JPH0890824A - Printing method and image printer - Google Patents

Abstract

PURPOSE: To provide a method for printing, and an image printer in which the distortion of an image is suppressed, and printing faithful to an image signal in which printing density is linearly increased with the increase in the luminance of the signal can be conducted. CONSTITUTION: A method for printing comprises the steps of timing-setting to deviate the timing for printing adjacent dots of dots arranged in a main scanning direction, and printing each dot along a sub-scanning direction based on the timing set by the timing-setting step. An image printer comprises a dot setter 1 for setting the dots of printing pixels for varying gradation by the dots to be printed and so setting as to deviate the timing for printing the adjacent dots of each print row of the dots to be printed along the sub-scanning direction Y, and a printing unit 2 for printing based on the set dots and the timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing method and an image printing apparatus using the printing method, and in particular, the gradation of an image is variably set by dividing dots into a plurality of dots and printing the dots in one pixel. The present invention relates to a printing method and an image printing apparatus using the printing method.

[0002]

2. Description of the Related Art Today, a video reproducing apparatus for reproducing an image signal recorded on a video tape, a disk reproducing apparatus for reproducing an image signal recorded on a disk-shaped recording medium such as an optical disk or a magneto-optical disk, or a radio. An image reproducing device that reproduces to output an image signal like a television receiver that receives and reproduces a propagated image signal is widespread, and based on the image signal reproduced by this image reproducing device. Image printing apparatuses for printing images, images, or characters have been put into practical use.

In this image printing apparatus, a thermal head is used to heat printing paper, which is thermal paper, or a thermal transfer head is used to heat a printing ribbon, and printing is performed from the printing ribbon onto the printing paper. There is a thermal transfer method for transferring the ink for use.

The above-mentioned image printing apparatus prints a pixel by a predetermined number of dots arranged in the main scanning direction and the sub-scanning direction orthogonal to the main scanning direction based on the image signal supplied from the image input terminal. A dot setting unit that sets the dot and a heating resistor that can generate heat for each dot are arranged in the main scanning direction, and heat is generated by the power supplied to the heating resistor of the dot set by the dot setting unit, and printing is performed. And a paper feeding unit that moves the printing paper in the sub-scanning direction in synchronization with printing by the printing unit.

The printing unit converts the image signal set by the dot setting unit into a printing signal for printing and a printing signal converting circuit for printing based on the printing signal supplied from the printing signal converting circuit. And a print head.

The print head includes a shift register 37 to which an image signal is supplied every time the clock signal CK is supplied from the print signal conversion circuit, as shown in FIGS.
A latch circuit 38 for storing the image signal supplied to the shift register 37 every time the data latch signal DL is supplied.
And heating parts J1, J2, J3, J4 that generate heat in synchronization with the strobe signals SR1, SR2, SR3, SR4, and one end of each heating resistor of these heating parts J1, J2, J3, J4 is commonly connected. And an electrode 39.

The heat generating section J1 has a strobe signal SR1.
, 81n and the output signals of the NAND circuits 81a, ..., 81n are supplied to one end of the NAND circuits 81a ,. , 91n connected to the common electrode 39 and arranged in the main scanning direction X for generating heat so that each dot can be thermally transferred.

The heat generating section J1 has a strobe signal SR1.
By variably setting the duty of the pulse, the heat generation temperatures of the heat generating resistors 91a, ..., 91n are variably set.

The heat generating parts J2, J3, J4 are supplied with the NAND circuit 8 to which the inverted signal of the strobe signals SR2, SR3, SR4 and the image signal stored in the latch circuit 38 are supplied.
2a, ..., 82n, 83a, ..., 83n, 84
, 84n, and the output signal of this NAND circuit is supplied to one end and the other end is connected to the common electrode 39.
Heat generating resistors 92a, ..., 92n, 93a, ... Arranged in the main scanning direction X that generate heat so that each dot can be thermally transferred.
, 93n, 94a, ..., 94n.

The heating portions J2, J3, J4 variably set the duty of the pulses of the strobe signals SR2, SR3, SR4 to generate heating resistors 92a ,.
92n, 93a, ..., 93n, 94a ,.
The heat generation temperature of 4n is variably set.

As described above, in the image printing apparatus, the pulses of the strobe signals SR1, SR2, SR3, and SR4 applied to the heat generating portions J1, J2, J3, and J4 of the print head of the printing unit are caused to generate a phase in the printing unit. The maximum power consumption is reduced by time-sharing the supplied power, and the driving power supply for the printing unit is made compact to enable printing.

[0012]

By the way, in the image printing apparatus, the printing ink is printed on the printing paper from the printing ribbon by the heat generated by the heating resistor arranged in the printing unit so as to be able to generate heat for each dot in the main scanning direction. Is printed by thermal transfer, and an image is formed by moving the printing paper in the sub-scanning direction in synchronism with this printing by the paper feeding unit.

In the above-mentioned image printing apparatus, the width length in the sub-scanning direction Y per dot of the heating resistor is W, and the moving speed of the printing paper by the paper feeding unit per unit time is constant at v. As shown in 15, strobe signal SR
Heat generating part J that generates heat by 1, SR2, SR3, SR4
Assuming that the heat generation times of 1, J2, J3, and J4 are Th, the moving distance K of the printing paper per pulse of the strobe signal is K.
Becomes equation (1).

K = v · Th (1) Formula Therefore, the printing JP by the heat generating portions J1, J2, J3, and J4
The positions of 1, JP2, JP3, and JP4 are sequentially displaced by the distance K in the sub-scanning direction Y every time the pulse of the strobe signals SR1, SR2, SR3, and SR4 is generated, and the positions of the print J1 to the print J4 are changed. There is a problem that the image becomes distorted and unnatural by shifting the distance by 3 · K.

When the image printing apparatus prints by making the print head generate heat, such as a heat-sensitive method or a thermal transfer method, when the dots of one pixel adjacent to each other are printed, the number of adjacent dots is reduced. As the number of print heads increases, the effect of heat storage in the print head increases, and an area larger than the specified area is printed.

Therefore, there is a problem in that the print density increases more than the brightness of the image signal, and printing with the print density faithful to the brightness of the image signal is not performed.

In view of the above problems, the present invention provides a printing method that suppresses image distortion, and that print density increases linearly with an increase in the brightness of an image signal so that printing faithful to the image signal can be performed. An object is to provide an image printing apparatus using the.

[0018]

In the printing method according to the present invention which has achieved this object, the dots arranged adjacent to each other in the main scanning direction are set so that the printing timings of the dots adjacent to each other are shifted. Based on the timing setting step and the timing set in the timing setting step,
And a printing step of printing for each dot along a sub-scanning direction orthogonal to the main scanning direction.

Further, the image printing apparatus according to the present invention uses the predetermined number of dots arranged in the main scanning direction and the sub scanning direction orthogonal to the main scanning direction based on the image signal supplied from the image signal input terminal. By setting dots to be formed and printing pixels whose gradation is changed by the dots to be printed, the timing of printing dots adjacent to each other in each print row of dots to be printed along the sub-scanning direction is set. A dot setting unit that is set to be shifted and a printing unit that prints on the dots set by the dot setting unit along the sub-scanning direction based on the timing of dots in each print row.

[0020]

According to the printing method of the present invention including the above steps, it is possible to set the timings of printing dots that are adjacent to each other with a shift in the timing setting step, and to print at this timing in the printing step.

Further, according to the image printing apparatus of the present invention having the above-mentioned configuration, it is possible to set the printing timings of the dots adjacent to each other by shifting them in the dot setting section, and to print at this timing in the printing section. is there.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a printing method and an image printing apparatus according to the present invention will be described below with reference to the drawings.

Here, the printing method is carried out by the image printing apparatus.

The image printing apparatus is a thermal transfer type image printing apparatus 10 as shown in FIG. 1, and is a dot to be printed based on an image signal supplied from an image signal input terminal 40.
A dot setting unit 1 that sets the printing timing for each dot, a printing unit 2 that prints on the dots set by the dot setting unit 1 at the set timing, the dot setting unit 1 and the printing unit 2 Of the dot print control unit 4 for controlling the start of the operation of the dot print control unit 4, switches 21 and 22 that can set the start of the operation of the dot print control unit 4 freely, and an image output signal generation for converting an image signal for printing into an image output signal. The unit 25, the monitor 28 that outputs an image based on the output signal, the ribbon winding unit 31 that winds the color ink ribbon 30 that is thermally transferred by the print head 12 of the printing unit 2, and the printing unit 2 performs printing. YM for detecting the color of the color ink ribbon 30 to be performed
The C detection unit 32 and the paper feeding unit 33 that moves the printing paper 60 in synchronization with the printing of the printing unit 2 are provided.

In the image reproducing apparatus, the monitor 41 is based on the image signal supplied to the image signal input terminal 40.
To screen.

The dot setting section 1 includes a decoder 5 for converting an image signal supplied from the image signal input terminal 40 into an RGB signal, and a digital RGB signal by A / D converting the RGB signal supplied from the decoder 5. A / D converter 6, an image memory 7 for storing the image signal converted into the digital RGB signal, and RGB signals Y (yellow), M based on the image signal stored in the image memory 7.
It has a color conversion / color correction circuit 8 for converting into a YMC signal of (magenta) = RY and C (cyan) = BY signal and correcting chromaticity.

The dot setting section 1 stores the image signal converted into the digital RGB signal in the image memory 7 when the "storage signal" is supplied from the dot printing control section 4, and the dot printing is performed. After the "transfer signal" is supplied from the control unit 4, the image signal stored in the image memory 7 is converted into a YMC signal by the color conversion / color correction circuit 8 to correct the chromaticity which is the luminance of each color. , To the printing unit 2.

The printing unit 2 includes the dot printing control unit 4
When the "transfer signal" is supplied from the image signal, the image signal converted into the digital RGB signal stored in the image memory 7 of the dot setting section 1 is converted into the YMC signal by the color conversion / color correction circuit 8 and the chromaticity is converted. It has a print signal conversion circuit 11 which is supplied after the correction and converts the chromaticity-corrected image signal into a printable print signal, and a print head 12 which performs printing based on the print signal.

In the print signal conversion circuit 11, the strobe signals SRb, SRc, SR which will be described later are the strobe signals SRb, SRc, SR.
a and SRd, pulses are generated in this order, dots arranged in the main scanning direction X of the pixel 35 are printed in the order shown in the pixel 35 of FIG. 2, and one pixel 35 is printed in the main scanning direction X,
And 16 dots arranged in 4 × 4 in the sub-scanning direction Y, and based on the image signal supplied from the color conversion / color correction circuit 8 of the dot setting unit 1, as the chromaticity of the image signal increases. , The dots are printed in the order shown in the pixel 35 of FIG. 3 so that the gradation level can be variably set.

Here, as shown in FIG. 3, there are no dots to be printed in the case of gradation 0, the dots of order 1 are printed in the case of gradation 1, and the orders 1 and 2 in the case of gradation 2. Dots are printed, and in case of gradation 3, order 1, order 2, and order 3
17 dots can be displayed by printing all dots in the case of gradation 16 by printing all dots in the case of gradation 16 and 17 × 17 × 3 colors. 1
It is possible to display a gradation level of 7 = 4913.

The print head 12 is provided with a shift register 37 to which an image signal is supplied every time the clock signal CK is supplied from the print signal conversion circuit 11, as shown in FIGS.
A latch circuit 38 for storing the image signal supplied to the shift register 37 each time the data latch signal DL is supplied, and strobe signals SRa, SRb, SRc, SR.
, GL that generate heat in synchronization with d
, And a common electrode 39 to which one ends of the heating resistors G1, G2, ..., GL are connected.

The heat generating section G1 has a strobe signal SR.
A NAND circuit 41 to which the inverted signals of a, SRb, SRc, and SRd and the image signal stored in the latch circuit 38 are supplied.
a, 41b, 41c, 41d and the NAND circuit 41
The heating resistors 51a, which are arranged in the main scanning direction X for supplying the output signals of a, 41b, 41c, and 41d to one end and connecting the other end to the common electrode 39 so as to generate heat so that each dot can be thermally transferred, 51b, 51c, and 51d.

The heat generating section G1 has a strobe signal SRa.
The heating temperature of the heating resistors 51a, 51b, 51c, 51d is variably set by variably setting the duty of the pulse.

, GL are NAND circuits 42a, 42b, 42c, 42d to which the inverted signals of the strobe signals SRa, SRb, SRc, SRd and the image signal stored in the latch circuit 38 are supplied.・ ・ ・ 4L
a, 4Lb, 4Lc, 4Ld and this NAND circuit 42
a, 42b, 42c, 42d, ... 4La, 4Lb,
4Lc and 4Ld output signals are supplied to one end, the other end is connected to the common electrode 39, and the heating resistor 52a is disposed in the main scanning direction X for generating heat so that thermal transfer is possible for each dot.
52b, 52c, 52d, ... 5La, 5Lb, 5L
c, 5Ld.

The heat generating portions G2, ..., GL variably set the duty of the pulses of the strobe signals SRa, SRb, SRc, SRd, and thereby generate the heat generating resistor 52.
a, 52b, 52c, 52d, ... 5La, 5Lb,
The heat generation temperatures of 5Lc and 5Ld are variably set.

As described above, in the image printing apparatus 10, the heating resistors 51a, 51b, 51c arranged in the main scanning direction X are arranged in the order shown in FIG. 2 of the pulses generated by the strobe signals SRb, SRc, SRa, SRd. , 51d, 52a, 5
2b, 52c, 52d, ... 5La, 5Lb, 5L
The dots shown in FIG. 3 corresponding to the gradations of c and 5 Ld are heated.

In the above image printing apparatus, the width of each heating resistor in the sub-scanning direction Y per dot is W, and the moving speed of the printing paper by the paper feeding unit per unit time is constant at v. 6, the strobe signal SRa,
The heat generation time of the heat generating portions G1, G2, ..., GL that generate heat by one pulse of SRb, SRc, and SRd is T
If h, the shift of the moving distance from the first pulse to the fourth pulse due to the four strobe signals is a moving distance of 4-1 = 3 pulses, and the moving distance per pulse is K.
Then, the equation (2) is obtained.

3 · K = 3 · v · Th (2) Therefore, for example, when one pixel is formed in the main scanning direction X, a strobe signal pulse is generated within a width of W + 3 · K. The dots are dispersed and printed in the main scanning direction X and the sub-scanning direction Y in the order shown in FIG. 2 in which they are generated, so that the deviation of the printing position is not noticeable, the distortion of the image is suppressed, and as shown in FIG. Printing is performed almost linearly in the main scanning direction X.

Further, even if the number of adjacent dots is increased, the effect of heat storage of the print head or the effect of coupling of inks in adjacent parts can be suppressed. Therefore, printing is performed in an area close to the specified area, and printing with printing density faithful to the chromaticity of the image signal is performed.

The duty of the pulse of the strobe signals SRb, SRc, SRa, SRd supplied to the print head 12 is variably set to adjust the print density for each print row.

The dot printing control section 4 controls the operation of the dot setting section 1 and the printing section 2 when the start of the operation is set by the switches 21 and 22, and the YMC
The color ink ribbon 3 based on the detection result of the detection unit 32
The color to be printed by 0 is determined, the image signal corresponding to the color is supplied from the image memory 7 of the dot setting unit 1 to the color conversion / color correction circuit 8, and the print head 12 of the printing unit 2 prints each color. It is configured with a microcomputer to control the operation of printing.

In the dot printing control section 4, when the start of the operation is set by the switch 21, the "storage signal" is sent to the dot setting section 1, and the start of the operation is set by the switch 22. At this time, the “transfer signal” is sent to the dot setting section 1 and the printing section 2.

The switches 21 and 22 are individually connected so that the dot print control section 4 can detect whether or not a button provided on each switch is pressed.

With this switch 21, the image printing device 10
While watching the image displayed on the monitor 41, the user presses the button when the image to be printed is displayed, so that the dot print control unit 4 changes the dot setting unit 1 to the dot setting unit 1. Send a "stored signal".

The switch 22 determines whether or not the image signal of the image to be printed is stored in the image memory 7 of the dot setting section 1 while the user looks at the image displayed on the monitor 28. When it is determined that the image signal is stored in the image memory 7, the user presses the button to send a “transfer signal” from the dot printing control unit 4 to the dot setting unit 1 and the printing unit 2. Send it out.

The image output signal generation section 25 is supplied with the image signal converted into the digital RGB signal stored in the image memory 7 of the dot setting section 1, and D / which converts this digital RBG signal into an analog RGB signal. A converter 26
And an encoder 27 for converting the image signal converted to the analog RGB signal supplied from the D / A converter 26 so that the image can be output.

The monitor 41 and the monitor 28 are composed of, for example, two independent CRTs or two CRTs display two screens depending on the specifications of the image reproducing apparatus and the image printing apparatus 10. Or 1
When confirming before printing using one CRT, the screen based on the image signal supplied from the image signal input terminal 40 is switched to the screen based on the image signal stored in the image memory 7 of the dot setting section 1. Is composed of.

The ribbon take-up section 31 takes up the color ink ribbon 30 wound in a roll shape at a constant speed in the main scanning direction X, and a take-up drive section 31a.
And a ribbon delivery section 31b for delivering the color ink ribbon 30.

The color ink ribbon 30 wound around the ribbon winding portion 31 is printed by the heat generation portions 45, 46, 47 and 48 of the print head 12 of the printing portion 2 by the heat of the printing paper 6.
"Y", "so that thermal transfer is performed for each color to 0.
It is divided into areas for each color of “M” and “C” or “Y”, “M”, “C”, and “black”, and each color is identified by the YMC detection unit 32 in the vicinity of the area for each color. Possible color discrimination marks 30y, 30m, 30c are provided.

For example, the color discrimination mark 30y is provided with a 2-bit discrimination signal of (1, 1) which can be read by the YMC detecting section 32, and similarly, the color discrimination mark 30y.
It is assumed that (1, 0) is formed on m and (0, 1) is formed on the color discrimination mark 30c.

The YMC detection section 32 supplies the dot printing control section 3 with the detection results of the color discrimination marks 30y, 30m, 30c of the color ink ribbon 30.
It has MC sensors 32a and 32b.

For example, the two first and second YMC sensors 32a and 32b have the color discrimination marks 30y and 30y.
Of the 2-bit discrimination signals formed in m and 30c, 1-bit on the different side can be read.

The paper feeding unit 33 transfers the printing paper 60 to the main scanning direction X and the sub scanning direction Y of the print head 12 of the printing unit 2.
Has a motor configured to be movable in the sub-scanning direction Y in synchronism with printing.

In the image printing apparatus 10 having the above structure,
When the user of the image printing apparatus 10 outputs an image to be printed while looking at the image output by the monitor 41,
When the user presses the button of the switch 21, the "printing signal" is supplied from the dot printing control unit 4 to the dot setting unit 1,
The image signal converted into the digital RGB signal by the dot setting unit 1 is stored in the image memory 7, and the image output signal generation unit 25 outputs the image on the monitor 28 based on the stored image signal.

Next, in the image printing apparatus 10, it is judged whether the user wants to print while watching the screen displayed on the monitor 28, and it is judged that the user wants to print the screen. In this case, when the user presses the button of the switch 22, the dot printing control unit 4 changes the dot setting unit 1
Also, a “transfer signal” is supplied to the printing unit 2, and the digital RGB signal stored in the image memory 7 of the dot print setting unit 1 is converted into a YMC signal by the color conversion / color correction circuit 8 to perform color correction. After that, the image signal is transferred to the printing unit 2, and printing is performed corresponding to each color of the color ink ribbon 30 based on the printing signal obtained by converting the transferred image signal in the printing unit 2.

As described above, the color conversion / color correction circuit 8 sets the printing timing for each print row so that the heating resistors for each print row adjacent to each other do not generate heat at the same time.

For this reason, the dots to be printed at the same time are dispersed without being concentrated, so that the deviation of the printing position in the sub-scanning direction is not noticeable and the image distortion can be suppressed. Further, even if the number of dots adjacent to each other increases, the effect of heat storage of the print head or the effect of coupling of inks in adjacent parts can be suppressed. Therefore, printing is performed in an area close to the specified area, and printing with printing density faithful to the chromaticity of the image signal is performed. .

Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the same members as those in the first embodiment are designated by the same member numbers and the description thereof is omitted.

The image printing apparatus is a thermal transfer type image printing apparatus 20 as shown in FIG. 7, which is a dot for printing based on the image signal supplied from the image signal input terminal 40.
A dot setting unit 1 that sets the printing timing for each dot, a printing unit 3 that prints on the dots set by the dot setting unit 1 at the set timing, the dot setting unit 1, and the printing unit 3 Of the dot print control unit 4 for controlling the start of the operation of the dot print control unit 4, switches 21 and 22 that can set the start of the operation of the dot print control unit 4 freely, and an image output signal generation for converting an image signal for printing into an image output signal. The unit 25, the monitor 28 that outputs an image based on the output signal, the ribbon winding unit 31 that winds the color ink ribbon 30 that is thermally transferred by the print head 12 of the printing unit 3, and the printing unit 3 performs printing. YM for detecting the color of the color ink ribbon 30 to be performed
The C detection unit 32 and the paper feeding unit 33 that moves the printing paper 60 in synchronization with the printing of the printing unit 3 are provided.

In the image reproducing apparatus, the monitor 41 is based on the image signal supplied to the image signal input terminal 40.
To screen.

The printing unit 3 includes the dot printing control unit 4
When a "transfer signal" is supplied from the image signal, the image signal converted into the digital RGB signal stored in the image memory 7 of the dot setting unit 1 is converted into the YMC signal by the color conversion / color correction circuit 8 and the chromaticity is converted. It has a print signal conversion circuit 15 which is supplied after the correction and converts the chromaticity-corrected image signal into a printable print signal, and a print head 16 which performs printing based on the print signal.

In the print signal conversion circuit 15, the strobe signals described below are strobe signals SRe, SRh, SRf,
Pulses are generated in the order of SRi, SRg, and SRj, the dots arranged in the main scanning direction X of the pixel 36 are printed in the order shown in the pixel 36 of FIG. 7, and one pixel 36 is set in the main scanning direction. 18 arranged in X and 6 × 3 in the sub-scanning direction Y
Based on the image signal supplied from the color conversion / color correction circuit 8 of the dot setting unit 1, each dot is formed in the order shown in the pixel 36 of FIG. 8 based on the increase of the chromaticity of the image signal. By printing dots, the gradation level is variably set.

Here, as shown in FIG. 8, when the gradation is 0, there is no dot to be printed, when the gradation is 1, the dots of order 1 are printed, and when the gradation is 2, the order 1 and the order 2 are printed. Dots are printed, and in case of gradation 3, order 1, order 2, and order 3
By printing the dots of ..., In case of gradation 16, by printing all dots, it is possible to display 19 gradation levels from gradation 0 to gradation 18, and with 3 colors 19 × 19 × 1
It is possible to display a gradation level of 9 = 6859.

The print head 16 receives the clock signal CK from the print signal conversion circuit 15 as shown in FIGS.
, A shift register 37 to which an image signal is supplied each time the data is supplied, a latch circuit 38 which stores the image signal supplied to the shift register 37 each time the data latch signal DL is supplied, and strobe signals SRe and SRf. , SRg,
A heat generating portion H that generates heat in synchronization with SRh, SRi, and SRj.
, HM, and a common electrode 39 to which one ends of the heat generating resistors of the heat generating portions H1, ..., HM are connected.

The heat generating portions H1, ..., HM have strobe signals SRe, SRf, SRg, SRh, SRi, S.
NAND circuits 61e, 61f, 61g, 6 to which the inverted signal of Rj and the image signal stored in the latch circuit 38 are supplied.
1h, 61i, 61j, ..., 6Me, 6Mf, 6M
g, 6Mh, 6Mi, 6Mj, and the output signal of this NAND circuit is supplied to one end, the other end is connected to the common electrode 39, and heat is generated so that heat transfer is possible for each dot in the main scanning direction X.
Heating resistors 71e, 71f, 71g, 71 disposed in
h, 71i, 71j, ..., 7Me, 7Mf, 7M
g, 7Mh, 7Mi, 7Mj.

The heat generating portions H1, ..., HM have strobe signals SRe, SRf, SRg, SRh, SRi, S.
By variably setting the duty of the Rj pulse,
Heating resistors 71e, 71f, 71g, 71h, 71i,
71j ..., 7Me, 7Mf, 7Mg, 7Mh, 7M
The heat generation temperatures of i and 7Mj are variably set.

As described above, in the image printing apparatus 20, the strobe signals SRe, SRh, SRf, SRi, SRg, SR are generated.
The heating resistors 71e, 71f, 71g, 7 arranged in the main scanning direction X are arranged in the order shown in FIG.
1h, 71i, 71j, ..., 7Me, 7Mf, 7M
The dots shown in FIG. 9 corresponding to the gradations of g, 7Mh, 7Mi, and 7Mj are heated.

In the above image printing apparatus, the width of one dot of the heating resistor in the sub-scanning direction Y is W, and the moving speed of the printing paper by the paper feeding unit per unit time is constant at v. As shown in 12, the strobe signal SR
e, SRf, SRg, SRh, SRi, SRj, a heat generating portion H1, ..., HM that generates heat by one pulse.
Assuming that the heat generation time of is Th, the displacement of the moving distance from the first pulse to the sixth pulse due to the six strobe signals is
6-1 = 5 pulse movement distances, where K is the movement distance per pulse, and is given by equation (3).

5 · K = 5 · v · Th (3) Therefore, for example, when one pixel is formed in the main scanning direction X, the strobe signal pulse is generated within the width of W + 5 · K. The dots are dispersed and printed in the main scanning direction X and the sub scanning direction Y in the order shown in FIG. 8 in which they are generated, so that the deviation of the printing position is not noticeable and the distortion of the image is suppressed, as shown in FIG. Printing is performed almost linearly in the main scanning direction X.

Further, even if the number of adjacent dots is increased, the effect of heat storage of the print head or the effect of coupling of inks in adjacent parts can be suppressed. Therefore, printing is performed in an area close to the specified area, and printing with printing density faithful to the chromaticity of the image signal is performed.

The strobe signals SRe, SRf, SRg, SRh, SRi, S supplied to the print head 16 are also provided.
By variably setting the duty of the Rj pulse,
Adjust the print density for each print row.

In the present embodiment, the case where the printing section 2 of the image printing apparatus 10 and the printing section 3 of the image printing apparatus 20 are of the thermal transfer type has been described, but the image printing apparatus according to the present invention is as follows. The present invention is not limited to such a printing method, but can be applied to a heat-sensitive method.

In this embodiment, the pulse duty and voltage value of the strobe signal are constant, but the image printing apparatus according to the present invention is not limited to such a strobe signal. However, it is also applicable to the case where the pulse duty or voltage value is arbitrarily set for each strobe signal.

In the present embodiment, when printing is performed line by line in the main scanning direction X in the order of strobe signals shown in FIG. 2, and in the order of strobe signals shown in FIG. The case of printing line by line has been described, but the image printing apparatus according to the present invention is not limited to such an order of strobe signals and an order of each line, and is arranged in the main scanning direction X. The present invention can be applied to the case where the timings of printing dots adjacent to each other are set to be different and the plurality of lines are printed at the same time.

[0075]

As described above, according to the printing method of the present invention, it is possible to set the printing timings of the dots adjacent to each other by shifting them in the timing setting step, and to print at this timing in the printing step. is there.

For this reason, the dots to be printed at the same time are dispersed without being concentrated, so that it is possible to print while suppressing the distortion of the image without making the deviation of the printing position noticeable. Further, the influence of heat storage of the adjacent dots or the influence of the coupling of the inks in the adjacent portions can be suppressed. Therefore, it is possible to provide a printing method capable of printing in an area close to a prescribed area and printing with a print density faithful to the chromaticity of an image signal.

Also, according to the image printing apparatus of the present invention, it is possible to set the printing timings of the dots adjacent to each other by shifting them in the dot setting section, and to print at this timing in the printing section.

Therefore, since the dots to be printed at the same time are not concentrated but dispersed, it is possible to perform printing while suppressing the distortion of the image without making the deviation of the printing position noticeable. Further, the influence of heat storage of the adjacent dots or the influence of the coupling of the inks in the adjacent portions can be suppressed. Therefore, it is possible to provide an image printing apparatus capable of printing in an area close to a prescribed area and printing with a print density faithful to the chromaticity of an image signal.

[Brief description of drawings]

FIG. 1 is a block diagram of an image printing apparatus that implements a printing method according to the present invention.

FIG. 2 is a layout diagram of pixels showing an order of dots to be printed in one line printed by the image printing apparatus.

FIG. 3 is an arrangement diagram showing an arrangement of dots for each gradation of one pixel printed by the image printing apparatus, in which pixels are formed in a 4 × 4 matrix.

FIG. 4 is a block diagram of a main part of a printing unit 2 of the image printing apparatus.

FIG. 5 is a timing chart of a main part of the printing unit 2 of the image printing apparatus.

FIG. 6 is an arrangement diagram of dots in one line printed by the image printing apparatus.

FIG. 7 is a block diagram of a second embodiment of the image printing apparatus according to the present invention.

FIG. 8 is an arrangement diagram of pixels showing an order of dots to be printed in one line printed by the image printing apparatus.

FIG. 9 is an arrangement diagram showing an arrangement of dots for each gradation of one pixel printed by the image printing apparatus, in which pixels are formed in a 6 × 3 matrix.

FIG. 10 is a block diagram of a main part of a printing unit 2 of the image printing apparatus.

FIG. 11 is a timing chart of a main part of the printing unit 2 of the image printing apparatus.

FIG. 12 is a layout diagram of dots in one line printed by the image printing apparatus.

FIG. 13 is a block diagram of a main part of a printing unit 2 of a conventional image printing apparatus.

FIG. 14 is a timing chart of a main part of the printing unit 2 of the image printing apparatus.

FIG. 15 is a layout diagram of dots in one line printed by the image printing apparatus.

[Explanation of symbols]

1 dot setting section 2, 3 printing section 8 color conversion / color correction circuit 10, 20 image printing device 11, 15 print signal conversion circuit 12, 16 print head 35, 36 pixel 40 image signal input terminal X main scanning direction Y sub-scan Direction SRa, SRb, SRc, SRd Strobe signal SRe, SRf, SRg, SRh, SRi, SRj Strobe signal

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Claims (2)

[Claims] 1. A timing setting step of setting the printing timing of dots adjacent to each other in the main scanning direction of the dots arranged in the main scanning direction, and a timing set in the timing setting step, based on the timing set in the timing setting step. A printing method comprising: a printing step of printing dot by dot in a sub-scanning direction orthogonal to the main scanning direction. 2. Based on an image signal supplied from an image signal input terminal, a predetermined number of dots arranged in a main scanning direction and a sub-scanning direction orthogonal to the main scanning direction are formed, and a dot is formed by printing dots. In addition to setting the dots for printing the pixels that change the tones, a dot setting unit that sets so as to shift the printing timings of the dots that are adjacent to each other in each print row of the dots that are printed along the sub-scanning direction. An image printing apparatus comprising: a printing unit that prints on the dots set by the dot setting unit along the sub-scanning direction based on the timing of dots in each print row.