JPH02143790A - Luminance signal processor - Google Patents

Abstract

PURPOSE:To attain small size and low power consumption by allowing a pre- stage 1H memory in two 1 horizontal period (1H) memories forming a comb-line filter to act like dropout compensation at the same time. CONSTITUTION:A 1H memory 1 stores an input luminance signal Y; by 1H to inhibit data write when a signal DOP representing dropout of the input luminance signal Y; is inputted. That is, the stored 1H preceding data is read at an output of the 1H memory 1 normally but the data before occurrence of dropout is left by 1H in the occurrence of dropout, the data is repetitively read at 1H period and a data Y1 subjected to dropout compensation is outputted. A 1H memory 2 outputs an output of the 1H memory 1 with further 1H delay. Since the memory circuit by 2H acts like dropout compensation of a luminance signal at the same time in this way, small size and low power consumption are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a luminance signal processing device for band-limiting a luminance signal necessary for obtaining a composite video signal using a simple reproduction method in a high-resolution VTR. It is something.

2. Description of the Related Art In recent years, video resolution has been increased in the field of VTRs, and VTRs have been commercialized that can record and record luminance signals by extending them to the carrier color signal band. For example, component VTRs that record luminance signals and chrominance signals on separate tracks (for example, Japanese Patent Laid-Open No. 60-124194) and home VTRs that have a higher recording band for luminance signals (for example, Nikkei Electronics, May 4, 1987 issue). , No. 420.
p87-69) are typical examples. These VTs
To reproduce an R video signal, the high-frequency components of the luminance signal and carrier color signal components interfere and appear as interference, so the luminance signal and carrier color signal must be sent on separate transmission paths, or a composite signal must be used. Before converting to , time axis correction is performed to make it possible to separate the luminance signal and color signal before outputting the reproduced signal. However, when obtaining a composite video signal using a simple method that does not perform time axis correction, the carrier color signal component of the luminance signal is removed by the following method.

Figure 6 shows a conventional example of simple playback of PAL high-resolution video signals, where 11 is an IH memory 1H that stores a luminance signal for one horizontal period (hereinafter referred to as IH), and 10 is normally Y.
When the signal of i is input to the IH memory 11 and the dropout signal DOP is input, the switch switches so that the output of the IH memory 11 circulates to the input, and 12 is a 2H memory I ha that delays the input signal by 2H. 13 and 16 are subtraction circuits, 14 is a band pass filter (BPF), and 15 is a delay circuit. 17 is an adder circuit, and 18 is a color signal processing circuit for generating a reproduced carrier color signal.

The operation of a conventional luminance signal processing device will be explained below with reference to the drawings. The switch 10 selects the brightness signal Yi during normal times, and when the signal DOP indicating dropout of the brightness signal Yi is input, the brightness signal Ydl after passing through the IH memory 11 is selected, and the brightness signal Ydl is selected, and the brightness signal Ydl after passing through the IH memory 11 is selected. Signal Y1 is supplied to IH memory 11 and 2H memory 12, respectively. A component X that interferes with the color signal in the carrier color signal band is extracted from the luminance signal Y1 by a comb filter and a bandpass filter 14, which are composed of a 2H memory 12 and a subtraction circuit 13, and a subtraction circuit 16 delays the luminance signal Y1. A circuit 15 removes the interference component X from the delayed signal to obtain a reproduced luminance signal YO. The delay circuit 15 is for adjusting the time axis of the luminance signal Y1 in accordance with the delay of the signal X caused by the bandpass filter 14.

With the above configuration, the luminance signal YO has a center frequency determined by the bandpass filter 14 from the luminance signal band A, as shown in the frequency distribution diagram of FIG. The frequency distribution is obtained by removing the part without 2H correlation. However, the seventh
The figure shows a gain of 1 in the passband of the bandpass filter 14.
2 is a frequency distribution diagram in the case of /2. The color signal processing circuit 18 generates a reproduced carrier color signal and uses the luminance signal Y.
o and an adder circuit 17 to output a composite video signal Q. With the circuit configuration described above, dropout of the luminance signal of the video signal Q is compensated for, and a composite video signal can be obtained in which there is no interference from the luminance signal component to the carrier color signal.

Problems to be Solved by the Invention Simple playback devices such as home VTRs and VTRs for news gathering use the method described above to play back composite video signals, but in particular play back PAL composite video signals. In this case, the conventional configuration requires an IH memory 11 for dropout compensation and an additional 2H memory 12 to configure a comb filter for removing interference with the carrier color signal. When configuring a dropout compensation function or a comb filter, the circuit size and power consumption increase, which is a big problem especially for VTRs in fields that require small size and low power consumption.

The present invention solves the above-mentioned conventional problems, and aims to provide a brightness signal processing device for a VTR that is small in size and consumes low power.

Means for Solving the Problems In order to achieve this object, a luminance signal processing device of the present invention includes a first memory circuit having a write inhibit function that delays a luminance signal by one horizontal period, and a first memory circuit connected to the first memory. a second memory circuit that further delays the luminance signal by one horizontal period; a first subtraction circuit that subtracts the output luminance signal of the second memory circuit from the luminance signal input to the first memory circuit; a bandpass filter that extracts a carrier color signal band signal from the output of the first subtraction circuit; and a second bandpass filter that subtracts the output signal of the bandpass filter from the luminance signal dropout-compensated in the first memory circuit. It is equipped with a subtraction circuit.

Operation The present invention operates with the above-described configuration so that, of the two IH memories forming the comb filter, the former IH memory also performs dropout compensation at the same time.

Embodiment Hereinafter, a luminance signal processing device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of a luminance signal processing device in a first embodiment of the present invention. Processing of the carrier color signal is the same as in the conventional example, so a description thereof will be omitted. 1st
In the figure, 1 is an IH memory with a write-protection function;
2 is an IH memory, 3.7 is a subtraction circuit, 4 is a band pass filter, 5 is a switch, and 6 is a delay circuit.

The IH memory 1 stores the input luminance signal Yi in an IH manner, and data writing is prohibited when a signal DOP indicating dropout of the input luminance signal Yi is input. That is, normal IH
The stored data before IH is read out from the output of memory 1, but when a dropout occurs, the data before dropout remains for IH, and that data is read out repeatedly in the same period as IH, and the dropout compensation is performed. The resulting data Y1 is output. IH memory 2 is the IH memory 1
The output is further delayed by IH and output. The switch 5 normally selects the input luminance signal Yi, and when a dropout occurs, selects and outputs the dropout compensated signal Y1. The subtraction circuit 3 subtracts the output of the IH memory 2 from the input luminance signal Yi to form a 2H comb filter.

FIG. 3 shows waveforms at various parts in the first embodiment of the present invention shown in FIG. In FIG. 3, the carrier color signal band component xi that causes interference has a frequency fsc that is inverted and repeated every 2H.
By subtracting the signal Y2, which is a nearby signal and is delayed by 2H from Yi, its component can be extracted as the signal X, and by subtracting the signal X from the signal Y1, the output signal Y is obtained.

1 is a signal in which the interference component xi has been removed or reduced. Dropout correction is performed for the portion where dropout occurs, but the interference component is output as is. The frequency response of the signal X to the input signal Yi is a synergistic characteristic of the band B determined by the bandpass filter 4 and the comb filter characteristics composed of the IH memory 1.2 and the subtraction circuit 3.
1/2fh (f
The frequency characteristic has a peak at each horizontal frequency (h is the horizontal frequency).

When a dropout occurs, the luminance signal Y1 selected by the switch 5 and the output of the IH memory 2 become the same signal, so the output of the subtraction circuit 3 becomes zero. After the delay circuit 6 gives the luminance signal Yi the same time delay as the bandpass filter, the subtraction circuit 7 removes the interference component X from the bandpass filter 4, as in the conventional example, and the luminance signal Yol is The frequency distribution diagram is also similar to the conventional example.

As described above, according to this embodiment, the 2H memory conventionally used exclusively for the comb filter can be used as an I
The luminance signal Yi is divided into the H memory 1 and the other IH memory 2, and a switch 5 is used to switch the luminance signal Yi supplied to the subtraction circuit 3 that creates the output of the comb filter to the dropout compensated signal Y1 when a dropout occurs. This makes it possible to perform dropout compensation without providing a dedicated memory for dropout compensation.

FIG. 2 is a block diagram of a luminance signal processing device showing a second embodiment of the present invention. In the same figure, since the constituent elements are the same as those in the first embodiment, the same reference numerals are given and redundant explanation will be omitted. The difference from the first embodiment is that the output luminance signal Yo2
In the first embodiment, the signal that will become a later signal is the signal Yi before being delayed, but in this embodiment, it is the luminance signal Y2 delayed by 2H after passing through the IH memory 2. Since the signal Y2 has already undergone dropout compensation, it is directly supplied to the subtraction circuit 3 and the delay circuit 6. The luminance signal Yi supplied to the subtraction circuit 3 is a signal without dropout compensation. Therefore, when a dropout occurs, the switch 5 is used to connect the subtraction circuit 3 and the bandpass filter 4.
By setting the signal obtained by cutting the interfering component at the time of passing through as the interfering component X, it is possible to prevent the signal at the time of dropout from leaking into the output luminance signal Yo2.

That is, when a dropout occurs, the luminance signal Y2 that has been compensated for dropout from the IH memory 2 is directly output as the luminance signal Y via the delay circuit 6.

Output as 2.

FIG. 5 shows waveforms at various parts in the second embodiment of the present invention shown in FIG. The frequency characteristics of the signal X with respect to the input Yi are similar to those of the first embodiment, and are as shown in FIG.

Therefore, the frequency distribution diagram of the luminance signal Yo2 is also as shown in FIG. 7, similar to the first embodiment and the conventional example.

As described above, in the second embodiment of the present invention, the IH memory 1,
The interference component X to the carrier color signal that has passed through the bandpass filter 4 is removed from the luminance signal Y2 that has passed through the bandpass filter 4. That is, the obtained luminance signal Y0 is the input luminance signal Y
The signal is delayed by 2H from i. In the case of a composite (composite) VTR in which the carrier color signal is demodulated into a color difference signal, compressed in the time axis, and recorded on a separate track with the luminance signal, the reproduced color signal is 2H for the luminance signal, IH for recording and IH for playback.
Because of the delay, it is necessary to perform processing to delay the luminance signal by 2H during reproduction to match the time axis with the color signal. However, the second aspect of the present invention
According to the embodiment, since the luminance signal is already a signal delayed by 2H, a new 2H memory is not required.

Effects of the Invention As described above, the present invention includes a first memory circuit having a write inhibit function that delays a luminance signal by one horizontal period;
a second memory circuit connected to the memory circuit and further delaying the luminance signal by one horizontal period; and a switch for switching between the luminance signal input to the first memory circuit and the luminance signal output from the first memory circuit. a first subtraction circuit that subtracts the output luminance signal of the second memory circuit from the luminance signal output from the switch; and a bandpass filter that extracts a carrier color signal band signal from the output of the first subtraction circuit. By providing a second subtraction circuit that subtracts the output signal of the band-pass filter from the output luminance signal of the switch, dropout of the luminance signal of the PAL composite video signal can be eliminated with just a 2H memory circuit. It is possible to simultaneously compensate and remove interference components from the carrier chrominance signal in the high frequency components of the luminance signal, which is extremely effective for downsizing the VTR.

Furthermore, a first memory circuit having a write inhibit function that delays the luminance signal by one horizontal period; a second memory circuit connected to the first memory circuit and further delaying the luminance signal by one horizontal period; a first subtraction circuit that subtracts the output luminance signal of the second memory circuit from the luminance signal input to the memory circuit; and a bandpass filter that extracts a carrier color signal band signal from the output of the first subtraction circuit. , a switch that cuts the output signal of the bandpass filter, and a second subtraction circuit that subtracts the output from the switch and the output luminance signal of the second memory circuit, the component VTR can be The effect is great because the memory for time axis alignment of the luminance signal and color signal can also be shared.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a luminance signal processing device in a first embodiment of the present invention, FIG. 2 is a block diagram of a luminance signal processing device in a second embodiment, and FIG. 3 is a block diagram of a luminance signal processing device in a second embodiment of the present invention. 4 is a frequency characteristic diagram of the signal X with respect to the input signal Yi in FIGS. 1 and 2, FIG. 5 is a waveform diagram of each part in FIG. 2, and FIG. The figure is a block diagram of a conventional luminance signal processing device, and FIG. 7 is a frequency distribution diagram of an output luminance signal in the luminance signal processing device of the present invention. DESCRIPTION OF SYMBOLS 1... First memory circuit, 2... Second memory circuit, 3, 7... Subtraction circuit, 4... Band pass filter, 5... Switch, 6... Delay circuit. Name of agent: Patent attorney Shigetaka Awano

Claims (2)

[Claims] (1) a first memory circuit having a write inhibit function that delays the luminance signal by one horizontal period; a second memory circuit connected to the first memory circuit and further delaying the luminance signal by one horizontal period; a first switch for switching between a luminance signal input to the first memory circuit and a luminance signal output from the first memory circuit; and a first switch for subtracting the output luminance signal of the second memory circuit from the luminance signal output from the switch. a subtraction circuit, a bandpass filter that extracts a carrier color signal band signal from the output of the first subtraction circuit, and a second subtraction circuit that subtracts the output signal of the bandpass filter from the output luminance signal of the switch. A luminance signal processing device comprising: (2) a first memory circuit having a write inhibit function that delays the luminance signal by one horizontal period; a second memory circuit connected to the first memory circuit and further delaying the luminance signal by one horizontal period; A first subtracting the output luminance signal of the second memory circuit from the luminance signal input to the first memory circuit.
a subtraction circuit, a bandpass filter for extracting a carrier color signal band signal from the output of the first subtraction circuit, and a switch for cutting the output signal of the bandpass filter;
A luminance signal processing device comprising a second subtraction circuit that subtracts the output from the switch and the output luminance signal from the second memory circuit.