JP3680909B2 - Serial printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a recording element is arranged on a recording head in the sub-scanning direction, and the recording head is moved in the main scanning direction to form an image of a belt-like region, and this is repeated to form a desired image. It relates to printers.
[0002]
[Prior art]
In a general serial printer, usually, the recording head is moved in the main scanning direction with the recording medium stopped, and a band-like area (hereinafter referred to as a line) corresponding to the recording width is recorded. Each time recording for one line is completed, the recording medium is fed by a specified amount in the sub-scanning direction and stopped, and then the next one line is recorded. As described above, a general serial printer intermittently feeds a recording medium.
[0003]
When such intermittent feeding is performed, the feeding accuracy varies due to the inertial force at the start and stop of feeding, the difference in frictional resistance of the recording medium, and the like. When this variation in feed accuracy occurs, there is a gap between the lines, resulting in white streaks, or lines that are partially overlapped and darkened, resulting in image quality degradation. There was a problem.
[0004]
In order to solve the above-described problems, conventionally, a technique has been developed in which a recording medium is continuously conveyed to suppress variation in intermittent feeding accuracy. For example, in a printer described in Japanese Patent Laid-Open No. 6-238978, a carriage on which a recording head is mounted is moved in a direction perpendicular to the sub-scanning direction, which is the moving direction of the recording medium, so as to correspond to the movement of the carriage. Thus, the recording head is moved in the sub-scanning direction. That is, the recording head moves in an oblique direction with respect to the direction orthogonal to the sub-scanning direction. Therefore, even if the recording medium is continuously conveyed, the recording head can be moved in the sub-scanning direction by the amount of movement of the recording medium during one scan. As a result, the same recording as in the case of recording with the recording medium being stopped can be performed while continuously moving the recording medium.
[0005]
However, in the configuration described in this document, in order to move the recording head, in addition to the motor that moves the recording head in the main scanning direction, the configuration for operating the recording head in the carriage in the sub-scanning direction. Is provided. Therefore, there has been a problem that the apparatus becomes large.
[0006]
For example, in the printer described in Japanese Patent Laid-Open No. 5-155008, the moving direction of the recording head (and the carriage) is inclined with respect to the direction orthogonal to the sub-scanning direction. As a result, even when the recording medium is continuously conveyed, an image can be formed in the same manner as when the recording medium is stopped and recorded. In the configuration described in this document, a configuration for moving the recording head in the carriage in the sub-scanning direction is not necessary, but the moving direction of the recording head is inclined with respect to the direction orthogonal to the sub-scanning. Therefore, there was a problem that the apparatus was increased in size.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a serial printer that can obtain good recording quality without increasing the size of the apparatus.
[0008]
[Means for Solving the Problems]
In the present invention, in the serial printer, the sub-scanning direction in which the recording medium is moved and the main scanning direction in which the recording head is moved are substantially orthogonal to each other, and the same configuration as that of a conventional printer that intermittently feeds the recording medium This prevents an increase in the size of the device. Then, the recording medium is continuously moved. As a result, the occurrence of white stripes and black stripes due to intermittent feeding of the recording medium can be prevented, and good image quality can be obtained.
[0009]
In this case, the recording medium moves even during recording by moving the recording head in the main scanning direction. That is, the recording head performs recording by moving in a direction substantially perpendicular to the moving direction of the recording medium while the recording medium is moved. Therefore, the recording area for one line recorded in one main scan is an oblique area on the recording medium. The control means creates recording data according to the amount of movement of the recording medium while the recording head is moving, and transfers the created recording data to the recording head. As a result, the image formed on the recording medium is not inclined, and the image can be formed normally.
In particular, the minimum unit in the main scanning direction of the transfer data amount for transferring recording data to the recording head is a pixel, and the shift amount of the recording medium in the sub-scanning direction every time the recording head moves ak pixels in the main scanning direction. When b pixels are used, the angle tan ⁻¹ (b / ak) is an angle tan ⁻¹ (based on the velocity Vm of the recording medium continuously moving and the moving velocity Vh of the recording head in the main scanning direction. A, b and k (a, b, k are integers, a, b, k ≧ 1) are determined so as to be close to Vm / Vh), and every time the amount of transfer data in the main scanning direction becomes ak pixels For each region shifted in the sub-scanning direction by the shift amount b pixels, print data is created from the input image data and transferred to the print head.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a configuration diagram showing an embodiment of a serial printer of the present invention. In the figure, 1 is a recording head moving motor, 2 is a sub-scanning drive motor, 3 is a recording medium conveying roller, 4 is a recording head, and 5 is a control unit. The sub-scanning drive motor 2 continuously rotates the recording medium conveyance roller 3 to continuously move the recording medium in the sub-scanning direction indicated by an arrow P in the drawing.
[0011]
The recording head 4 includes a plurality of recording elements arranged in a line 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 a heater in the case of a thermal method or a thermal transfer method, for example. A recording element corresponding to each recording method is arranged in the recording head 4.
[0012]
The recording head moving motor 1 moves the recording head 4 in the main scanning direction substantially orthogonal to the sub-scanning direction that is the conveyance direction of the recording medium. While the recording head 4 is moving, an image can be formed on the recording medium by driving the recording elements arranged in the recording head 4 according to the image to be recorded. As described above, since the plurality of recording elements are arranged substantially in the sub-scanning direction, recording is performed in a band-shaped region corresponding to the width in which the recording elements are arranged by one movement of the recording head 4 in the main scanning direction. be able to.
[0013]
The control unit 5 performs drive control of the recording head moving motor 1, the sub-scanning driving motor 2, the recording medium conveyance roller 3, and the like. Also, recording data corresponding to the image to be recorded is generated and transferred to the recording head 4. Further, a recording timing signal of a recording element provided in the recording head 4 may be transferred. When generating recording data, the amount of movement of the recording medium in the sub-scanning direction during movement of the recording head 4 in the main scanning direction is taken into consideration. That is, in the present invention, since the recording head 4 is moved in the main scanning direction substantially orthogonal to the sub-scanning direction while continuously moving the recording medium in the sub-scanning direction, the recording head 4 is moved in the main scanning direction. Even during movement, the recording medium moves in the sub-scanning direction. Therefore, the area that can be formed on the recording medium by one main scanning of the recording head 4 is a band-like area that is oblique to the recording medium. The control unit 5 divides the image to be formed into oblique band-like regions so that the image is not inclined on the recording medium, and generates recording data to be formed by the main scanning of each recording head 4. Details will be described later.
[0014]
FIG. 2 is a block diagram showing a configuration example for realizing an embodiment of the serial printer of the present invention. In the figure, 11 is a CPU, 12 is an I / F driver, 13 is ROM, 14 is RAM, 15 is a recording head moving circuit, 16 is a sub-scanning moving circuit, 17 is a recording timing generation circuit, 18 is a sensor unit, 19 is A control panel, 20 is a head driver, and 21 is a host device. In particular, FIG. 2 shows a configuration example of the control unit 5.
[0015]
The CPU 11 controls each part of the recording apparatus using the RAM 14 in accordance with the control procedure and data stored in the ROM 13 or the detection data by the sensor unit 18 including a recording medium detection sensor. The CPU 11 is connected to a host device 21 such as a computer via the I / F driver 12, stores image data to be recorded sent from the host device 21 in the RAM 14, and receives data from the host device 21. The recording operation is controlled while decoding command signals such as commands and recording information signals. In particular, an image of a slanted belt-like area recorded by the recording head 4 is generated as recording data from the image to be recorded in consideration of the amount of movement of the recording medium during the main scanning of the recording head 4 in the sub-scanning direction. Then, the data is transferred to the recording head 4 via the head driver 20.
[0016]
The RAM 14 has a work area for the CPU 11, and also stores data related to an image to be recorded sent from the host device 21, recording data to be transferred to the recording head 4, and the like. The recording head moving circuit 15, the sub-scanning moving circuit 16, and the head driver 20 control and drive the recording head moving motor 1, the sub-scanning drive motor 2, and the recording head 4, respectively, according to instructions from the CPU 11. 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 part of the apparatus, such as the temperature and the presence / absence of a recording medium, and transmits it to the CPU 11. The control panel 19 displays the status of the apparatus and receives instructions from the user.
[0017]
A method for creating recording data to be transferred to the recording head 4 in the control unit 5 will be further described. FIG. 3 is an explanatory diagram of a recording area for one line formed on a recording medium in the 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 perpendicular to the sub-scanning direction while continuously moving the recording medium in the sub-scanning direction. Now, consider a case in which the recording medium is continuously moved from the bottom to the top in the drawing and the recording head 4 is moved from the left to the right in the drawing as shown in FIG. Since the recording medium moves from the bottom to the top in the figure while the recording head 4 moves from the left to the right in the figure, for example, the portion recorded by the recording head 4 at the left end in the figure is the recording medium. Moves upward in the figure along with the movement. 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.
[0018]
FIG. 4 is an explanatory diagram illustrating an example of a 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 scanning of the recording head 4. Consider a case where an image as shown in FIG. At this time, as in the case where recording is performed with the conventional recording medium stopped, as shown in FIG. 4B, when recording data obtained by dividing an image in the horizontal direction is applied to the recording head 4, FIG. ), The image formed on the recording medium is italicized. Accordingly, in the present invention, recording data is generated by dividing an image as an oblique area as shown in FIG. 4D, corresponding to an oblique area when an image is formed on a recording medium. By providing such recording data to the recording head 4, a normal image can be formed on the recording medium as shown in FIG.
[0019]
The recording areas on the recording medium shown in FIG. 3 and FIG. 4 are shown at a steeper angle 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 drawing shown in FIG. 3A, moved to the right end position in the drawing 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 scanning, it is necessary to perform recording in an area adjacent to the previous recording area. Otherwise, white stripes or blank areas will occur between the recording areas.
[0020]
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 becomes a constant speed state after some acceleration period, and recording is performed in the period (1) in the figure. Then, it reaches the end of the recording medium and decelerates and stops when it passes the recording area. And it accelerates in the reverse direction, returns to the original position, and stops. Thereafter, the recording is accelerated to start the next main scanning. The recording head 4 forms an image by such repeated operations.
[0021]
As described above, after one main scan is performed by the recording head 4, the time of one cycle from the return to the original position to the next main scan is the two pr times shown in FIG. The sum of th times, that is, (2pr + 2th). If the length of movement of the recording medium in this period of one cycle is within the width h in the sub-scanning direction of the band-like area that can be recorded by the recording head 4 by one main scanning, the recording area is recorded by the next main scanning. Will be continuous. That is, if the moving speed of the recording medium is Vm, the maximum value of the moving speed Vm is Vm = h / (2pr + 2th)
It becomes. 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 in the main scanning direction of the recording area on the recording medium.
Vm = h / (2W / Vh + 2th)
It is. In general, 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. Since the moving speed Vm of the recording medium is obtained from these set values, the sub-scanning drive motor only needs to move the recording medium within the obtained moving speed Vm.
[0022]
In the example shown in FIG. 5, the case where the recording head 4 performs the recording and the case where the speed is the same when returning to the original position is shown. The time for one cycle may be calculated from the different speeds. Also, regarding the time th, the time required for the recording head 4 at the left end may differ from the time required at the right end. In such a case as well, if the time is calculated individually and the time of one cycle is obtained. Good.
[0023]
In addition, there is a printer of a type that completes an image in the same area on a recording medium by a plurality of main scans. In this case, the recording medium is moved at a speed of 1 / N of the moving speed Vm of the recording medium obtained as described above so that the recording medium moves by a 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.
[0024]
When recording is performed at such a moving speed Vh of the recording head 4 and a moving speed Vm of the recording medium, the angle θ of the band-like region recorded by the recording head 4 is
θ = tan ⁻¹ (Vm / Vh)
Can be expressed as That is, when the image to be recorded is transferred to the recording head 4 as shown in FIG. 4D, it is divided into band-shaped areas inclined by the angle θ and transferred to the recording head 4 for each band-shaped area. Recording. As a result, an image is normally formed on the recording medium as shown in FIG.
[0025]
In this way, an image is formed by continuously moving the recording medium in the configuration in which the recording head 4 is moved in the main scanning direction substantially perpendicular to the sub-scanning direction, which is the moving direction of the recording medium, as in the prior art. Can do. Therefore, it is possible to prevent generation 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. Further, there is an advantage that the same mechanical configuration as that of a conventional serial printer that intermittently feeds a recording medium can be used as it is, and it can be realized only by changing the control unit 5. 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.
[0026]
FIG. 6 is an explanatory diagram of an example of creating recording 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 where an image of an oblique band-like region indicated as the recording width is transferred to the recording head 4 as recording data. At this time, some pixels in the upper right and lower left are deviated from the band-like region of the recording width.
[0027]
As described above, the angle θ of the band-like area is obtained from the moving speed Vh of the recording head 4 and the moving speed Vm of the recording medium, and whether or not each pixel is included in the band-like area is determined. It is possible to generate recording data composed of pixels included in the oblique belt-like region. However, for the convenience of processing input image data with a digital signal, it is difficult to accurately determine whether or not the input data is included in an oblique band region from the angle θ. Bad effects occur. Therefore, it is conceivable to obtain the shift amount in the sub-scanning direction in advance for each pixel.
[0028]
That is, when the minimum unit of the data amount of the recording data transferred to the recording head 4 is a pixel and the shift amount in the sub-scanning direction is b pixel, the angle θ ′ = tan ⁻¹ (b / ak) is almost equal. What is necessary is just to match | combine with the above-mentioned angle (theta). Here, the coefficient k is a natural number. Specifically, when the above-mentioned angle θ is tan ⁻¹ (1/16) = 3.576 deg and the minimum unit for data transfer is 8 pixels, ak = 16 and b = 1. Thus, after transferring 16 pixels in the main scanning direction, that is, 2 minimum units, the pixel is shifted by 1 pixel in the sub-scanning direction. This state is shown in FIG. The hatched image in FIG. 6B is transferred to the recording head 4 as recording data. As a result, the angle θ ′ of the recording data in 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.
[0029]
In this way, a normal image can be formed on the recording medium while continuously feeding the recording medium while avoiding complication of processing when transferring the image of the oblique band-shaped area as recording data. it can. The values of ak or k and b may be obtained in advance and stored in a ROM or the like. Further, when there are a plurality of sets of values of ak or k and b due to having several kinds of recording modes, a table may be formed.
[0030]
【The invention's effect】
As is clear from the above description, according to the present invention, recording is performed by continuously feeding the recording medium, so that defects in image quality such as white stripes and black stripes are generated compared to the case of intermittent feeding. Therefore, an image with good image quality can be obtained. At this time, in the present invention, the same mechanical configuration as in the conventional case in which main scanning is performed by moving the recording head in a direction orthogonal to the sub-scanning direction in which the recording medium moves can 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 showing an embodiment of a serial printer of the present invention.
FIG. 2 is a block diagram illustrating a configuration example for realizing an embodiment of a 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 the embodiment of the serial printer of the present invention.
FIG. 4 is an explanatory diagram illustrating 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 showing an example of the moving speed of the recording head.
FIG. 6 is an explanatory diagram of an example of creating recording data of an oblique band-like region in units of pixels.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Recording head movement motor, 2 ... Sub scanning drive motor, 3 ... Recording medium conveyance roller, 4 ... Recording head, 5 ... Control part, 11 ... CPU, 12 ... I / F driver, 13 ... ROM, 14 ... RAM , 15 ... print head moving circuit, 16 ... sub-scanning moving circuit, 17 ... print timing generating circuit, 18 ... sensor unit, 19 ... control panel, 20 ... head driver, 21 ... host device.

Claims (2)

A recording head having a recording element array composed of a plurality of recording elements arranged in the sub-scanning direction, a recording head moving means for moving the recording head in the main scanning direction, and a recording medium in the sub-scanning direction And a sub-scanning moving unit for generating recording data and transferring the recording data to the recording head and controlling each unit, and the main scanning direction and the sub-scanning direction are substantially orthogonal to each other. The main scanning of the transfer data amount for transferring the recording data to the recording head by causing the recording head moving means to perform the recording while continuously moving the recording medium to the sub-scanning moving means. When the minimum unit in the direction is a pixel, and the shift amount of the recording medium in the sub-scanning direction every time the recording head moves ak pixels in the main scanning direction is b pixel, the angle tan ⁻¹ (b / ak) becomes close to an angle tan ⁻¹ (Vm / Vh) based on the velocity Vm of the recording medium continuously moving and the moving velocity Vh of the recording head in the main scanning direction. Thus, a, b and k (a, b, k are integers a, b, k ≧ 1) are determined, and every time the amount of transfer data in the main scanning direction becomes ak pixels, the shift amount is b pixels. A serial printer, wherein the recording data is created from the input image data area shifted in the sub-scanning direction and transferred to the recording head.   The sub-scanning moving unit sets the moving speed Vm of the recording medium in the sub-scanning direction to 1 / N when an image of the same area on the recording medium is formed by the main scanning of the recording head N times. The serial printer according to claim 1.

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