JP2007125747A - Liquid droplet jet device, liquid droplet jet system, method for detecting ejection of liquid droplet, and program for detecting ejection of liquid droplet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a time period for detecting ejection of all the nozzles on a liquid droplet ejection section in a liquid droplet jet device such as an inkjet recorder or the like. <P>SOLUTION: A light 113 from a light emitting device 102 is reflected by a front face 101a of a recording head to be incident on a photodetector device 103. The light is blocked by ink liquid droplets ejected from each of nozzles in a nozzle array 106, and then a voltage of a detection signal of an ejection detection sensor is changed. As the light intensity in a region through which the light passes is varied along the arrangement direction of the nozzle array 106 so that a change value of the voltage of the detection signal is varied depend on the position of the nozzle that ejects the ink liquid droplet. By using the reflected light, the change value is varied depending on the number of nozzles that eject the ink liquid droplets. When detecting the ejection, the nozzles are driven by N (an integer not smaller than 2) nozzles at every predetermined cycle Tc. Based on the change value of the voltage of the detection signal, it is judged whether or not the ink liquid droplet is ejected from each of the nozzles in each N nozzles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet discharge device having a droplet discharge portion that discharges droplets from a plurality of nozzles, such as an inkjet recording device, a droplet discharge system including this device and a control device that controls the device, and these liquids Droplet discharge detection method for detecting presence / absence (discharge / non-discharge) of droplets from each nozzle of a droplet discharge unit of a droplet discharge device and droplet discharge detection in a droplet discharge device or a droplet discharge system It is about the program.

  2. Description of the Related Art Inkjet recording apparatuses that perform image recording by ejecting ink droplets from a plurality of nozzles of a recording head to a recording medium are widely used. The inkjet recording apparatus has advantages such as low running cost, suitable for color recording, quiet sound during recording operation, downsizing of the apparatus, and stable acquisition of desired images. is there. On the other hand, non-ejection of the ink droplets from the nozzles of the recording head and so-called twist ejection in which the ejection direction is shifted may occur. This is due to clogging of the nozzle outlet due to dust, sticking with thickened ink, disconnection of the heating element, and covering of the outlet with ink droplets in the case of using the thermal energy effect for ink ejection. Occur. Due to non-ejection or twist ejection, problems such as white stripes along the scanning direction of the recording head and image quality degradation due to missing dots occur.

  On the other hand, a method of detecting ejection / non-ejection of ink droplets by an ejection detection sensor (transmission type photointerrupter sensor) as an optical sensor composed of a light emitting element and a light receiving element is employed. Patent Documents 1 and 2 describe this. FIG. 13 shows the configuration of the detection unit of the discharge detection sensor.

  In FIG. 13, reference numeral 1301 denotes a recording head, and a plurality of nozzle rows 1305 in which a plurality of nozzles each ejecting ink droplets 1306 are arranged in a straight line are arranged on the front surface (lower surface in the drawing) 1301a. . Reference numeral 1307 indicates a flight path of the ink droplet 1306 normally ejected from the nozzles of the nozzle array 1305.

  Reference numeral 1302 denotes a light emitting element that emits detection light. Reference numeral 1303 denotes a light receiving element that receives light emitted from the light emitting element 1302. Reference numerals 1304 and 1304 ′ denote apertures (apertures) provided in the vicinity of the front surfaces of the light emitting element 1302 and the light receiving element 1303, and openings 1304a and 1304a ′ through which light passes are formed. Light 1309 emitted from the light emitting element 1302 enters the light receiving element 1303 directly through the openings 1304a and 1304a ′. Reference numeral 1310 denotes a total luminous flux of incident light. The area in the range of the arrow A through which the light beam 1310 passes is a detection area where detection is performed (hereinafter denoted by reference symbol A). The size of the cross section of the detection area A is limited by the size of the openings 1304a and 1304a ′. Since the ejected ink droplet 1306 is very small, limiting the size of the detection area A can increase the S / N ratio and increase the detection accuracy.

  Further, the optical axis connecting the light emitting element 1302 and the light receiving element 1303 is arranged to be parallel to the nozzle row 1305 of the recording head 1301. By doing so, when the ejection detection of each nozzle is performed for each row, it is not necessary to move the recording head or the ejection detection sensor during the detection of one row.

  At the time of detection, the recording head 1301 or the sensor is moved to a position where one nozzle row 1305 is directly above the detection area A. Then, each nozzle of the one nozzle row 1305 is sequentially driven one by one to discharge ink droplets 1306 one by one. For example, when the ejected ink droplet 1306 travels on a normal flight path 1307 and passes through the light beam 1310 in the detection area A to be shielded, the amount of light received by the light receiving element 1303 changes and the output changes. The ejection / non-ejection of each nozzle is detected based on the detection signal obtained by converting the output. Actually, the ink droplet 1306 is separated into a main droplet and a satellite immediately before and after the ejection, and each passes back and forth through the light beam 1310.

  FIG. 14 shows signal waveforms of the nozzle drive signal 1401 and the detection signal 1402 when the ejection frequency (nozzle drive frequency) of the recording head is 1 KHz. One nozzle is driven at the falling edge of the drive signal 1401 to eject ink droplets. Thereafter, a change in the voltage of the detection signal 1402 as shown in the figure appears due to light shielding of the flying ink droplet. Note that, here, the case where the voltage level of the detection signal 1402 is lowered when the light amount is reduced due to light shielding is shown due to the circuit configuration.

FIG. 15 schematically shows where the ink droplets exist in the detection area A at points (a), (b), and (c) in FIG. FIG. 15A shows the timing when the main droplet 1306a flying in the head of the ink droplet starts to cross the detection area A. Thereafter, the detection signal reaches a peak. At the point (b) at that time, it is estimated that the main droplet 1306a is at the center position where the light intensity is the strongest in the light beam 1310, or the light shielding amount including the following satellite is the largest. After that, the detection signal returns to the original state through the point (c) (the signal level increases), but the return method is gentler than that at the time of the rise (the signal level decreases). This is due to the influence of the satellite 1306b shown in FIG. Since the satellite 1306b is smaller in size and slower in flight speed than the main droplet 1306a, such a waveform is obtained. Note that changes in the detection signal as shown in FIG. 14 are obtained at intervals of a period corresponding to the ejection frequency of the ink droplets.
JP 08-332735 (FIG. 4, paragraphs [0044], [0045]) Japanese Patent No. 3368194 (FIG. 2, paragraphs [0035] to [0039])

  In recent years, in an ink jet recording apparatus, the number of nozzles of a recording head has been greatly increased in order to achieve high speed and high image quality. For this reason, the time required to detect the presence / absence of ejection of all the nozzles is increased as compared with before. In order to shorten the detection time, it is sufficient to simply increase the ejection frequency (shorten the ejection cycle) to shorten the time taken to detect one nozzle. However, in the conventional configurations such as Patent Documents 1 and 2, if the ejection frequency is increased excessively, detection becomes impossible even if the ejection itself is within a possible range. This will be described with reference to FIGS.

  FIGS. 16A and 16B show the waveforms of the respective detection signals when the discharge frequency is 5 KHz and 10 KHz in the configuration of the conventional discharge detection sensor as shown in FIG. Compared with FIG. 14, the ejection frequency is 5 times and 10 times. In the case of 10 kHz, it can be confirmed that a detection signal corresponding to the ejection frequency is not obtained. At this time, the ejection speed (flying speed) of the ink droplets is about 10 m / sec, and the size of the detection area is 2 × 4 mm (vertical × horizontal). The time required to pass through the detection area is theoretically 200 μsec, and the limit ejection frequency that can ensure that there is always only one ink droplet in the detection area (does not fly) is 5 KHz. Become. When the detection is impossible, since it is driven at a discharge frequency of 10 KHz that is twice that, a plurality of ink droplets (a plurality of main droplets 1306a and satellites 1306b are included in the detection area A, as schematically shown in FIG. ) Are present (flying) at the same time. As a result, the light shielding area is averaged, and the detection signals are also averaged, making detection difficult.

  There is also a method of reducing the size of the detection area and shortening the light shielding time (passing time). However, the amount of light received decreases, so the S / N decreases and the detection accuracy decreases. On the other hand, there is a method using a laser having a high light output, but the laser is considerably expensive in comparison with an LED.

  As another means for reducing the detection time, a configuration in which a plurality of ejection detection sensors are provided and the presence or absence of ejection of ink droplets from a plurality of nozzles at the same time is detected by each sensor is also conceivable. However, this also increases the cost. In addition, the limitation of the space for installing a plurality of sensors is also a problem.

  Such a problem is not limited to an ink jet recording apparatus, but includes a droplet discharge unit provided with a plurality of nozzles that discharge droplets, and a discharge detection sensor that detects whether or not droplets are discharged from the plurality of nozzles. This is common to the liquid droplet ejection apparatus having the same.

  An object of the present invention is to reduce the time required to detect the presence or absence of ejection of all nozzles of a droplet ejection section in the above-described droplet ejection device or a droplet ejection system comprising this device and a control device that controls the device. In other words, the detection accuracy can be improved, and the cost of the droplet discharge device can be reduced.

In order to solve the above problems, the present invention provides:
A droplet discharge device (or a droplet discharge system comprising this droplet discharge device and a control device for controlling the droplet discharge device) having a droplet discharge portion in which a plurality of nozzles each discharging droplets are provided on one surface. ,
A light-emitting element and a light-receiving element arranged opposite to each other in the vicinity of the one surface of the droplet discharge unit, and light emitted from the light-emitting element and incident on the light-receiving element is shielded by the droplets discharged from the plurality of nozzles A discharge detection sensor configured to output a detection signal in which the voltage is changed and the change value of the voltage varies depending on the position and the number of nozzles that discharge the liquid droplets;
Drive control means for simultaneously driving or substantially simultaneously driving the plurality of nozzles by N, which is an integer of 2 or more, at a predetermined period Tc at the time of discharge detection for detecting the presence or absence of droplet discharge from the plurality of nozzles;
At the time of the discharge detection, there is a determination means for determining the presence or absence of droplet discharge from each of the N nozzles based on the voltage change value of the detection signal output from the discharge detection sensor for each cycle Tc. It is characterized by that.

  In the present invention, the configuration of the droplet ejection detection method and droplet ejection detection program of the droplet ejection device or droplet ejection system corresponding to the configuration of the droplet ejection device or droplet ejection system of the present invention is adopted. .

  According to the present invention, at the time of discharge detection, N nozzles are driven at a cycle Tc similar to the conventional case where the nozzles are driven one by one as in the prior art, and the liquid from each nozzle is driven N times. Since the presence / absence of droplet ejection can be reliably detected, the time required to detect the presence / absence of ejection of all the nozzles of the droplet ejection unit can be greatly reduced. In addition, since the change value of the detection signal in the case of normal ejection by driving N nozzles simultaneously or almost simultaneously becomes larger than that in the case of normal ejection by driving one nozzle alone as in the prior art, The S / N ratio is improved, the detection accuracy can be improved, and the cost can be reduced by using an inexpensive LED or the like for the light emitting element.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, an embodiment of an ink jet recording apparatus as a liquid droplet ejection apparatus that ejects ink droplets from a recording head as a liquid droplet ejection section and records an image on a recording medium will be described. The ink jet recording apparatus according to the embodiment is, for example, a bubble jet (registered trademark) system, that is, an ink droplet from a nozzle by pressure of bubbles generated in ink in the nozzle by heat generated by a heater provided in each nozzle of the recording head. It is assumed that the method of discharging

  FIG. 2 is a schematic perspective view illustrating a schematic configuration of the ink jet recording apparatus (serial ink jet printer) according to the first embodiment. In FIG. 2, a guide rail 202 is installed in the recording apparatus main body 201 along the main scanning direction. A carriage 203 is slidably provided on the guide rail 202. On the carriage 203, cartridge-type recording heads 209, 210, 211, and 212 corresponding to a plurality of colors of ink, for example, four colors of black, cyan, magenta, and yellow, are detachably mounted. A predetermined number, for example, 320 nozzles (not shown) are formed on each front face (lower face in the drawing) of the recording heads 209 to 212 so as to be arranged as one nozzle line on a straight line along the sub-scanning direction. Has been. Since the recording heads 209 to 212 are mounted side by side in the main scanning direction, the nozzle rows are also arranged at intervals in the main scanning direction.

  As the carriage 203 reciprocates on the guide rail 202 by driving a main scanning motor (see FIG. 3), the recording heads 209 to 212 reciprocate along the main scanning direction.

  Further, a recording medium (paper) 204 is fed onto a platen 206 that regulates its recording surface flatly by an auto sheet feeder 208 provided on the back side of the recording apparatus main body 201, and is sub-scanned by a feed roller 207. It is conveyed to.

  While the recording heads 209 to 212 reciprocate along the main scanning direction, the respective nozzles are driven and ink droplets are ejected, whereby an image is recorded on the recording medium 204.

  Further, an ejection detection sensor 205 configured as an optical sensor (transmission type photo interrupter type sensor) is provided below a predetermined position outside the recording area at the left end in FIG. 2 of the moving range of the recording heads 209 to 212. . The ejection detection sensor 205 detects ejection / non-ejection of ink droplets from each nozzle in each nozzle row of the recording heads 209 to 212. Details of the discharge detection sensor 205 will be described later. Based on the detection result of the discharge detection sensor 205, discharge recovery control of the recording heads 209 to 212, non-discharge interpolation control for performing image recording by using other nozzles instead of non-discharge nozzles, and the like are performed. . Thereby, it is possible to always realize good image recording.

  FIG. 3 shows the configuration of the control system of the ink jet recording apparatus of this embodiment. In FIG. 3, the recording head 101 is a combination of all the recording heads 209 to 212 in FIG. Hereinafter, in order to simplify the description, the recording head 101 will be described as an integral unit. The recording head 101 is provided with a plurality of nozzle rows corresponding to a plurality of colors. It is assumed that at least one nozzle row ejects ink droplets having a different size from the other nozzle rows. For example, a plurality of nozzle rows that eject ink droplets of the same color and different sizes are provided. A nozzle row that ejects ink droplets having a different color and a different color from the other nozzle rows may be provided. However, all the nozzles in the same nozzle row eject ink droplets of the same size.

  Reference numeral 302 denotes a recording head control circuit that electrically controls the recording head 101 and drives each nozzle according to image data to eject ink droplets.

  A discharge detection control circuit 304 converts a detection signal from the discharge detection sensor 205 into a discharge state signal indicating discharge / non-discharge (or normal discharge / discharge failure) for each nozzle.

  Reference numeral 305 denotes a CPU that executes a control program stored in the ROM 306 to control overall operations of each unit of the illustrated inkjet recording apparatus. The control program stored in the ROM 306 includes a discharge detection program for controlling the ink droplet discharge detection operation, which will be described later with reference to FIG.

  Reference numeral 307 denotes a RAM used for temporarily storing various parameters used in the process of the CPU 305 executing the control process and for storing image data and the like. Reference numeral 308 denotes a nonvolatile memory such as an EEPROM for storing information such as ejection detection results even when the apparatus power is off.

  Reference numeral 309 denotes an operation / display unit that provides information such as various switches for the user to perform necessary operations such as power-on and online / offline settings with the host PC (personal computer) 311 and the state of the apparatus. Is displayed to notify the user.

  A communication interface control unit 310 communicates with the PC 311 to transmit / receive image data, other commands, status signals, and the like. The PC 311 performs creation of data such as an image related to printing, printing processing, and the like, and supplies image data to the inkjet recording apparatus. Note that the control of the discharge detection operation described later may be performed by the control of the PC 311 by a control program such as a printer driver operating on the PC 311.

  Further, instead of the PC 311, image data may be input from a reader unit for an image reading device, an image input device such as a digital camera, or the like. Alternatively, the image data may be simply input from a recording medium such as a flash memory, a hard disk drive, or a magneto-optical disk that holds and stores the image data.

  Reference numeral 312 denotes a mechanism control circuit that controls and manages various motors 313 to 315, a recovery operation actuator 316, and a recovery operation sensor 317 described below.

  Reference numeral 313 denotes main scanning as a drive source for reciprocating the carriage 203 in FIG. 2 along the main scanning direction in order to scan the recording head 101 in the main scanning direction perpendicular to the paper feed direction (sub-scanning direction). It is a motor. Reference numeral 314 denotes a sub-scanning motor as a drive source for transporting the recording medium 204 in the sub-scanning direction. Reference numeral 315 denotes a recovery operation motor as a drive source for performing an ink suction operation from each nozzle in the recovery operation of a recovery processing unit (not shown) that recovers the ejection of the non-ejection nozzles of the recording head 101. Reference numeral 316 denotes a recovery operation actuator as a drive source for performing another recovery operation (such as wiping for wiping the front surface of the recording head). Reference numeral 317 denotes a recovery operation sensor for detecting the operation state of the recovery processing unit.

  In the above configuration, when the communication interface control unit 310 receives image data from the PC 311, the CPU 305 controls each unit in FIG. 3 to record an image according to the image data. An ejection detection operation for detecting whether or not ink droplets are ejected from each nozzle of the recording head 101 is performed.

  At that time, first, the main scanning motor 313 is driven to move the recording head 101 onto the ejection detection sensor 205, and one or a plurality of rows to be detected once in the nozzle row is the detection area of the sensor 205. Stop at a position directly above. Then, a drive signal is sent from the print head control circuit 302 to the print head 101, and each nozzle in the nozzle row to be detected is driven as described later to discharge ink droplets. At the same time, based on the detection signal from the ejection detection sensor 205 and the ink ejection timing signal from the recording head control circuit 302, the ejection detection control circuit 304 indicates the ejection status information (non-ejection nozzle information) for each nozzle. The signal is converted into a signal, and the information is temporarily stored in the RAM 307. In this example, the discharge state information is converted into a signal by the discharge detection control circuit 304. However, part or all of the conversion processing is realized by software processing by a program executed on the CPU 305. You may make it do. When the discharge detection of all the nozzles in the one or more rows is completed, the recording head 101 is moved to a position where the next detection target nozzle row is directly above the detection area of the discharge detection sensor 205. Thereafter, the discharge detection of the nozzle row to be detected is performed in the same manner.

  FIG. 1 is a conceptual diagram showing the configuration and arrangement of a detection unit including a light emitting element and a light receiving element of the discharge detection sensor 205, and shows a state in which the recording head 101 is at a detection position on the discharge detection sensor 205. . (A) is the figure seen toward the side surface of the recording head 101, (b) is the figure seen toward the front surface 101a which is a lower surface in (a). A direction perpendicular to the paper surface in (a) and one or both directions along the vertical direction in (b) are main scanning directions, and one direction along the left and right directions in (a) and (b) is one direction along the horizontal direction. This is the sub-scanning direction.

  On the front surface 101a of the recording head 101, a plurality of rows are arranged at intervals in the main scanning direction, including two rows in which the nozzle row 106 shown in (a) is denoted by reference numerals 106a and 106b as shown in (b). (6 rows here) are provided. Each nozzle row 106 has a predetermined number, for example, 320 nozzles arranged in a straight line at a minute predetermined interval along the sub-scanning direction.

  Reference numeral 102 denotes a light emitting element that emits light for detection. Here, although LED is assumed, the kind will not be ask | required if it can utilize as light sources, such as a semiconductor laser. Further, the wavelength of light emission is not particularly limited. However, since light is irradiated on the front surface 101a of the recording head 101 and reflected light is used for detection, directivity and an incident angle must be taken into consideration. Reference numeral 103 denotes a light receiving element that receives light emitted from the light emitting element 102 and assumes a photoelectric conversion element such as a photodiode.

  The light emitting element 102 and the light receiving element 103 sandwich an area near the lower side of the front surface 101a of the recording head 101 at the detection position (an area through which ink droplets discharged from each nozzle of the nozzle row 106 pass), It is arranged so as to face the sub-scanning direction at a predetermined position in the main scanning direction. In the vicinity of the front surfaces of the light emitting element 102 and the light receiving element 103, apertures 104, 104 'in which openings 104a, 104a' through which light passes are formed are provided. This is for improving the S / N ratio of the detection signal by reducing the cross-sectional area of the light incident from the light emitting element 102 to the light receiving element 103 because the light shielding area of the ink droplet is very small.

  In the present embodiment, only the reflected light beam 113 that is irradiated from the light emitting element 102 to the front surface 101a of the recording head 101, reflected by the front surface 101a, and incident on the light receiving element 103 is used for ejection detection. Therefore, the directions of the optical axes of the light emitting element 102 and the light receiving element 103 are along the sub-scanning direction (the nozzle arrangement direction of the nozzle row 106) when viewed from the front surface 101a as shown in FIG. However, as seen from the side of the recording head 101 as shown in FIG.

  In addition, a light shielding member 105 that shields direct light that is directed to the light receiving element 103 out of the light emitted from the light emitting element 102 is provided. As a result, only the reflected light beam 113 of the light emitted from the light emitting element 102 enters the light receiving element 103, and the influence of direct light is eliminated.

  Although the direct light is large in intensity, the light amount decreases as the distance from the light emitting element 102 increases, and the output voltage of the detection signal corresponding to the light decreases, indicating an almost theoretical value. For this reason, if the component by the influence of direct light can be subtracted from the obtained output voltage, it is not necessary to provide the light shielding member 105.

  Further, on the front surface 101 a of the recording head 101, a reflecting member 107 that reflects light with high reflectivity is provided around the plurality of nozzle rows 106. Here, a special member dedicated to the reflection member 107 is assumed. However, if a highly reflective member such as a flexible cable that conveys various signals to the recording head 101 covers the periphery of the nozzle row, if the reflected light sufficient for detection can be obtained as it is, a dedicated reflecting member May not be provided.

  The reflected light beam 113 incident on the light receiving element 103 is the total of the light beams reflected by the portions of the reflecting member 107 and incident on the light receiving element 103 out of the light emitted from the light emitting element 102. FIG. 1A shows two light beams 113a and 113b among the light beams. Reference numeral 113 a denotes a light beam that is reflected by the light emitting element 102 side end of the reflecting member 107 and enters the light receiving element 103. The light beam 113b is a light beam that is reflected and incident at the end of the reflecting member 107 on the light receiving element 103 side. The light beam 113 is a sum total of various light beams that are reflected by the respective parts of the reflecting member 107 including the light beams 113 a and 113 b and have different intensities incident on the light receiving element 103.

  Hereinafter, the region through which the light beam 113 passes is referred to as a detection area. Within the detection area, depending on the arrangement direction of the nozzles of each nozzle row 106, that is, the position in the sub-scanning direction in which the light emitting element 102 and the light receiving element 103 face each other, the amount of addition of the light intensity varies depending on the overlap of the light beams, The light intensity is different. The light intensity distribution in the nozzle array direction is made appropriate by varying the amount of reflected light by varying the reflectance depending on the part of the reflecting member 107. Specifically, the light intensity increases as the distance from the center of the nozzle array 106 approaches the nozzle array direction. As a result, it is possible to improve detection accuracy and increase the number of ink droplets that can be detected.

  The width of the detection area in the main scanning direction (the width in the same direction of the light beam 113) is limited by the width of the openings 104a and 104a 'of the apertures 104 and 104'. The width of the detection area is a width in which the nozzle row (one or a plurality of rows) to be detected once when the ejection detection is performed for each of the nozzle rows or for each of a plurality of rows fits. FIG. 1 shows a case where one detection target is two rows, and the width of the detection area is set so that two adjacent nozzle rows 106a and 106b can be accommodated.

  When the ejection of each nozzle in the nozzle rows 106a and 106b is detected, one nozzle at a position apart in the nozzle arrangement direction is simultaneously driven in the nozzle rows 106a and 106b every predetermined cycle Tc. For example, the nozzles 108 and 109 are driven simultaneously, and large-sized ink droplets 110 and 111 having a volume of, for example, 30 pl are ejected, respectively. In the case of normal ejection, the ink droplet 110 travels along the flight path 112 and passes through a portion having a high light intensity where the light beams 113a and 113b overlap in the detection area through which the light beam 113 passes. Further, the ink droplet 111 travels along the flight path 114 and passes through a portion with low light intensity where the light beams 113a and 113b do not overlap to block light. The presence or absence of ejection from the nozzles 108 and 109 is simultaneously detected based on the change in the voltage of the detection signal of the ejection detection sensor 205 in accordance with the change in the amount of light received by the light receiving element 103 due to this light shielding. Details thereof will be described later. The ink droplets 110 and 111 fly on the paths 112 and 114 and then land and be absorbed on a waste ink collection member (not shown) constituting the ejection detection sensor 205.

  Note that only one nozzle row may be detected at a time, and discharge detection is performed by simultaneously driving two nozzles whose positions in the nozzle arrangement direction are separated in the nozzle row for each period Tc. Good. In addition, if it is possible to separate the signal components for 3 drops or more by processing the detection signal, the width of the detection area is increased to make the detection target at least 3 rows, and one nozzle in each row is driven simultaneously. May be. Note that it is essential that all nozzle rows to be detected once fall within the width of the detection area, but nozzle rows that are not to be detected may exist within the width of the detection area. In that case, it is a matter of course that the nozzle rows within the width of the detection area are selected and driven so that the nozzle rows not to be detected are not driven at the time of detection. In addition, in the case where a single detection target is a plurality of rows, the size of the ink droplets ejected from each nozzle row is the same.

  FIG. 4 is a block diagram showing the configuration of the signal processing circuit of the ejection detection sensor 205.

  Reference numeral 401 denotes a light emitting unit including the light emitting element 102 in FIG. 1 and a circuit for driving the light emitting element 102. Reference numeral 402 denotes a control unit that controls driving of the light emitting unit 401. A light receiving unit 403 includes the light receiving element 103 in FIG. 1 and a circuit for driving the light receiving element 103. Reference numeral 404 denotes a current-voltage conversion unit for converting the photocurrent obtained by photoelectric conversion output from the light receiving element 103 of the light receiving unit 403 into a manageable voltage to obtain a detection signal. This can be constituted by an operational amplifier. Reference numeral 405 denotes an analog filter for removing disturbance noise and signal components other than a necessary band from the detection signal output from the current-voltage conversion unit 404.

  Reference numeral 406 denotes an amplifier circuit that amplifies a minute detection signal obtained through the filter 405. In order to stabilize the signal output, the output of the amplifier circuit 406 is fed back to the control unit 402. Reference numeral 407 denotes an A / D converter that converts an analog signal as a detection signal output from the amplifier circuit 406 into a digital signal. Reference numeral 408 denotes a detection determination unit that determines whether ink droplets are ejected or not based on a digital signal output from the A / D converter 407. Here, detection determination is performed after conversion to a digital signal, but a configuration may be adopted in which the determination is performed by comparing the levels at the time of the analog signal. The detection determination unit 408 corresponds to part or all of the ejection detection control circuit 304 in FIG. A part or all of the functions of the detection determination unit 408 may be performed by software processing of the CPU 305.

  With such a configuration, the change in the output current corresponding to the minute change in the amount of light received by the light receiving element 103 caused by the ink droplets ejected from the nozzles of the recording head 101 passing through the detection area and shielding the light beam 113 can be changed. The current-voltage conversion unit 404 converts it into a detection signal. Then, after removing noise and unnecessary band signal components from the detection signal by the filter 405, the detection signal is amplified by the amplifier circuit 406. Further, the A / D conversion unit 407 performs A / D conversion of the detection signal, and the detection determination unit 408 determines and detects ejection / non-ejection of ink droplets based on the digital signal.

  Next, the discharge detection method in the present embodiment will be described with reference to FIGS. In order to simplify the description, ejection detection is performed for each nozzle row, and two nozzles in the same nozzle row are simultaneously driven every predetermined cycle Tc, and ink droplets from the two nozzles are driven. A case where the presence / absence of discharge is simultaneously detected will be described.

  Each of the nozzle rows 106 provided on the front surface 101a of the recording head 101 shown in FIG. 5 is assumed here to have 320 nozzles arranged in one row at a minute predetermined interval along the sub-scanning direction. For convenience, it is assumed that the nozzles of each nozzle row are numbered in the order of arrangement from the light emitting element 102 side, and the positions of the nozzles No. 1, 161, and 320 of the nozzle row 106 are denoted by reference numerals (a), ( b) and (c).

  6 (a), 6 (b) and 6 (c) show normal ejection by detecting each of the nozzle positions (a), (b) and (c) in FIG. The respective detection signal waveforms in the case of The time on the horizontal axis is shown as 100 μs between the dotted lines of 1 cm.

  Reference numeral 601 denotes a drive signal for driving each nozzle, and the voltage level indicated by the arrow Ch3 on the vertical axis is 0V, and the distance between the dotted lines of 1 枡 is 2V. A trigger is activated at the falling edge of the drive signal 601, the heater provided in the nozzle generates heat, ink droplets are ejected from the nozzle, fly through the detection area, and shield the light beam 113, thereby detecting the detection signal 602. The voltage changes. In the detection signal 602, the voltage level indicated by the arrow Ch2 on the vertical axis is 0V, and the voltage between the dotted lines is 5V.

  The change value (pp value; hereinafter referred to as output voltage) of the detection signal 602 is about 13 V in (a), about 15 V in (b), and about 5 V in (c). Here, the sizes of the ink droplets ejected from each nozzle are all 30 pl, and although there are some errors depending on the nozzles, all can be regarded as the same size. Nevertheless, the output voltage is different because the light intensity of the detection area through which the ink droplets pass differs depending on the position in the nozzle arrangement direction. That is, the absolute amount of light amount change due to light shielding of a single ink droplet at each of the nozzle positions (a), (b), and (c) is different, and it appears as a difference in output voltage as it is.

  In FIG. 7, the horizontal axis represents the nozzle positions of all the nozzles in one nozzle array 106, and the vertical axis represents the output voltage in the case of normal ejection by independently driving the nozzles at each nozzle position by ejection detection. It is a graph showing the relationship between the two. Note that the detection signal waveform shown in FIG. 6 is a waveform of the detection signal in which the gain is increased so that the difference between the waveform and the output voltage becomes clear. FIG. 7 shows a result obtained by adjusting the output of the detection signal so that the output voltage becomes an appropriate value.

  As shown in FIG. 7, the output voltage increases as it approaches the center along the nozzle array arrangement direction, and the maximum output voltage is obtained in the vicinity of the center nozzle position (b). This is because the reflected light (light beams 113a, 113b, etc. in FIG. 1) before and after the nozzle row with a large amount of light intersect and overlap at the center. The output voltage is larger on the nozzle position (a) side closer to the light emitting element 102 (nozzle number) than on the (c) side closer to the light receiving element 103 because the light intensity is higher as the light emitting element 102 is closer. It is.

  In this example, since the nozzle array 106 is located in the center between the light emitting element 102 and the light receiving element 103 on the front surface 101a of the recording head 101, the maximum output is obtained at a position near the center of the nozzle array. . However, the peak location differs depending on the position of the nozzle row. Nevertheless, if the difference in light intensity depending on the detection position (nozzle position in the nozzle row) is clear, there is no problem in detection. However, when the detection accuracy or the number of ink droplets that can be detected is hindered, adjustment can be made by partially changing the reflectance of the reflecting member 107. That is, if the ratio of the reflected light in the portion closer to the light emitting element 102 seems to be too large, it can be dealt with by making the reflectance of the reflecting member 107 in that portion smaller than that in other portions. Although all the portions around the nozzle row 106 in the reflecting member 107 affect the light intensity distribution along the nozzle arrangement direction of the detection area, the dominant effect is that the light emitting element 102 side from the nozzle row 106 is affected. And a portion closer to the light receiving element 103 than the nozzle row 106.

  In this way, in the present embodiment, when each nozzle of one nozzle row is independently driven and discharge detection is performed, even if the size of the ink droplets discharged from each nozzle is the same, The output voltage of the detection signal is made different depending on the nozzle position of the nozzle.

  FIG. 8 shows a combination of two different nozzle positions (a), (b), and (c) in FIG. The waveforms of the drive signal 801 and the detection signal 802 are shown in the same format as in FIG. In FIG. 8, (a) + (b) shows nozzles with nozzle numbers 1 and 161, (b) + (c) shows nozzles with nozzle numbers 161 and 320, and (a) + (c) shows nozzle numbers 1 and 161. A case where 320 nozzles are simultaneously driven is shown. The output voltage of each detection signal 802 is about 20V in (a) + (b), about 20V in (b) + (c), and about 18V in (a) + (c). These values are significantly larger than any of about 13V in FIG. 6A, about 15V in FIG. 6B, and about 5V in FIG. 6C when each nozzle is driven independently. In particular, in (b) + (c) and (a) + (c), the values are almost the same as the sum of the output voltages in the respective cases. In this way, the output voltage when the two nozzles are driven at the same time and normal ejection is significantly larger than the output voltage when each of the two nozzles is driven independently and is normal ejection. , With a significant difference that can be clearly distinguished from the single case.

  Therefore, there is a significant difference that can be clearly distinguished in the output voltage between the case where the two nozzles are driven at the same time and both are normal ejection and the case where either one is non-ejection. Thereby, it can be determined from the output voltage whether both are discharged or one is not discharged. Further, in the case of non-ejection in both cases, the output voltage becomes zero, so that determination can be made. Further, since the output voltage varies depending on the nozzle position, when one of the nozzles does not discharge, it can be determined from the output voltage which one is not discharging. These determinations can be made by comparing the output voltage with an appropriate threshold voltage. In particular, in order to make it easy to determine which of the last nozzles does not eject, it is preferable to combine two nozzles that are driven at the same time so that the difference in output voltage due to the difference in the nozzle positions is as great as possible.

  By the way, in general, in a transmissive photointerrupter type ejection detection sensor, the magnitude of the output voltage is proportional to the light shielding area of the ink droplet. In the configuration in which only the direct light directly incident on the light receiving element from the light emitting element is used for detection as in the conventional example of FIG. 13, it can be regarded as one when a plurality of ink droplets are ejected simultaneously by simultaneous driving of a plurality of nozzles. A plurality of ink droplets overlap and shield the same part of the direct light beam in the same direction, and the light shielding areas overlap. For this reason, the output voltage is not much different from the case where each of the plurality of nozzles is driven independently and shielded by one ink droplet, and it is difficult to distinguish from the case, and the discharge detection cannot be performed sufficiently. Therefore, it is necessary to devise such as shifting the discharge timing of a plurality of nozzles.

  In contrast, in the present embodiment, the reflected light beam 113 in FIG. 1 is used for detection, and this light beam 113 is the sum of the overlapping of many reflected light beams whose directions are different from each other. Therefore, when performing discharge detection by simultaneously driving a plurality of nozzles, for example, two nozzles, the respective light-blocking areas can be selected by combining the positions of the respective nozzles so that the light-blocking light of each discharged ink droplet is different. Can be prevented from overlapping substantially. As a result, a sufficiently larger output voltage than that obtained when each nozzle is driven independently can be obtained, and discharge detection can be sufficiently performed even during simultaneous driving.

  FIG. 9 illustrates an example of a combination of two nozzles when ejection detection is performed by driving two nozzles simultaneously. In this example, first, as shown in (a) and (b), the nozzles of nozzle numbers 1 to 320 of the nozzle row 106 are equally divided into eight, and A, B, C, D, D ′, C in order of increasing nozzle numbers. Blocks are divided into ', B' and A '. One block is 40 nozzles. These 8 blocks are combined into 2 blocks as shown in (c). Here, each of the first half blocks A to D of the nozzle row and the second half blocks A 'to D' are combined without being adjacent to each other. That is, the nozzle positions are separated, and blocks having a large difference in output voltage at the time of ejection detection are combined. Then, as shown in No. 1 to No. 4, the order of driving of 4 groups is determined every 2 blocks.

  At the time of ejection detection, from the No. 1 block (A, C ′), one nozzle and one nozzle are sequentially driven every predetermined cycle Tc, and two nozzles are simultaneously driven to eject ink droplets and perform ejection detection. . Here, detection can be surely performed by combining blocks apart from each other. It should be noted that the blocks in the first half of the nozzle row or combinations of the blocks in the second half may be combined as in blocks A and C, but the light intensity is determined by combining the blocks in the first half and the blocks in the second half. The dominant reflected light is different from each other, and good detection can be performed even with simultaneous ejection.

  As described above, two nozzles in one nozzle row 106 can be simultaneously driven to reliably detect whether ink droplets are ejected from each nozzle. Basically, in the same manner as described above, the number of nozzle rows 106 to be detected is two, and each nozzle is driven at the same time, and whether or not ink droplets are ejected from each nozzle. Can be detected. Furthermore, it is possible to perform detection by setting one or a plurality of nozzle rows to be detected at a time and simultaneously driving three or more nozzles.

  Next, the entire ink droplet discharge detection operation in this embodiment will be described with reference to FIG. FIG. 10 is a flowchart illustrating a control procedure of the CPU 305 that controls the discharge detection operation. An ink droplet discharge detection program corresponding to the control procedure of this flowchart is stored in the ROM 306 and executed by the CPU 305. Note that a program corresponding to the ink droplet discharge detection program is included in a control program such as a printer driver for the PC 311 to control the ink jet recording apparatus of the present embodiment, and under the control of the PC 311 by the program. It is also possible to perform a discharge detection operation similar to the following.

  In the control procedure of FIG. 10, first, in step S <b> 1001, the recording head 101 is moved to the position on the ejection detection sensor 205 in the main scanning direction by driving the carriage 203, and becomes a detection target in the nozzle row 106 of the recording head 101. The head position is adjusted so that one or more nozzle rows are positioned directly above the detection area of the sensor 205.

  In step S1002, an integer of 2 or more (hereinafter referred to as N) nozzles in the nozzle row to be detected are simultaneously driven to eject ink droplets one by one. Here, if the N nozzles eject ink droplets normally, N ink droplets fly simultaneously in the detection area, and the reflected light flux 113 is shielded.

  The processing of steps S1003 to S1006 is performed by the detection determination unit 408, but may be performed by the CPU 305 by software.

  In step S1003, the output voltage value (hereinafter referred to as sensor output value) V0 of the detection signal of the ejection detection sensor 205 is grasped. That is, the digital value change value V0 indicating the voltage of the detection signal output from the A / D converter 407 is grasped.

  In step S1004, it is determined whether the sensor output value V0 has reached a predetermined first threshold value V1 (V0 ≧ V1). The threshold value V1 is a threshold value for determining whether the N nozzles that are simultaneously driven in step S1002 are normally ejected, and is determined in advance corresponding to the sensor output value when both N nozzles are normally ejected. Keep it. A plurality may be determined and used corresponding to the difference in sensor output value due to the difference in the combination of N nozzles. If V0 ≧ V1, the process proceeds to step S1005, and if not, the process proceeds to step S1006.

  In step S1005, it is determined that all the N nozzles driven in step S1002 are normally ejected, that is, ejection failure such as non-ejection or insufficient ejection near this (hereinafter simply referred to as ejection failure) has not occurred. To do.

  In step S1006, it is determined whether all of the N nozzles are defective in discharge, and if not, which are defective in discharge, and a defective nozzle is specified. Therefore, first, it is determined whether or not all N sensor output values V0 are less than the upper limit second threshold value V2 (V0 <V2). The threshold value V2 is smaller than the minimum sensor output value in the case of normal ejection when each of the N nozzles is driven independently. For this, only one set may be used, or a plurality may be set according to N combinations. If V0 <V2, all N nozzles are determined to be ejection failures.

  If V0 <V2, it is determined that any one of N is a discharge failure, and the sensor output value V0 is compared with a third threshold value V3 for determining which is a discharge failure. When N is 2, two threshold values V3 are used corresponding to the sensor output values when the two nozzles are driven independently and normal ejection is performed. When N is 3 or more, the threshold value V3 is set to N threshold values determined corresponding to the sensor output values when each of the N nozzles is independently driven to perform normal ejection. , And a plurality of threshold values determined corresponding to each of the sensor output values in the case of normal ejection by combining and driving a number smaller than N. By determining whether or not the sensor output value V0 has reached (V0 ≧ V3) in descending order of the plurality of threshold values V3, it is possible to determine which of the N nozzles is defective in ejection.

  When a defective nozzle is identified from the N nozzles in this way, information on the defective nozzle (nozzle row and nozzle number, etc.) is stored in the RAM 307.

  In step S1007, it is determined whether or not ejection detection has been completed for all nozzles in one or more nozzle rows that are currently detected. If completed, the process advances to step S1008. If not completed, the process returns to step S1002, and the processing of steps S1002 to S1007 is repeated to detect ejection of other N nozzles in the detection target nozzle row. The discharge detection of N nozzles by repeating steps S1002 to S1007 is performed at a predetermined cycle Tc.

  In step S1008, it is determined whether or not the ejection detection of all nozzle rows of the recording head 101 has been completed. If it has been completed, the process proceeds to step S1009. If not completed, the process returns to step S1001 to move the recording head 101 to position the next detection target nozzle row at the detection position directly above the detection area. Thereafter, the processes in steps S1002 to S1007 are repeated, and the discharge detection of N nozzles is repeated.

  In step S1009, the presence / absence of an ejection failure nozzle is confirmed based on the presence / absence of the ejection failure nozzle information stored in the RAM 307 in step S1006. Then, if there is no defective ejection nozzle, the process is terminated. If there is a defective discharge nozzle, the process proceeds to step S1010, and recovery control is performed to restore the normal discharge state of the defective discharge nozzle. For example, an operation of sucking ink from the nozzles of the recording head 101 by a pump (not shown), a preliminary ejection operation of removing ink or viscous ink fixed to the ejection failure nozzles, or wiping bounce ink or mist adhering to the front of the recording head Perform wiping, etc. After these recovery control operations, the discharge detection operation is performed again. Further, it is possible to specify a nozzle that cannot be recovered and to perform control such as non-ejection interpolation for performing alternative ejection with other nozzles.

  In the above, after the ejection detection of all the nozzles of all the nozzle rows of the recording head is completed, if there is a defective ejection nozzle, the recovery control is performed. On the other hand, it is also conceivable that the recovery control operation is performed immediately when at least one defective nozzle is found during discharge detection.

  According to the present embodiment as described above, the reflected light is used for detection by the ejection detection sensor 205, and the light intensity in the detection area through which the reflected light passes varies depending on the position of the nozzle row 106 in the arrangement direction. By doing so, even when N nozzles that are integers of 2 or more are driven at the same time, it is possible to reliably detect each discharge. Further, the detection cycle Tc can be set to the same length as the cycle in the case where the conventional discharge detection is performed for each nozzle. Since N detections can be performed at this cycle Tc, the time required to detect the ejection of all the nozzles of the recording head can be significantly shortened compared to the prior art. In addition, by shortening the detection time, it is possible to reduce the amount of preliminary discharge required for detection (recovery discharge for preventing ink from adhering to the nozzle outlet).

  Moreover, since the reflected light is used for detection, detection can be performed based on a change in detection signal due to light shielding of an ink droplet that has not yet been separated from the main droplet and satellite immediately after ejection. Therefore, the influence by the satellite can be avoided and the detection accuracy can be improved.

  In addition, in the case of normal ejection with simultaneous driving of N nozzles, the output voltage of the detection signal is significantly higher than in the case of normal ejection with single driving, so that the S / N ratio is also improved and detected from this point. Accuracy can be improved. In addition, the discharge detection sensor 205 can use an inexpensive LED for the light emitting element 102, and can use a sensor having a general configuration as it is without increasing the cost.

  In this embodiment, N nozzles are simultaneously driven at the time of ejection detection. However, the nozzles may be driven almost simultaneously at slightly different timings. However, the amount of timing deviation is within a range in which a period in which N ink droplets normally ejected from N nozzles driven almost simultaneously are simultaneously present (flying) in the detection area can occur. Shall be.

  Further, in this embodiment, the light shielding member 105 that shields the direct light that is going to be directly incident on the light receiving element 103 from the light emitting element 102 is provided. On the other hand, if the influence of the reflected light can be sufficiently predicted and the component due to the influence of the reflected light can be removed from the detection signal by the configuration of the signal processing circuit of the ejection detection sensor 205, it is not necessary to provide the light shielding member 105.

  In the present embodiment, the nozzle row 106 is positioned between the light emitting element 102 and the light receiving element 103 in the center of the front surface 1a of the recording head 1, but either the light emitting element 102 side or the light receiving element 103 side. It may also be in a position that is offset. However, since the position and size of the reflecting member 107 change, the light intensity distribution in the detection area in that case may be different from the content described in this embodiment. Even in that case, the same ejection detection is possible if the light intensity of the combined blocks can be discontinuous in the block division and combination of the nozzle row 106 for the combination of N nozzles that are driven simultaneously. It becomes.

  FIG. 11 illustrates the configuration of the discharge detection sensor according to the second embodiment of the present invention. In FIG. 11, portions common to or corresponding to those in FIG. The description of the part is omitted.

  The configuration of the ejection detection sensor of the second embodiment is substantially the same as that of the first embodiment, but the light shielding member 105 provided in the first embodiment is not provided. Of the light emitted from the light emitting element 102, the reflected light flux including the light fluxes 113a and 113b and the direct light flux 115 directed directly from the light emitting element 102 to the light receiving element 103 in parallel with the front surface 101a of the recording head 101. The light is incident on the light receiving element 103 through the openings 104a and 104a 'of the apertures 104 and 104'. In a normal ejection direction of ink droplets 108 and 109 (vertical direction in the figure), a region through which the direct light beam 115 passes and a region through which reflected light returning after protruding from there overlaps (hereinafter referred to as a direct light region). The width is indicated by the symbol W1. In addition, a width of an area between the direct light area and the front surface 101a through which only reflected light that protrudes from the direct light area (hereinafter referred to as a reflected light area) is indicated by a symbol W2. Here, for convenience, the width W1 of the direct light region is shown to be smaller than the width W2 of the reflected light region, but in reality, the width W1 is greater than the width W2. Other hardware configurations of the present embodiment are the same as those of the first embodiment, including configurations other than the ejection detection sensor.

  Under such a configuration, at the time of ejection detection, basically, similarly to the first embodiment, N (for example, 2) nozzles are simultaneously driven every predetermined cycle Tc, and N is determined based on the output voltage of the detection signal. The presence or absence of ejection from each nozzle is determined and detected. However, in this embodiment, the period Tc is set so that the influence of the direct light beam 115 on the ejection detection can be suppressed. Note that the setting of the cycle Tc is also the setting of the ejection frequency of N droplets (the driving frequency of N nozzles), which is the reciprocal thereof.

  The period Tc is shorter than the time T1 required for the ink droplets normally ejected from the nozzles to pass through the direct light region having the width W1, and is longer than the time T2 required to pass through the reflected light region having the width W2. Set to the length of. That is, T1> Tc> T2. Theoretically, T1 and T2 are T1 = W1 / S and T2 = W2 / S because of the normal ejection speed (flying speed) S of ink droplets and widths W1 and W2. For example, when the discharge speed S is 10 m / sec and the width W1 is 2 mm, the time T1 is 2 mm / 10 m / sec = 200 μsec.

  By setting T1> Tc, 2N or more ink droplets ejected by driving each of the N nozzles twice or more are present in the direct light region at the same time before and after the N droplets. Period) will occur. In particular, when (T1 / 2) Tc is set, 2N drops or more are always present. In such a case, the light blocking area of the direct light by the ink droplets is averaged, and the change in the voltage of the detection signal due to the light blocking of the direct light is also averaged and becomes smaller.

  Further, by setting Tc ≧ T2, there are always only N ink droplets ejected by driving N nozzles once in the reflected light region. As a result, the light-blocking area of the reflected light is not averaged by 2N or more ink droplets, and the change in the voltage of the detection signal due to the light-blocking of the reflected light is not averaged and appears clearly. become.

  In FIG. 12, as an example, the discharge speed S is 10 m / sec, the width W1 is 2 mm, the width W2 is about 0.5 mm (time T1 is 200 μsec, T2 is about 50 μsec), and the cycle Tc is 100 μsec (discharge frequency is 10 KHz). The waveform of the nozzle drive signal 1201 and the detection signal 1202 of the discharge detection sensor when discharge detection is performed is shown.

  Each time the drive signal 1201 falls at a cycle of 100 μsec, N nozzles are driven. The ejected ink droplets pass through the reflected light region and the direct light region and shield the light, whereby the voltage of the detection signal 1202 changes. First, a change due to shielding of reflected light appears, and then a change due to shielding of direct light appears. Here, the change due to the direct light shielding is significantly smaller than the change due to the reflected light shielding, so the waveform of the change due to the reflected light shading is not affected by the direct light shielding change, A waveform that reliably captures changes in the amount of light due to light blocking appears. In this way, even if the direct light is not physically blocked, it is possible to accurately detect the ejection while suppressing the influence of the direct light.

  In the configuration of the first embodiment, the direct light directly directed from the light emitting element 102 to the light receiving element 103 is shielded by the light shielding member 105, but is reflected by the mirror 101 or the like on the front surface 101a side of the recording head 101, and the reflected light is reflected. Further, the light may be reflected by the front surface 101 a and enter the light receiving element 103. In this way, the direct light that has been wasted in the first and second embodiments can be used as reflected light to increase the amount of detection light.

  In the above, the embodiment of the bubble jet (registered trademark) type ink jet recording apparatus has been described. However, the technique of the present invention can be applied to other types of ink jet recording apparatuses such as a method using a piezoelectric element. is there. The present invention can also be applied to a recording system including the inkjet recording apparatus and a control device such as a PC that controls the inkjet recording apparatus. Furthermore, the present invention can be applied not only to ink droplets but also to droplet ejection devices that eject droplets of other liquids such as reaction liquids, chemicals, or liquids that become conductors when dried. The present invention can also be applied to a droplet discharge system including a controller.

It is explanatory drawing which shows a structure, arrangement | positioning, etc. of the discharge detection sensor of the inkjet recording device in Example 1 of this invention. 1 is a perspective view schematically showing an overall mechanical configuration of an ink jet recording apparatus of Example 1. FIG. FIG. 2 is a block diagram illustrating a configuration of a control system of the ink jet recording apparatus according to the first exemplary embodiment. FIG. 3 is a block diagram illustrating a configuration of a signal processing circuit of the discharge detection sensor according to the first embodiment. FIG. 3 is an explanatory diagram showing the arrangement and nozzle positions of nozzle rows of the recording head of Example 1. FIG. 6 is a signal waveform diagram showing detection signal waveforms in ejection detection of each nozzle at nozzle positions (a), (b), and (c) in FIG. 5. It is a graph which shows the relationship between the nozzle position of all the nozzles of 1 row, and the output voltage of the detection signal in the discharge detection of each nozzle. FIG. 5 is a signal waveform diagram showing detection signal waveforms when two nozzles at nozzle positions (a), (b), and (c) are combined and driven simultaneously. It is explanatory drawing explaining the block division and combination of a nozzle row for determining the combination of the nozzle driven simultaneously at the time of discharge detection. FIG. 6 is a flowchart illustrating a control procedure of a discharge detection operation in the first embodiment. FIG. 6 is an explanatory diagram illustrating a configuration and an arrangement of a discharge detection sensor according to a second embodiment. FIG. 6 is a signal waveform diagram illustrating a detection signal waveform in ejection detection according to the second embodiment. It is explanatory drawing which shows a structure, arrangement | positioning, etc. of the discharge detection sensor of the conventional inkjet recording device. It is a signal waveform diagram which shows a detection signal waveform when it can detect by the discharge detection in the conventional apparatus. It is explanatory drawing which shows a mode that an ink droplet passes a detection area by the discharge detection in the conventional apparatus (when it can detect). It is a signal waveform diagram which shows the detection signal waveform at the time of the detection limit by the discharge frequency by the discharge detection in the conventional apparatus, and the impossible time. It is explanatory drawing which shows a mode that a some droplet passes simultaneously through a detection area at the time of a detection impossible.

Explanation of symbols

101, 209 to 212 Recording head 101a Front of recording head 102 Light emitting element 103 Light receiving element 104, 104 'Aperture 105 Light blocking member 106 Nozzle array 107 Reflecting member 108, 109 Nozzle 110, 111 Ink droplet 113, 113a, 113b Reflected light Light beam 115 Direct light beam 205 Discharge detection sensor 302 Recording head control circuit 304 Discharge detection control circuit 305 CPU
306 ROM
311 PC
408 Detection determination unit

Claims (12)

A plurality of nozzles each for discharging droplets, a droplet discharge section provided on one surface;
A light emitting element and a light receiving element which are disposed opposite to each other in the vicinity of the one surface of the liquid droplet ejection unit, and light emitted from the light emitting element and incident on the light receiving element is shielded by the liquid droplets ejected from the plurality of nozzles. A discharge detection sensor configured to output a detection signal in which the voltage is changed and the change value of the voltage varies depending on the position and the number of nozzles that discharge the liquid droplets;
Drive control means for simultaneously driving or substantially simultaneously driving the plurality of nozzles by N, which is an integer of 2 or more, at a predetermined period Tc at the time of discharge detection for detecting the presence or absence of droplet discharge from the plurality of nozzles;
At the time of the discharge detection, there is a determination means for determining the presence or absence of droplet discharge from each of the N nozzles based on the voltage change value of the detection signal output from the discharge detection sensor for each cycle Tc. A droplet discharge apparatus characterized by the above.   2. The droplet discharge device according to claim 1, wherein the N nozzles are combined with ones having a large difference in voltage change value of a detection signal due to a difference in position. The plurality of nozzles are arranged as at least one nozzle row along one direction on one surface of the droplet discharge section,
In the ejection detection sensor, the light emitting element and the light receiving element face each other along the one direction, and light emitted from the light emitting element is reflected by the one surface of the liquid droplet ejecting portion and incident on the light receiving element. 3. The droplet discharge device according to claim 1, wherein light intensity in a passing region differs depending on a position in the one direction.   In the ejection detection sensor, a light shielding member is provided for shielding direct light directed from the light emitting element directly toward the light receiving element, and the droplet ejection unit within the light emitted from the light emitting element. 4. The droplet discharge device according to claim 1, wherein only the reflected light reflected by the one surface is incident on the light receiving element. 5. In the discharge detection sensor, the light emitted from the light emitting element is directly directed to the light receiving element in parallel with the one surface together with the reflected light that is irradiated on the one surface of the droplet discharge unit and reflected by the one surface. The light is configured to enter the light receiving element, and
The width of the first region through which the direct light passes in the direction of droplet discharge from the nozzle is larger than the width of the second region through which the reflected light passes between the first region and the one surface. Tc is set to a length within a range shorter than the time required for a droplet normally ejected from the nozzle to pass through the first region and longer than the time required to pass through the second region. The droplet discharge device according to any one of claims 1 to 3, wherein   2. The reflecting member for reflecting light from the light emitting element to the light receiving element side with high reflectivity is provided around the plurality of nozzles on the one surface of the droplet discharge unit. 6. The droplet discharge device according to any one of items 1 to 5.   The light intensity in the region through which the light emitted from the light emitting element and reflected by the one surface of the droplet discharge portion including the surface of the reflecting member and incident on the light receiving element passes is the one where the light emitting element and the light receiving element face each other. The liquid according to claim 6, wherein the amount of reflected light is different depending on a portion of the reflecting member so as to become stronger along a direction toward a central portion of the arrangement region of the plurality of nozzles. Drop ejection device. A droplet discharge system comprising a droplet discharge device having a droplet discharge portion in which a plurality of nozzles each discharging droplets are provided on one surface, and a control device for controlling the droplet discharge device,
A light-emitting element and a light-receiving element arranged opposite to each other in the vicinity of the one surface of the droplet discharge unit, and light emitted from the light-emitting element and incident on the light-receiving element is shielded by the droplets discharged from the plurality of nozzles A discharge detection sensor configured to output a detection signal in which the voltage is changed and the change value of the voltage varies depending on the position and the number of nozzles that discharge the liquid droplets;
Drive control means for simultaneously driving or substantially simultaneously driving the plurality of nozzles by N, which is an integer of 2 or more, at a predetermined period Tc at the time of discharge detection for detecting the presence or absence of droplet discharge from the plurality of nozzles;
At the time of the discharge detection, there is a determination means for determining the presence or absence of droplet discharge from each of the N nozzles based on the voltage change value of the detection signal output from the discharge detection sensor for each cycle Tc. A droplet discharge system characterized by that. A plurality of nozzles each for discharging droplets, a droplet discharge section provided on one surface;
A light emitting element and a light receiving element which are disposed opposite to each other in the vicinity of the one surface of the liquid droplet ejection unit, and light emitted from the light emitting element and incident on the light receiving element is shielded by the liquid droplets ejected from the plurality of nozzles. A discharge detection sensor configured to output a detection signal in which the voltage is changed and the change value of the voltage varies depending on the position and the number of nozzles that discharge the liquid droplets;
A droplet discharge detection method for detecting whether or not droplets are discharged from each of the plurality of nozzles of the droplet discharge unit,
A drive control step of driving the plurality of nozzles at the same time or almost simultaneously by N, which is an integer of 2 or more, every predetermined cycle Tc at the time of discharge detection;
At the time of ejection detection, a determination step is performed for determining whether or not droplets are ejected from each of the N nozzles based on the voltage change value of the detection signal output from the ejection detection sensor at each cycle Tc. A method for detecting droplet discharge. A plurality of nozzles each for discharging droplets, a droplet discharge section provided on one surface;
A light emitting element and a light receiving element which are disposed opposite to each other in the vicinity of the one surface of the liquid droplet ejection unit, and light emitted from the light emitting element and incident on the light receiving element is shielded by the liquid droplets ejected from the plurality of nozzles. A discharge detection sensor configured to output a detection signal in which the voltage is changed and the change value of the voltage varies depending on the position and the number of nozzles that discharge the liquid droplets;
In a droplet discharge system comprising a droplet discharge device having a liquid crystal and a control device for controlling the droplet discharge device, a droplet for detecting whether or not droplets are discharged from each of a plurality of nozzles of the droplet discharge portion A discharge detection method comprising:
A drive control step of driving the plurality of nozzles at the same time or almost simultaneously by N, which is an integer of 2 or more, every predetermined cycle Tc at the time of discharge detection;
At the time of ejection detection, a determination step is performed for determining whether or not droplets are ejected from each of the N nozzles based on the voltage change value of the detection signal output from the ejection detection sensor at each cycle Tc. A method for detecting droplet discharge. A plurality of nozzles each for discharging droplets, a droplet discharge section provided on one surface;
A light emitting element and a light receiving element which are disposed opposite to each other in the vicinity of the one surface of the liquid droplet ejection unit, and light emitted from the light emitting element and incident on the light receiving element is shielded by the liquid droplets ejected from the plurality of nozzles. A discharge detection sensor configured to output a detection signal in which the voltage is changed and the change value of the voltage varies depending on the position and the number of nozzles that discharge the liquid droplets;
A droplet discharge detection program for a droplet discharge apparatus having
A control procedure for controlling each part of the droplet discharge device so as to detect whether or not droplets are discharged from each of the plurality of nozzles of the droplet discharge unit by the droplet discharge detection method according to claim 9. A droplet discharge detection program comprising: A plurality of nozzles each for discharging droplets, a droplet discharge section provided on one surface;
A light emitting element and a light receiving element which are disposed opposite to each other in the vicinity of the one surface of the liquid droplet ejection unit, and light emitted from the light emitting element and incident on the light receiving element is shielded by the liquid droplets ejected from the plurality of nozzles. A discharge detection sensor configured to output a detection signal in which the voltage is changed and the change value of the voltage varies depending on the position and the number of nozzles that discharge the liquid droplets;
A droplet discharge detection program for a droplet discharge system comprising: a droplet discharge device having a control device for controlling the droplet discharge device;
A control procedure for controlling each part of the droplet discharge device so as to detect whether or not droplets are discharged from each of the plurality of nozzles of the droplet discharge unit by the droplet discharge detection method according to claim 10. A droplet discharge detection program comprising:

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