JP2012131086A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make inconspicuous a deviation in a nozzle arrayed direction of drop reaching positions of two colors with simple configuration when carrying out two-color printing using two arrays of nozzles arranged zigzag.SOLUTION: In the case of two-color printing, ejection data of 2 bits are generated based on bit map data 1 (A-H) of colors output in the nozzle array I, and ejection data of 2 bits are generated based on bit map data 2 (a-h) of colors output in the nozzle array II. At this time, in the ejection data for the nozzle array I, 0, 1 or 2 is generated according to ejection data generating logic, referring to two adjacent pixel data for one nozzle, and in the ejection data for the nozzle array II, 0 or 2 is generated according to ejection data generating logic, referring to one pixel data for one nozzle.

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with a recording head for discharging droplets.

  As an image forming apparatus such as a printer, a facsimile, a copying machine, a plotter, or a complex machine of these, for example, a liquid discharge recording type image forming using a recording head composed of a liquid discharge head (droplet discharge head) that discharges ink droplets. As an apparatus, an ink jet recording apparatus or the like is known. This liquid discharge recording type image forming apparatus means that ink droplets are transported from a recording head (not limited to paper, including OHP, and can be attached to ink droplets and other liquids). Yes, it is also ejected onto a recording medium or a recording medium, recording paper, recording paper, etc.) to form an image (recording, printing, printing, and printing are also used synonymously). And a serial type image forming apparatus that forms an image by ejecting liquid droplets while the recording head moves in the main scanning direction, and a line type head that forms images by ejecting liquid droplets without moving the recording head There are line type image forming apparatuses using

  In the present application, the “image forming apparatus” of the liquid discharge recording method is an apparatus that forms an image by discharging liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or the like. In addition, “image formation” means not only giving an image having a meaning such as a character or a figure to a medium but also giving an image having no meaning such as a pattern to the medium (simply It also means that a droplet is landed on a medium). “Ink” is not limited to ink, but is used as a general term for all liquids capable of image formation, such as recording liquid, fixing processing liquid, and liquid. DNA samples, resists, pattern materials, resins and the like are also included. In addition, the “image” is not limited to a planar image, and includes an image given to a three-dimensionally formed image and an image formed by three-dimensionally modeling a solid itself.

  By the way, there are two nozzle rows in which a plurality of nozzles for ejecting liquid droplets are arranged, and a line in which the two nozzle rows are arranged in a fixed manner by a half pitch of the nozzle interval in the nozzle arrangement direction. When a two-color image is formed by ejecting droplets of different colors from each nozzle row in the type image forming apparatus, the landing positions of the droplets of each color are between two colors and are also referred to as the nozzle arrangement direction (hereinafter also referred to as “width direction”). )).

  Therefore, conventionally, there is known a technique that controls the deflection of the ejection direction of ink particles so that the ink particles ejected from a plurality of nozzles can land at or near the same pixel position of the recording medium (Patent Document). 1).

JP 2006-096054 A

  As described above, there is a problem that the configuration is complicated if the droplet discharge direction is controlled to be deflected.

  The present invention has been made in view of the above problems, and an object of the present invention is to make a shift in the nozzle arrangement direction of two-color droplet landing positions inconspicuous with a simple configuration.

In order to solve the above problems, an image forming apparatus according to the present invention provides:
A recording head having two nozzle rows in which a plurality of nozzles for ejecting liquid droplets are arranged, and the two nozzle rows are shifted by a half pitch of the nozzle interval in the nozzle arrangement direction;
Discharge control means for discharging droplets from the nozzles of the recording head, and
The recording head ejects droplets of different colors from two nozzle rows,
The discharge control means includes
For one nozzle row, generate data to eject droplets from pixel data corresponding to the position of each nozzle,
The other nozzle row is configured to have means for generating data for ejecting droplets from pixel data corresponding to the positions of two adjacent nozzles.

  According to the image forming apparatus of the present invention, data for ejecting droplets is generated from pixel data corresponding to the position of each nozzle for one nozzle row, and the positions of two adjacent nozzles for the other nozzle row. Since the data for ejecting droplets is generated from the pixel data corresponding to, the shift in the nozzle arrangement direction of the two-color droplet landing positions can be made inconspicuous.

1 is a side view of an image forming apparatus according to the present invention. It is a plane explanatory view of the device. FIG. 3 is an explanatory plan view illustrating an example of a recording head. It is sectional explanatory drawing which shows an example of a head. It is block explanatory drawing which shows an example of a control part. It is a block explanatory view showing an example of a head driver. It is explanatory drawing with which it uses for operation | movement description of a head driver. FIG. 6 is an explanatory diagram for explaining generation of ejection data for two-color printing. It is explanatory drawing with which it uses for description of the production | generation of the discharge data of monochrome printing. It is explanatory drawing with which it uses for description of the discharge droplet of 2 color printing.

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, an example of an image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is an explanatory side view of the image forming apparatus, and FIG. 2 is an explanatory plan view of the apparatus.
This image forming apparatus includes a line-type recording head 101, and a continuous recording sheet 112 supplied from a continuous recording sheet supply apparatus 111 is corrected in meandering via a meandering correction apparatus 113 and then conveyed in a sheet conveying direction Y. Then, the liquid is guided directly below the recording head 101, and a droplet corresponding to the image is ejected from the recording head 101 to record a predetermined image. Thereafter, the continuous recording paper 112 is wound around the winding device 115 via the speed control roller 114. An appropriate tension is applied to the continuous recording paper 112 by the continuous recording paper supply device 111 and the winding device 115, and the paper conveyance speed is determined by the rotational speed of the speed control roller 114.

  As shown in FIG. 3, the recording head 101 has seven liquid ejection heads 200 arranged in a staggered manner in the width direction (nozzle arrangement direction) of the paper 112. One head 200 has two nozzle rows 5A and 5B in which a plurality of nozzles 4 for discharging droplets are arranged.

Next, an example of a head constituting the recording head will be described with reference to FIG. FIG. 4 is an explanatory sectional view of the head.
The liquid discharge head 200 includes a flow path substrate (liquid chamber substrate) 1 formed of a SUS substrate, a vibration plate member 2 bonded to the lower surface of the flow path substrate 1, and a nozzle plate bonded to the upper surface of the flow path substrate 1. And a plurality of liquid chambers (pressure liquid chambers, pressure chambers) as individual channels through which the plurality of nozzles 4 that discharge droplets (liquid droplets) communicate with each other via the nozzle communication passages 5 , Also referred to as a pressurizing chamber, a flow path, etc.) 6. A fluid resistance portion 7 that also serves as a supply path for supplying ink to the liquid chamber 6 is formed, and a supply port (not shown) formed in the diaphragm member 2 is formed. Ink is supplied from the common liquid chamber 10 formed by the frame member 17.

  The flow path substrate 1 is configured by bonding a flow path plate 1A and a communication plate 1B. The flow path substrate 1 is formed by etching the SUS substrate using an acidic etchant or machining such as punching (pressing) to open openings such as the communication path 5, the pressurized liquid chamber 6, and the fluid resistance portion 7. Each is formed.

  The vibration plate member 2 has a first layer 2A that forms each vibration region (diaphragm portion) 2a that forms a wall surface corresponding to each liquid chamber 6, and a second layer 2B that is a support plate, and the surface of the vibration region 2a. The upper end face (joint face) of the piezoelectric element 12 as a drive means (actuator means, pressure generating means) that deforms the vibration region 2a is joined to the outside (on the side opposite to the liquid chamber 6) via the elastic material 11. . The lower end surface of the piezoelectric element 12 is bonded to the base member 13.

  The piezoelectric element 12 is connected to an FPC 15 as a flexible wiring member for giving a drive signal.

  The nozzle plate 3 is formed from a nickel (Ni) metal plate, and is manufactured by an electroforming method (electroforming). In this nozzle plate 3, nozzles 4 having a diameter of 10 to 35 μm are formed corresponding to the respective liquid chambers 6 and bonded to the flow path plate 1 with an adhesive. A water repellent layer is provided on the droplet discharge side surface (surface in the discharge direction: discharge surface or surface opposite to the liquid chamber 6 side) of the nozzle plate 3.

  Further, on the surface opposite to the liquid chamber 6 of the vibration plate member 2 (the surface on the second layer 2B side which is the support plate), the outer peripheral side of the actuator unit composed of the piezoelectric element 12, the base member 13, the FPC 15, and the like. The frame member 17 is joined to the frame. The frame member 17 is formed with the common liquid chamber 10 described above, and further, a supply port (not shown) for supplying the recording liquid from the outside to the common liquid chamber 10 is formed. It is connected to an ink supply source such as an ink cartridge.

  In the liquid discharge head configured as described above, by selectively applying a drive pulse voltage to the piezoelectric element 12 according to the image to be recorded, the piezoelectric element 12 to which the pulse voltage is applied is displaced, and the diaphragm member 2 The vibration region 2 a is deformed in the direction of the nozzle plate 3, and the liquid in the liquid chamber 6 is pressurized by a change in volume (volume) of the liquid chamber 6, whereby droplets are ejected from the nozzles 4 of the nozzle plate 3. As the liquid droplets are discharged, the pressure in the liquid chamber 6 decreases, and a slight negative pressure is generated in the liquid chamber 6 due to the inertia of the liquid flow at this time. Under this state, by turning off the application of voltage to the drive piezoelectric column 12A, the vibration region 2a of the diaphragm member 2 returns to the original position, and the liquid chamber 6 becomes the original shape. Negative pressure is generated. At this time, ink is filled from the common liquid chamber 10 into the liquid chamber 6, and droplets are ejected from the nozzles 4 in response to the next drive pulse application.

  Here, the head 200 includes, for example, 384 × 2 nozzles 4. The pitch (nozzle density) of the nozzle centers is 300 nozzles / inch and is equally spaced. The nozzle center positions of the two nozzle rows 5A and 5B are formed to be shifted by 1/600 inch in the nozzle row direction.

  Therefore, when printing output of one color is performed using the two nozzle rows 5A and 5B, the recording density in the nozzle row direction is 600 dpi, and print outputs of different colors are performed in the nozzle row 5A and the nozzle row 5B. The recording density in the nozzle array direction is 300 dpi per color. Since the recording head 101 includes the seven heads 200 having 384 × 2 nozzles, the number of nozzles is 5376, and recording on a sheet having A4 size short sides in the width direction is possible.

Next, the control unit of this image forming apparatus will be described with reference to the block diagram of FIG.
The control unit includes a buffer memory 301 that receives print data from the outside, a data processing unit 302 that includes a microcomputer that includes a CPU that controls the entire apparatus, and a discharge that stores discharge data generated from the print data. A data memory 303, a conveyance control unit 304 that controls the paper conveyance system 110, a drive signal generation unit 305 that generates and outputs a drive waveform (drive signal) for driving each head 200 of the recording head 101, and each head 200 is driven. A discharge signal generation unit 306 that outputs a discharge signal to be output is provided.

  The paper transport system 110 transports the paper 112 at a constant speed. In addition, a paper position signal indicating the movement distance of the paper 112 is generated.

  In this image forming apparatus, print data is transferred as bitmap data page by page from a host side (personal computer or the like) (not shown) and temporarily stored in the buffer memory 301. Here, the bitmap data is 1-bit data in which “1” is on and “0” is off.

  The data processing unit 302 sequentially converts the bitmap data temporarily stored in the buffer memory 301 into the discharge data according to the discharge specifications during or after the storage of the bitmap data in the buffer memory 301, and the discharge data memory 303. To store.

  When the storage in the ejection data memory 303 is completed, the transport control unit 304 outputs an operation instruction to the paper transport system 110 to instruct the start of paper transport and starts receiving a paper position signal from the paper transport system 101.

  When the paper 112 reaches a required recording position, the paper control unit 304 generates a paper position synchronization signal that matches the resolution, and outputs this to the ejection data memory 303, the drive signal generation unit 305, and the ejection signal generation unit 306. .

  Here, assuming that the resolution of the apparatus is 300 dpi, every time the paper 112 advances 1/300 inch, a paper position synchronization signal is generated once. The generation interval of the paper position synchronization signal corresponds to the time for recording one line.

  The drive signal generator 305 generates a drive waveform including two types of drive signals for large droplets and medium droplets, and supplies all seven head drivers 201.

  The ejection signal generation unit 306 transfers a clock signal to the ejection data memory 303 and the head driver 201, and transfers ejection data read from the ejection data memory 303 to each head driver 201 as an ejection signal at a predetermined timing.

Next, an example of the head driver will be described with reference to a block diagram of FIG.
Next, the head driver 202 will be described as a piezoelectric element driver.
The piezoelectric element driver includes a shift register 401 that registers the ejection signal (serial data) L from the ejection signal generation unit 306 according to the shift clock from the ejection signal generation unit 306, and the resist value of the shift register 401 from the ejection signal generation unit 306. Similarly, the latch circuit 402 that latches by the latch signal, the shift register 403 that registers the ejection signal (serial data) H from the ejection signal generation unit 306 according to the shift clock from the ejection signal generation unit 306, and the registration of the shift register 403 And a latch circuit 404 that latches the value by a latch signal from the ejection signal generation unit 306.

  In addition, the large droplet drive signal and the medium droplet drive signal from the drive signal generation unit 305 are input to the input terminals, respectively, the latch data from the latch circuits 402 and 404 are input to the selection terminals, and one of the drive signals is input. An analog switch 6 is provided which performs an operation of passing through and not passing any drive signal.

  The drive signal is, for example, a trapezoidal pulse having a peak value of 24V. Further, in the present embodiment, the number of analog switches 406 is 768 × 2 when the number of analog switches 406 includes 768 nozzles 4 in one nozzle row. The ejection signals H and L are both 768-bit serial data corresponding to 768 nozzles.

  When “0” is applied to the analog switch 406 and the selection terminal, the output terminal is opened. When “1” is applied, the drive signal is output to the output terminal, and the ejection signals H and L are When “0, 0”, the output terminal is opened, and when the discharge signals H and L are “0, 1”, the medium droplet drive signal is output to the output terminal, and the discharge signal HL is “1, 0”. Sometimes, a large droplet drive signal is output to the output terminal. The output terminal of the analog switch 406 is connected to one signal input terminal of the corresponding nozzle (piezoelectric element 12), and the other signal input terminal is grounded.

Here, the relationship between the ejection data, the ejection signals H and L, and the ejection state is as follows.
Discharge data 0 1 2 3
Discharge signal H 0 0 1 1
Discharge signal L 0 1 0 1
Discharge status Non-discharge Medium drop Large drop Not used

Next, the basic operation of the head driver 201 will be described with reference to the timing chart of FIG.
As shown in the figure, when a paper position synchronization signal is generated, a latch clock is generated. With this latch clock, the ejection signals stored in the shift registers 401 and 403 in the previous cycle are collectively stored in the latch circuits 402 and 404 and output to the selection terminal of the corresponding analog switch 406. At the same time, a drive signal is input to the input terminal of the analog switch 406.

  As a result, droplets are not ejected from the nozzle 4 whose ejection signals H and L are “0, 0”. Medium-sized droplets (medium droplets) are ejected from the nozzles 4 with the ejection signals H and L being “0, 1”, and large-sized from the nozzles 4 with the ejection signals being “1, 0”. Droplets (large droplets) are ejected.

  Next, the digital ejection signals are sequentially stored in the shift register in synchronization with the shift clock, and when 768 are arranged, one cycle is completed, and the next paper position synchronization signal is awaited. That is, the content of the discharge signal in the figure represents the discharge state in the next cycle.

Next, generation of ejection data will be described with reference to FIGS.
First, in the case of two-color printing, as shown in FIG. 8A, the bitmap data D1 (A to H in the figure) of the color output by the nozzle row 5A (this is referred to as “nozzle row I”). Based on the above, 2-bit ejection data is generated. In addition, 2-bit ejection data is generated based on the color bitmap data D2 (blue in the drawing) output from the nozzle row 5B (this is referred to as “nozzle row II”).

  Here, the discharge data for the nozzle row I refers to two pixel data adjacent to one nozzle, and generates 0, 1, or 2 according to the discharge data generation logic shown in FIG. 8B. . Further, the discharge data for the nozzle array II refers to one pixel data for one nozzle, and generates 0 or 2 according to the discharge data generation logic shown in FIG.

  The generated ejection data is ejected as a serial data string in the order of II-1, I-1, II-2, I-2,... (Numbers 1, 2,... Are circled numbers). Store in the data memory 303.

  Thus, when performing two-color printing, the nozzle row I and the nozzle row II are displaced by 1/600 inch in the nozzle hole center position in the nozzle row direction, but the discharge data for the nozzle row I is It is created by referring to two adjacent pixel data for one nozzle, and a droplet is ejected according to this, and the ejection data for nozzle row II is one pixel for one nozzle. Since it is created by referring to the data and a droplet is ejected in accordance with this, a pixel can be generated at a position that should be essentially matched.

  For example, as shown in FIG. 10, when the bitmap data (Data) is “00100”, one large droplet is ejected from the nozzle row I at a position corresponding to Data = “1”. Land. On the other hand, the droplets ejected from the nozzle row II have two medium droplet dots landed at positions corresponding to between “01” and “10” with respect to Data = “1”. The center of gravity of the combined droplets is the same position as one large droplet from nozzle row I.

  In the case of monochromatic printing, as shown in FIG. 9, the discharge data to be output by the nozzle arrays I and II is created with reference to one pixel data for one nozzle, and the liquid is generated accordingly. Discharge drops.

  As described above, for one nozzle row, data for ejecting droplets is generated from pixel data corresponding to the position of each nozzle, and for the other nozzle row, liquid is obtained from pixel data corresponding to the positions of two adjacent nozzles. Since the data for generating the droplets is generated, it is possible to make the shift in the nozzle arrangement direction of the two-color droplet landing positions inconspicuous.

  The above-described discharge data generation processing according to the present invention is executed by a computer using a program stored in the ROM constituting the data processing unit 302. This program can be downloaded to the information processing apparatus and installed in the image forming apparatus. Further, the above processing may be performed by a printer driver on the information processing apparatus (host 600) side. Furthermore, the image forming apparatus according to the present invention and an information processing apparatus or an image forming apparatus and an information processing apparatus having a program for performing processing according to the present invention can be combined to form an image forming system.

4 nozzles 5A, 5B nozzle array 101 recording head 200 head 302 data processing unit

Claims (1)

A recording head having two nozzle rows in which a plurality of nozzles for ejecting liquid droplets are arranged, and the two nozzle rows are shifted by a half pitch of the nozzle interval in the nozzle arrangement direction;
Discharge control means for discharging droplets from the nozzles of the recording head, and
The recording head ejects droplets of different colors from two nozzle rows,
The discharge control means includes
For one nozzle row, generate data to eject droplets from pixel data corresponding to the position of each nozzle,
An image forming apparatus comprising: means for generating data for discharging droplets from pixel data corresponding to positions of two adjacent nozzles for the other nozzle row.

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