JP4208488B2 - Inkjet recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to a recording apparatus that records an image on a recording medium such as paper using a print head, and is used as an information output unit such as a printer, a copying machine, and a facsimile.
[0002]
[Prior art]
2. Description of the Related Art A serial type recording apparatus having an operation unit equipped with a recording head that reciprocates perpendicularly to the conveyance direction of a recording medium such as paper or an OHP sheet has been proposed in which recording heads using various recording methods are mounted.
[0003]
The recording head used in this serial printer includes a wire dot type, a thermal type, a thermal transfer type, and an inkjet type.
[0004]
Among the serial printers, the ink jet type ejects ink directly onto the recording paper, so that the running cost is easy and the noise during recording is small. In the ink jet system, the recording head is provided at a fixed interval with respect to the recording medium, and is always in a non-contact state, and the ink ejected from the recording head flies through the space between the recording head and the recording medium. Then, since the recording medium reaches the recording medium and desired recording is performed, the sliding load of the carrier is small, which is advantageous for realizing high speed.
[0005]
When printing vertical ruled lines as shown in FIG. 6 in the serial printer, if the recording head is not accurately positioned on the carrier, and the ink discharge ports are inclined and arranged not correctly in the conveyance direction of the recording medium, There is a problem that a ruled line for each printed line causes a tilted ruled line shift. Also, in a recording apparatus that performs color printing by arranging a plurality of such heads in parallel and ejecting ink of different colors with each head, even a slight deviation may cause uneven color and have a significant adverse effect on the image. End up.
Conventionally, in such a serial printer, not only the accuracy of mounting the head to the carrier is improved, but also the ink discharge ports arranged in the recording medium conveyance direction are divided into a plurality of blocks as shown in JP-A-7-40551, Some of them have an electrical correction means such that the drive interval for each block is changed according to the magnitude of the inclination and discharged.
[0006]
[Problems to be solved by the invention]
With the recent increase in speed of PCs, color images can be easily handled, and it is desired to process large volumes of data in image recording.
[0007]
Furthermore, it is necessary to process a large capacity at a higher speed with higher definition of recorded images and higher processing speed.
[0008]
The speeding up of the recording operation in the serial ink jet printer can be realized by increasing the ink discharge frequency and increasing the number of recording nozzles.
Here, a description will be given of a case where high speed is achieved by adding a recording nozzle.
[0009]
The plurality of nozzles increased in order to increase the speed of the recording operation are arranged to extend in the recording medium conveyance direction with respect to the previous nozzles.
[0010]
That is, it is intended to increase the speed by increasing the recording width in one scan when the recording operation is performed by ejecting ink while the print head moves in the vertical direction with respect to the recording medium. Therefore, in this case, the recording head is configured to be extended in the recording medium conveyance direction.
[0011]
Assuming that the limit value of the mechanical accuracy is an inclination of θ from the normal position, there is a problem that the printing position deviation when the deviation θ is attached becomes larger as the recording head becomes longer.
[0012]
Furthermore, when the recorded image has a higher definition, it is required to land the ink droplet on the recording medium with higher accuracy from the relative relationship between the size of the recording pixel and the absolute deviation.
[0013]
As described above, maintaining the positional relationship between the recording head and the recording medium with high accuracy is necessary for high-quality image formation.
[0014]
However, there is a problem that a large cost is required to prepare a print head that is long to obtain higher speed and a high-accuracy mechanism that supports high definition for high image quality of recorded images. is there.
[0015]
This proposal proposes a method of electrically correcting such head tilt.
[0016]
[Means for Solving the Problems]
In order to solve the above problems, an ink jet recording apparatus of the present invention uses a recording head having a plurality of ejection openings and dividing the plurality of ejection openings into a plurality of groups in the arrangement direction of the ejection openings. In an ink jet recording apparatus that performs recording by ejecting ink onto a recording medium, a first memory that holds data corresponding to an ejection port of a recording head, and a thinning process is performed after the data is read from the first memory. In order to hold the data, a region for a plurality of columns based on a predetermined inclination of the ejection port array with respect to the scanning direction of the recording head is prepared, and a region for one column among the regions is prepared as a writing region for writing, A second memory that is divided so that each column position area constituting the plurality of columns corresponds to each group, and an input for inputting correction information for the predetermined inclination. A selection unit that selects a region corresponding to each group from a column range based on the inclination and the correction information, and the selection unit in synchronization with the drive timing of the recording head. A transfer means for reading out the data in the area selected in (1) and transferring it to the recording head; a control for changing the column position of the column range and the column position of the writing area for each driving period of the recording head; And a control means for performing control to use the column area in a ring shape.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
Embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 3, the ink jet recording apparatus of this embodiment has four ink jet recording heads responsible for recording each color, Bk (black) head 2-1, Y (yellow) head 2-2, M (magenta) head 2- 3, a carriage 3 mounted with a C (cyan) head 2-4, an integrated ink tank 1-1 to 1-4, and an optical home position sensor (hereinafter referred to as an HP sensor) 8, respectively. It is connected to a part of the driving belt 4 that transmits the driving force of the motor and is movably attached to a guide shaft 6 that is arranged in parallel to the scanning direction, and is driven by the driving force of the carriage driving motor 5. The recording paper fed from a medium feeding device (not shown) to the platen 7 arranged to face the ejection surfaces of the ink jet recording heads 2-1 to 2-4. It reciprocates across the width and has a configuration for performing recording on the recording paper.
[0018]
The above-described ink jet recording heads 2-1 to 2-4 have a plurality of thin pipe-like nozzle nozzles arranged in parallel on the discharge surface facing the recording surface of the recording paper, and are further integrated. A heater that gives ejection energy to the ink supplied from the ink tanks 1-1 to 1-4 is provided in the vicinity of the nozzle opening.
[0019]
The nozzle openings of the recording heads 2-1 to 2-4 are arranged in a direction perpendicular to the scanning direction of the carriage 3, and four recording heads are arranged side by side in the carriage scanning direction. .
[0020]
Further, the HP sensor 14 determines the reference position (carriage home position) in the scanning direction of the recording operation by detecting the reference position detecting projection 12 when the carriage 3 moves on the guide shaft 6 in the initial operation. Used to do.
[0021]
The above-described ink jet recording apparatus receives data such as image information and control commands input from an external host device or the like by a print control unit (not shown) described later, and develops the image data of each color according to the received data. Data is transferred to the recording head and the carriage 3 is scanned to control a series of recording operations for ejecting ink at a necessary timing.
[0022]
The print control unit and the carriage 3 are connected by a flexible cable 13 and receive various signals and power necessary for ejection.
[0023]
Next, the print control unit of the ink jet recording apparatus of this embodiment will be described with reference to FIG.
[0024]
2 includes a CPU 31, a ROM 32, a RAM 33-1, and a RAM 33-2 that are storage units, an interface circuit 34 for a host device 41 that is an external device, the carriage drive motor 5, and the LF motor 10. A motor control circuit 35 to be driven and a gate array 36 composed of a logic circuit that performs various controls by supplementing the operation of the CPU 31. The head control block 37 and the RAM 33-2 for controlling and driving the ejection timing of the interface recording head 2 are configured in the gate array 36 described above.
[0025]
A stepping motor is used as the carriage drive motor 5. The CPU 31 sends the operation signal of the carriage drive motor 5 to the motor control circuit 35 to move the carriage 3, and at the same time, calculates the number of operation signals from the reference position in the scanning direction by the signal from the position encoder 15 mounted on the carriage. By managing the position of the carriage 3 at present, the necessary data processing is started when the carriage 3 approaches the print area. Further, when the carriage 3 moves and the mounted recording heads 2-1 to 2-4 reach positions where ink ejection should be performed, the head control block 37 controls to eject ink.
[0026]
The CPU 31 controls the overall operation of the inkjet recording apparatus according to a program stored in advance in the ROM 32 or a control command input from the host device 41 via the interface circuit 34.
[0027]
The ROM 32 stores a program for operating the CPU 31 and various table data necessary for head control.
[0028]
The operation panel 51 includes various user settings of the recording apparatus, for example, a key switch for performing online / offline settings and a building, and LEDs indicating a power-on state and an online state.
[0029]
The interface circuit 34 is an interface unit for inputting / outputting control commands and control data from the host device 41 to the inkjet recording apparatus.
[0030]
The RAM 33-1 is a bit in which the work area at the time of calculation of the CPU 31 or the temporary storage area of the recording data and control code input from the host device 41 via the interface circuit 34 or the recording data is associated with the nozzle of the head. A print buffer for storing image data expanded into data is also configured on the RAM 33-1.
[0031]
The image recording apparatus of this embodiment has a plurality of print modes, and may perform various processes on image data sent from the host device if necessary. For example, when it is desired to perform printing with reduced ink consumption, it is also possible to print by thinning out image data at a certain rate.
[0032]
As described above, the RAM 33-2 has the G. For example, data obtained by performing a thinning process on the image data developed in the print buffer described above, for example, as described above is stored in A36. The data stored in the RAM 33-2 is sent as it is to the recording heads 2-1 to 2-4 and becomes data for directly controlling the heat. In this embodiment, the RAM 33-2 is formed by 21 independent SRAMs.
[0033]
Further, the ejection circuit and ejection control of the inkjet recording head 2 will be described in detail with reference to FIG. In this embodiment, four heads are mounted as described above, but since the operation principle of each is the same, the Bk head 2-1 will be described.
[0034]
A data transfer circuit 37-1 in the head control block 37 performs address management in order to read out data corresponding to each head from the RAM 33-2, and sends out the read data as ejection data to the head. A data signal 37-8, a clock signal 37-9, and a latch signal 37-10 are transmitted. Each signal is connected to the Bk head 2-1.
[0035]
The data signal 37-13 selects which nozzle is to be ejected among the nozzles that are sequentially stored in the shift register 2-101 configured on the Bk head 2-1 in synchronization with the clock signal 37-15. Used for purposes. When the transmission of the data for the number of nozzles is completed, the latch signal 37-14 is transmitted, the data stored in the shift register 2-101 is moved to the register 2-102, and the data setting is completed.
[0036]
When the data setting is completed, three block selection signals 37-11 and a heat signal 37-12 are sent from the heat timing controller 37-2 in accordance with the position of the carriage 3. In this embodiment, nozzles of the same heat block are arranged every 20 nozzles. The block selected by the five block selection signals 37-16 activates the input of the AND circuit 2-104 of the corresponding block by the decoder 2-103 configured on the Bk head 2-1.
[0037]
When the heat signal 37-12 is input to the nozzles for which the data set and the block are selected according to the above procedure, the output conditions of the AND circuit 2-104 are met and the drive connected to the heater resistor 2-106 of each nozzle. The transistor 2-105 operates and a heat current flows. The heat signal 37-12 is used for the purpose of controlling the actual heat time for temperature control and the like.
[0038]
In the head control block 37, the above-described data set and the heating operation are processed in parallel. In other words, the parallel processing is realized by performing the heat data set of the next cycle during the heat of a certain cycle.
[0039]
By a series of the operations described above, a series of recording operations are realized by ejecting ink droplets to a desired position.
[0040]
FIG. 4A is a diagram illustrating the nozzle configuration of the recording head.
[0041]
The recording head of this embodiment has 640 nozzles arranged on a straight line at a pitch of 600 dpi. The recording head is mounted on a carrier and ejects ink droplets while moving in a direction perpendicular to the recording medium conveyance direction. At that time, instead of discharging ink droplets simultaneously from all nozzles in consideration of distributed supply of electric power for supplying energy necessary for ink supply and discharge, 640 nozzles are divided into 32 heat blocks and discharged in order. Perform the action.
[0042]
FIG. 4B shows the positional relationship of the recording head with respect to the recording medium. The recording head is mounted inclined as shown in the figure with respect to the moving direction of the carrier.
[0043]
This is because the printing results are linear from the relationship between the scanning speed of the carrier, the nozzle pitch, and the ejection timing so that when ink is ejected while scanning the carrier from the nozzles arranged on a straight line, the landing is linear. Set in a relationship.
[0044]
If this relationship breaks down, it causes printing defects such as ruled line shifts, which are mentioned as problems.
[0045]
The recording head is generally moved at a constant cycle determined by the time required for ink supply to each nozzle and the heat time required for ejection, and all the nozzles are driven in one cycle. Recording operation is continuously performed by repeating this cycle. FIG. 4-3 is a drawing showing the landing positions of ink droplets in one-cycle recording operation. The recording head performs recording over 20 columns in one cycle. Since the above recording operation is performed by 640 nozzles, recording is performed by 32 nozzles per column.
[0046]
As described above, the ink ejected by the nozzles arranged in a straight line on the head mounted at an angle with respect to the recording medium conveyance direction is landed sequentially to obtain a print result without inclination.
[0047]
FIG. 4-4 is a diagram for explaining the printing of one column and 32 dots. The recording head of this embodiment has 20 groups shown in FIG. 4-4, and each of them is continuously arranged to constitute 640 nozzles.
[0048]
Since the column has a 1200 dpi pitch and a discharge frequency of 10 kHz, 32 heat blocks are discharged in a period of 100 μs per cycle. At this time, the moving speed of the carrier is 8.33 inches / sec. The heat block 1 is sequentially driven from the heat block 1 to the heat block 32 as shown in the time chart.
[0049]
As a result, the sequentially ejected ink droplets land without tilting for each column as shown in FIG.
[0050]
Next, an electrical correction method for the head tilt, which is the object of this embodiment, will be described in more detail.
[0051]
FIG. 1 is an image diagram showing the configuration of the print buffer configured in the RAM 33-2 described above in comparison with the actual print result position. In the figure, the values 00h to 13h written at the left end and 00h to 14h written at the upper end represent the memory address of the print buffer. Each square represents a memory access unit, which is 32 bits in this embodiment.
[0052]
The relationship between each area and the address is expressed as 1400h at the top leftmost area and 0013h at the bottom rightmost area.
[0053]
Since 20 in the vertical direction and 21 in the horizontal direction are arranged, it indicates that 640 dot data is stored over 21 columns. For the sake of explanation, the drawing shows an area for one color. However, as described above, in order to perform the same control for the recording head of each color, the same area is actually assigned to each color, that is, four. A surface storage area is provided.
[0054]
Hatched 1- 1 applied from 0100h to 1413h in the figure shows the normal position of the inclination of the print head in this embodiment to correspond to the memory areas. The recording head discharges data for 20 columns in one cycle from the inclination.
[0055]
Therefore, the head control block 37 manages the print buffer address on the RAM 33-2, and the memory of the portion colored gray such as 01000h, 02011,0302h, 0403h,. Transfer content. These data are driven according to the procedure described above, and the printing result of FIG. 4-3 is obtained.
[0056]
The area from the rightmost memory area 0000h to the first column 0013h is an area prepared for data writing.
[0057]
As described above, while data is being read across 20 areas for data transfer to the head, data is written to this area. Data is read sequentially from the region where the oblique line 1-a moves in parallel and contacts each cycle.
[0058]
Taking the 32-bit data at the top as an example, data is read from 0000h in the next cycle when 0100h is accessed in FIG. In the next cycle, data is read from 1400h.
[0059]
In this way, the memory area is used in a ring shape with the writing area across the entire area.
[0060]
The hatched line 1-2 shown in FIG. 1 also shows an example when the head is attached with an offset from the normal position. Here, when the upper end is used as a reference, the lower end is shifted by 4 columns.
[0061]
The correction value is set by the user from the operation panel 51 based on the result of the test printing, and the CPU 31 sets the set correction value in the head control block 37 to change the read address management content.
[0062]
In this case, the address management is changed so that data to be transferred to the head is performed from the area in contact with the hatched line 1-2 .
[0063]
As a result, 0100h, 0201h, 0302h, etc. are equivalent to the regular addresses, but next, 0303h data is read. In the figure below, the contents colored in light gray are read out and transferred to the head.
[0064]
(Example 2)
In Example 1, the plurality of nozzles in the recording head are arranged on a straight line. Therefore, in order to absorb the deviation due to the operation speed when a plurality of nozzles are driven sequentially, it is necessary to mount the recording head itself with a mechanical tilt. As a result, when the inclination correction method according to the present invention is to be carried out, there is a drawback in that it is necessary to prepare a column corresponding to the head inclination even in a normal state in the print buffer configured in the RAM 33-2.
[0065]
The second embodiment differs from the first embodiment in that the arrangement of the ejection openings of the recording head is configured according to the scanning speed.
[0066]
FIG. 7 is a diagram illustrating the ejection port array of the recording head in the second embodiment.
[0067]
As is apparent from the drawing, the discharge ports are divided into 20 groups, and are arranged obliquely according to the scanning speed.
[0068]
Therefore, the recording head itself does not need to be offset in the recording medium conveyance direction and is configured vertically.
[0069]
FIG. 8 shows a print buffer according to the second embodiment. Each area similar to the first embodiment is 32 bits.
[0070]
Data from 0100h to 0113h is read out and transferred to a properly set print head. The hatched line 8-1 represents the head tilt for four columns. As in the first embodiment, the correction method is performed by reading data from an area with a long path through the oblique line.
[0071]
A hatched line 8-2 shows the case where the inclination of the recording head is in the opposite direction. In this case as well, correction can be performed by reading out data in an area with a long path in contact with the oblique line.
[0072]
(Effects specific to Example 2)
In this way, if a region necessary for correction is prepared in addition to the normal position print buffer, both positive angle deviation and negative angle deviation from the normal position can be corrected.
[0073]
【The invention's effect】
FIG. 5 shows the recording result when the above correction is made for the head mounting inclination deviation and the recording result when it is not performed, focusing on one column.
[0074]
Here, FIG. 5 illustrates a case where a deviation of 4 columns occurs at the lower end as described in FIG.
[0075]
FIG. 5A shows the case where the correction is not performed, and the tilt deviation of the head is reflected in the recording result as it is, and the deviation of four columns is generated in the horizontal direction with the width of 640 nozzles in the vertical direction. In this embodiment, since one column has a 1200 dpi pitch, the deviation is about 80.7 μm. On the other hand, FIG. 5-2 shows a recording result when correction is performed.
[0076]
The recording head is physically tilted. Naturally, some influence appears in the printing result. However, the deviation is distributed in four places. As a result, the absolute deviation in each part is 20.16 μm.
[0077]
As described above, in the present embodiment, it is possible to electrically correct the head tilt generated mechanically, and to suppress the absolute deviation of the landing position of the ink droplet in the recording result. As a result, the deviation is suppressed to a level at which there is no visual problem, and a good recording result can be obtained.
[0078]
Therefore, it is possible to provide an image recording apparatus that can perform a recording operation with high definition and high speed at low cost without providing a large tilt correction mechanism.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram comparing the configuration of a print buffer with a print buffer and a memory area.
FIG. 2 is an electrical configuration block diagram of the present embodiment.
FIG. 3 is an overall configuration diagram of a recording apparatus according to the present embodiment.
FIG. 4 is a diagram illustrating a relationship between a recording head and a recording medium and a recording result of one cycle.
FIG. 5 is a diagram showing the effect of this embodiment.
FIG. 6 is a diagram showing ruled line deviation in a conventional example.
7 is a print head nozzle arrangement of Example 2. FIG.
FIG. 8 is a print buffer according to the second embodiment.

Claims (3)

In an inkjet recording apparatus that uses a recording head having a plurality of ejection openings and divides the plurality of ejection openings into a plurality of groups in the arrangement direction of the ejection openings, and performs recording by ejecting ink from the recording head to a recording medium ,
A first memory for holding data corresponding to the ejection port of the recording head;
An area for a plurality of columns based on a predetermined inclination of the ejection port array with respect to the scanning direction of the recording head is provided to hold data that has been read out after being read from the first memory. A second memory in which an area for each column is prepared as a writing area for writing, and an area at each column position constituting the plurality of columns is divided so as to correspond to each group;
An input unit for inputting correction information for the predetermined inclination;
Selecting means for selecting a region corresponding to each group from a column range based on the inclination and the correction information for the second memory;
Synchronizing with the drive timing of the recording head, transfer means for reading the data in the area selected by the selection means and transferring it to the recording head;
Control means for performing control to change the column position of the column range and the column position of the writing area and control to use a plurality of columns of areas in a ring shape for each drive cycle of the recording head An ink jet recording apparatus.   The inkjet recording apparatus according to claim 1, wherein the ejection ports included in the group are sequentially driven within a drive cycle of the recording head.   The inkjet recording apparatus according to claim 1, wherein the second memory is an SRAM, and the control unit and the second memory are provided in a gate array.

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