JP2008120048A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder which can save power consumption and prevent solidification of the ink in nozzles and deformation of a recording medium by controlling drying of the ink in the case of a necessary minimum. <P>SOLUTION: The inkjet recorder is equipped with a drying means which dries the ink on the recording medium, a calculating means which calculates a printing ratio of each color of image data recorded to the recording medium, and a judging means which judges that the printing ratio exceeds a predetermined reference value. The inkjet recorder has a driving means which drives the drying means when the excess is judged. In other words, the ink on the recording medium is left to spontaneously dry when the printing ratio is low. Drying of the recording medium is carried out only when the printing ratio exceeds the reference value. The reference value is different by each color and set higher for the color of a line head arranged more upstream, taking the fact into consideration that the need for drying the ink of the color printed upstream decreases because it takes a longer time to reach a drier. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that ejects ink droplets from a plurality of nozzles by driving a piezoelectric element or the like.

  In recent years, inkjet recording apparatuses that eject ink droplets from a plurality of nozzles and perform printing on a recording medium such as paper have been widely marketed because they have advantages such as being small and inexpensive, and being quiet during operation.

  As a recording method of such an ink jet recording apparatus, there are the following methods. That is, as shown in FIG. 5, a head unit 402 in which a plurality of nozzles 401 are arranged is mounted on a moving body (carriage) 403, and a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) A of the recording medium P ) B causes the carriage 403 to perform main scanning. This is a recording method in which printing is performed by ejecting ink droplets from the nozzle 401 during the main scanning.

However, recently, the following recording method has also been adopted due to the demand for high-speed printing. That is, as shown in FIG. 4, a line head 404 having the head units 402 arranged in a row or a plurality of rows over the entire width of the recording medium P is provided, and the entire width is simultaneously measured without performing the main scanning as described above. This is a recording method in which ink droplets are ejected from nozzles 401.
In particular, in an ink jet recording apparatus that performs color printing, as shown in FIG. 4, four line heads 114K for each color of black (K), cyan (C), magenta (M), yellow (Y), With 114C, 114M, and 114Y, faster printing is realized. An ink jet recording apparatus provided with such a line head is disclosed, for example, in Patent Document 1 below.

  On the other hand, as the printing speed increases, it becomes necessary to quickly dry the ejected ink droplets. This is because if the ink is insufficiently dried, the ink will be blurred or smeared when the recording medium after printing is touched by hand. Further, for example, when printing several pages of images, if the ink is not sufficiently dried, the recording media for several pages will be accumulated on the paper discharge tray or the like. In addition, there is a problem that ink of other recording media adheres.

In order to solve such a problem, an inkjet recording apparatus provided with a drying device such as a heater is disclosed in Patent Document 2 below, for example.
JP 2006-88568 A JP 2006-231696 A

  However, the technique of Patent Document 2 has the following problems.

  First, this technique has a problem that power consumption increases because the heater, which is a drying device, is always operating.

  Second, if the heater is operated for a long time, the ink is solidified in the nozzle 401, and ink droplets are not ejected, and printing cannot be performed.

  Third, there is a problem that if the recording medium is heated excessively, deformation such as bending or wrinkles occurs in the recording medium.

  The present invention has been made in view of such problems, and by controlling the drying of ink when it is the minimum necessary, it is possible to save power consumption, solidify ink droplets in the nozzle, and record medium. An object of the present invention is to provide an ink jet recording apparatus capable of preventing the deformation of the ink jet recording apparatus.

  In order to achieve the above object, the present invention employs the following means.

  First, the present invention is premised on an ink jet recording apparatus in which line heads for ejecting ink of each color are arranged in parallel in a direction orthogonal to the conveyance direction of the recording medium.

  Next, in such an ink jet recording apparatus, a drying device for drying the ink on the recording medium, a calculating means for calculating the printing ratio of each color of the image data recorded on the recording medium, and exceeding the reference value of the printing ratio And determining means for determining. And when this excess is determined, the drive means which drives a drying apparatus is provided. That is, when the printing rate is low, the ink on the recording medium is left to dry naturally, and the printing medium is dried only when the printing rate exceeds the reference value. Thereby, it is possible to control the drying of the ink when it is the minimum necessary.

  Here, the reference value is different for each color, and is set higher for the color of the line head arranged upstream in the transport direction. This takes into account the fact that the color ink printed on the upstream side takes a long time to reach the drying device, so that the necessity for drying is reduced.

  Further, the determination means can be configured to determine the excess when the print rate exceeds a reference value for at least one color. That is, when the printing rate is lower than the reference value for all colors, the drying device is left to operate without being operated.

  Alternatively, the determination unit may be configured to determine the excess when the sum of the print ratios of the colors exceeds the reference value. This is because, for example, even if the printing rate for one color exceeds the reference value, if the printing rate for other colors is extremely low and the amount of ink as a whole is judged to be small, it is left to natural drying as well. is there.

  As described above, according to the present invention, by controlling the drying of ink when it is the minimum necessary, it is possible to save power consumption and to prevent ink droplet solidification in the nozzle and deformation of the recording medium. A recording apparatus can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an internal structure diagram of an embodiment of an ink jet recording apparatus 100 according to the present invention.

  The ink jet recording apparatus 100 includes a paper feed cassette 111 disposed at a lower portion, an ink tank 112 disposed above the paper feed cassette 111, and a conveyance belt 113 disposed above the ink tank 112. Further, a recording head 114 disposed above the transport belt 113 and a sheet transport path 116 disposed at the right end of the apparatus are provided.

  The paper feed cassette 111 stores a recording medium P on which printing is performed. In the paper feed cassette 111, a paper feed roller 121 for feeding paper is disposed at an end portion on the paper transport path 116 side. Yes. The paper transport path 116 is configured by a guide plate that guides the recording medium P fed from the paper feed cassette 111 to the transport belt 113. In this paper transport path 116, a transport roller pair 122 for transporting the fed paper is disposed on the paper feed cassette 111 side, and a registration roller pair 123 for performing secondary paper feed is disposed on the transport belt 113 side. .

  The ink tank 112 includes ink tanks 112K, 112C, 112M, and 112Y arranged in parallel in the left-right direction, and stores black (K), cyan (C), magenta (M), and yellow (Y) ink, respectively. is doing.

  The conveyor belt 113 conveys the recording medium P, which has been secondarily fed by the registration roller pair 123, to the left, and to the left and right outer sides (downstream and upstream in the sheet conveyance direction) of the recording head 114. The driving roller 124 and the driven roller 125 that are arranged are stretched.

  Below the drive roller 124, a recovery port 126 having an opening on the upper surface for recovering excess ink during printing is disposed. Below the recovery port 126, a waste ink tank 127 is disposed. Has been placed. The collection port 126 and the waste ink tank 127 communicate with each other through a communication pipe 128 to constitute a collection ink storage unit.

  Further, a discharge roller pair 129 is disposed on the left side of the conveyor belt 113, and a discharge port 130 is formed in the left side wall of the device on the left side of the discharge roller pair 129. A discharge tray 131 protruding outside is disposed.

  In the recording head 114, the nozzle surface 141 on the lower surface is supported at a printing position at a minute interval from the paper conveyance surface of the conveyance belt 113. The recording head 114 includes line heads 114K, 114C, 114M, and 114Y (see FIG. 4) arranged in parallel in the left-right direction. Each of the line heads 114K, 114C, 114M, and 114Y ejects black (K), cyan (C), magenta (M), and yellow (Y) inks with the following structure.

  On the nozzle surface 141 of the recording head 114, for each of the line heads 114K, 114C, 114M, 114Y, a large number of nozzles are arranged in the paper width direction by the paper width (see FIG. 4). Each of these nozzles communicates with a pressurization chamber (not shown) formed corresponding to each nozzle in the line head, and each pressurization chamber is further formed in each line head 114K, 114C, 114M, 114Y. The ink chamber communicates with the ink chamber (not shown). The ink liquid chambers of the line heads 114K, 114C, 114M, and 114Y communicate with the ink tanks 112K, 112C, 112M, and 112Y, respectively, through ink supply tubes (not shown).

  Further, downstream of the recording head 114, drying means 115 for drying the ink discharged from the line heads 114K, 114C, 114M, 114Y onto the recording medium P is disposed.

  FIG. 2 is a schematic configuration diagram relating to control of the inkjet recording apparatus 100 in the present embodiment.

  The ink jet recording apparatus 100 includes a CPU (Central Processing Unit) 201, a RAM (Random Access Memory) 202, a ROM (Read Only Memory) 203, an HDD (Hard Disk Drive) 204, a conveyance belt 113, a feed roller 121, and the like in printing. A driver 205 corresponding to each drive unit is connected via an internal bus 206. The CPU 201 uses, for example, the RAM 202 as a work area, executes a program stored in the ROM 203, the HDD 204, and the like, and exchanges data and commands with the driver 205 based on the execution result, thereby allowing each of the drive units to Control the behavior. Further, each means (shown in FIG. 3) to be described later other than the above-described drive unit operates as each means when the CPU 201 executes the program.

  FIG. 3 is a software configuration diagram of the inkjet recording apparatus 100 according to the present embodiment.

  For example, the user can specify image data stored in the HDD 204 and print it. In the case of copying, image data is generated in the RAM 202 based on a document read by a CCD (Charge Coupled Device) or the like and printed.

  The calculation means 301 calculates the printing rate of each color (K, C, M, Y) of the image data related to this printing. This calculation is performed, for example, by counting the number of pixels per unit area for each color (K, C, M, Y) in the image data. The image data with a low printing rate is specifically image data consisting only of characters, and the image data with a high printing rate is specifically image data such as a photograph.

  Next, the determination unit 302 determines whether the printing rate calculated in this way exceeds a reference value. This reference value is different for each color, for example, 20%, 16%, 12%, 7% for black (K), cyan (C), magenta (M), yellow (Y), respectively. Set. In the ink jet recording apparatus 100 of the present embodiment, as described in FIG. 1 or FIG. 4, from the upstream in the paper conveyance direction, black (K), cyan (C), magenta (M), yellow (Y) in this order. Line heads 114K, 114C, 114M, 114Y are arranged. The present invention is characterized in that the reference value is set higher as the color of the line head arranged upstream as illustrated. Its significance will be described later.

  Now, for example, assume that the printing rates of the colors (K, C, M, Y) of the image data are 12%, 10%, 5%, and 3%, respectively. In this case, the printing rate of all colors does not exceed the reference value. Specifically, this is considered to be image data in which all areas are composed only of characters and do not include areas such as photographs. In such a case, the driving means 303 does not drive the drying means 115.

  That is, the fact that the printing rates of all colors do not exceed the reference value means that the amount of ink ejected on the recording medium P is small. In this case, the drying means 115 is driven. Instead, this ink is left to dry naturally. This is because if the drying means 115 is always driven, not only the power consumption increases, but also the ink solidifies inside the nozzles of the recording head 114 and printing cannot be performed, or the recording medium is bent or wrinkled. Because there is.

  On the other hand, for example, it is assumed that the printing ratio of each color (K, C, M, Y) of the image data is 12%, 20%, 5%, and 3%, respectively. In this case, the determination unit 302 determines that the cyan (C) printing rate exceeds the reference value. Then, the driving unit 303 drives the drying unit 115 to dry the ink on the recording medium P.

  That is, when the determination unit 302 determines that the printing rate exceeds the reference value for at least one color, this image data is a solid portion of a specific color (when a specific character is colored like a marker, etc. ) And a photograph-like area, and the amount of ink ejected from any of the line heads 114K, 114C, 114M, 114Y is also increased. Therefore, in this case, the drying means 115 is driven to dry the ink on the recording medium P.

  Here, as described above, the present invention is characterized in that the reference value for each color used by the determination unit 302 for determination is set higher for the color of the line head arranged upstream. This takes into account the fact that the color ink printed on the upstream side takes a long time to reach the drying means 115, so that the necessity for drying is reduced. By doing this, it is possible to control the drying of the ink when it is the minimum necessary, and to prevent the adverse effects such as the high power consumption as described above.

  Alternatively, the determination unit 302 determines that the printing rate exceeds the reference value when the sum of the printing rates of each color (the maximum value is 400%) exceeds a reference value (for example, 55%). It can also be programmed to do. This is because, for example, even if the printing rate for one color exceeds the reference value, if the printing rate for other colors is extremely low and the amount of ink as a whole is judged to be small, it is left to natural drying as well. is there.

  As the drying means 115, it is appropriate to specifically employ a laser light source for heating ink, but when the printing speed of the inkjet recording apparatus 100 is slow, a blower fan or the like is sufficient.

  In the above description, it has been described that the line heads are arranged in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream in the conveyance direction of the recording medium. It is an example, and the arrangement order of each color may be different. It is sufficient if the reference value used by the determination unit 302 is set higher for the color of the line head arranged upstream.

  The ink jet recording apparatus according to the present invention can save power consumption by controlling the drying of ink when it is the minimum necessary, and can prevent solidification of ink in the nozzle and deformation of the recording medium. Therefore, it is particularly useful as a printer, a copier, a multi-function machine, or the like that performs printing by an inkjet method.

1 is an internal structure diagram of an ink jet recording apparatus of the present invention. FIG. 3 is a schematic configuration diagram relating to control of the ink jet recording apparatus of the present invention. FIG. 2 is a software configuration diagram of the inkjet recording apparatus according to the invention. FIG. 3 is a structural diagram of a line head of an ink jet recording apparatus. FIG. 3 is a structural diagram of a head unit of an ink jet recording apparatus.

Explanation of symbols

100 Inkjet recording device
115 Drying means
116 Paper transport path
201 CPU
202 RAM
203 ROM
204 HDD
301 Calculation means
302 Judgment means
303 Drive means

Claims (4)

In an inkjet recording apparatus in which line heads that discharge ink of each color are arranged in parallel in a direction orthogonal to the conveyance direction of the recording medium,
Drying means for drying the ink on the recording medium;
Calculating means for calculating the printing ratio of each color of image data to be recorded on the recording medium;
Determining means for determining whether or not the printing rate exceeds a predetermined reference value;
An ink jet recording apparatus comprising: a drive unit that drives the drying unit based on a determination result by the determination unit.   The inkjet recording apparatus according to claim 1, wherein the reference value is different for each color, and is set higher as the color of the line head arranged upstream in the transport direction. The determination means determines whether or not the printing rate exceeds a predetermined reference value for at least one color;
The inkjet recording apparatus according to claim 1, wherein the driving unit drives the drying unit based on a determination result of the determination unit. The determination means determines whether or not the sum of the print ratios of each color exceeds a predetermined reference value;
The inkjet recording apparatus according to any one of claims 1 to 3, wherein the driving unit drives the drying unit based on a determination result of the determination unit.

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