JP2019155874A - Liquid discharge device and program - Google Patents

Abstract

To transmit pixel data with increased bit numbers to a driving circuit of liquid discharge means without reducing speed at which an image is formed.SOLUTION: A liquid discharge device according to one embodiment of a disclosed technique has liquid discharge means for discharging liquid and driving means for driving the liquid discharge means on the basis of a driving waveform signal, and discharges the liquid to a recording medium, which has control means for transmitting pixel data having predetermined bit numbers, included in the recording data, to the driving means. The control means transmits pixel data having bit numbers increased more than the predetermined bit numbers, in a non-adhesion area other than an area to which the liquid is made to adhere in the recording medium.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a device for discharging a liquid and a program.

  An apparatus for ejecting liquid, such as a liquid ejection printer, ejects liquid from a liquid ejecting unit based on image data or the like, and forms an image or the like on a recording medium.

  In such a device for ejecting liquid, a technique for forming a multi-tone image by adjusting the density of pixels by changing the number of droplets of ejected liquid in units of pixels based on pixel data is known. .

  Also, it accepts input of pixel data in a multi-value format or binary format, and when the pixel data is in a binary format, converts it into pixel data having a designated multi-value format to form a multi-gradation image. A technique is disclosed (for example, see Patent Document 1).

  However, in the technique of Patent Document 1, it takes time to transmit pixel data in which the binary format is converted to the multi-value format and the number of bits is increased to the drive circuit of the liquid ejection unit, and the speed at which an image is formed May be reduced.

  The present invention has been made in view of the above points, and it is an object of the present invention to transmit pixel data with an increased number of bits to a drive circuit of a liquid ejecting unit without reducing the speed of forming an image. And

  An apparatus for ejecting a liquid according to an aspect of the disclosed technology includes a liquid ejecting unit that ejects a liquid, and a driving unit that drives the liquid ejecting unit based on a drive waveform signal. An apparatus for ejecting the liquid onto a recording medium, comprising: control means for transmitting pixel data included in the recording data and having a predetermined number of bits to the driving means, wherein the control means includes the recording medium The pixel data in which the number of bits is increased from the predetermined number of bits is transmitted in a non-attachment region other than the region to which the liquid is attached.

  According to the embodiment of the present invention, it is possible to transmit pixel data with an increased number of bits to the drive circuit of the liquid ejecting unit without reducing the image forming speed.

It is a figure which shows an example of a structure of the apparatus which discharges the liquid of 1st Embodiment. FIG. 2 is a block diagram illustrating an example of a hardware configuration related to control of a device that ejects liquid according to the first embodiment. It is a block diagram which shows an example of the function structure regarding control of the apparatus which discharges the liquid of 1st Embodiment. It is a figure explaining an image area and a non-image area. 6 is a flowchart illustrating an example of a control process of the apparatus for ejecting liquid according to the first embodiment. It is a figure explaining an example of the drive waveform signal in the apparatus which discharges the liquid of 1st Embodiment. It is a figure explaining the detection method of the change of the bit number in the apparatus which discharges the liquid of 1st Embodiment. It is a figure explaining the notification method of the change of the bit number in the apparatus which discharges the liquid of 1st Embodiment. It is a figure explaining the response | compatibility method at the time of the error generation in the apparatus which discharges the liquid of 1st Embodiment. It is a figure explaining the utilization method of the signal which shows the increase in the number of bits in the apparatus which discharges the liquid of 1st Embodiment. It is a figure which shows an example of a structure of the liquid discharge unit in the apparatus which discharges the liquid of 2nd Embodiment. It is a block diagram which shows an example of the function structure regarding control of the apparatus which discharges the liquid of 2nd Embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

  The terms “image formation”, “recording”, “printing”, “printing”, “printing”, “modeling” and the like in the terms of the embodiments are all synonymous.

  In the embodiment, the “device for ejecting liquid” is a device that includes a liquid ejection head or a liquid ejection unit and that drives the liquid ejection head to eject liquid. The apparatus for ejecting liquid includes not only an apparatus capable of ejecting liquid to an object to which liquid can adhere, but also an apparatus for ejecting liquid toward the air or liquid.

  This “apparatus for discharging liquid” may include means for feeding, transporting, and discharging a liquid to which liquid can adhere, as well as a pre-processing apparatus and a post-processing apparatus.

  For example, as “an apparatus for ejecting liquid”, an image forming apparatus which is an apparatus for ejecting a liquid such as ink to form an image on a sheet, and a powder to form a three-dimensional structure (three-dimensional structure) There is a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that discharges a modeling liquid onto a layered powder layer.

  Further, the “apparatus for ejecting liquid” is not limited to an apparatus in which significant images such as characters and figures are visualized by the ejected liquid. For example, what forms a pattern etc. which does not have a meaning in itself, and what forms a three-dimensional image are also included.

  The above-mentioned “applicable liquid” means that the liquid can be attached at least temporarily and adheres and adheres, or adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic parts such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, and test cells. Yes, unless specifically limited, includes everything that the liquid adheres to.

  The material of the above-mentioned “material to which liquid can adhere” is not limited as long as liquid such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics can be adhered even temporarily.

  The “liquid” is not particularly limited as long as it has a viscosity and surface tension that can be ejected from the head, and the viscosity is 30 mPa · s or less at room temperature, normal pressure, or by heating and cooling. Preferably there is. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, functional materials such as polymerizable compounds, resins, and surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , Edible materials such as natural pigments, solutions, suspensions, emulsions, and the like. These include, for example, inkjet inks, surface treatment liquids, components of electronic devices and light emitting devices, and formation of electronic circuit resist patterns. It can be used in applications such as liquids for use, three-dimensional modeling material liquids, and the like.

  In addition, the “device for ejecting liquid” includes a device in which the liquid ejection head and the device to which the liquid can adhere move relatively, but is not limited thereto. Specific examples include a serial type apparatus that moves the liquid discharge head, a line type apparatus that does not move the liquid discharge head, and the like.

  In addition to the “device for discharging liquid”, a processing liquid coating apparatus for discharging a processing liquid onto a sheet for applying a processing liquid to the surface of the sheet for the purpose of modifying the surface of the sheet, or a raw material There is an injection granulating apparatus or the like that granulates fine particles of a raw material by spraying a composition liquid in which a solution is dispersed in a solution through a nozzle.

  A “liquid ejection unit” is a unit in which functional parts and mechanisms are integrated with a liquid ejection head, and is an assembly of parts related to liquid ejection. For example, the “liquid discharge unit” includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

  Here, the term “integrated” refers to, for example, a liquid discharge head, a functional component, and a mechanism that are fixed to each other by fastening, adhesion, engagement, etc., and one that is held movably with respect to the other. Including. Further, the liquid discharge head, the functional component, and the mechanism may be configured to be detachable from each other.

  For example, there is a liquid discharge unit in which a liquid discharge head and a head tank are integrated. Also, there are some in which the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter may be added between the head tank and the liquid discharge head of these liquid discharge units.

  In addition, there is a liquid discharge unit in which a liquid discharge head and a carriage are integrated.

  In addition, there is a liquid discharge unit in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably on a guide member that constitutes a part of the scanning movement mechanism. In some cases, a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

  Also, there is a liquid discharge unit in which a cap member that is a part of the maintenance / recovery mechanism is fixed to a carriage to which the liquid discharge head is attached, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. .

  In addition, there is a liquid discharge unit in which a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. The liquid from the liquid storage source is supplied to the liquid discharge head via this tube.

  The main scanning movement mechanism includes a guide member alone. The supply mechanism includes a single tube and a single loading unit.

  A “liquid ejection head” is a functional component that ejects and ejects liquid from a nozzle.

  As energy generation sources for discharging liquid, piezoelectric actuators (laminated piezoelectric elements and thin film piezoelectric elements), thermal actuators using electrothermal transducers such as heating resistors, electrostatic actuators consisting of a diaphragm and counter electrode are used. To be included.

[First embodiment]
In the present embodiment, a case where “a liquid can be attached” is a sheet will be described as an example. An example in which the liquid ejecting apparatus is an image forming apparatus, the recording data is image data, and the ejected liquid is a recording liquid such as water-based or oil-based ink will be described as an example. Hereinafter, the paper is referred to as a recording medium, and the recording liquid is referred to as a liquid.

<Configuration of image forming apparatus>
First, an example of the configuration of the image forming apparatus 100 of the present embodiment will be described with reference to FIG. FIG. 1 shows an example of the configuration of the image forming apparatus 100. A direction A indicated by a solid arrow indicates a main scanning direction, and a direction B indicates a sub-scanning direction. The main scanning direction is an example of a “direction intersecting the recording medium conveyance direction”, and the sub-scanning direction is an example of a “recording medium conveyance direction”.

  As shown in FIG. 1, the image forming apparatus 100 includes a liquid discharge head 1, a carriage unit 2, a main scanning motor 3, a gear 4, a pressure roller 5, and a timing belt 6. ing. The image forming apparatus 100 is a so-called serial type image forming apparatus in which the liquid discharge head 1 is scanned by the carriage unit 2. The image forming apparatus 100 is an example of “an apparatus that ejects liquid”.

  The liquid discharge head 1 includes a black liquid discharge head 1 k, a cyan liquid discharge head 1 c, a magenta liquid discharge head 1 m, and a yellow liquid discharge head 1 y, and is fixed to the carriage unit 2. Each liquid discharge head 1k-1y discharges the liquid of each color. The liquid discharge head 1 is an example of a “liquid discharge unit”.

  The main scanning motor 3 transmits the driving force accompanying the rotation to the carriage unit 2 via the gear 4, the pressure roller 5, and the timing belt 6. The carriage unit 2 reciprocates along the guide rod 7 in a direction A indicated by a white arrow in FIG. The liquid ejection head 1 can change the position in the main scanning direction by the reciprocating movement of the carriage unit 2 in the main scanning direction.

  The encoder sheet 9 has a linear scale indicating the position in the main scanning direction. The encoder sensor 8 provided in the carriage unit 2 reads the linear scale of the encoder sheet 9 and detects the position in the main scanning direction when the carriage unit 2 moves in the main scanning direction. The position of the liquid ejection head 1 in the main scanning direction is detected by the output of the encoder sensor 8.

  On the other hand, the recording medium 10 is transported in the sub-scanning direction along a predetermined transport path from the paper feeding unit of the image forming apparatus 100 and reaches the position of the platen 11.

  The liquid discharge head 1 discharges liquid at a predetermined timing toward the recording medium 10 that moves in the sub-scanning direction on the platen 11 while moving to a predetermined position in the main scanning direction. By repeating the movement of the liquid ejection head 1 in the main scanning direction, the movement of the recording medium 10 in the sub-scanning direction, and the accompanying ejection by the liquid ejection head 1, a color image is formed on the recording medium 10. The

  Next, an example of a hardware configuration related to the control of the image forming apparatus 100 of the present embodiment will be described with reference to the block diagram of FIG. As shown in FIG. 2, the image forming apparatus 100 includes a controller 200, a head control board 214, and a head drive circuit 1a. The head control board 214 is an example of a “control unit”, and the head drive circuit 1a is an example of a “drive unit”.

  The controller 200 controls processing and operation of the image forming apparatus. The controller 200 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, an NVRAM (Non-Volatile Random Access Memory) 204, and an ASIC (Application Specific Integrated Circuit). 205, a connection I / F (Interface) 206, and a sensor I / F 207.

  The CPU 201 controls the overall processing and operation of the image forming apparatus 100. The CPU 201 uses the RAM 203 as a work area (working area) and executes a program stored in the ROM 202, the NVRAM 204, or the like, thereby controlling the operation of the entire image forming apparatus 100 and realizing various functions described later. The CPU 201, the ROM 202, and the RAM 203 constitute a main control unit 200A that executes processing according to the program.

  The NVRAM 204 retains data even when the image forming apparatus 100 is powered off. The ASIC 205 processes input / output signals for controlling the image forming apparatus 100 as a whole, as well as image processing for performing various signal processing on image data.

  The connection I / F 206 is connected to an external device 230 such as a computer and transmits / receives data and signals to / from the computer. The data sent from the computer includes image data for image formation. The connection I / F 206 may not be directly connected to an external computer, but may be connected to a network such as the Internet or an intranet.

  The sensor I / F receives the output signal of the encoder sensor 8.

  An operation panel 209 for inputting and displaying information necessary for the image forming apparatus 100 is connected to the controller 200. The controller 200 also includes a motor driving unit 210 that operates according to instructions from the CPU 201 or the ASIC 205, and a maintenance driving unit 211.

  The motor driving unit 210 outputs a driving signal and drives the main scanning motor 3 that moves the carriage unit 2 of the image forming apparatus 100 in the main scanning direction. The motor driving unit 210 drives a sub-scanning direction motor 212 that conveys the recording medium 10 and moves it in the sub-scanning direction.

  The maintenance drive unit 211 outputs a drive signal and drives the maintenance mechanism 213.

  The above units are electrically connected to each other by an address bus, a data bus, or the like. Further, part or all of the processing performed by the CPU 201 may be realized by an electronic circuit such as an FPGA (Field-Programmable Gate Array) or an ASIC.

  On the other hand, the controller 200 is electrically connected to the head control board 214 via the connection I / F 206. The head control board 214a is a rigid board on which an electric circuit, an electronic circuit, and the like are mounted. The head control board 214a controls the ejection of the liquid by the liquid ejection head 1 by generating or acquiring and outputting an image data signal, a driving voltage, and the like for driving the piezoelectric element included in the liquid ejection head 1.

  The head control board 214 includes an I / F 215, a D / A (Digital / Analog) converter 216, an ASIC 217, and a memory 218.

  The I / F 215 is connected to the controller 200 and receives data and signals from the controller 200. The I / F 215 is connected to an external computer or the like, and receives data and signals from the computer or the like. The data sent from the computer includes drive waveform data for discharging the liquid discharge head 1.

  The D / A converter 216 is an electric circuit that D / A converts drive waveform data. The ASIC 217 performs various signal processing and the like on the data and signals received from the controller 200, and processes input / output signals for controlling the ejection of liquid. The memory 218 inputs drive waveform data from a computer or the like and stores it.

  The above units are electrically connected to each other by an address bus, a data bus, or the like. A part or all of the processing performed by the ASIC 217 may be realized by a CPU or FPGA.

  On the other hand, the head control board 214 is electrically connected to the head drive circuit 1a via the connection I / F 215. The head drive circuit 1 a is provided in the liquid ejection head 1. The head drive circuit 1 a drives the liquid discharge head 1 by outputting a drive voltage to a piezoelectric element included in the liquid discharge head 1.

  The head drive circuit 1 a includes an I / F 219, an ASIC 220, and a piezoelectric element drive unit 221. The I / F 219 is connected to the head control board 214 and receives data and signals from the head control board 214.

  The ASIC 220 performs various signal processing and the like on data and signals received from the head control board 214, and processes input / output signals for driving the liquid ejection head 1. The piezoelectric element driving unit 221 is connected to the piezoelectric element 222 and outputs a driving voltage for discharging liquid to the piezoelectric element 222.

  The piezoelectric element 222 contracts and expands according to the drive waveform signal input from the piezoelectric element driving unit 221. The piezoelectric element 222 includes a plurality of piezoelectric elements, and each piezoelectric element is provided in each individual liquid chamber of the liquid discharge head 1. Due to the contraction and expansion of the piezoelectric element 222, the pressure of each individual liquid chamber is changed, and the liquid is discharged from the nozzle provided in each individual liquid chamber.

  The above units are electrically connected to each other by an address bus, a data bus, or the like. A part or all of the processing performed by the ASIC 220 may be realized by a CPU or FPGA.

  The controller 200, the head control board 214, and the head drive circuit 1a can realize a functional configuration described below by an instruction from the CPU and the hardware configuration shown in FIG.

  FIG. 3 shows an example of a functional configuration related to the control of the image forming apparatus 100 of the present embodiment.

  The controller 200 includes a pixel data generation unit 301, a bit increase signal generation unit 302, and an ejection timing signal generation unit 303. The head control board 214 includes a pixel data conversion unit 304, a serialization unit 305, and a drive waveform signal acquisition unit 306. The head drive circuit 1 a includes a deserialization unit 307, a bit number detection unit 308, a bit number notification unit 309, and a drive waveform signal generation unit 310, and is connected to the piezoelectric element 222.

  The pixel data generation unit 301 generates pixel data SD1 for forming each pixel of the image based on image data input from a computer or the like, and outputs the pixel data SD1 to the pixel data conversion unit 304. In the present embodiment, the density of each pixel of the image to be formed is expressed by the volume of the liquid ejection droplets by the liquid ejection head 1. Hereinafter, the liquid ejection droplets are simply referred to as droplets. Droplets are classified into large drops, medium drops, and small drops according to volume. A droplet is a small droplet. Large droplets are large droplets, for example, 3 droplets are combined and formed. The medium droplet is intermediate between the large droplet and the small droplet. For example, two droplets are combined and formed.

  The pixel data SD1 is 2-bit data indicating the volume of the liquid droplet by the liquid ejection head 1. Large droplets are represented by “11”, medium droplets by “10”, small droplets by “01”, and when no droplets are ejected, that is, no droplets by “00”.

  The bit increase signal generation unit 302 generates a signal ADD for increasing the number of bits of the pixel data SD1. “Increasing the number of bits” means, for example, adding 1 bit to the above-described 2-bit pixel data to make 3-bit pixel data. The “signal for increasing the number of bits” is a signal indicating “ON” when increasing the number of bits and indicating “OFF” when not increasing the number of bits. Such a signal is generated for each pixel.

  In the present embodiment, whether to increase the number of bits is determined based on whether the target pixel is a pixel corresponding to an image forming area or a pixel corresponding to a non-image forming area. Here, the image forming area refers to an area where an image is formed by adhering the liquid ejected by the liquid ejecting head 1 to a recording medium. Further, the non-image forming area refers to an area where no liquid is adhered to the recording medium 10 and an image is not formed. The non-image forming area and the non-attachment area are synonymous.

  For example, the non-image forming area is a so-called out-of-page area where an image is not formed at the end of the recording medium 10 in the main scanning direction. Alternatively, this is a so-called inter-page region, which is a region from when an image is formed on the recording medium 10 to the next image formation in the sub-scanning direction. Further, even in a so-called in-page region where an image is originally formed, a region where no liquid adheres is included in the non-image forming region.

  The image forming area and the non-image forming area will be described more specifically with reference to FIG. In the direction indicated by the solid arrows in FIG. 4, the direction A is the main scanning direction and the direction B is the sub-scanning direction, as in FIG.

  (A) shows an example in which the image 12 is formed on the recording medium 10 which is a cut sheet of A4 size or the like based on the image data. The area 13 in which no image is formed is an example of a so-called out-of-page area in which an image is not formed at the edge of the recording medium 10 in the main scanning direction. The region 13 is an example of “a region outside the image from one end of the image formed on the recording medium to one end of the recording medium close to one end of the image”.

  (B) shows an example in which two images 12 are formed based on image data on a recording medium 10 which is a roll paper of a continuous book. The area 14 in which no image is formed is an example of a so-called inter-page area in which the image is formed on the recording medium 10 and the next image is formed in the sub-scanning direction. The region 14 is an example of “an inter-image region from when an image is formed on a recording medium until the next image is formed”.

  (C) shows an example in which an image 15 is formed on the recording medium 10 which is a cut sheet of A4 size or the like based on the image data. In the image 15, only the pattern 15a is formed, and the other areas are blank areas. The region 16 in which the pattern 15a is not formed in the image 15 is an example of a region where no liquid adheres in a so-called in-page region where an image is originally formed.

  The above-described regions 13, 14, and 16 are examples of “a non-attachment region other than a region to which the liquid of the recording medium is attached”.

  Based on the input image data, the bit increase signal generation unit 302 sets the signal ADD to “ON” when the pixel to be image-formed is a pixel in the non-image forming area. If the pixel to be image-formed is a pixel in the image forming area, the signal ADD is set to “OFF”. The bit increase signal generation unit 302 outputs the generated signal ADD to the pixel data conversion unit 304.

  The discharge timing signal generation unit 303 receives the output of the encoder sensor 8 through the sensor I / F 207 and generates a signal indicating the timing at which the liquid discharge head 1 discharges the liquid in synchronization with the movement of the carriage unit 2. The ejection timing signal generation unit 303 outputs the generated signal LS to the pixel data conversion unit 304.

  Based on the input pixel data SD1, signal ADD, and signal LS, the pixel data conversion unit 304 includes pixel data SD2, a signal MN that represents a mask signal, a signal RT that represents a latch signal, a signal CS that represents a chip select signal, and A signal CLK representing the clock signal is generated.

  When the signal ADD is “OFF”, the pixel data conversion unit 304 generates the same 2-bit pixel data SD2 as the pixel data SD1. That is, the pixel data SD1 is applied as it is to the pixel data SD2, and the pixel data SD2 is any one of “11”, “10”, “01”, or “00” depending on the pixel data SD1.

  On the other hand, when the signal ADD is “ON”, the pixel data conversion unit 304 generates pixel data SD2 in which the number of bits is increased to the pixel data SD1. For example, 3-bit data in which 1 bit is increased is generated for 2-bit pixel data SD1. In other words, in addition to “large droplets”, “medium droplets”, “small droplets”, and “no droplets” that can be represented by 2-bit pixel data, data representing four types of droplets can be added. it can. For example, data representing “microvibration” can be added. Details of this will be described later.

  The signal MN is a signal for masking the drive waveform data in accordance with the pixel data SD1. That is, the signal MN is a signal for selecting a predetermined period of the drive waveform data according to the volume of the droplet to be ejected. For example, one drive waveform data capable of ejecting three small droplets is prepared, and in the case of “no droplet”, all the data ejecting three droplets are masked, that is, invalidated. In the case of “small droplet”, the data for ejecting 2 droplets out of 3 droplets is masked. In the case of “medium drop”, the data for ejecting one of the three drops is masked, and in the case of “large drop”, the mask is not masked and all the drive waveform data is used. These details will be described in detail with reference to FIG.

  The signal RT is a latch signal for shifting the discharge timing according to the position because the positions of the liquid discharge heads 1k to 1y are different. In other words, it is a signal for shifting the ejection timing in accordance with the color of the pixel data SD1.

  The signal CS is a chip select signal for selecting which liquid discharge head among the liquid discharge heads 1k to 1y is to be discharged. That is, it is a signal for selecting the liquid ejection head according to the color of the pixel data SD1.

  The signal CLK is a clock signal that serves as a reference for timing such as ejection.

  The pixel data SD2, the signal MN, the signal RT, the signal CS, and the signal CLK generated by the pixel data conversion unit 304 are output to the serialization unit 305.

  The serialization unit 305 serializes the pixel data SD2, the signal MN, the signal RT, the signal CS, and the signal CLK. Serialization means that a plurality of parallel data is serialized and transmitted. The serialized data and signal are transmitted to the deserialization unit 307 of the head drive circuit 1a by serial communication.

  Here, as described above, when the pixel to be image-formed is a pixel in the non-image forming area, the signal ADD is “ON”, and the pixel data SD2 having an increased number of bits is generated. Accordingly, the pixel data SD2 with the increased number of bits is transmitted to the head drive circuit 1a only when the pixel that is the target of image formation is a pixel in the non-image formation region. In other words, the pixel data SD2 with the increased number of bits is transmitted to the head drive circuit 1a only during the period for forming the pixels in the non-image forming area.

  The drive waveform signal acquisition unit 306 reads drive waveform data input from a computer or the like and stored in the memory 218, performs D / A conversion, and acquires an analog voltage signal of the drive waveform. The analog voltage signal of the drive waveform is transmitted to the drive waveform signal generation unit 310.

  The head control board 214 is an example of “a control unit that transmits pixel data having a predetermined number of bits to a driving unit”. The configuration including the bit increase signal generation unit 302, the pixel data conversion unit 304, and the serialization unit 305 is configured to transmit “pixel data with an increased number of bits in a non-attachment region other than a region where a liquid of a recording medium is attached. This is an example of a means for realizing the “Yes” function.

  The deserialization unit 307 restores the data and signal received from the serialization unit 305 to the original state.

  The bit number detection unit 308 detects an increase in the number of bits in the pixel data SD2, that is, a change in the number of bits, based on the signal RT and the signal CLK. The bit number notification unit 309 notifies the drive waveform signal generation unit 310 of the switching of the bit number detected by the bit number detection unit 308. The drive waveform signal generation unit 310 notified of the change in the number of bits switches the reception cycle for receiving the pixel data SD2. In other words, the drive waveform signal generation unit 310 increases the number of data to be received due to the increase in the number of bits of the pixel data SD2, and thus lengthens the reception cycle in accordance with the increase.

  The bit number detection unit 308 is an example of a “detection unit that detects a change in the number of bits”, and the bit number notification unit 309 is an example of a “notification unit that detects a change in the number of bits”.

  The drive waveform signal generation unit 310 receives the pixel data SD2, the signal MN, the signal RT, the signal CS, and the signal CLK, and generates a drive waveform signal that masks the analog voltage signal of the drive waveform according to the pixel data SD2. . Then, a drive waveform signal is output to the piezoelectric element 222 of the liquid ejection head 1 defined by the signal CS at a timing defined by the signal RT and the signal CLK.

  The piezoelectric element 222 ejects droplets at a predetermined timing based on the drive waveform signal.

  In the above example, the controller 200, the head control board 214, and the head drive circuit 1a are shown as separate configurations. However, with a hardware configuration in which some or all of these are integrated, The above function may be realized.

  The head drive circuit 1a is an example of “drive means”.

  Next, an example of processing performed by the image forming apparatus 100 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, in step S501, the controller 200 receives image data from a computer or the like, and generates pixel data SD1 and a signal LS indicating ejection timing based on the image data. Further, a signal ADD indicating an increase in the number of bits is generated according to whether the pixel data SD1 is pixel data corresponding to the image forming area or pixel data corresponding to the non-image forming area. These data and signals are output to the head control board 214.

  Subsequently, in step S503, the pixel data conversion unit 304 determines whether to increase the number of bits. This determination is made based on whether the signal ADD is “ON” or “OFF”.

  If it is determined in step S503 that the number of bits is to be increased, in step S505, the pixel data conversion unit 304 generates pixel data SD2 in which the pixel data SD1 is increased by 1 bit. If it is determined in step S503 that the number of bits is not increased, the process proceeds to step S509.

  In step S509, the drive waveform signal acquisition unit 306 acquires drive waveform data, performs D / A conversion, and acquires an analog voltage signal of the drive waveform. On the other hand, the pixel data conversion unit 304 generates a signal MN, a signal RT, and a signal CS based on the pixel data SD1 and the signal LS. The pixel data SD2, the signal MN, the signal RT, the signal CS, and the signal CLK are serialized by the serialization unit 305.

  Subsequently, in step S511, the pixel data SD2, the signal MN, the signal RT, the signal CS, the signal CLK, and the analog voltage signal of the driving waveform are transmitted to the head driving circuit 1a.

  Subsequently, in step S513, the pixel data SD2, the signal MN, the signal RT, the signal CS, and the signal CLK are deserialized by the deserialization unit 307. The bit number detection unit 308 detects a change in the number of bits of the pixel data SD2 based on the signal RT, the signal CS, and the signal CLK. The detected switching of the number of bits is notified to the drive waveform signal generation unit 310 by the bit number notification unit 309. In response to this, the drive waveform signal generation unit 310 switches the reception cycle of the pixel data SD2.

  Subsequently, in step S515, the drive waveform signal generation unit 310 generates a drive waveform signal in which the analog voltage signal of the drive waveform is masked based on the pixel data SD2 and the signal MN.

  Subsequently, in step S517, the drive waveform signal generator 310 outputs a drive waveform signal to the piezoelectric element 222 of the liquid ejection head 1 defined by the signal CS at a timing based on the signal RT and the signal CLK.

  As described above, the number of bits of the control signal including the pixel data is increased according to the image forming area, and the liquid is ejected from the liquid ejection head 1 based on the control signal and the drive waveform signal.

  As described above, the image forming apparatus 100 transmits the pixel data with the increased number of bits to the head driving circuit 1a only in the non-image forming area where no image is formed, that is, the non-adhered area of the liquid. In other words, the image forming apparatus 100 transmits the pixel data SD2 with the increased number of bits to the head driving circuit 1a only during the period in which the pixels in the non-image forming area are formed. Since image formation is not performed in the non-adhered region of the liquid, even if the transmission of pixel data takes time corresponding to the increase in the number of bits, the speed of image formation is not affected. That is, according to the image forming apparatus 100, the pixel data with the increased number of bits can be transmitted to the head driving circuit 1a, that is, the driving circuit of the liquid ejecting unit without reducing the speed of forming an image.

  On the other hand, for example, by increasing the number of signal lines and signal input / output pins for transmitting pixel data in accordance with the increase in the number of bits, the number of bits was increased without reducing the speed of image formation. It is possible to transmit the pixel data to the drive circuit of the liquid ejection means. However, an increase in the number of signal lines and input / output pins leads to an increase in the size and cost of the device. According to the present embodiment, since the number of signal lines and input / output pins is not increased, pixel data with an increased number of bits is transmitted to the drive circuit of the liquid ejecting unit without increasing the size of the apparatus and increasing the cost. I can do it.

  The above is the overall configuration of the image forming apparatus 100. Details of each configuration will be described below.

<Drive waveform signal>
Details of the drive waveform signal will be described with reference to FIG. FIG. 6 is a diagram for explaining an example of the drive waveform signal.

  In FIG. 6, (a) is a signal LS representing ejection timing, (b) is an analog voltage signal Vp of a drive waveform, and (c-0) to (c-4) are signals M0 to M4 representing mask signals. Yes. In (a), (b) and (c-0) to (c-4), the horizontal axis represents time, and the vertical axis represents voltage.

  The signal LS is a synchronization signal for causing the liquid ejection head 1 to eject liquid at a predetermined cycle and timing as described above.

  The drive waveform analog voltage signal Vp is a voltage signal representing the entire drive waveform signal. During a time T corresponding to one cycle of the signal, an analog voltage signal Vp having a drive waveform is generated and output to the head drive circuit 1a, and the piezoelectric element 222 is driven. Note that the potential Ve in (b) is a reference potential. The reference potential is a DC voltage applied to the piezoelectric element 222 when the voltage of the drive waveform signal is not applied and the liquid ejection head is not operating.

  As shown in (b), when a pulse waveform signal that lowers the potential from the potential Ve for a predetermined period is applied to the piezoelectric element 222, the liquid is ejected from the liquid ejection head 1. A predetermined period during which the potential is lowered from the potential Ve is called a pulse width. The amount of liquid ejected varies depending on the level of the potential to be lowered and the length of the pulse width. In the example of (b), a total of four pulse waveform signals are shown in each of the periods (i) to (iv).

  The signals M0 to M4 are mask signals for switching “valid” or “invalid” of the analog voltage signal Vp of the drive waveform for each period. The period during which the mask signal is High is “valid”, and the voltage of the analog voltage signal Vp having the driving waveform during that period is applied to the piezoelectric element 222. On the other hand, the period during which the mask signal is Low is “invalid”, and a voltage holding the potential immediately before going Low is applied to the piezoelectric element 222.

  The drive waveform signal applied to the piezoelectric element 222 differs depending on which period of the analog voltage signal Vp of the drive waveform is “valid”, and the volume of the liquid ejected by the liquid ejection head 1 depends on the drive waveform signal. Change.

  The signal M0 corresponds to the case of “no drop”, and all four pulse waveform signals in the periods (i) to (iv) are “invalid”. Since the voltage of the analog voltage signal Vp having the driving waveform is not applied to the piezoelectric element 222, no liquid is ejected from the liquid ejection head 1.

  The signal M1 is a signal corresponding to the case of “droplet”, and is “valid” only in the period (iv). Of the analog voltage signal Vp of the driving waveform, the voltage of the pulse waveform signal in the period (iv) is applied to the piezoelectric element 222, and one droplet is ejected.

  The signal M2 is a signal corresponding to the case of “medium droplet”, and the periods (ii) and (iv) are valid. Of the analog voltage signal Vp of the drive waveform, the voltage of the pulse waveform signal in the periods (ii) and (iv) is applied to the piezoelectric element 222, and two droplets are continuously ejected. Since the voltage is higher in the period (iv) than in the period (ii), the droplet ejection speed in the period (iv) is faster than the droplet in the period (ii). Therefore, before reaching the recording medium, the droplets in the period (iv) catch up with the droplets in the period (ii) and become one droplet. In this case, since it is a droplet for two drops, it is a medium drop having a larger volume than a small drop.

  The signal M3 is a signal corresponding to the case of “large droplet”, and the periods (ii) to (iv) are valid. Of the analog voltage signal Vp of the drive waveform, the voltage of the pulse waveform signal in the periods (ii) to (iv) is applied to the piezoelectric element 222, and three droplets are continuously ejected. Since the voltage is higher in the period (iv) than in the periods (ii) to (iii), the ejection speed of the droplets in the period (iv) is faster than the droplets in the periods (ii) to (iii). Therefore, before reaching the recording medium, the droplets in the period (iv) catch up with the droplets in the periods (ii) to (iii) to form one droplet. In this case, since it is a droplet for three drops, it becomes a large drop with a larger volume than the medium drop.

  The signal M4 is a signal corresponding to the case of “micro vibration”. “Fine vibration” means that the liquid in the liquid discharge head 1 is only vibrated without being discharged. By vibrating the liquid, the liquid can be stirred and an increase in viscosity can be suppressed. In the signal M4, only the period (i) is effective, and the voltage of the pulse waveform signal of the period (i) is applied to the piezoelectric element 222 among the analog voltage signals Vp of the drive waveform. Since the voltage of the pulse waveform signal in period (i) is low, the liquid is not ejected and only vibrates.

  Referring to FIG. 3, the pixel data conversion unit 304 generates a signal MN such as signals M0 to M4 according to the pixel data SD1. The drive waveform signal acquisition unit 306 reads the drive waveform data stored in the memory 218, performs D / A conversion, and acquires the analog voltage signal Vp of the drive waveform. The drive waveform signal generation unit 310 generates a drive waveform signal to be output to the piezoelectric element 222 using the received analog voltage signal Vp and signal MN of the drive waveform.

  Here, when the pixel data is 2 bits, there are four drive waveform signals that can be expressed by the pixel data: for large drops, for medium drops, for small drops, and without drops. On the other hand, when the pixel data is increased to 3 bits, eight drive waveform signals can be expressed by the pixel data. That is, four drive waveform signals can be added to the case of 2 bits. In the above, “100” of the pixel data is used for the drive waveform signal of “fine vibration” as an example.

  The pixel data “100” representing the “fine vibration” drive waveform signal is an example of “data representing the drive waveform signal for causing the liquid in the liquid ejection means to vibrate”. The 3-bit pixel data including “100” is an example of “pixel data with an increased number of bits that includes data representing a drive waveform signal for finely vibrating the liquid in the liquid ejecting means”.

  In addition to this, for example, “101” can be used to represent a drive waveform signal for flushing. Here, the flushing is an ejection signal for cleaning out the liquid whose viscosity has increased in the individual liquid chamber of the liquid ejection head 1. For example, the drive waveform signal for ejecting large droplets in FIG. 6 may also be used. Alternatively, the driving waveform analog voltage signal Vp is formed so as to include five pulse waveform signals, and the driving waveform signal for flushing is selected by the signal MN that makes all the five pulse waveform signals “valid”. You may do it.

  The pixel data “101” representing the “flushing” driving waveform signal is an example of “data representing the driving waveform signal for flushing the liquid in the liquid ejecting means”. The 3-bit pixel data including “101” is an example of “pixel data with an increased number of bits including data representing a drive waveform signal for flushing the liquid in the liquid ejection unit”.

  Furthermore, for example, “110” can be used to represent a drive waveform signal used during the cleaning operation of the liquid ejection head 1. The cleaning of the liquid discharge head 1 is an operation for removing the liquid having increased viscosity in all the individual liquid chambers of the liquid discharge head 1 by sucking the liquid from the liquid discharge head 1. At this time, for example, by inputting a sinusoidal drive waveform signal to the liquid discharge head 1, the cleaning operation can be efficiently performed by the stirring effect of the liquid in the individual liquid chamber. In this case, for example, a period for applying a sinusoidal voltage change is provided in a part of the analog voltage signal Vp having the driving waveform shown in FIG. A drive waveform signal can be selected.

  The pixel data “110” representing this “sinusoidal drive waveform signal” is an example of “data representing a sinusoidal drive waveform signal for stirring the liquid in the liquid ejection means”. The 3-bit pixel data including “110” is an example of “pixel data with an increased number of bits, including data representing a sinusoidal drive waveform signal for stirring the liquid in the liquid ejection means”. .

  Any one of the pixel data “100”, “101”, and “110” may be used, or a part or all of them may be used in combination.

<Number of bits detection>
Next, a method for detecting a change in the number of bits by the bit number detection unit 308 will be described with reference to FIG.

  In FIG. 7, a signal RT is a latch signal for shifting the ejection timing, and a signal CLK is a clock signal. When the 2-bit pixel data SD1 is converted into 3-bit pixel data SD2, the signal period of the signal RT is extended. As shown in (a), when the pixel data SD2 is 2 bits, the number of pulses of the signal CLK is 3, and when the pixel data SD2 is 2 bits, the number of pulses of the signal CLK is 5. That is, the signal period of the signal RT is extended by two pulses of the signal CLK. Therefore, the change in the number of bits can be detected by detecting the extension of the signal period of the signal RT by counting the number of pulses of the signal CLK.

  Such an extension of the signal period of the signal RT is an example of “change in ejection time interval”.

  Next, a method of notifying the bit number switching by the bit number notifying unit 309 will be described with reference to FIG.

  In FIG. 8, a signal CS is a chip select signal for selecting a liquid ejection head, and a signal CLK is a clock signal. Normally, the signal CLK is input to the head driving circuit 1a only when the signal CS is “HIGH”, but when the signal CS is “LOW”, a few pulses of the signal CLK are input to reset the signal according to the number of pulses. Etc. can be provided. Using such a function, when the signal CS is “LOW”, a signal CLK having a predetermined number of pulses is input to notify the drive waveform signal generation unit 310 of the switching of the number of bits. For example, by inputting a two-pulse signal CLK as indicated by a circle 17 in FIG. 8, the drive waveform signal generation unit 310 is notified that the number of bits has been switched to 3 bits.

  The signal CS is an example of a “selection signal for selecting a liquid ejection unit”. “When the signal CS is“ LOW ”, the signal CLK having a predetermined number of pulses is input” is an example of “generating a clock signal having a predetermined number of pulses when the selection signal is LOW”.

<Response to error detection>
Next, a response at the time of error detection of the image forming apparatus 100 of the present embodiment will be described with reference to FIG. When an error is detected in the image forming apparatus 100 during image formation, the controller 200 adds a bit by a signal ADD indicating an increase in the number of bits and sets it to “1”. This is detected by the head control board 214, and the pixel data SD2 from the next cycle are all replaced with “00” representing no drop. Thereby, it is possible to prevent erroneous ink ejection at the time of an error.

<Use of bit increase signal>
The use of the signal ADD indicating the increase in the number of bits in the head driving circuit 1a will be described with reference to FIG. At the time of image formation, the signal RT is set to none by adding the signal ADD. As a result, it is possible to achieve a state equivalent to drip-free “00”, and the number of bits can be increased without adding bits.

[Second Embodiment]
Next, an image forming apparatus according to the second embodiment will be described. In the first embodiment, the description of the same components as those of the already described embodiments may be omitted.

  In the first embodiment, an example of a device that discharges a so-called serial type liquid has been described. On the other hand, the image forming apparatus of the present embodiment is a device that discharges a so-called line type liquid that does not cause the liquid discharge head 1 to scan in the main scanning direction.

  FIG. 11 shows an example of the configuration of the liquid ejection unit 400 included in the image forming apparatus 100a of the present embodiment. The liquid discharge unit 400 includes a liquid discharge head 401, a head control board 214, an adjustment plate 402, and a flat cable 403.

  The liquid discharge head 401 includes four liquid discharge heads 401K, 401C, 401M, and 401Y corresponding to black (K), cyan (C), magenta (M), and yellow (Y). The liquid discharge heads 401K, 401C, 401M, and 401Y are arranged in this order from the upstream side in the transport direction 30 of the recording medium 20, and are fixed to the adjustment plate 402. In addition, each of the liquid discharge heads 401 to 401 </ b> Y for each color is provided four by four in the width direction intersecting the transport direction 30. By arranging the liquid discharge heads 401 to 401Y of the respective colors in the width direction, it is possible to discharge a liquid to the entire area in the width direction without scanning the liquid discharge head in the width direction, thereby forming a color image.

  The width direction is an example of a “direction intersecting the transport direction”, and the transport direction is an example of a “transport direction”.

  As shown in the figure, the liquid ejection heads 401 to 401Y of the respective colors are electrically connected to the head control board 214 via the flat cable 403, respectively. Although omitted in FIG. 11, four head control boards 214 are provided. The four head control substrates 214 are connected to all the liquid discharge heads via the flat cable 403. The head control board 214 is a rigid board on which an electric circuit, an electronic circuit, and the like are mounted in the same manner as described in the first embodiment.

  FIG. 12 shows an example of a hardware configuration related to the control of the image forming apparatus 100a of the present embodiment. The image forming apparatus 100 a includes a conveyance roller sensor 404. The transport roller sensor 404 is a rotary encoder provided on the transport roller on the upstream side of the liquid ejection head 401 in the transport direction. Based on the output of the transport roller sensor 404, the transport position of the transported recording medium is detected. The output of the conveyance roller sensor 404 is transmitted to the controller 200 via the sensor I / F 207, and is used as a signal for synchronizing the conveyance of the recording medium and the ejection by the liquid ejection head 401. The conveyance roller sensor 404 is preferably provided on a conveyance roller located as close as possible on the upstream side of the liquid ejection head 401. This is because the closer the position is, the more the detection error of the position of the recording medium is reduced.

  Other hardware configurations, functional configurations, and processes are the same as those described with reference to FIGS. According to the present embodiment, in the line-type image forming apparatus, the pixel data with the increased number of bits is transmitted to the head drive circuit 1a, that is, the drive circuit of the liquid ejecting unit without reducing the image forming speed. Can do.

  The effects other than those described above are the same as those described in the first embodiment.

  Although the apparatus for ejecting liquid according to the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention.

1, 1k, 1c, 1m, 1y, 401, 401K, 401C, 401M, 401Y Liquid ejection head (an example of liquid ejection means)
1a Head drive circuit (an example of drive means)
2 Carriage unit 3 Main scanning motor 4 Gear 5 Pressure roller 6 Timing belt 7 Guide rod 8 Encoder sensor 9 Encoder sheet 10, 20 Recording medium 11 Platen 30 Conveying direction 100, 100a Image forming apparatus (an example of apparatus for discharging liquid)
200 Controller 214 Head control board (an example of control means)
221 Piezoelectric element driving unit 222 Piezoelectric element 301 Pixel data generation unit 302 Bit increase signal generation unit 303 Discharge timing signal generation unit 304 Pixel data conversion unit 305 Serialization unit 306 Drive waveform signal acquisition unit 307 Deserialization unit 308 Bit number detection unit (detection) Example of means)
309 bit number notification section (an example of notification means)
310 Drive waveform signal generator 400 Liquid discharge unit 402 Adjustment plate 403 Flat cable 404 Transport roller sensors LS, MN, RT, CS, CLK, M0, M1, M2, M3, M4 Signal Vp Analog voltage signal A of drive waveform A main scan Direction B Sub-scanning direction

JP 2014-113754 A

Claims (10)

An apparatus for discharging the liquid onto a recording medium based on recording data, the apparatus including: a liquid discharging unit that discharges the liquid; and a driving unit that drives the liquid discharging unit based on a drive waveform signal.
Control means for transmitting pixel data included in the recording data and having a predetermined number of bits to the driving means;
The control means transmits pixel data in which the number of bits is increased from the predetermined number of bits in a non-attachment region other than the region to which the liquid of the recording medium is attached.
A device for discharging a liquid characterized by the above. The apparatus for ejecting the liquid forms an image by ejecting the liquid onto the recording medium transported in the transport direction and attaching the liquid to the recording medium.
The non-adhesion region is a region outside the image from one end of the image formed on the recording medium to one end of the recording medium close to one end of the image in a direction crossing the transport direction. The apparatus for discharging a liquid according to claim 1. The apparatus for ejecting the liquid forms an image by ejecting the liquid onto the recording medium transported in the transport direction,
2. The liquid ejection according to claim 1, wherein the non-attachment area is an inter-image area in the transport direction until the image is formed on the recording medium and the next image is formed. Device to do. 4. The liquid according to claim 1, wherein the driving unit includes a detection unit that detects a change in the number of bits and a notification unit that notifies the change in the number of bits. 5. Discharge device. 5. The pixel data with the increased number of bits includes data representing the drive waveform signal for finely vibrating the liquid in the liquid ejecting means. The apparatus which discharges the liquid as described in a term. 6. The pixel data in which the number of bits is increased includes data representing the drive waveform signal for flushing the liquid in the liquid ejecting means. The apparatus which discharges the liquid of description. 7. The pixel data in which the number of bits is increased includes data representing the drive waveform signal having a sinusoidal shape for stirring the liquid in the liquid ejection unit. An apparatus for discharging the liquid according to claim 1.   The apparatus for ejecting liquid according to claim 4, wherein the detection unit detects switching of the number of bits based on a change in the time interval of the ejection. The liquid ejecting means ejects the liquid based on a selection signal for selecting the liquid ejecting means;
5. The apparatus for ejecting liquid according to claim 4, wherein the notifying means notifies the switching of the bit number by generating a clock signal having a predetermined number of pulses when the selection signal is LOW. The program is executed by an apparatus that discharges a liquid onto a recording medium based on recording data, the apparatus including a liquid discharging unit that discharges the liquid and a driving unit that drives the liquid discharging unit based on a drive waveform signal. And
A control step of transmitting pixel data included in the recording data and having a predetermined number of bits to the driving means;
The control step executes a process of transmitting pixel data in which the number of bits is increased from the predetermined number of bits in a non-attachment region other than the region to which the liquid of the recording medium is attached. .