JPH0265391A - Video printer - Google Patents

Abstract

PURPOSE:To prevent the stripe pattern of a print line in a picture, which is recorded to a receiving medium, from being conspicuous and to improve recording picture quality by successively recording every other dot in the respective lines by the 1/2 pitch of a line interval practically. CONSTITUTION:When the color video signal of one frame to be recorded is inputted from a video signal source to an input terminal 10, A/D conversion is executed in an input circuit 16 and the color video signal is housed to a frame memory 20 in the form of digital data under the control of a system control part 24. These video signal data are read to a D/A converter 30 under the control of the system control part 24 and a monitor picture is projected on a display part 32. In recording operation, the odd-number-th dot of a line L1 is recorded with the half density of prescribed picture element density. When the recording is completed, the system control part 24 controls a recording part 12 and feeds a receiving medium 14 in a prescribed feeding direction F by the practically 1/2 pitch of the pitch between lines together with a color sheet. Thus, respective cianic, magenta and yellow pictures are overlapped and recorded to one frame of the receiving medium 14 in the picture element arrangement of a diagonal lattice. Then, the color picture of one frame is completed.

Description

TECHNICAL FIELD The present invention relates to a video printer, and more particularly to a video printer suitable for a thermal printer such as a thermal transfer printer, which receives a video signal and records an image on an image receiving medium.

Background Art For example, as is well known, a thermal transfer printer records visible information by heating a heat-sublimable dye with a thermal print head and transferring it to a transfer medium such as paper.The heat-sublimable dye is printed on a ribbon or sheet. The dye-coated side of the ribbon or sheet is brought into contact with the transfer or image receiving medium, and the opposite side is heated by a thermal print head. The thermal print head has a heating element array in which a large number of heating elements are arranged in a straight line, and each of them generates heat according to the information to be recorded. This causes the dye in the heated portion of the ribbon or sheet to diffuse and be transferred to the receiving medium. Such thermal transfer printers are effectively applied to color video printers, for example.

Color video printers that print color still images are required to have increasingly higher print quality. As previously mentioned, the thermal print head has a large number, e.g., 512, linear arrays of resistive heating element elements. In conventional video printers, this one row of heating elements records pixels for one horizontal scanning line, that is, one life of an image. For example, as shown in FIG. 4, when the print head is fed in the direction of arrow F with respect to the receiving paper, print line L1. L2, L3, L4. , , are recorded in this order.

As can be seen from this figure, in the conventional recording method, pixels for one line are simultaneously recorded for each print line. Therefore, in the screen area of the image-receiving paper, lines in which pixels dots and dots are recorded with a certain degree of density exist at a predetermined pitch P, and between adjacent lines there are quite a few lines in which no pixels are recorded. There is an area with a width of . Therefore, from a microscopic perspective, there is a large difference in concentration between good people.
This may make the print lines stand out as a clearly distinguishable striped pattern in the overall image recorded on the image receiving paper, thereby degrading the quality of the recorded image.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the deficiencies of the prior art and to provide a video printer that minimizes the deterioration in image quality due to printing line defects.

Disclosure of the Invention According to the present invention, there is provided a video printer having an input means into which a video signal representing one image by raster scanning of a plurality of scanning lines is input, and a recording means for recording the image represented by the video signal on an image receiving medium. The recording means records each pixel forming a scanning line on the image receiving medium, and records a plurality of recording columns arranged corresponding to each pixel in response to a pixel signal. a first driving means for driving every other recording head element to perform recording; and a first driving means for driving every other recording head element to perform recording; and a first driving means for driving the remaining recording head elements according to one pixel signal when a pixel signal is changed, for recording. The video printer includes a second driving means for causing the recording means to record an image by controlling the recording means according to the video signal received by the input means, and the control means for causing the recording means to record an image. When a video signal is input to the input means, the pixel signals of every other pixel forming one scanning line of the input video signal are applied to the first driving means, and the signals of every other pixel forming one scanning line of the input video signal are applied to the first driving means. The second driving means corresponds to the second driving means so as not to be substantially driven, and then the recording means records Δ, and the image receiving medium is moved with respect to the rad element to substantially 1/1 of the pitch of the scanning line. 2, the pixel signals of the remaining pixels forming the scanning line are fed to the second driving means, and among the plurality of recording head elements, those corresponding to the first driving means are driven by the first driving means. First, the recording means feeds the image receiving medium to the recording head element by substantially 1/2 of the pitch of the scanning line, and hereinafter, by turning the image receiving medium to the recording head element. DESCRIPTION OF EMBODIMENTS FOR RECORDING IMAGES ON IMAGE RECEIVING MEDIUM Next, embodiments of a video printer according to the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 2, the color video printer according to the embodiment has an input terminal 10, and a recording section 12 records a color image represented by a color video signal input thereto on an image receiving medium 14. The recording unit 12 is the above-mentioned thermal transfer type image recording mechanism unit, which heats a sheet (not shown) coated with a heat-sublimable dye using a thermal print head heating element 100 (FIG. 1) to print paper, etc. Visible information is recorded by sublimating and transferring the dye in the heated portion to the transfer medium, that is, the image receiving medium 14.Density control is performed by adjusting the number and width of pulses applied to the print head heating element +00. This is done by controlling the temperature and heating time.

A color video signal is input from an input terminal 10 to the input circuit 16 in the form of an NTSC video signal or an RGB signal from a video signal source such as a video camera, a videotape playback device, or a personal computer. The input circuit 16 receives the input N
It has an analog-to-digital conversion function (ADC) that decodes the TSC signal and converts the decoded luminance and color difference signals or RGB signals into corresponding digital data.

An output 18 of input circuit 18 is connected to a write input of frame memory 20. The frame memory 20 is, for example, an RA having a storage capacity for storing color video signal data for E frames, and its storage is controlled by a system control section 24 through a control line 22. The frame memory 20 has a data readout output 2B, which includes a color converter 28 and a digital-to-analog converter (DAC).
30.

The digital-to-analog converter 30 converts the frame memory 2
The 0 display unit 32, which has a signal conversion function of converting color video signal data read from 0 to a corresponding analog signal and outputting it to the display unit 32, includes a color video monitor device such as a CRT, for example, The CRT has an image display function of driving a CRT in accordance with a video signal and visually displaying a color image represented by the CRT. This allows the operator to monitor the image recorded on the image receiving medium 14 by the recording section 12. Note that the display section 32 and its associated circuit 30 do not necessarily need to be provided.

The color conversion section 28 includes a line memory, and converts data for one line of the field video signal read from the frame memory 20 into color component signals suitable for the format of the recording section 12, such as cyan (Cy), magenta (M), and It has a data conversion function to convert to yellow (Ye). The output 36 is connected to the gradation control unit 3. The 0 gradation control unit 38 is a gradation control unit that adjusts the gradation (γ) for each of the color component signals converted by the 1-color conversion unit 28. Has a function.

The tone control section 38 has an output 44, which is connected to a data input of the recording section 12. The recording unit 12 has an input 44
The thermal head heating element 10 according to the color component signal data of
0 is driven and the image it represents is recorded on the image receiving medium 14.

The system control unit 24 is a control function unit that centralizes control of the entire apparatus, and is connected to an operation unit 50 to which an operator gives instructions such as image recording.

Referring to FIG. 1, the number of recording units 12 is 51 in this embodiment.
It includes a thermal print head having two resistive heating elements 100, which are arranged in a straight line to form a recording head element array for printing a print line 6
One terminal +02 of the heating element 100 is commonly connected to a positive M source of, for example, 12 ports for each element. heating element 1
The other terminal 104 of 00 is a two-man power NA as a drive circuit.
The individual resistance heating elements 100 individually connected to the output of the ND gate 10B correspond to each bit position of the information to be recorded, and are independently controlled by the drive NANO game +013 to correspond to the focus, that is, to correspond to the dot. Driven. For convenience of explanation, each resistance heating element 100 is assigned an order as shown in the figure for one line of pixels.

One input 107 of the two-power NAND gate 106 is commonly connected to the output of the inverter 108.
The input 8+15 receives the wristlobe signal r1''1- from the control line 54 of the system control section 24. The other input +10 of the NAND gate 1 (16) is connected to the output of each stage of two latch circuits 112 with 256 heating elements 100 as one group as shown in the figure. Each stage of the latch circuit 112 is has a data input 114 and a latch signal input 116, and a latch signal LATfl from the latch signal input 116.
In response to l, a shift register 118a or ll, which will be described later,
This is a holding circuit that temporarily holds data from 8b.

The launch signal input 11B is connected to the control line 54 of the system control unit 24, and receives the latch signal LATCH from this line.The feature of this embodiment is that two latch circuits 11
Data input for each stage of 2! 14 are connected to the data outputs of the corresponding stages of the same shift register every other time. More specifically, the data output 114 of each latch circuit 112 is connected to the data output of the corresponding stage of one shift register 18a for the odd numbered heating element 100, and to the data output of the corresponding stage of the shift register 18a for the even numbered heating element 100.
They are respectively connected to the data outputs of the corresponding stages of 18b. The two shift registers 118a and 118b are storage circuits that step the data received from the data inputs 44a and 44b through the stages by f5'MJ to the rear input 120. clock human power 12
0 is connected to the control line 54 of the system control unit 24, and the data input lines 44a and 44b are connected to the gradation control unit 34, respectively.
receives DATAI and DATA2 from data output 44 of.

A drive circuit for the resistance heating element 100 is formed by these elements.

To control the heat generation temperature of the resistance heating element 100, pulse width modulation or pulse number modulation is advantageously applied. For example, in the case of a thermal transfer method, dots desired to obtain high density are heated to a relatively high temperature for a relatively long time.

To achieve this, the width or number of driving pulses that bring the output 104 of the HAND gate 108 to a low level must be increased or the width of the driving pulse must be increased. Reduce the number of pulses.

In this embodiment, 711 light is controlled by increasing or decreasing the number of pulses. The strobe signal output from the system control unit 24 includes a single pulse with a relatively wide pulse width for starting up the resistance heating element 100, and a predetermined number of pulses with a relatively narrow pulse width for adjusting the concentration. These pulses are, for example, 6
Of the 4 or 32 HAND gates 10B activated by the strobe signal, the one in the stage where the data stored in the latch circuit +12 is significant "1" drives the corresponding heating element 100. In this way, the latch circuit 11
The recording density is adjusted by increasing or decreasing the number of strobe pulses depending on the contents of each stage of 2.

Explain the operation. When a color video signal representing one frame of an image to be recorded is input from the video signal source to the input terminal 10, the input circuit 16 performs necessary conversion such as analog-to-digital conversion, and the signal is sent to the system controller 24.
The data is stored in the frame memory 20 in the form of digital data under the control of. This video signal data is read out to the digital-to-analog converter 30 under the control of the system control section 24, and displayed as a monitor image on the display section 32.

When a recording instruction is given from the operation unit 50, the system control unit 2
4 controls the recording section 12 through the control line 54 to first feed the cyan portion of the dye sheet to the image receiving medium 14;
To explain in more detail, the system control unit 24 sequentially reads video signal data for recording a cyan image from the frame memory 20 line by line by raster scanning. This is divided into two halves and read out twice.
The 0 gradation control section 38 converts the signal into a cyan component signal in the color conversion section 28 under the control of 4 and transfers it to the gradation control section 38 in sequence, according to the gradation control data set therein. A gradation transformation is applied to the color component signal. This is the recording section 12
and recorded on the image receiving medium 14 as a cyan image. Here, "line J" means a horizontal scanning line in a raster-scanned image signal, and in the description of the embodiment, it is interpreted as including a plurality of linear dot rows actually recorded on the image receiving medium 14. Therefore, in this example,
Two dot rows or print lines recorded on the image receiving medium 14 form one horizontal scanning line or line (image line).

(2) Pixel data of odd-numbered dots included in a line, for example Ll (FIG. 3), is inputted from the output 44a of the two-tone control section 38 to one shift register 118a of the recording section 12, and the shift register 118a is connected to the memory 'KJI'. This line data is incremented in response to the clock CLK received from the control line 54 of the sub section 24. In this way, shift register 11
Pixel data of odd numbered dots are set in each row of 8a. At this time, "all 0s" are set in the other shift register 118b under the control of the system control unit 24. The system control unit 24 then applies the latch signal LATCH from the control line 54 to the input 11Ei of the latch circuit 112,
As a result, each stage of the latch 112 has a shift register 11
The dot data of 8a and "all O's" of shift register 118b are set.

That is, the data of the line L1 is latched in the latch stage corresponding to the odd numbered dot, and rQJ is latched in the launch stage corresponding to the even numbered dot. As a result, one input +10 of the NAND gate 106 of the stage in which significant dot data is latched is activated.

The system ftjl W fA 24 then transmits the strobe pulses from the control line 54 to the input 11 of the inverter 108.
Give to 5. This is inverted by inverter 108 and energizes the other input +07 of all NANO games +06. Therefore, the output of the NANO gate 10Ei of the stage with significant dot data becomes "0", and the output of the other stages becomes "1".
maintain. Therefore, NANO gate 1 with output "0"
Resistance heating element compatible with 06! 00 is supplied with power from the power supply terminal +02 and generates heat.

As can be understood from the above description, in this recording operation, first, odd-numbered dots in the line Ll are recorded at a density that is half the predetermined pixel density. When this recording is completed, the system control unit 24 controls the recording unit 12 to move the image receiving medium 14 together with the dye sheet (not shown) by a predetermined distance of substantially 1/2 of the interline pitch P (FIG. 4). It is fed in the feeding direction F (FIG. 3). Therefore, the system control unit 24
reads the pixel data of the even numbered dots on the same line L1 from the frame memory 20 to the color conversion unit 28, and #yA
#J Makes the m unit 38 perform similar gradation control.

This even-numbered pixel data is inputted from the output 44b of the gradation control section 38 to the other shift register +18b of the recording section 12 and accumulated in the same manner as described above. At this time, one shift register 118a also has "all O".
is set. The system control unit 24 then generates a latch signal LATC:H and sets "all O's" of the shift register I 18a in the latch circuit +12, and sets dot data in each stage of the shift register 118b. In other words,
The latch stage corresponding to an even numbered dot has its line L1.
data is latched, and "0" is latched in the latch stage corresponding to the odd numbered dot.

Thereafter, the system control unit 24 generates strobe pulses on the control line 54 in the same manner as described above, thereby reducing the total NA.
When the other input 107 of NO gate 10B is activated,
The NANO gate 108 of the stage with significant dot data drives the resistive heating element 100, and the other dots are not recorded, thus the recording of the remaining dots in the same line L1, that is, the even-numbered dots, is performed at the predetermined pixel. It was carried out at half the density. After the recording is completed, the system control unit 24
feeds the image receiving medium 14 and the dye sheet in the feeding direction F by half the line-to-line pitch (+/2) P. Thereafter, the next line is moved to the second recording operation in the same manner.

In this way, when alternate recording of every other dot on each line is continued at a pitch of 1/2 of the line interval, pixels are formed in a twilled dot arrangement as shown in FIG.

As a result, the print lines of the image recorded on the image receiving medium 14 do not stand out as a clear striped pattern, and the deterioration in recorded image quality due to this is minimized.

When one frame of cyan i'i image is recorded on the image receiving medium 14 in this way, the system control section 24
is controlled to feed the magenta portion of the dye sheet to the image receiving medium 14, and a video signal for recording the magenta component is read out from the frame memory 20 in the same way.This magenta component signal is also transferred to the image receiving medium 14 by the recording section 12 recorded in the same frame. Similarly, the yellow image is also read out from the frame memory 20, and the recording section 12 reads it out from the image receiving medium 14.
recorded in the same frame. In this way, one frame of the image receiving medium 14 has cyan, cyan, and pixel arrays in the twill grid shown in FIG.
The magenta and yellow images are overlaid and recorded to complete one frame of color image. The image receiving medium 14 on which the color image has been completed is discharged from the recording section 12.

In this embodiment, the shift register 1]8 to the heating element 1
Up to 00, the pixels were configured in two groups, but the present invention is not necessarily limited to this, and may be in three or more groups.For example, in the case of a three group configuration, pixels every two dots in one line are Preferably, the images are recorded simultaneously and the feeding pitch of the image receiving medium 14 is (1/3)P.

Although an example in which the present invention is applied to a color video printer has been described, there is no reason why the present invention is technically limited to color images, and it goes without saying that the present invention can also be effectively applied to recording black and white images. It is also noted that the term "image" also includes letters, numbers, and symbols.

Effect As described above, according to the present invention, since every other dot in each line is sequentially recorded at a pitch that is substantially 1/2 of the line interval, each pixel is formed in a twilled dot arrangement. Ru. Therefore, in the present invention, the clear striped pattern of print lines of an image recorded on an image receiving medium, which was noticeable in the prior art, is not noticeable, and the deterioration in recorded image quality due to this is minimized.

[Brief explanation of the drawing]

FIG. 1 is a functional circuit diagram showing a configuration example of a thermal print head in the embodiment of the present invention shown in FIG. 2, and FIG. 2 is a functional block diagram showing an embodiment in which the present invention is applied to a color video printer. FIG. 3 is an explanatory diagram showing an example of a pixel arrangement recorded by the embodiment shown in FIG. 2. FIG. 4 is an explanatory diagram showing an example of a pixel arrangement recorded by a conventional video printer. 4 Figure 20゜24. 106,. +12. . 18a Main part code explanation recording section, frame memory 9, system control section, resistance heating element, NANO gate, latch circuit +18b, shift register

Claims (1)

[Scope of Claims] A video printer comprising an input means into which a video signal representing an image by raster scanning of a plurality of scanning lines is input, and a recording means for recording an image represented by the video signal on an image receiving medium. The recording means are
A plurality of recording head elements are arranged corresponding to each pixel and record each pixel forming the scanning line on the image receiving medium; and when a pixel signal is given, the plurality of recording heads are arranged according to the pixel signal. a first driving means for driving every other element to perform recording; and a first driving means for driving the remaining of the plurality of recording head elements to perform recording in accordance with the pixel signal when a pixel signal is applied. 2
The printer includes a control means that controls the recording means in response to a video signal received by the input means to cause the recording means to record an image, and the control means includes the following: When the video signal is input to the input means, pixel signals of every other pixel forming one scanning line of the input video signal are applied to the first driving means, and the plurality of recording head elements Among them, those corresponding to the second driving means are not substantially driven by the second driving means, and then the recording means moves the image receiving medium to the recording head element at a pitch of the scanning line. The pixel signals of the remaining pixels forming the one scanning line are supplied to the second driving means, and the recording head elements correspond to the first driving means among the plurality of recording head elements. the image receiving medium is moved by the recording means to the recording head element by substantially 1/2 the pitch of the scanning line;
1. A video printer characterized in that the image is recorded on the image receiving medium by recording the image on the image receiving medium.