JP2012061661A - Recording apparatus, and ejection failure detection method - Google Patents

Abstract

An object of the present invention is to detect nozzle defects with high accuracy during the operation of the conveyor belt without being affected by vibration or deflection during the operation of the conveyor belt.
SOLUTION: Detection means for detecting ejection of ink droplets, a moving mechanism for moving a print head unit in a direction perpendicular to the conveyance direction of the recording paper, drive control means for controlling driving of the movement mechanism, and detection means Discharge detection control means for controlling the discharge failure detection processing of the used ink droplets, and the drive control means receives a print instruction for the recording paper, and moves the nozzle opening and the transport belt by the moving mechanism. The print head unit is moved so as to widen the gap, and the discharge detection control means performs the discharge failure detection process after the movement of the print head unit by the moving function is completed.
[Selection] Figure 1

Description

  The present invention has a print head unit having a plurality of print heads, and discharges ink droplets from nozzle openings of the print head so as to print on a recording sheet conveyed by the convey belt. The present invention relates to a recording apparatus and an ejection failure detection method for detecting ejection failure of the ink droplet during operation.

  As one of image forming apparatuses such as a printer, a facsimile machine, a copying apparatus, and a plotter, for example, a liquid discharge recording type ink jet recording apparatus using a recording head that discharges ink droplets is known.

  Some conventional inkjet recording apparatuses include, for example, a line head having a length that is approximately the same as the width of printing paper that is a recording medium. In an inkjet recording apparatus provided with a line head, the line head is not moved during normal printing, and image formation is performed by ejecting ink from the line head when transporting printing paper. In this printing method, when ink is no longer ejected due to clogging of the nozzles of the line head or the like, it is not possible to compensate for the nozzles in which other nozzles have failed, and image formation cannot be performed normally.

  Therefore, the conventional ink jet recording apparatus is provided with a detecting unit for detecting the state of the nozzle in order to solve the above-described problems. As the detecting means, there is a means for detecting a nozzle defect by, for example, irradiating a laser beam during printing, detecting forward scattered light generated when the laser beam intersects an ink droplet, and the like. Further, before printing, there is a means for detecting a nozzle defect at a maintenance position where the recovery operation is performed and performing the recovery operation.

  In addition to the above, various devices have been made to detect nozzle defects. For example, Patent Document 1 discloses that a print area and a maintenance area are separated to perform highly accurate nozzle defect detection, to ensure that there is no nozzle defect, and to provide a highly accurate print image quality. . Patent Document 2 discloses a mechanism that always maintains the distance between the ejection detection unit and the recording head at an appropriate amount. Patent Document 3 describes that a determination pattern for determining a nozzle defect formed with droplets can be detected with high accuracy, and determination and detection of a defective nozzle with high accuracy can be performed.

  For example, in a recording apparatus configured to operate a conveyance belt before a printing operation and detect ink droplets on the conveyance belt, a method for detecting forward scattered light generated when a laser beam and an ink droplet intersect with each other is There is a problem that the laser beam is blocked by the bending during the operation of the conveying belt for conveying the laser beam, so that the forward scattered light cannot be detected, and the nozzle defect on the conveying belt cannot be detected accurately.

  The present invention has been made in view of the above circumstances, and detects nozzle defects with high accuracy during the operation of the conveyor belt without being affected by vibration or deflection during the operation of the conveyor belt. It is an object of the present invention to provide a recording apparatus and an ink droplet detection method that can perform this.

  The present invention employs the following configuration in order to achieve the above object.

  The present invention has a print head unit having a plurality of print heads, and discharges ink droplets from nozzle openings of the print head so as to print on a recording sheet conveyed by the convey belt. A recording apparatus for detecting defective ejection of the ink droplets during operation, the detecting means for detecting ejection of the ink droplets, and a movement for moving the print head unit in a direction perpendicular to the conveyance direction of the recording paper A drive control unit that controls the drive of the moving mechanism; and a discharge detection control unit that controls a discharge failure detection process of the ink droplet using the detection unit. Upon receiving a print instruction for the recording paper, the print head unit is moved by the moving mechanism so as to widen the gap between the nozzle opening and the transport belt. , The discharge detection control means performs the ejection failure detection process after the movement of the print head unit by said moving function has been completed.

  Further, in the recording apparatus of the present invention, the detecting means includes a light emitting means for irradiating a laser beam between the print head unit and the conveyor belt, and a signal having a level corresponding to the amount of light received by receiving the laser light. And a light receiving means for outputting, wherein the moving mechanism moves the print head unit such that a distance between the conveyance belt and the optical axis of the laser beam is larger than a bending width of the conveyance belt.

  In the recording apparatus of the present invention, the light receiving means is disposed on the optical axis of the laser beam.

  In the recording apparatus of the present invention, the light receiving means is disposed at a position shifted from the optical axis of the laser light.

  In the recording apparatus of the present invention, the moving amount of the print head unit can be set by the moving mechanism.

  In the recording apparatus according to the aspect of the invention, the drive control unit may return the position of the print head unit to the position before the movement by the movement mechanism by the movement mechanism after the ejection failure detection process is completed.

  The present invention has a print head unit having a plurality of print heads, and discharges ink droplets from nozzle openings of the print head so as to print on a recording sheet conveyed by the convey belt. An ejection failure detection method by a recording apparatus, comprising: a detecting unit that detects ejection of the ink droplets during operation; and a moving mechanism that moves the print head unit in a direction perpendicular to a conveyance direction of the recording paper. A drive control procedure for controlling the drive of the moving mechanism, and a discharge detection control procedure for controlling a discharge failure detection process for the ink droplet using the detection means. In the drive control procedure, the recording paper The print head unit is moved by the moving mechanism so as to widen the gap between the nozzle opening and the conveyor belt. Are allowed, in the discharge detection control procedure performs the ejection failure detection process after the movement of the print head unit by said moving function has been completed.

  According to the present invention, it is possible to detect nozzle defects with high accuracy during the operation of the conveyor belt without being affected by vibrations or deflection during the operation of the conveyor belt.

It is a figure for demonstrating the recording device of 1st embodiment. It is a figure explaining the system configuration | structure of the recording device of 1st embodiment. It is a figure explaining the detection means in 1st embodiment. It is a figure which shows an example of the drive signal of a print head, and the waveform of the output of a photodiode. It is a figure explaining the discharge defect detection process in the printing position of a print head unit. 6 is a flowchart for explaining ejection failure detection processing in the printing apparatus according to the first embodiment. It is a figure which shows the printing state by the print head unit of 1st embodiment. It is a figure explaining the bending width of a conveyance belt. It is a figure explaining the state which has a print head unit on a maintenance unit. It is a figure for demonstrating the recording device of 2nd embodiment.

The present invention moves the print head unit so as to widen the gap between the print head unit and the conveyance belt when performing ejection failure detection processing for detecting nozzle defects.
(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining a recording apparatus according to the first embodiment.

  In the recording apparatus 100 of the present embodiment, a print head unit 110 corresponding to a print width fixed on a line is disposed, and printing is performed on a recording sheet (not shown) that has been conveyed. The recording apparatus 100 of this embodiment is also called a line printer, for example.

  The recording apparatus 100 of this embodiment includes a drive unit 120, a print head 130, a maintenance unit 140, a paper feed unit 150, a paper discharge unit 160, a transport belt 170, a waste liquid unit 180, and an air adsorption fan 190. The drive unit 120 moves the print head unit 110 in the Y1-Y2 direction. The print head 130 is a print head that the print head unit 110 has.

  In the recording apparatus 100 of the present embodiment, the ejection failure detection process of the print head 130 is performed while rotating the conveyor belt 170 before the start of printing. The conveyance belt 170 of the present embodiment is provided with a suction hole for adsorbing the recording paper. In the present embodiment, when the ejection failure detection process is performed, the ink droplets are ejected in synchronization with the movement of the suction holes so that the ink droplets are sucked into the suction holes.

  Hereinafter, the configuration of the recording apparatus 100 of the present embodiment will be further described.

  The print head unit 110 according to the present embodiment includes a detection unit that detects ejection defects of the plurality of print heads 130. Details of the detection means will be described later.

  The print head unit 110 according to the present embodiment is installed so as to be movable in the Y1-Y2 direction by a moving mechanism including a wire 111 and a motor 112. The motor 112 is driven by the drive unit 120. The drive unit 120 is controlled by a drive control unit described later.

  The print head unit 110 according to this embodiment includes a plurality of print heads 130 that discharge yellow (Y), cyan (C), magenta (M), and black (Bk) inks. The plurality of print heads 130 are arranged side by side in the conveyance direction of the recording paper, and are mounted so that the ink discharge direction is in the Y2 direction. Note that the number of ink colors and the arrangement order with respect to the conveyance direction of the recording paper are not limited thereto.

  The print head unit 110 of this embodiment is equipped with sub tanks (not shown) for each color for supplying each color ink to a plurality of print heads 130. Ink is replenished and supplied to the sub tank from an ink cartridge mounted in a cartridge loading section (not shown) via an ink supply tube (not shown). The cartridge loading unit is provided with a supply pump unit (not shown) for feeding ink in the ink cartridge (ink tank).

  The print head unit 110 stands by in a state where the nozzle openings are closed (capped) in the maintenance unit 140 in order to prevent ink from drying in the nozzle openings of the print head 130.

  In the present embodiment, when the user issues a print instruction, the print head unit 110 releases the state capped by the maintenance unit 140 and moves to the home position for starting printing. Printing is usually performed with the print head unit 110 fixed at the home position.

  When printing is completed, the recording apparatus 100 moves the print head unit 110 to above the maintenance unit 140 to cap the nozzle opening, and sets the standby state. In the recording apparatus 100 according to the present embodiment, the nozzle opening is capped by the maintenance unit 140 when printing is not performed for a long time or when the power is turned off.

  The paper feed unit 150 has a paper feed tray in which recording paper is stored. When printing is instructed and discharge failure detection processing is completed, the paper feed unit 150 separates and feeds the paper one by one from the paper feed tray. The paper feed tray of the present embodiment is configured to be applicable to any paper size, so that when the paper is set, the sensor detects the paper size and the paper direction (vertical or horizontal). It has become. Also, it is possible to detect an error when the paper runs out or during feeding. Further, in the case of continuous printing, the interval between sheets can be changed and can be adjusted each time according to the sheet size and the conveyance speed (printing speed).

  The recording paper fed from the paper feeding unit 150 is sucked to the transport belt 170 from the suction hole by the air suction fan 190 and transported one by one. When the recording paper passes through the print head unit 110, ink is ejected from the print head 130 to print characters and images. The recording paper for which printing has been completed is conveyed to the paper discharge unit 160 and accumulated in the paper discharge tray.

  The waste liquid unit 180 is for storing the waste liquid ink discharged on the conveyor belt 170 during the discharge failure detection process. The waste liquid unit 180 is disposed at a predetermined position below the print head unit 110. Normally, when the accumulated amount of waste liquid exceeds a predetermined amount, the waste liquid unit 180 detects this by a sensor and prompts the user to discard.

  Next, the system configuration of the recording apparatus 100 of the present embodiment will be described with reference to FIG. FIG. 2 is a diagram illustrating a system configuration of the recording apparatus according to the first embodiment.

  The recording apparatus 100 according to the present embodiment includes a head control board 200, a paper feed / conveyance control unit 210, a maintenance / supply control unit 220, and USB (Universal Serial Bus) converters 230 and 240. The head control board 200, the paper feed / conveyance control unit 210, and the maintenance / supply control unit 220 of this embodiment are connected to a personal computer (hereinafter referred to as PC) 300, which is an information processing apparatus, via a USB, for example. In the present embodiment, data and commands are exchanged between the PC 300 and each unit by USB communication.

  The head control board 200 of this embodiment controls the print head 130 included in the print head unit 110. In this embodiment, ten print heads 130 arranged on a line are controlled by one head control board 200, but the present invention is not limited to this. The number of print heads 130 controlled by one head control board 200 may be determined by, for example, the print size.

  The sheet feeding / conveying control unit 210 according to the present embodiment controls the sheet feeding unit 150 to feed the recording sheet from the sheet feeding tray, and controls the driving unit of the conveying belt 170 to convey the recording sheet. The maintenance supply control unit 220 of this embodiment controls the maintenance unit 140 to perform maintenance of the print head unit 110 and supply ink to the print head unit 110.

  In this embodiment, the sheet feed control unit 210 and the maintenance supply control unit 220 communicate with each other by RS232C (Recommended Standard 232). However, in order to achieve commonality, the RS232C is converted to USB by the USB converters 230 and 240. ing. The USB converters 230 and 240 can be realized by, for example, a commercially available conversion cable. In the present embodiment, this enables the PC 300 and each unit to perform USB communication. The PC 300 recognizes each connected unit as a different USB device, assigns each identification ID, and communicates and controls each unit. It can be performed.

  Next, a configuration for performing the ejection failure detection process in the recording apparatus 100 of the present embodiment will be described.

  The head control board 200 according to this embodiment includes a discharge detection control unit 201. The paper feed conveyance control unit 210 according to the present embodiment includes a drive control unit 211.

  The discharge detection control unit 201 according to the present embodiment receives an instruction to execute a discharge failure detection process, and controls a detection unit provided in the print head unit 110 to detect the presence or absence of a print head 130 with discharge failure. The drive control unit 211 of the present embodiment controls the drive unit 120 to drive the motor 112 to wind up the wire 111 and move the print head unit 110 in the Y1 direction.

  The discharge detection control unit 201 according to the present embodiment notifies the drive control unit 211 that the discharge detection process is started upon receiving an instruction to execute the discharge failure detection process. Upon receiving this notification, the drive control unit 211 instructs the drive unit 120 to drive the motor 112 and drives the motor 112. The drive control unit 211 notifies the ejection detection control unit 201 when the print head unit 110 is moved to a predetermined position by driving the motor 112. Upon receiving this notification, the discharge detection control unit 201 starts discharge failure detection processing. In the present embodiment, the execution instruction for the ejection failure detection process is issued by the user from the PC 300, for example.

  When the ejection failure detection process ends, the ejection detection control unit 201 notifies the drive control unit 201 of this. Upon receiving this notification, the drive control unit 201 controls the drive unit 120, drives the motor 112, moves the print head unit 110 in the Y2 direction, and returns it to the original position.

  In the present embodiment, the motor 112 is, for example, a stepping motor. When the motor 112 is a stepping motor, the drive control unit 211 controls the rotation of the motor 112 and the moving distance of the print head unit 110 according to the number of drive pulses. The motor 112 may be a DC motor.

  Next, detection means provided in the print head unit 110 of the present embodiment will be described with reference to FIG. FIG. 3 is a diagram for explaining detection means in the first embodiment. FIG. 3 is a view of FIG. 1 as viewed from the direction of arrow A, FIG. 3A is a diagram for explaining the case of detecting discharge by direct light, and FIG. 3B is a view of detecting discharge by indirect light. It is a figure explaining a case.

  The print head 130 according to the present embodiment includes, for example, an ink liquid chamber to which ink liquid is supplied and a nozzle opening for discharging ink droplets supplied to the ink liquid chamber. Piezo elements are formed at opposing positions. The print head 130 drives the piezo element to vary the pressure in the ink liquid chamber and causes ink droplets to be ejected from the nozzle openings. A large number of ink liquid chambers having ink openings are formed in one print head 130 based on the resolution of the recording apparatus 100.

  The size of the ink droplet can be changed by a drive signal applied to the piezo element. For example, when a large droplet having a large ink droplet size is ejected from the nozzle opening, several small droplets are merged to create a large droplet. The ejected ink droplets land on the recording paper 131 and an image is recorded.

  In the present embodiment, as detection means, light emitting means for irradiating laser light between the nozzle opening of the print head 130 and the conveyor belt 170 (hereinafter referred to as gap G), and light reception for receiving the emitted laser light. Means. Specifically, in this embodiment, a laser diode 132 is disposed as a light emitting unit, and a photodiode 133 is disposed as a light receiving unit. The laser diode 132 and the photodiode 133 are arranged so that the laser beam is orthogonal to the conveyance direction of the recording paper 131. The laser diode 132 of the present embodiment is included in the light emitting unit, and the photodiode 133 is included in the light receiving unit. The light emitting unit and the light receiving unit will be described later.

  The photodiode 133 converts the detected amount of laser light into a current, and various types are used depending on the intended use. In this embodiment, the light amount of the laser beam detected by the photodiode 133 is converted into a voltage on the circuit. However, since the output level is usually low, it is amplified by an operational amplifier or the like and raised to a predetermined voltage level. It is common. Thereby, the waveform detected by the photodiode 133 can be acquired, and the ink droplet can be detected electrically.

  In the present embodiment, a collimating lens 134 for condensing the laser beam is provided immediately after the laser diode 132, and an aperture 135 for reducing the beam diameter is further provided. The shape of the aperture 135 may vary depending on the intended use, but a shape having a circular hole is usually used.

  As a method for detecting ejection, there are a method for directly detecting laser light emitted from the laser diode 132 and a method for detecting scattered light scattered by reflection of the laser light emitted from the laser diode 132.

  FIG. 3A shows an example using direct light. In this case, the photodiode 133 is disposed on the optical axis of the laser light emitted from the laser diode 132. The waveform of the output of the photodiode 133 decreases when the laser beam is blocked by the passage of the ink droplet. The discharge detection control unit 201 of the present embodiment determines whether or not there is a discharge failure based on the change in the voltage level.

  FIG. 3B shows an example using indirect light. In this case, the photodiode 133 is disposed at a position shifted from the optical axis of the laser light emitted from the laser diode 132. When indirect light is used, when the ink droplet is ejected, the laser light is reflected by the ink droplet and becomes scattered light. When the photodiode 133 receives this scattered light, the voltage level of the waveform of the output of the photodiode 133 rises. Further, when ink droplets are not ejected, the photodiode 133 does not detect the laser beam and therefore does not output a voltage. Therefore, it turns out that it is a discharge defect.

  Hereinafter, the drive signal of the print head 130 and the waveform of the output of the photodiode 133 when ink droplet ejection is detected in the recording apparatus 100 of the present embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating an example of a drive signal of the print head and an output waveform of the photodiode. FIG. 4 is a diagram corresponding to an example using indirect light. The example shown in FIG. 4 is a waveform for simply ejecting a single droplet, and the ejection cycle is variable.

  In this embodiment, when an H level drive signal is supplied from the head control board 200 to the piezo elements formed on the print head 130 of the print head unit 110, the piezo elements are deformed and ink drops are caused by pressure fluctuations in the ink liquid chamber. Is discharged. When the ink droplet is ejected, the laser light emitted from the laser diode 132 is reflected by the ink droplet and becomes scattered light. Since the photodiode 133 receives the scattered light and outputs a signal corresponding to the amount of received light, ejection of ink droplets is detected in the example of FIG.

  For example, in the example of FIG. 4, the discharge detection control unit 201 of the present embodiment determines that there is no discharge failure from the output waveform of the photodiode 133. For example, if a signal corresponding to the amount of received light is not output in the waveform of the photodiode 133, the discharge detection control unit 201 determines that there is a discharge failure (nozzle defect).

  Next, the ejection failure detection process at the print position of the print head unit 110 of the present embodiment will be described. FIG. 5 is a diagram illustrating ejection failure detection processing at the print position of the print head unit. FIG. 5 is an example in the case of using direct light, and is a view of FIG. 1 viewed from the direction of arrow A.

  In the print head unit 110 of this embodiment, a light emitting unit 136 is mounted on one end and a light receiving unit 137 is mounted on the other end.

  The light emitting unit 136 and the light receiving unit 137 of the present embodiment are attached so that the optical axis of the laser light emitted from the laser diode 132 is adjusted within the gap G. The light emitting unit 136 and the light receiving unit 137 of the present embodiment are usually attached using an attachment jig or the like.

  Further, the print head unit 110 of the present embodiment is provided with wires 111 at four points, and moves in the Y1-Y2 direction by winding the wires 111 by the four motors 112.

  In this embodiment, when the print head unit 110 is at the print position and an instruction to start printing and an execution instruction for ejection failure detection processing are made, the print head unit 110 is lifted by the motor 112 and the wire 111 and moved in the Y1 direction. Increase the width of G. In the present embodiment, the print head unit 110 is moved so that the normal gap G is about 1 mm and the moved gap G is 2 to 3 mm. That is, in the present embodiment, the print head unit 110 is lifted and the gap G is widened only when the ejection failure detection process is performed. When the print head unit 110 is lifted, the ejection detection control unit 201 ejects ink droplets for ejection failure detection onto the transport belt 170.

  Next, the ejection failure detection process in the recording apparatus 100 of the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart for explaining ejection failure detection processing in the printing apparatus according to the first embodiment.

  In the recording apparatus 100, when receiving a print start instruction from the PC 300, the head control board 200 moves the print head unit 110 to the print position (step S61). Next, when the printing apparatus 100 receives a print start instruction, the printing apparatus 100 instructs the paper feed conveyance control unit 210 to move the print head unit 110 from the discharge detection control unit 201. In response to this instruction, the supply transport unit 210 controls the drive unit 120 by the drive control unit 211 to drive the motor 112, and moves the print head unit 110 in the Y1 direction (upward as viewed from the transport belt 170) (step S62). ).

  In this embodiment, the movement amount of the print head unit 110 is set in advance in the drive control unit 211. For example, when the motor 112 is a stepping motor, the amount of movement of the print head unit 110 is determined by the number of pulses. Further, the movement amount of the print head unit 110 may be variable.

  Note that the recording apparatus 100 of the present embodiment may notify the PC 300 of this after the print head unit 110 has moved to the print position in step S61. The PC 300 may display a screen that allows the user to select whether or not to execute the ejection failure detection process in response to the notification of the completion of the movement of the print head unit 110. When the execution of the ejection failure detection process is instructed on this screen, this instruction may be notified to the head control board 200 and the supply / discharge unit 210.

  When the print head unit 110 moves upward in step S62 and the gap G increases to about 2 mm, the drive control unit 211 notifies the head control board 200 of the completion of movement of the print head unit 110. In the head control board 200, the ejection detection control unit 201 receives this notification and starts executing the ejection failure detection process (step S63).

  Specifically, the ejection detection control unit 201 irradiates laser light from the light emitting unit 136 and ejects ink droplets from the nozzle openings of the print head 130. Then, the light receiving unit 137 acquires the output waveform of the photodiode 133. Then, it is determined whether or not there is a discharge failure.

  Subsequently, the discharge detection control unit 201 determines whether or not to end the discharge failure detection process (step S64). If it is determined in step S64 that the discharge failure detection process is to be terminated, the discharge detection control unit 201 notifies the drive control unit 211 of this. Upon receiving this notification, the drive control unit 211 controls the drive unit 120 to restore the position of the print head unit 110 by the motor 112 (step S65). Specifically, the drive control unit 211 moves the print head unit 110 in the Y2 direction (downward) so that the gap G is about 1 mm, and ends the process.

  The case where it is determined in step S64 that the ejection detection is not performed may be a case where the print head 130 is cleaned and the ejection failure detection process is performed again, for example, when an ejection failure is detected.

  When the ejection failure detection process shown in FIG. 6 is completed, the recording apparatus 100 starts printing by the print head unit 110. FIG. 7 is a diagram illustrating a printing state by the print head unit of the first embodiment. In FIG. 7, it can be seen that the laser light is not irradiated from the light emitting unit 136, and the gap G is narrower than the gap G shown in FIG.

  As described above, in this embodiment, after the print head unit 110 is moved to the print position after receiving the print start instruction, the ejection failure detection process is performed while the transport belt 170 is rotated. Then, the print head unit 110 is lifted to widen the gap G.

  In this embodiment, with this configuration, it is possible to prevent the laser beam from being blocked due to bending during operation of the conveyance belt 170 and the like, and it becomes impossible to detect ejection failure, and influences vibration and bending during operation of the conveyance belt 170. Without receiving it, it is possible to detect nozzle defects on the conveyor belt 170 with high accuracy.

  In the present embodiment, the gap G is set to about 2 to 3 mm when the ejection failure detection process is executed. However, the present invention is not limited to this. The gap G of the present embodiment may be determined so that the processing from the conveyance belt 170 to the optical axis of the laser beam is larger than the bending width of the conveyance belt 170. The bending width of the conveyance belt 170 varies depending on the material of the conveyance belt 170, the belt length, and the like, and is a value determined in advance at the design stage of the recording apparatus 100. Further, when determining the bending width at the design stage, it is preferable to take into account the amount of bending due to deterioration of the conveying belt 170 or the like.

  FIG. 8 is a diagram illustrating the bending width of the conveyance belt. When the transport belt 170 is operated, bending is mainly generated at both ends of the transport belt 170. In the present embodiment, the gap G is widened so that the distance W1 between the optical axis S of the laser light emitted from the laser diode 132 and the surface of the conveyor belt 170 is larger than the deflection width W2 of the conveyor belt 170. did. If the distance W1> the width W2, the laser beam is not blocked by the bending of the conveyor belt 170, and a highly accurate ejection failure detection process can be performed while the conveyor belt 170 is rotating.

  In the present embodiment, it is preferable to provide an upper limit for the value of the gap G. The upper limit value is preferably a value at which the ink droplets ejected from the print head 130 do not protrude from the suction holes of the transport belt 170. In the present embodiment, for example, the upper limit value of the gap G may be about 10 mm.

  In addition, when printing by the print head unit 110 is completed, the recording apparatus 100 according to this embodiment moves the print head unit 110 to above the maintenance unit 140. In the recording apparatus 100 of this embodiment, the maintenance unit 140 may perform the ejection failure detection process when the print head unit 110 is at the print position. FIG. 9 is a diagram illustrating a state in which the print head unit is on the maintenance unit.

  In the recording apparatus 100 of the present embodiment, the maintenance unit 140 is provided with a cap 161 at a position corresponding to the nozzle opening of the print head 130. In the recording apparatus 100, when the print head unit 110 moves so that the nozzle opening of the print head unit 110 is positioned on the cap 161, the discharge detection control unit 201 performs a discharge defect detection process. The maintenance unit 140 performs a recovery operation such as cleaning of the print head 130.

  As described above, according to the present embodiment, it is possible to detect nozzle defects with high accuracy during the operation of the conveyor belt without being affected by vibration or deflection during the operation of the conveyor belt.

(Second embodiment)
A second embodiment of the present invention will be described below with reference to the drawings. The second embodiment of the present invention differs from the first embodiment only in the configuration of the maintenance unit. Therefore, in the following description of the second embodiment, only differences from the first embodiment will be described, and those having the same functional configuration as the first embodiment will be used in the description of the first embodiment. The same reference numerals as those used are assigned, and the description thereof is omitted.

  FIG. 10 is a diagram for explaining a recording apparatus according to the second embodiment. In the recording apparatus 100 </ b> A of the present embodiment, the maintenance unit 140 </ b> A is configured to move on the transport belt 170 and is fixed to the print position of the print head unit 110 on the transport belt 170. The print head unit 110 moves only in the Y1-Y2 direction.

  In the recording apparatus 100 </ b> A of the present embodiment, the maintenance unit 140 </ b> A is positioned between the print head unit 110 and the conveyance belt 170 when not printing, and caps the nozzle openings of the print head 130.

  Further, when an instruction to start printing is given to the recording apparatus 100A of the present embodiment, the maintenance unit 140A moves from the printing position toward the paper discharge unit 160 on the conveyance belt 170. Then, the print head unit 110 is moved in the Y2 direction, the processing from step S62 to step S65 in FIG. 6 is executed, and printing is performed.

  In this embodiment, the print head unit 110 is moved in the Y2 direction until the gap G is about 2 mm (position where the distance W1> the width W2), and when the ejection failure detection process is completed, the gap G is further about 1 mm. The print head unit 110 is moved in the Y2 direction. When printing is completed, the print head unit 110 is pulled up in the Y1 direction, and the maintenance unit 140A moves between the print head unit 110 and the conveyance belt 170.

  In the present embodiment, with the above configuration, within the range of control of the movement of the print head unit 110 during the normal printing operation, it is not affected by vibration or bending during the operation of the conveying belt, and is high during the conveying belt operation. It is possible to detect nozzle defects with high accuracy.

  As mentioned above, although this invention has been demonstrated based on each embodiment, this invention is not limited to the requirements shown in the said embodiment. With respect to these points, the gist of the present invention can be changed without departing from the scope of the present invention, and can be appropriately determined according to the application form.

100, 100A Recording device 110 Print head unit 111 Wire 112 Motor 120 Drive unit 130 Print head 132 Laser diode 133 Photo diode 136 Light emitting unit 137 Light receiving unit 140, 140A Maintenance unit 150 Paper feed unit 160 Paper discharge unit 170 Carry belt 180 Waste liquid unit 200 Head Control Board 201 Discharge Detection Control Unit 210 Paper Feed Transport Unit 211 Drive Control Unit

Japanese Patent Laying-Open No. 2005-119071 Japanese Patent Laying-Open No. 2005-007809

Claims (7)

A print head unit having a plurality of print heads, and during the operation of the transport belt immediately before printing on a recording paper transported by the transport belt by discharging ink droplets from the nozzle openings of the print head; A recording apparatus for detecting ejection failure of the ink droplets,
Detecting means for detecting ejection of the ink droplets;
A moving mechanism for moving the print head unit in a direction perpendicular to the conveyance direction of the recording paper;
Drive control means for controlling the drive of the moving mechanism;
Discharge detection control means for controlling discharge failure detection processing of the ink droplet using the detection means,
The drive control means includes
In response to a print instruction for the recording paper, the print mechanism unit is moved by the moving mechanism so as to widen the gap between the nozzle opening and the transport belt,
The discharge detection control means includes
A recording apparatus that performs the ejection failure detection process after the movement of the print head unit by the movement function is completed. The detection means includes
A light emitting means for irradiating a laser beam between the print head unit and the conveyor belt;
Light receiving means for receiving the laser light and outputting a signal of a level corresponding to the amount of light received,
The moving mechanism is
The recording apparatus according to claim 1, wherein the print head unit is moved so that a distance between the conveyance belt and the optical axis of the laser beam is larger than a bending width of the conveyance belt.   The recording apparatus according to claim 2, wherein the light receiving unit is disposed on an optical axis of the laser beam.   The recording apparatus according to claim 2, wherein the light receiving unit is disposed at a position shifted from an optical axis of the laser beam.   The recording apparatus according to any one of claims 1 to 4, wherein the moving amount of the print head unit can be set by the moving mechanism. The drive control means includes
The recording apparatus according to any one of claims 1 to 5, wherein after the ejection failure detection process is completed, the position of the print head unit is returned to a position before the movement by the movement mechanism by the movement mechanism. A print head unit having a plurality of print heads, and during the operation of the transport belt immediately before printing on a recording paper transported by the transport belt by discharging ink droplets from the nozzle openings of the print head; An ejection failure detection method by a recording apparatus, comprising: a detecting unit that detects ejection of the ink droplets; and a moving mechanism that moves the print head unit in a direction perpendicular to the conveyance direction of the recording paper.
A drive control procedure for controlling the drive of the moving mechanism;
A discharge detection control procedure for controlling discharge failure detection processing of the ink droplet using the detection means,
In the drive control procedure,
In response to a print instruction for the recording paper, the print mechanism unit is moved by the moving mechanism so as to widen the gap between the nozzle opening and the transport belt,
In the discharge detection control procedure,
A discharge failure detection method for performing the discharge failure detection process after the movement of the print head unit by the moving function is completed.

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