JPH0486088A - Horizontal scan inverter for pal signal - Google Patents

Abstract

PURPOSE:To accurately reproduce a hue by performing the inversion processing of the hue after inverting a time base other than a horizontal synchronizing signal and a color burst signal. CONSTITUTION:The horizontal scan inverter of a PAL signal consists of a scan inversion circuit A which inverts the time base of a carrier signal, and a hue inversion circuit B which inverts the hue. The scan inversion circuit A, after converting a composite PAL signal to a digital signal by an A/D converter 1, stores it by allocating alternately by every line in one-line memory 3 and one-line memory 4 an electronic switch 2. In a readout operation, the time base other than the horizontal synchronizing signal and the color burst signal is inverted by receiving an address operation by an address counter 7. An inverted signal is analogized and outputted from a D/A converter 6. Thereby, a color can be accurately reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a PAL signal horizontal scanning inversion device that inverts the time axis of a PAL signal to horizontally invert a television image.

<Prior Art> In recent years, television cameras have been used in place of rearview mirrors in large vehicles due to the reduction in price and size of electronic equipment, and due to policies that emphasize safety in the automobile industry.

There are eight methods for displaying the images by reversing the left and right images, but conventionally, when the display device is a CRT, a method of reversing the direction of the horizontal current has been used. In addition, even if the display device is shared with other image signals even if it is a CRT, or if the display device is an LCD, the composite PAL signal that is sent is temporarily stored in memory for each scanning line, and it can be changed by address operation. A method was used in which the data were read out in the reverse order of the stored order to obtain an output with the time axis reversed.

<Problem to be solved by the invention> However, what is the problem with the above method of reversing the time axis by memory address manipulation? Although the time axis of the carrier color signal among the signals included in the I/I combined PAL signal is reversed, the time axis of the color burst signal is not reversed, resulting in a problem that color reproduction becomes unnatural.

SUMMARY OF THE INVENTION An object of the present invention is to provide a horizontal scanning inversion device for a PAL signal that can also invert the time axis of a color burst signal and accurately reproduce one color.

Means for Solving the Problems> The present invention has been made to achieve the above object, and is a horizontal scanning inversion device for PAL signals that inverts the time axis of horizontal synchronization signals and color burst signals.
separation means for separating the L signal into a luminance signal and a carrier color signal; a calculation means for calculating and outputting a carrier color signal having the same hue as the original image of the carrier color signal; and output from the calculation means for the luminance signal. The present invention is characterized by comprising a combining means for combining the carrier color signals and outputting a composite PAL signal.

Function> The horizontal synchronization signal and the PAL signal whose time axis has been reversed, other than the color burst signal, are separated into a luminance signal and a carrier color signal by the separation means. Based on the carrier color signal, the calculating means calculates and outputs a carrier color signal having the same hue as that of the original image. 8. The synthesizing means synthesizes the carrier color signal having the same hue as the original image and the luminance signal and outputs a PAL signal. do.

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing the overall configuration.

This horizontal scanning inversion device for PAL signals includes a scanning inversion circuit A that inverts the time axis of a conveyed color signal, and a hue inversion circuit B that inverts one hue.

Scan inversion circuit A converts the composite PAL signal into A/D converter 1.
After converting the signal into a digital signal, the electronic switch 2 alternately distributes and stores each line in a 1-line memory 3 and a 1-line memory 4. The data stored in the 1-line memory 3 and the 1-line memory 4 are read out alternately by the electronic switch 5.
The reading is performed in response to an address operation by the address counter 7, and the time axes of signals other than the horizontal synchronization signal and the color burst signal are inverted. Then, the inverted signal is converted into an analog signal by a D/A converter 6 and output. Further, the operations of the electronic switch 2 and the electronic switch 5 are configured to be synchronized by a flip-flop 8.

The operation of this scan inversion circuit A will be explained with reference to FIG.

The composite PAL signal input to this circuit A is distributed to a 1-line memory 3 and a 1-line memory 4 by an electronic switch 2, and a signal 2 is written to the 1-line memory 3.

At this time, the electronic switch 5 reverses the time axes of the signals other than the horizontal synchronizing signal 30 and the color burst signal 31, which have already been written in the 1-line memory 4, and outputs them as a signal ■'. Then, the signal ■' is converted into analog data by the D/A converter 6, and the composite PA at this time is
It becomes an L signal output.

When the writing of the signal ■ to the 1-line memory 3 and the reading of the signal ■' from the 1-line memory 4 are completed, the electronic switch 2 subsequently starts writing the signal ``■'' to the 1-line memory 4. On the other hand, the te: child switch 5 inverts the time axis of the signal ■ written in the 1-line memory 3 and outputs the signal ■.
’ is output. Then, the signal ``2'' is converted into analog data by the D/A converter 6 and becomes a composite PAL signal output at this time. However, in the composite PAL signal after the scanning inversion, the time axes of the horizontal synchronization signal 30 and the color burst signal 31 are not inverted, but only the time axis of the carrier color signal 32 is inverted, which will be explained using an equation.

A composite PAL signal shown in equation (1) is input to the scan inversion circuit A.

EM(t)=EY(t)+ELI(t)+S i
n c, +set±Ev(t)・CO5ωsct
(1) EM(t): Composite PAL signal EY(t): Luminance signal Ell(t): Chromaticity signal EV(t): Chromaticity signal ωSC dichromatic subcarrier angular frequency (=2πfsc) fsc:
The color subcarrier frequency (=4.43361875 MHz) and the composite color signal EC(t) are expressed by equation (2).

EC(t)=EU(t) ・S i n (inse
t±EV(t)・Cos ωsct '−(2) Here, if the time axis is reversed as described above, the composite color signal EC(
t) is as shown in equation (3).

E' C(t)=EC(-t) =-EU(-t) TS i n (+)SCj±E
V(-t)・Cos ωsct (3)E'
C(t): Composite color signal formula (2), formula (3) after scan inversion
The carrier color signal vector 51 shown in FIGS. 3 and 4 was delayed by a phase Φ with respect to the color burst signal 50 before inversion to 0, but after the inversion, the carrier signal vector 51 is ahead by a phase Φ.

As it is, the hue cannot be accurately reproduced, so the hue inversion circuit B continues the hue of the inverted signal.
It is configured to invert and accurately reproduce the hue.

The hue inversion circuit B is configured to process the carrier color signal shown in equation (2) and a signal with twice the frequency of the color subcarrier (2Cos2ω5ct) using a multiplier to obtain the output shown in equation (4). ing.

(2Cos2ω5et)XE' C(t)= (2Co
s 2ω5ct) X (-EU(-t) ・S in ωsct±E
V(-t)・Cos ω5ct)=EU(-t)・
S i n ωsct±EV(-t) ・Cos
ω5ct-Elf(-t) ・S in 3 ωs
ct+EV(-t)・Cos 3ωsct (4
), and is configured to extract only the first and second terms of equation (4) to obtain a carrier color signal of the same hue as the original image.

The color phase inversion circuit B is processed by the scan inversion circuit A and the D/A
The composite P A, L signal output from converter 6 is
/C separation circuit 9 separates a luminance signal 41 and a carrier color signal 40.
It is configured to be separated into two parts.

The carrier color signal 40 is divided into two color subcarriers in a multiplier 11.
It is processed together with the signal 42 of twice the frequency (2Cos2ω5et) to become the signal shown in equation (4). And further 4.
The first and second terms of equation (4) based on 43MHzBPF12
The configuration is such that only the signal corresponding to the term is extracted.

Thereafter, the extracted signal is combined with the luminance signal 41 in the Y/C combining circuit 10, and is configured to be outputted again as a composite PAL signal.

Next, the operation will be explained.

The composite PAL signal whose time axis has been inverted except for the horizontal synchronization signal 30 and the color burst signal 31 by the scan inversion circuit A is then sent to the Y/C separation circuit 9 of the hue inversion circuit B to be converted into a luminance signal 41 and a carrier color signal 40. It is separated into Then, the carrier color signal 40 is passed to the multiplier 11 by two of the color subcarriers.
Processed together with the signal 42 of twice the frequency, the above equation (4)
The signal is output as shown in . Further, from this signal, a signal corresponding to the first and second terms of equation (4), that is, a signal having the same hue as the original image, is extracted by the 4.43 MHz BPF 12. Thereafter, the signal is converted into a luminance signal 41 separated by a Y/C separation circuit 9 in a Y/C combining circuit 10.
This results in a composite PAL signal that can accurately reproduce hue.

In this embodiment, the hue inversion circuit B is placed behind the scanning and inversion circuit A, but it may be placed in front of the scanning and inversion circuit gA.

In the embodiments described above, after inverting the time axes of signals other than the horizontal synchronization signal and the color burst signal, the hue inversion process is further performed, so that the hue can be accurately reproduced.

<Effects of the Invention> The horizontal scanning inversion device for PAL signals of the present invention provides effects such as being able to accurately reproduce the hue of an image after horizontal inversion.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing its operation, and FIGS. 3 and 4 are vector diagrams explaining the operation of the embodiment of the present invention. 1: A/D converter, 2: Electronic switch, 3: 1 line memory, 4: 1 line memory, 5: Electronic switch, 6
: D/A converter, 7: Address counter, 8:
Flip-flop, 9: Y/C separation circuit, 10:
Y/C synthesis circuit, 11: Multiplier, 12: 4.43
MHzBPF, 30: Horizontal synchronization signal, 31: Color burst signal, 32: Carrier color signal, 40: Carrier color signal, 41
: Luminance signal, A: Scan inversion circuit, B: Color phase inversion circuit. Patent applicant: Clarion Co., Ltd. Representative: Patent attorney Kiyoshi Takahashi

Claims (1)

[Claims] In a PAL signal horizontal scanning inversion device that inverts the time axis of signals other than a horizontal synchronization signal and a color burst signal of a PAL signal, the separation means separates a composite PAL signal into a luminance signal and a carrier color signal. a calculation means for calculating and outputting a carrier color signal having the same hue as the original image of the carrier color signal; and combining the luminance signal and the carrier color signal output from the calculation means to output a composite PAL signal. A horizontal scanning inversion device for a PAL signal, comprising: combining means;