control area, the area pulse 17B output from the area generator 16 and the framing pulse 17A are used to control the changeover switches 14B and 14A, respectively. During the period, the area level β and its framing level α are switched to the luminance signal (A). Switching output waveforms at this time are shown in (D) and (E) of FIG.

In addition, for example, when it is desired to designate an area to be displayed in the electronic zoom or the like, the area pulse (F) output from the area generator 16 is supplied to the luminance signal (E) and the resistance mix circuit 18 at a predetermined ratio. When mixed, the output waveform at that time becomes like (G).

Although the edging level α and the area level β are shown as the resistance volumes VR1 and VR2 in FIG. 3, there is also a means for arbitrarily setting them under the control of the microcomputer 11.

[0008]

However, in the conventional character display device as described above, there are three control lines for the character signal to be multiplexed with the luminance signal (A) which is the main signal. , Since it is a pulse in the effective area of the image, it is necessary to be careful when guiding it around the mounting board.

Further, for example, if the control area of the lens iris is to be mixed with the luminance signal and displayed, it is necessary to change the hardware and the degree of freedom is insufficient.

Further, in the above conventional resistance mix circuit,
Due to the performance of the analog circuit, the edge portion tends to be blurred (blunted), degrading the quality of the area display. Even if an attempt is made to add edging to correct this, the accuracy is not good because the phase shift, one-sided effect, and edge blurring occur due to the analog circuit.

The present invention solves such a conventional problem by reducing the control lines of the character signal and switching between inserting or mixing the character signal into the luminance signal without changing the hardware. It is an object of the present invention to provide a character display device that can be easily performed, can eliminate edge blurring in a mixed area, can be displayed with high quality, and can be accurately framed in a mixed area.

[0012]

SUMMARY OF THE INVENTION According to the present invention, control lines of area regions such as a title, a lens iris control area and an electronic zoom area, and control lines of an edging region are shared by digital processing.
By the microcomputer control, it is possible to select the type of character to be multiplexed on the luminance signal (type of character to be placed on the control line) and the mode of inserting or mixing the character, and the level at which the character is inserted or mixed,
It can be set separately by a microcomputer.

Further, a limiter is provided so as not to cause synchronization disturbance when a black edge is mixed with a luminance signal of a small level, which is also provided with an edge in the mixed area. is there.

[0014]

Therefore, according to the present invention, since the control lines for the character areas and the framing are shared, the circuit can be reduced, and the insertion or mixing can be freely performed by the mode setting from the microcomputer. Become. Further, since the digital signal processing is performed, the input level of the character can be set accurately and freely, and the fluctuation of the character position is eliminated and the stability is improved.

Further, the edge of the character signal at the time of mixing is not blurred, and the area can be framed even at the time of mixing. By providing a limiter, it is possible to prevent the synchronization disturbance that tends to occur when mixing the black frame, and it is possible to achieve higher quality. It enables various displays.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a character display device according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram of its essential part.

First, in FIG. 1, the parts having the same functions as those in FIG. 3 are denoted by the same reference numerals, and the area pulse (A) and the edging pulse (B) corresponding to the displayed character are characters controlled by the microcomputer 11, respectively. Output from the generator 12 or area generator 16.

These are latch circuits (L) 31 for synchronizing with the digital luminance signal of CCD driving frequency (f _CK ).
It is latched at CCD drive frequency f _CK in A and 31B. In addition, in order to prevent the area width and border width from being unbalanced by the latch, and to obtain stability that does not cause edge jersey phenomenon, etc.
The area generator 16 and the area generator 16 need to be operated using the f _CK oscillation clock that drives the CCD.

The area pulse (A) and the framing pulse (B) of the latched character are supplied to the logic circuit 32,
The edging pulse is formed into an edging pulse (C) without the area. And area pulse (A) and edging pulse
(C) is an insert or mix switch (SW) 33A,
It is supplied to 33B. In the present embodiment, the sixth bit (indicated by C6) of the output c obtained by decoding and latching the data from the microcomputer 11 by the decode / latch circuit 30 is used for the control of the above insertion or mix.

In the mixed mode ((1) in FIG. 2), the area level of 35B is selected by the area switch 34A while the character pulse (A) is active, and 35A is selected in other periods.
0 is input to the OR circuit 37. On the other hand, in the edging switch 34B, the edging level of 36B is selected while the edging pulse (C) is active, and in the other period, 0 of 36A is selected.
Is input to the OR circuit 37.

In this embodiment, the area level of 35B is quadrupled by hardware using the 0th to 5th bits of the signal C of the decode / latch circuit 30. On the other hand, the framing level of 36B is × ± 0.5 times the area level of 35B and × ± 0.2.
Selected from 4 types of data multiplied by 5 using the 6th and 7th bits of the output a of the decode / latch circuit 30 (Se
l) Yes. These are done to reduce the circuit.

The signal (D) obtained by combining the area level 35B and the edging level 36B mixed with the luminance signal generated by the OR circuit 37 is combined with the digital luminance signal (E) which has passed through the latch circuit (L) 31C by the adder 38. A mixed signal (F) is obtained. In this embodiment, since the signals (E) and (F) are 8-bit data,
The upper limit is FFh and the lower limit is 00h. However, since the luminance signal (E) includes an offset in addition to the pedestal, when the lower limit is 00h, when the composite video signal is used, it may fall below the dark level and periodic disturbance may occur.

Therefore, in this embodiment, the limiter circuit is used.
39 is set to limit the lower limit. The lower limit level is the area level (when negative) 42B at the time of insertion, which will be described later, or the framing level.
(Positive) 41B. As the limiter level, the decision circuit 40 selects the smaller one of the signals 41B and 42B as the limiter level.

The output (G) of the limiter circuit 39 is supplied to the frame insertion switch 41. In the mixed mode, the control signal of the sixth bit of the signal C output from the decode / latch circuit 30 is the switch circuit. (SW) 43A output 41
Since the edging pulse (C) is masked by A, the edging insertion switch 41 always selects the output (G). That is, the output (G) passes through the edging insertion switch 41 as it is. Similarly, since the area pulse (A) is masked by the output 42A of the switch circuit (SW) 43B, the area insertion switch 42
Also passes through.

Next, in the character insertion mode (see FIG.
(2)) Since the switches 34A and 34B always select 0 of 35A and 36SA, the adder 38 does not mix the character with the luminance signal (E).

On the other hand, the edging switch 41 selects the edging level 41B while the edging pulse (C) is active, selects the output (G) of the limiter circuit 39 during the other period, and inserts the edging into the main line. (H) is obtained. With the area insertion switch 42, the area level 42B is selected while the character (A) is active, the main line signal (H) is selected during the other period, and the signal (I) obtained by inserting the area into the main line is obtained. The edging level 41B is a value obtained by multiplying the 0th to 5th bits of the signal a obtained by decoding and latching the data from the microcomputer 11 by the decoding / latch circuit 30. Similarly, the area level 42B is decoded by the decode / latch circuit 30.
It is a value obtained by multiplying the 0th to 5th bits of the latched signal b by four.

The signal (I) thus obtained is used for the latch circuit.
Latch at 43 to obtain digital luminance signal output for character multiplexing. If you do not add framing, you can use the edging pulse
(B) will always be negative.

[0029]

As described above, according to the present invention, in a CCD video camera or the like, a control signal for displaying, for example, a title, a lens iris control area, or an electronic zoom area is utilized, and a brightness signal is converted into a brightness signal by controlling a microcomputer. The types of characters to be multiplexed, their signal levels, and whether to insert or mix in the luminance signal can be freely set, and further, the circuit scale and wiring can be reduced. Further, according to the present invention, the character insertion circuit can be realized with high accuracy because of the digital signal processing, and even when the characters are mixed, the edges are not blurred and the edging can be formed with high accuracy, which enables high-quality character display.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a character display device according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram of a main part of FIG.

FIG. 3 is a configuration diagram of a conventional character insertion and mix circuit.

FIG. 4 is a diagram showing signal waveforms of respective parts of FIG.

[Description of symbols] 11 ... Microcomputer (abbreviated as microcomputer), 30 ... Decode / latch circuit, 31A, 31A, 31C, 43 ... Latch circuit (L), 32 ... Logic circuit, 33A, 33B ... Insertion or mix switch (SW), 43A, 43B ... Switch circuit (S
W), 34A ... area switch, 34B ... edging switch, 38 ... adder, 39 ... limiter circuit, 40 ... determination circuit, 41 ... edging insertion switch, 42 ... area insertion switch.

Claims (1)

Claim: What is claimed is: 1. In a video camera for digital processing under microcomputer control, means for switching between inserting or mixing a character signal in an image pickup signal, and means for framing the mixed character signal. , A means for arbitrarily setting the area to be inserted and mixed and the level of framing under the control of the microcomputer, and a screen generated by subtracting the framing level from the image pickup signal level when edging at the time of mixing A character display device, comprising means for applying a limiter to the edging level at the area level for inserting the mix or at the edging level thereof in order to prevent blackening.