JP2000052595A - Serial printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a serial printer ensuring high recording quality without increasing the size. SOLUTION: A sub-scan drive motor 2 turns a recording medium carrying roller 3 continuously to move a recording medium continuously. A recording head moving motor 1 moves a recording head 4 in the direction substantially orthogonal to the carrying direction of the recording medium. Since the recording medium is moved even during recording operation with a recording head 4, an inclining stripe area is recorded. A control section 5 divides an image to be recorded as oblique areas corresponding to the inclination, and each area is transferred as a recording data to the recording head 4. Consequently, normal image is formed on the recording medium. Furthermore, white and black streaks are decreased between respective stripe areas because the recording medium is fed continuously and a high quality image can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of arranging recording elements in a sub-scanning direction on a recording head, moving the recording head in the main scanning direction to form an image of a band-shaped area, and repeating the operation. The present invention relates to a serial printer for forming a desired image.

[0002]

2. Description of the Related Art In general serial printers,
With the recording medium stopped, the recording head is moved in the main scanning direction, and recording is performed on a band-shaped area (hereinafter, referred to as a line) corresponding to the recording width. Then, every time printing of one line is completed, the recording medium is fed in the sub-scanning direction by a specified amount and stopped, and then printing of the next one line is performed. in this way,
In a general serial printer, a recording medium is intermittently fed.

When such intermittent feed is performed, the feed accuracy varies due to the inertial force between the start and stop of the feed and the difference in the frictional resistance of the recording medium. When such a variation in the feeding accuracy occurs, a gap is generated at a joint between the lines, a white streak is generated, or a line having a high density due to partial overlap is generated, which leads to deterioration of image quality. There was a problem.

[0004] In order to solve the above-mentioned problems, techniques for continuously transporting a recording medium and suppressing variations in intermittent feeding accuracy have been developed. For example, JP-A-6-23
In the printer described in JP-A-8978, a carriage on which a recording head is mounted is moved in a direction orthogonal to a sub-scanning direction which is a moving direction of a recording medium, and a recording head is moved in accordance with the movement of the carriage. Are moved in the sub-scanning direction. That is, the recording head moves obliquely to a direction orthogonal to the sub-scanning direction. Therefore, even if the recording medium is continuously transported, the recording head can be moved in the sub-scanning direction by the moving amount of the recording medium during one scan. This makes it possible to perform the same recording as when recording is performed while the recording medium is stopped, while continuously moving the recording medium.

However, in the configuration described in this document, in order to move the recording head, in addition to the motor for moving the recording head in the main scanning direction, the recording head in the carriage is operated in the sub scanning direction. Is provided. For this reason, there is a problem that the device becomes large.

In a printer described in, for example, Japanese Patent Application Laid-Open No. 5-155008, the moving direction of a recording head (and a carriage) is inclined with respect to a direction orthogonal to the sub-scanning direction. Thus, even when the recording medium is continuously transported, an image can be formed in the same manner as when recording is performed with the recording medium stopped. In the configuration described in this document, although a configuration for moving the recording head in the carriage in the sub-scanning direction is not required, the moving direction of the recording head is inclined with respect to a direction orthogonal to the sub-scanning. However, there is a problem that the size of the apparatus increases accordingly.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a serial printer capable of obtaining good recording quality without increasing the size of the apparatus. Things.

[0008]

According to the present invention, in a serial printer, a sub-scanning direction for moving a recording medium and a main scanning direction for moving a recording head are substantially orthogonal to each other. The same configuration as the printer that intermittently feeds the medium prevents the apparatus from being enlarged.
Then, the recording medium is continuously moved. As a result, it is possible to prevent the occurrence of white streaks or black streaks due to intermittent feeding of the recording medium, and to obtain good image quality.

In this case, the recording medium moves even during recording due to the movement of the recording head in the main scanning direction. In other words, the recording head performs recording while moving the recording medium in a direction substantially orthogonal to the moving direction of the recording medium. Therefore, the recording area for one line recorded in one main scan is an oblique area on the recording medium. The control means creates print data according to the amount of movement of the recording medium while the print head is moving, and transfers the created print data to the print head. Thus, the image formed on the recording medium does not tilt obliquely, and the image can be formed normally.

[0010]

FIG. 1 is a block diagram showing an embodiment of a serial printer according to the present invention. In the figure, 1 is a print head moving motor, 2 is a sub-scanning drive motor, 3 is a recording medium transport roller, 4 is a print head, and 5 is a control unit.
The sub-scanning drive motor 2 continuously rotates the recording medium transport roller 3 to continuously move the recording medium in the sub-scanning direction indicated by an arrow P in the figure.

The recording head 4 has a plurality of recording elements arranged in one or a plurality of rows substantially in the sub-scanning direction. The recording element is, for example, a nozzle that ejects ink in the case of an ink jet recording method, and is, for example, a heater in the case of a heat-sensitive method or a thermal transfer method. A recording element corresponding to each recording method is arranged on the recording head 4.

The recording head moving motor 1 moves the recording head 4 in a main scanning direction substantially orthogonal to a sub-scanning direction, which is a conveying direction of a recording medium. While the recording head 4 is moving, an image can be formed on a recording medium by driving a recording element disposed on the recording head 4 according to an image to be recorded. Since a plurality of printing elements are arranged in the sub-scanning direction substantially as described above, printing is performed in a band-shaped area of the width in which the printing elements are arranged by one movement of the printing head 4 in the main scanning direction. be able to.

The control unit 5 controls the driving of the recording head moving motor 1, the sub-scanning driving motor 2, the recording medium transport roller 3, and the like. Further, it generates and transfers recording data corresponding to an image to be recorded to the recording head 4. In some cases, a recording timing signal of a recording element provided in the recording head 4 is also transferred. When generating print data, the amount of movement of the recording medium in the sub-scanning direction while the print head 4 is moving in the main scanning direction is considered. That is,
In the present invention, recording is performed by moving the recording head 4 in the main scanning direction substantially orthogonal to the sub-scanning direction while continuously moving the recording medium in the sub-scanning direction. Also, the recording medium moves in the sub-scanning direction. Therefore, the area that can be formed on the recording medium by one main scan of the recording head 4 is a belt-like area oblique to the recording medium. The control unit 5 divides the image to be formed into oblique belt-shaped regions so that the image is not inclined on the recording medium, and generates print data to be formed by main scanning of each print head 4. The details will be described later.

FIG. 2 is a block diagram showing a configuration example for realizing one embodiment of the serial printer of the present invention. In the figure, 11 is a CPU, 12 is an I / F driver, 13 is RO
M and 14 are RAMs, 15 is a print head moving circuit, 16 is a sub-scan moving circuit, 17 is a print timing generation circuit, 18
Denotes a sensor unit, 19 denotes a control panel, 20 denotes a head driver, and 21 denotes a host device. FIG. 2 particularly shows a configuration example of the control unit 5.

The CPU 11 operates in accordance with control procedures and data stored in the ROM 13 or data detected by a sensor unit 18 including a recording medium detection sensor.
The control of each part of the printing apparatus is performed using the control unit 14. Also, C
The PU 11 is connected to a host device 21 such as a computer via the I / F driver 12.
The image data to be recorded sent from the
And controls a recording operation while decoding a command signal such as a command from the host device 21 and a recording information signal.
In particular, from the image to be printed, an image of an obliquely inclined band-shaped region to be recorded by the recording head 4 is generated as recording data in consideration of the amount of movement of the recording medium in the sub scanning direction during the main scanning of the recording head 4. Then, the data is transferred to the recording head 4 via the head driver 20.

The RAM 14 not only has a work area for the CPU 11 but also stores data relating to an image to be recorded transmitted from the host device 21 and recording data to be transferred to the recording head 4. Recording head moving circuit 15,
The sub-scanning movement circuit 16 and the head driver 20 correspond to the CPU 1
1 according to the instruction of the recording head moving motor 1,
The sub-scanning drive motor 2 and the recording head 4 are controlled and driven. The recording timing generation circuit 17 generates a timing signal for driving a recording element provided in the recording head 4 based on an instruction from the CPU 11 and supplies the timing signal to the head driver 20. The sensor unit 18 detects each unit of the apparatus, such as the temperature and the presence or absence of a recording medium, and transmits the detection to the CPU 11. The control panel 19 displays the state of the apparatus and receives instructions from the user.

A method of creating print data to be transferred to the print head 4 in the control unit 5 will be further described. FIG.
FIG. 3 is an explanatory diagram of a recording area for one line formed on a recording medium in an embodiment of the serial printer of the present invention. As described above, in the present invention, recording is performed by moving the recording head 4 in a direction substantially orthogonal to the sub-scanning direction while continuously moving the recording medium in the sub-scanning direction. Now
Consider a case where the recording medium is continuously moved from the bottom to the top in the figure as shown in FIG. 3A, and the recording head 4 is moved from the left to the right in the figure. Since the recording medium also moves from bottom to top in the figure while the recording head 4 moves from left to right in the figure, for example, the portion recorded by the recording head 4 at the left end in the figure is a portion of the recording medium. It moves upward in the figure as it moves. Therefore, as shown in FIGS. 3B and 3C, the area on the recording medium recorded by the recording head 4 is an obliquely inclined area.

FIG. 4 is an explanatory diagram showing an example of the relationship between an image to be recorded and an image formed on a recording medium. As shown in FIG. 3, in the serial printer of the present invention, an image is formed in an obliquely inclined area on the recording medium by one main scan of the recording head 4. Now, consider the case of forming an image as shown in FIG. At this time, as in the case where the recording is stopped and the conventional recording medium is stopped, when the recording data obtained by dividing the image in the horizontal direction as shown in FIG. As shown in ()), the image formed on the recording medium becomes oblique. Therefore, in the present invention, an image is formed on a recording medium by using an oblique area as shown in FIG.
The recording data is generated by dividing the image as an oblique area as shown in FIG. By providing such recording data to the recording head 4, a normal image can be formed on the recording medium as shown in FIG.

The recording area on the recording medium shown in FIGS. 3 and 4 is shown at an angle steeper than the actual inclination for convenience of explanation. Actually, the recording head 4 is moved in the main scanning direction from the left end position in the figure shown in FIG. 3A, and is moved to the right end position in the figure as shown in FIG. The recording head 4 is returned to the position shown in FIG. When the recording head 4 returns and performs the next main scan,
Recording needs to be performed in an area adjacent to the previous recording area. Otherwise, white stripes or blank areas will occur between the recording areas.

FIG. 5 is a time chart showing an example of the moving speed of the recording head. The recording head 4 is driven by the recording head moving motor 1, but after a certain period of acceleration, becomes a constant speed state, and performs recording in the period shown in FIG. Then, the recording medium reaches the end of the recording medium, and after passing through the recording area, decelerates and stops. Then, the vehicle accelerates in the reverse direction, returns to the original position, and stops. Thereafter, the printing is accelerated to start the next main scan. The recording head 4 forms an image by such a repetitive operation.

As described above, after one main scan is performed by the recording head 4, one cycle time from returning to the original position and performing the next main scan is two pr times shown in FIG. ,
It is the sum of the two th times, that is, (2pr + 2th). If the length of movement of the recording medium in the time of this one cycle is within the width h in the sub-scanning direction of the band-shaped area that can be printed by the print head 4 in one main scan, the print area is printed by the next main scan. Will be continuous. That is, assuming that the moving speed of the recording medium is Vm, the maximum value of the moving speed Vm is Vm = h / (2pr + 2th). Here, the recording time pr is pr = W / Vh, where Vh is the moving speed of the recording head 4 and W is the length of the recording area on the recording medium in the main scanning direction, so that Vm = h / ( 2W / Vh + 2th). Generally, the moving speed Vh of the recording head 4 is determined by the resolution of an image to be recorded, the driving frequency of the recording head 4, and the like, and is often limited to a predetermined speed in order to maintain recording quality. The time th is also determined by the characteristics of the recording head moving motor 1 and the like. From these set values, the moving speed Vm of the recording medium is obtained.
The sub-scanning drive motor may move the recording medium within the determined moving speed Vm.

In the example shown in FIG. 5, the case where the recording head 4 performs recording and the case where the recording head 4 returns to the original position have the same speed are shown. However, one cycle time may be calculated from the different speeds. As for the time th, the time required by the recording head 4 at the left end and the time required at the right end may be different. In such a case, if the time is calculated individually and the time of one cycle is obtained. Good.

Further, there is a printer of a system in which an image is completed by performing a plurality of main scans on the same area on a recording medium. In this case, the recording medium is moved at a speed of 1 / N of the moving speed Vm of the recording medium determined as described above so that the recording medium moves by the width h by N main scans. Just do it. In this case, divided printing can be performed without changing the moving speed Vh of the recording head 4 in the main scanning direction.

When recording is performed at the moving speed Vh of the recording head 4 and the moving speed Vm of the recording medium, the angle θ of the belt-shaped region recorded by the recording head 4 is θ = tan ⁻¹ (Vm / Vh). That is, when an image to be recorded is transferred to the recording head 4 as shown in FIG.
What is necessary is just to divide into the belt-shaped area | region inclined by the angle (theta), and to transfer and print to the recording head 4 for every band-shaped area | region. As a result, an image is normally formed on the recording medium as shown in FIG.

As described above, in the configuration in which the recording head 4 is moved in the main scanning direction substantially orthogonal to the sub-scanning direction, which is the moving direction of the recording medium, as in the conventional case, the recording medium is continuously moved to form an image. Can be formed. Therefore, it is possible to prevent the occurrence of white stripes and black stripes caused by intermittent feeding of the recording medium without increasing the size of the apparatus, and to obtain a high-quality image. Also, there is an advantage that the same mechanical configuration as that of a conventional serial printer for intermittently feeding a recording medium can be used as it is and only the control unit 5 is changed. For example, if the operation of the control unit 5 is described in a program, the present invention can be realized only by changing the program.

FIG. 6 is an explanatory diagram of an example of creating print data of an oblique band-like area in pixel units. It is assumed that recording is performed for an area indicated by hatching in FIG. The cells in the hatched area indicate pixels. Here, a case is considered in which an image in an oblique band-shaped area indicated as a recording width is transferred to the recording head 4 as recording data. At this time, some of the upper right and lower left pixels deviate from the band area of the recording width.

As described above, the angle θ of the band-like region is obtained from the moving speed Vh of the recording head 4 and the moving speed Vm of the recording medium, and it is determined whether or not each pixel is included in the band-like region. Thus, it is possible to generate print data including pixels included in the oblique band-like area. However, for the purpose of processing the input image data with a digital signal, determining whether or not the input data is correctly included in a belt-like area oblique from the angle θ complicates the processing. Evils occur. Therefore, it is conceivable to previously determine the shift amount in the sub-scanning direction for each pixel.

That is, when the minimum unit of the data amount of the print data to be transferred to the print head 4 is a pixel and the shift amount in the sub-scanning direction is b pixels, the angle θ ′ = tan ^−1.
(B / ak) may be substantially adjusted to the angle θ described above. Here, the coefficient k is a natural number. Specifically, the angle θ is tan ⁻¹ (1/16) = 3.576 deg,
If the minimum unit for data transfer is 8 pixels, ak
= 16, b = 1. Thus, after transferring 16 pixels in the main scanning direction, that is, two minimum units, the pixel is shifted by one pixel in the sub-scanning direction. This state is shown in FIG. The image in the hatched area in FIG. 6B is transferred to the recording head 4 as recording data. As a result, the angle θ ′ of the recording data of the oblique band area transferred to the recording head 4 becomes substantially the same as the angle θ of the oblique band area recorded on the recording medium.

In this manner, a complicated image is formed on the recording medium while the recording medium is continuously fed, while avoiding complication of processing when transferring the image of the oblique band-shaped area as recording data. can do. Note that ak or k
May be obtained in advance and stored in a ROM or the like. If there are a plurality of sets of the value of ak or k and the value of b due to having several types of recording modes, a table may be stored.

[0030]

As is clear from the above description, according to the present invention, recording is performed by continuously feeding the recording medium.
The occurrence of image quality defects such as white stripes and black stripes can be suppressed as compared with the case where intermittent feeding is performed, and an image with good image quality can be obtained. At this time, in the present invention, the same mechanical configuration as in the related art in which the recording head is moved in the direction orthogonal to the sub-scanning direction in which the recording medium moves to perform main scanning may be used, and a high-quality image can be easily obtained. There is an effect that the obtained printer can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a serial printer according to the present invention.

FIG. 2 is a block diagram illustrating a configuration example that realizes an embodiment of the serial printer of the present invention.

FIG. 3 is an explanatory diagram of a recording area for one line formed on a recording medium in an embodiment of the serial printer of the present invention.

FIG. 4 is an explanatory diagram showing an example of a relationship between an image to be recorded and an image formed on a recording medium.

FIG. 5 is a time chart illustrating an example of a moving speed of a recording head.

FIG. 6 is an explanatory diagram of an example of creating print data of an oblique band-shaped area in pixel units.

[Explanation of symbols]

1. Printhead moving motor, 2. Sub-scanning drive motor, 3.
.., Recording medium transport rollers, 4... Recording head, 5... Control unit, 11... CPU, 12... I / F driver, 13.
M, 14 RAM, 15 print head moving circuit, 16
Sub-scanning moving circuit, 17 ... Recording timing generating circuit, 18
... Sensor part, 19 ... Control panel, 20 ... Head driver, 21 ... Host device.

Claims (4)

[Claims] 1. A recording head having a recording element array comprising a plurality of recording elements arranged in a sub-scanning direction, a recording head moving means for moving the recording head in a main scanning direction, and a recording medium. Sub-scanning moving means for moving in the sub-scanning direction;
Control means for creating print data, transferring the print data to the print head, and controlling each section, wherein the main scanning direction and the sub-scanning direction are substantially orthogonal to each other; While continuously moving the recording medium, the recording head moving means moves the recording head to perform recording, creates the recording data according to the movement of the recording medium, and transfers the recording data to the recording head. And a serial printer. 2. The image processing apparatus according to claim 1, wherein the control unit calculates an angle tan ^-1 based on a speed Vm of the continuously moving recording medium and a moving speed Vh of the recording head in the main scanning direction from the input image data. 2. The serial printer according to claim 1, wherein the recording data is created as a band-shaped area forming (Vm / Vh). Wherein the control means, the minimum unit of transfer data amount for transferring the recording data to said recording head and a pixel, the shift amount to the sub-scanning direction is taken as b pixels, the angle tan ^{- 1} (b / ak) is an angle tan ^-1 (Vm / m) based on the speed Vm of the continuously moving recording medium and the moving speed Vh of the recording head in the main scanning direction.
Vh), a, b, and k (a, b, and k are integers, a, b, k ≧ 1) are determined, and the transfer data amount is shifted by b pixels for each a pixel in the sub-scanning direction. 2. The serial printer according to claim 1, wherein the recording data is created from image data input for each shifted area. 4. When the image in the same area on the recording medium is formed N times by the main scanning of the recording head, the sub-scanning moving means sets the moving speed Vm of the recording medium in the sub-scanning direction. The serial printer according to any one of claims 1 to 3, wherein 1 / N is set.