JP2737110B2 - Superimpose circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a superimposing circuit for creating one image by superimposing two or more images, and more particularly to superimposing a character such as a character on an image. Related to a superimpose circuit. [Related Art] In an image reproducing apparatus that reproduces an image recorded on a recording medium such as a so-called magnetic floppy disk or magnetic tape and displays the image on an image display device such as a monitor television,
For example, a superimposition circuit superimposes a character such as a character representing image information (for example, frame number) related to the operation state of the apparatus or the reproduced image on the reproduced image, and displays it on the display screen.
Further, in such an image display device, for the display content that the viewer particularly wants to pay attention to, the outline of the image around the character is not visible so that the character is clearly displayed on the display screen. The image of the area is completely missing. [Problems to be Solved by the Invention] However, in the superimpose circuit of the image reproducing apparatus, since the image around the character is completely omitted, many or large characters are displayed. In such a case, there is a problem that an image is lost over a wide range by displaying the character. The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a superimpose circuit for displaying a character clearly on an image and preventing an image around the character from being completely missing. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a color image displayed on an image display device based on an input color video signal and a white peak level output from a character generating means. In a superimposing circuit for superimposing a nearby white character, the level of a luminance signal of the input color video signal is adjusted in accordance with a predetermined output timing of the character output from the character generation output. A luminance signal level setting means for setting a value lower than the level to lower the luminance of the image around the character within a range in which the outline of the image can be understood; and a predetermined output timing of the character output from the character generation output. The color signal of the input color video signal is deleted, and an image around the character is deleted. And a color signal erasing means for making a monochrome image. [Operation] In the superimpose circuit of the present invention, the level of the luminance signal of the input video signal is adjusted in accordance with the predetermined output timing of the white character near the white peak level, which is output from the character generation means. The input level is set to a value lower than the input level by the level setting means, the brightness of the image around the character is reduced to the extent that the outline can be recognized, and the color signal is erased by the color signal erasing means, so that the image around the character is monochrome. I try to make it an image. Thus, even if a character is superimposed on a large or large number of images, the image around the character is not completely missing, and the brightness of the image around the white character near the white peak level is reduced. Since the image is a monochrome image, the character is displayed clearly. Hereinafter, preferred embodiments of a superimpose circuit according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the overall configuration of an image reproducing apparatus to which the present invention is applied. In FIG. 1, a magnetic recording medium 2 such as a magnetic sheet is detachably mounted on a rotating shaft 4A of a DC motor 4. The magnetic sheet 2 has a small size of 50 mm in diameter in the present embodiment, and a plurality of, for example, 50 recording tracks are formed on the recording surface 2A in a concentric manner at a pitch of about 100 μm. The signal recorded on each recording track is a video signal for one field corresponding to one frame, and this video signal is, for example, a color video signal. The luminance signal Y of the color video signal is FM-modulated using a frequency band of about 2.5 MHz or more, including the composite synchronization signal S, and the sync tip level is set to 6 MHz and the white peak level is set to 7.5 MHz centering on 7 MHz. ing. In addition, the color signal C is composed of two line-sequential color difference signals R−
Y and BY are FM-modulated using a frequency band of about 2.5 MHz or less, and the center frequency of the line-sequential color difference signal RY is 1.2 MHz.
z, the line-sequential color difference signal BY is set to 1.3 MHz. The DC motor 4 is supplied with power by a motor drive circuit 6 and is driven and controlled so that the magnetic sheet 2 rotates at a predetermined speed, for example, at a constant speed of 3,600 rpm. Motor drive circuit 6
Is controlled by the control circuit 30, and controls the rotation drive and stop of the magnetic sheet 2 in response to the control signal DISK output from the control circuit 30. On the recording surface 2A of the magnetic sheet 2, a magnetic transducer, that is, a magnetic head 8 is provided. Magnetic head 8
The FM video signal reproduced from the recording track is amplified by the reproduction amplifier 9 to a level that can be demodulated, and then the high-pass filter (HPF) 10 and the low-pass filter (LPE) 20
Is input to The high-pass filter 10 has a frequency characteristic of passing a signal of about 2.5 MHz or more, whereby an FM luminance signal (Y + S) _FM is extracted from the FM video signal. FM luminance signal (Y + S) _FM is demodulated by a demodulation circuit 12, and then input to a superimpose circuit 14 and a synchronization separation circuit 13. The sync separation circuit 13 converts the luminance signal Y + S from the vertical sync signal V _D
And extracting a horizontal synchronizing signal H _D, and outputs to the control circuit 30. The low-pass filter 20 has a frequency characteristic of passing a signal of about 2.5 MHz or less, thereby extracting an FM line-sequential color difference signal (RY, BY) _FM from the FM video signal. FM line-sequential color difference signals (RY, BY) _FM are demodulated by a demodulation circuit 22 and input to a synchronization circuit 24. The synchronization circuit 24 outputs the demodulated line-sequential color difference signals RY, B
−Y are synchronized, and the color difference signals RY and BY of parallel signals are output to the encoder 26. The encoder 26 has a color difference signal R-
Y and BY are generated into a color signal C conforming to the NTSC system, for example. The output signal from the encoder 26 is input to the superimpose circuit 14. The superimpose circuit 14 is provided with a monitor television 32 to be described later.
Is a circuit for superimposing a character such as a character representing the operating state of the apparatus or image information on the image displayed on the screen. The luminance signal Y + S input to the circuit 14 is clamped to a fixed DC voltage value by the clamp circuit 15 at the portion of the composite synchronizing signal S, and is supplied to the level adjustment circuit 16 and the contact a of the analog switch SW1. Level adjustment circuit 16
Comprises resistors R1, R2 and a DC constant voltage power supply 17, and sets the luminance signal Y + S to a predetermined low level. The signal level is determined by the voltage division ratio between the resistors R1 and R2. The luminance signal Y + S from the level adjustment circuit 16 is applied to the contact b of the analog switch SW1.
Supplied to the side. The analog switch SW1 performs a switching operation based on a switch signal 42 output from the control circuit 30, and a contact b is selected during a predetermined period before and after displaying a character, and a contact a is selected during a period during which an image is displayed. . Switch signal 42 is output synchronizing signal V _D, based on the H _D at a predetermined timing. The output signal from the analog switch SW1 is supplied to the contact a of the analog switch SW2. Further, a DC constant voltage power supply 18 is connected to the contact b side of the analog switch SW2. Output voltage V ₂ of the DC constant voltage power supply 18 in this embodiment is set to be substantially equal to the peak white level of the luminance signal Y + S. The analog switch SW2 performs a switching operation based on a switch signal 46 output corresponding to the character from the control circuit 30, and in a predetermined period for displaying an image, the contact a side is in a predetermined period for superimposing the character on the image. The contact b side is sequentially selected. The output signal from the analog switch SW2 is input to the mixer 19. On the other hand, the analog switch SW to which the color signal C is supplied
The opening / closing control of 3 is performed based on the switch signal 44 output from the control circuit 30. The analog switch SW3 sets the color signal C within a predetermined period before and after the character is displayed.
Is not input to the mixer 19, and the color signal C
Can be erased. As a result, a monochrome video signal is created for that period. Switching signal 44 the switching signal 42 similarly to the synchronizing signal V _D, it is output with respect to the H _D, has its output timing is substantially the same. That is, the analog switch SW3 is
The switch is opened when the analog switch SW1 is connected to the contact b, and is closed when the analog switch SW1 is connected to the contact a. The mixer 19 mixes the luminance signal Y + S and the chrominance signal C output from the superimposing circuit 14 to create an NTSC television signal. The television signal is supplied to an image display device 32 such as a monitor television and a signal output terminal T1, and the monitor television 32 displays an image based on the television signal. The control circuit 30 controls image reproduction, display control of image information,
A warning process or the like is performed, and the state can be represented by a character on the display screen 32A of the monitor television 32. Also,
The control circuit 30 has a character generator is provided for generating a character output timing synchronization signal V _D of the switch signal 42, 44, 46, and in addition to the generation timing also reference the character H _D . Further, an operation unit 34 for instructing various controls is connected to the control circuit 30. The operation unit 34 is a forward key for instructing to send the magnetic head 8 from the outer peripheral side to the inner peripheral side of the magnetic sheet 2 (forward direction), and a reverse key for instructing to send the magnetic head 8 in the reverse direction opposite to the forward key. A feed key, a frame key for instructing display of a frame number, and the like are provided. Next, the operation of the image reproducing apparatus configured as described above will be described. When the magnetic sheet 2 is rotated at a constant speed of 3,600 rpm, the magnetic head 8 is transferred from the outer peripheral side to the inner peripheral side of the magnetic sheet 2 by operating, for example, a forward key of the operation unit 34, and a predetermined number of times. It is arranged on the recording track. The FM video signal reproduced from the recording track via the magnetic head 8 is input to the high-pass filter 10 and the low-pass filter 20 via the reproduction amplifier 9. High pass filter 10
FM luminance signal (Y +
S) _FM is input to the mixer 19 via the demodulation circuit 12 and the superimpose circuit 14. Further, the luminance signal F + S from the demodulation circuit 12 is also input to the synchronization separation circuit 13. On the other hand, by the low-pass filter 20 is extracted from the FM video signal FM chrominance signal C _FM is, the demodulation circuit 22, a synchronization circuit 24, a mixer via an encoder 26 and a superimposing circuit 14
Entered in 19. The luminance signal Y + S and the chrominance signal C mixed by the mixer 19 are converted into a television signal by a monitor television 32.
It is supplied to the call signal output terminal T1. The monitor television 32 displays an image based on the input television signal. When an image is displayed on the monitor television 32 in this way, for example, if the operator gives a warning to the operator from the apparatus side, the control circuit 30 controls the analog switches SW1, SW2, and SW3 of the superimpose circuit 14 to operate. Control is performed so that a warning is displayed as a character at a predetermined position on the display screen 32A. The control circuit 30 controls the synchronization signals V _D and H _D from the synchronization separation circuit 13.
For example, in the second scan (A ₂ ) of the odd field A shown by a broken line in FIG.
During the period T corresponding to the display position a from the display position a, the analog switch SW1 is switched to the contact b, and the analog switch SW3 is opened. As a result, the level of the luminance signal Y + S decreases at a predetermined ratio during the period T, and the color signal is erased, resulting in a monochrome image with reduced luminance. In the third scan (A ₃ ) of the odd field, the display position a on the display screen 32A is the same as in the _second scan (A ₂ ).
Switches the analog switch SW1 from the contact a to the contact b, and opens the analog switch SW3 so that a low-luminance monochrome image is displayed. Next, the analog switch SW2 is set to, for example, a four-character character (A, B, C,
D), the contact a is switched from the contact a to the contact b for a predetermined period of time in correspondence with the character of the character “A”.
Along with this, the level of the luminance signal Y + S rises in correspondence with the character of the character "A", and a part of the character of the character "A" is displayed on the display screen 32A with a high luminance by the _second scan (A2). Is displayed. After the display of the character "A" is completed, the contact "a" of the analog switch SW2 is again selected for a period corresponding to the space between the character "B" to be displayed next and the low-brightness monochrome. The image is displayed. Hereinafter, similarly, the remaining characters “C” and “D” are sequentially displayed with a certain space by the _second scanning (A ₂ ). In the present embodiment, the second field of the odd field A is
Fourth scan (A ₂ to A ₄₎ by four characters from th (A, B, C, D) character (white characters the white peak level near) are sequentially monochrome images low brightness , And are displayed with high brightness with a certain space. After the scanning of the odd field A is completed, these three analog switches SW1, SW2, and SW3 are similarly controlled for the period T also in the scanning of the even field B shown by a solid line in FIG. The second to fourth of this even field B
Four characters (A, A, A) in the area not displayed by the scan (A2 to A4) of the odd field A by the second scan (B2 to B4)
The remaining characters (B, C, D) are sequentially displayed at high luminance on the low-luminance monochrome image. As described above, the display screen 32A displays four characters (A, A, B) which indicate a warning by scanning the odd field A and the even field B.
The characters B, C, and D) are displayed with high luminance in the low-luminance monochrome image area. Further, in addition to the character indicating a warning or the like shown in FIG. 2, for example, a frame key of the scanning unit 34 is operated to display a character representing image information such as a frame number shown by a signal 35 in FIG. Is also good. Also in this case, the character is displayed at a constant high luminance, the luminance of the image around the character is reduced, and the character is displayed as a monochrome image. As described above, in the image reproducing apparatus according to the present embodiment, a character such as a character indicating the operating state of the apparatus or image information related to the reproduced image is displayed on the image displayed on the monitor television 32 by the superimposing circuit according to the present invention. When superimposing is performed, the level of the luminance signal Y + S corresponding to the image around the character is set low enough to make the outline of the image understandable, thereby lowering the luminance of the image and making the image around the character a monochrome image. . As a result, a white character near the white peak level is clearly displayed. [Effects of the Invention] As described above, according to the present invention, it is possible to superimpose a character such as a character output from an image character generating means displayed on an image display device based on an input video signal. In the superimpose circuit, a white character near the white peak level is superimposed on a color image, the image around the character is reduced in brightness, and the color image around the character is monochrome. , The character can be clearly displayed. Although the image around the character is reduced in brightness and converted to monochrome, the image is displayed. Therefore, even when a large number or large size of characters is displayed, the image is not lost over a wide range.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram showing an overall configuration of an image reproducing apparatus to which a superimpose circuit according to the present invention is applied, and FIGS. 2 and 3 are images shown in FIG. FIG. 4 is an explanatory diagram for describing an example of a composite image displayed on a display screen of a display device. 15: Clamp circuit, 16: Level adjustment circuit, 18: DC constant voltage power supply, SW1, SW2, SW3: Analog switch.

Claims (1)

(57) [Claims] A superimposing circuit for superimposing a white character near a white peak level output from a character generating means on a color image displayed on an image display device based on an input color video signal; In accordance with a predetermined output timing of the character output from the output, the level of the luminance signal of the input color video signal is set to a value lower than the signal level, and the luminance of the image around the character is adjusted to the contour of the image. A luminance signal level setting means for lowering the color signal of the input color video signal in accordance with a predetermined output timing of the character output from the character generation output, and an image surrounding the character; And a color signal erasing means for making a monochrome image. Over par imposing circuit.