JPH0456487A - Video printer - Google Patents

Abstract

PURPOSE:To enable high definition photographic printing without increasing the capacity of a picture memory by operating the photographic printing after operating an A/D conversion by a second A/D conversion circuit which has high resolution, without the picture memory, when the picture whose quality is high is inputted. CONSTITUTION:When the picture input of a still picture whose quality is high is printed photographically, a movable contact 5a of a switching circuit 5 is switched into an analog signal processing circuit side 5b, by the operation of a selection operating part 12. Thus, an inputted video signal is directly applied through an analog signal processing circuit 1 and a switching circuit 5 to a decoder circuit 6, and resolved into color signals R, G, and B by this decoder circuit 6. Then, the color signal selected successively by a color signal selecting circuit 7 is A/D converted by a second A/D conversion circuit 8 prepared by 8 bits, which has high resolution, and applied to a photographic printing processing circuit 9. Then, the photographic printing of 8 bit gradation who is high definition can be operated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a video printer that prints images from images from televisions, VTRs, and the like.

<Prior Art> Generally, in a conventional video printer, a human-powered video signal is A/D converted and loaded into an image memory, and energization of a thermal head is controlled based on the video signal data read from this image memory. It is configured to perform printing.

<Problems to be Solved by the Invention> However, with such conventional video printers, for example, in response to high-quality video input from an external device such as a professional video camera, it is difficult to output high-quality images with high gradation. To make printing possible, it is necessary to use a high-resolution A/D conversion circuit that A/D converts the input video signal, and also requires a large capacity image memory. It is not desirable to use a large-capacity image memory just to accommodate high-quality video input.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to enable high-quality printing for high-quality images without increasing the capacity of the image memory.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present invention is configured as follows.

That is, the present invention includes a first A/D conversion circuit that A/D converts an input video signal, and an A/D conversion circuit that converts an input video signal into A/D.
An image memory into which /D-converted video signal data is written, a D/A conversion circuit that performs D/A conversion of the video signal data read from this image memory, and an input video signal or from the D/A conversion circuit. a switching circuit for switching and outputting one of the video signals based on a switching control signal; and A/D converting the video signal from the switching circuit,
and a second A/D conversion circuit with higher resolution than the first A/D conversion circuit.
Based on the video signal data from the A/D conversion circuit and the second A/D conversion circuit, energization of the thermal head is controlled to obtain a gradation corresponding to the resolution of the second A/D conversion circuit. and a print processing circuit that performs printing.

<Operation> According to the above configuration, the switching circuit allows printing to be performed based on the video signal read out from the image memory, or based on the directly input video signal without going through the image memory. can be switched, and
Since the resolution of the second A/D conversion circuit after the switching circuit is higher than that of the first A/D conversion circuit, for example,
In the case of high-quality video input, A/D conversion is performed by a high-resolution second A/D conversion circuit without going through an image memory.
By converting and performing printing processing, high-quality printing is possible. On the other hand, the resolution of the first A/D conversion circuit in the front stage of the image memory is lower than the resolution of the second A/D conversion circuit. Therefore, there is no need to increase the capacity of the image memory in response to high-quality video input.

<Examples> Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, 1 is an analog signal processing circuit that performs predetermined signal processing such as synchronous separation on the input video signal, and 2 is a 6-bit first circuit that A/D converts the video signal from this analog signal processing circuit 1. 3 is an image memory into which the A/D converted video signal data is written, and 4 is a D/D converter for the video signal data read out from the image memory 3.
This is a D/A conversion circuit that performs A conversion and outputs.

5 is a switching circuit that switches and outputs either the video signal from the D/A conversion circuit 4 or the input video signal from the analog signal processing circuit 1 based on a switching control signal; 6 is a switching circuit that outputs the video signal from the switching circuit 5; R,C;.

7 is a color signal selection circuit that selects and outputs color signals according to the printing order; 8 is an 8-bit second A/D conversion circuit that converts the color signals from A/D;
9 controls the energization of the thermal head 10 based on the color signal data from the second A/D conversion circuit 8 to produce 8-bit gradations corresponding to the resolution of the second A/D conversion circuit 8. 11 is a control circuit that controls each section; 12 is a selection operation section that selects whether to print directly according to the input video signal or to print according to the video signal once stored in the image memory 3; be.

In the video printer of this embodiment, the first
The resolution of the A/D conversion circuit 2 is 6 bits, while the resolution of the second A/D conversion circuit 8 for print processing is 8 bits.
The switching circuit 5 allows the user to select whether to print using the video signal temporarily stored in the image memory 3 or directly input video signal without going through the image memory 3. It is configured such that it can be selected by 12.

Therefore, in the video printer having the above configuration, for example, when a high-quality still image is inputted from a professional video camera or the like and the input is to be printed, the selection operation section 12 must be operated. As a result, the movable contact 5a of the switching circuit 5 is switched to the analog signal processing circuit side 5b.

As a result, a high-quality input video signal is directly given to the decoder circuit 6 via the analog signal processing circuit 1 and the switching circuit 5.
The color signals separated into G and H color signals and sequentially selected by the color signal selection circuit 7 are sent to a high-resolution 8-bit second A/D.
The signal is A/D converted by the conversion circuit 8 and then sent to the print processing circuit 9, where high-quality printing with 8-bit gradation is performed.

In the case of high-quality video input like this, the image memory 3
High-resolution second A/D conversion circuit 8
By performing A/D conversion and printing processing, high-quality printing is possible without increasing the capacity of the image memory 3 to accommodate high-quality video input.

On the other hand, in the case of inputting a video signal of a normal moving image, etc., the movable contact 5a of the switching circuit 5 is
Switch to the D/A conversion circuit side 5C.

As a result, the input video signal is transferred to the 6-pit first A/
It is A/D converted by the D conversion circuit 2, written to the image memory 3, read out from this image memory 3, and converted into D/A.
The signal is D/A converted by the conversion circuit 4 and is applied to the decoder circuit 6 via the switching circuit 5.

The video signals given to this decoder circuit 6 are R, G,
The color signals that are decomposed into H color signals and sequentially selected by the color signal selection circuit 7 are A/D converted by the 8-bit second A/D conversion circuit 8 and sent to the print processing circuit 9 to be printed. will be held.

In this way, even in the case of a video signal once stored in the image memory 3, it is A/D converted at 8 bits and subjected to gradation processing, so that it is possible to print a high-quality image in appearance.

It goes without saying that the present invention is equally applicable to the case where R, G, and H color signals are directly input as input video signals.

<Effects of the Invention> As described above, according to the present invention, printing is performed based on the video signal once stored in the image memory, or printing is performed based on the directly input video signal without going through the image memory. The switching circuit can select whether the image memory is to be used or not, and the resolution of the second A/D conversion circuit after the switching circuit is higher than the resolution of the first A/D conversion circuit for image memory. Therefore, for example, in the case of high-quality video input, a high-resolution second A/D conversion circuit performs A/D conversion and print processing without going through the image memory, resulting in high-quality prints. On the other hand, since the resolution of the first A/D conversion circuit before the image memory is lower than the resolution of the second A/D conversion circuit, the capacity of the image memory can be used for high-quality video input. There is no need for a corresponding increase.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention. 2. First A/D conversion circuit, 3... Image memory, 4.
- D/A conversion circuit, 5... switching circuit, 8... second A/D conversion circuit, 9 - print processing circuit.

Claims (1)

[Claims] (1) A first A/D conversion circuit (2) that A/D converts the input video signal;
an image memory (3) into which D-converted video signal data is written; a D/A conversion circuit (4) which performs D/A conversion on the video signal data read from the image memory (3);
A switching circuit (5) that switches and outputs either the input video signal or the video signal from the D/A conversion circuit (4) based on a switching control signal; A second A/D conversion circuit (8) that performs A/D conversion and has a higher resolution than the first A/D conversion circuit (2), and this second A/D conversion circuit Based on the video signal data from (8), the thermal head (10)
A print processing circuit (9) that controls energization of the second A/D conversion circuit (8) to perform printing with a gradation corresponding to the resolution of the second A/D conversion circuit (8).