JP2020151904A - Discharge state detection device, discharge state detection method, and ink jet recording device - Google Patents

Abstract

To provide a discharge state detection device, a discharge state detection method, and an ink jet recording device which can accurately discriminate a recording medium and ink without increasing consumption of the ink.SOLUTION: A discharge state detection device includes: an irradiation part which irradiates a recording medium, on which ink absorbing light having a wavelength of a short wavelength range as a wavelength range shorter than a wavelength of a visible light range is discharged from a discharge part, with the light having the wavelength in the short wavelength range as irradiation light; a light receiving part which has higher sensitivity to the light of the wavelength in the short wavelength range than the light of the wavelength in the visible light range, and receives light which is based on the irradiation light and passes through the recording medium; and a detection part which detects a discharge state of the ink from the discharge part on the basis of intensity of the received light.SELECTED DRAWING: Figure 2

Description

The present invention relates to a discharge state detection device, a discharge state detection method, and an inkjet recording device.

In an inkjet recording device, ink is ejected onto a recording medium from a plurality of nozzles arranged in an inkjet head to form an image on the recording medium. In this inkjet recording device, nozzle clogging or failure of the ejection mechanism (ink ejection failure) may occur.

Such clogging of the nozzle or failure of the ejection mechanism causes blurring or unevenness of the image, and thus deteriorates the image quality. In order to detect ink ejection defects, the inkjet recording apparatus can discriminate between the recording medium and the colored ink, for example, based on the reading density difference between the recording medium and the colored ink (CMYK ink). It is equipped with an image reading sensor (in-line sensor).

Further, for example, in Patent Document 1, by ejecting colored ink on a blank sheet of paper and ejecting an inspection pattern with white ink on the colored ink, the white ink is overcoated on the colored ink to obtain the white ink. A technique for detecting a discharge defect of the ink is disclosed.

Japanese Unexamined Patent Publication No. 2010-12605

However, with the above image reading sensor, for example, when white ink is applied on a blank sheet of paper, it is difficult for a difference in reading density between the blank sheet and the white ink to occur, and it becomes difficult to distinguish between the blank sheet and the white ink. There was a problem.

Further, in the technique described in Patent Document 1, in order to detect a ejection defect of white ink, it is necessary to apply colored ink as a base to blank paper, so that there is a problem that the consumption amount of colored ink increases. is there.

An object of the present invention is to provide a discharge state detection device, a discharge state detection method, and an inkjet recording device capable of accurately discriminating between a recording medium and ink without increasing the consumption of ink.

In order to achieve the above object, the discharge state detection device in the present invention is
Irradiation in which the recording medium ejected from the ejection unit is irradiated with light having a wavelength in the short wavelength region as irradiation light, which is an ink that absorbs light having a wavelength in the short wavelength region, which is shorter than the wavelength in the visible light region. Department and
A light receiving unit that has higher sensitivity to light having a wavelength in the short wavelength region than light having a wavelength in the visible light region and receives light via the recording medium based on the irradiation light.
A detection unit that detects the ink ejection state by the ejection unit based on the intensity of the received light, and a detection unit.
To be equipped.

The discharge state detection method in the present invention
A recording medium ejected from an ejection unit is irradiated with light having a wavelength in the short wavelength region as irradiation light, and an ink absorbing light having a wavelength in the short wavelength region, which is a wavelength region shorter than the wavelength in the visible light region, is irradiated to the recording medium ejected from the ejection unit.
The sensitivity to the light having a wavelength in the short wavelength region is made higher than the light having a wavelength in the visible light region, and the light is received through the recording medium based on the irradiation light.
The ink ejection state by the ejection unit is detected based on the intensity of the received light.

The inkjet recording device in the present invention is
The discharge state detection device and the discharge unit are provided.

According to the present invention, the recording medium and the ink can be accurately discriminated without increasing the consumption of the ink.

It is a figure which shows the schematic structure of the inkjet recording apparatus which concerns on embodiment of this invention. It is a block diagram which shows the main functional structure of the inkjet recording apparatus which concerns on embodiment of this invention. It is a figure which shows the spectral reflectance of a recording medium, and the spectral reflectance of a white ink. It is a flowchart which shows an example of the discharge state detection processing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an inkjet recording device 1 according to the present embodiment. The inkjet recording device 1 includes a paper feeding unit 10, an image recording unit 20, a paper ejection unit 30, and a control unit 40 (see FIG. 2).

In the inkjet recording device 1, under the control of the control unit 40, the recording medium P stored in the paper feeding unit 10 is conveyed to the image recording unit 20, the image recording unit 20 records the image on the recording medium P, and the image is recorded. The recorded recording medium P is conveyed to the paper ejection unit 30. As the recording medium P, in addition to paper such as plain paper and coated paper, various media such as cloth or sheet-shaped resin capable of fixing the ink landed on the surface can be used.

The paper feed unit 10 includes a paper feed tray 11 for storing the recording medium P, and a medium supply unit 12 for transporting and supplying the recording medium P from the paper feed tray 11 to the image recording unit 20. The medium supply unit 12 includes a ring-shaped belt whose inside is supported by two rollers, and the recording medium P is transferred from the paper feed tray 11 by rotating the rollers with the recording medium P placed on the belt. It is conveyed to the image recording unit 20.

The image recording unit 20 includes a transport drum 21, a delivery unit 22, a heating unit 23, a head unit 24, a fixing unit 25, and a delivery unit 26.

The transport drum 21 is around a rotation axis extending in a direction perpendicular to the drawing of FIG. 1 (hereinafter, referred to as “orthogonal direction”) while holding the recording medium P on a cylindrical outer peripheral curved surface (convey surface). The recording medium P is conveyed in the conveying direction along the conveying surface by rotating with. The transport drum 21 includes a claw portion and an intake portion (not shown) for holding the recording medium P on the transport surface. The recording medium P is held on the transport surface by pressing the end portion by the claw portion and attracting the recording medium P to the transport surface by the intake portion. The transfer drum 21 has a transfer drum motor (not shown) for rotating the transfer drum 21, and rotates by an angle proportional to the amount of rotation of the transfer drum motor.

The delivery unit 22 delivers the recording medium P conveyed by the medium supply unit 12 of the paper feed unit 10 to the transfer drum 21. The delivery unit 22 is provided at a position between the medium supply unit 12 of the paper feed unit 10 and the transfer drum 21, and one end of the recording medium P conveyed from the medium supply unit 12 is held by the swing arm unit 221 and picked up. , Delivery to the transfer drum 21 via the delivery drum 222.

The heating unit 23 is provided between the arrangement position of the transfer drum 222 and the arrangement position of the head unit 24, and the transfer drum 21 is provided so that the recording medium P conveyed by the transfer drum 21 has a temperature within a predetermined temperature range. The transport surface and the recording medium P of the above are heated. The heating unit 23 has, for example, an infrared heater or the like, and energizes the infrared heater based on a control signal supplied from the control unit 40 (see FIG. 2) to heat the infrared heater.

The head unit 24 refers to the recording medium P from a nozzle opening provided on the ink ejection surface facing the transport surface of the transport drum 21 at an appropriate timing according to the rotation of the transport drum 21 holding the recording medium P. Ink is ejected and an image is recorded. The head unit 24 is arranged so that the ink ejection surface and the transport surface are separated by a predetermined distance.

In the inkjet recording apparatus 1 of the present embodiment, five head units 24 corresponding to five colors of ink of white (W), yellow (Y), magenta (M), cyan (C), and black (K) are provided. The recording media P are arranged so as to be arranged at predetermined intervals in the order of W, Y, M, C, and K colors from the upstream side in the transport direction.

Each head unit 24 includes a recording head 242 (see FIG. 2, corresponding to the "discharge section" of the present invention). The recording head 242 is provided with a plurality of recording elements each having a pressure chamber for storing ink, a piezoelectric element provided on the wall surface of the pressure chamber, and a nozzle. When a drive signal for deforming the piezoelectric element is input to this recording element, the pressure chamber is deformed due to the deformation of the piezoelectric element, the pressure in the pressure chamber changes, and ink is discharged from a nozzle communicating with the pressure chamber.

The arrangement range of the nozzles included in the recording head 242 in the orthogonal direction covers the width of the recording medium P conveyed by the conveying drum 21 in the orthogonal direction in the region where the image is recorded. The head unit 24 is used with its position fixed with respect to the rotation axis of the transport drum 21 when recording an image. That is, the inkjet recording device 1 is a single-pass type inkjet recording device.

As the ink ejected from the recording head 242, an ink having a property of changing its phase into a gel or sol depending on the temperature and being cured by irradiating with energy rays such as ultraviolet rays is used. Further, in the present embodiment, an ink that is gel-like at room temperature and becomes sol-like when heated is used. The head unit 24 includes an ink heating unit (not shown) that heats the ink stored in the head unit 24. The ink heating unit operates under the control of the control unit 40 and heats the ink to a sol-like temperature. The head unit 24 ejects the heated and sol-like ink. When the sol-shaped ink is ejected to the recording medium P, the ink droplets land on the recording medium P and then are naturally cooled so that the ink quickly becomes a gel and solidifies on the recording medium P.

The fixing portion 25 has a light emitting portion arranged over the width in the orthogonal direction of the transport drum 21. The fixing unit 25 applies a predetermined energy to the ink ejected on the recording medium P by irradiating the recording medium P placed on the transport drum 21 with energy rays such as ultraviolet rays from the light emitting unit. This cures and fixes the ink. The light emitting portion of the fixing portion 25 is arranged so as to face the transport surface of the transport drum 21 from the placement position of the recording head 242 in the transport direction to the placement position of the delivery drum 261 (delivery unit 26).

The delivery unit 26 has a belt loop 262 having a ring-shaped belt whose inside is supported by two rollers, and a cylindrical transfer drum 261 that transfers the recording medium P from the transfer drum 21 to the belt loop 262. The recording medium P delivered from the transfer drum 21 onto the belt loop 262 by the transfer drum 261 is conveyed by the belt loop 262 and sent to the paper ejection unit 30.

The paper ejection unit 30 has a plate-shaped paper ejection tray 31 on which the recording medium P sent out from the image recording unit 20 by the delivery unit 26 is placed.

FIG. 2 is a block diagram showing a main functional configuration of the inkjet recording device 1. The inkjet recording device 1 includes a heating unit 23, a recording head drive unit 241 and a recording head 242 included in the head unit 24, a fixing unit 25, a detection unit 27A, a control unit 40, a transport drive unit 51, and input / output. It includes an interface 52.

The recording head drive unit 241 supplies a drive signal for deforming the piezoelectric element according to the image data at an appropriate timing to the recording element of the recording head 242 based on the control of the control unit 40, thereby supplying the recording head 242. An amount of ink corresponding to the pixel value of the image data is ejected from the nozzle of.

The control unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a storage unit 44.

The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, executes the programs, and performs various arithmetic processes. In addition, the CPU 41 controls the overall operation of the inkjet recording device 1.

The RAM 42 provides the CPU 41 with a working memory space and stores temporary data. The RAM 42 may include a non-volatile memory.

The ROM 43 stores various control programs, setting data, and the like executed by the CPU 41. Instead of the ROM 43, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The storage unit 44 stores a print job (image recording command) input from the external device 2 via the input / output interface 52 and image data related to the print job. As the storage unit 44, for example, an HDD (Hard Disk Drive) may be used, or a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

The transfer drive unit 51 supplies a drive signal to the transfer drum motor of the transfer drum 21 based on the control signal supplied from the control unit 40 to rotate the transfer drum 21 at a predetermined speed and timing. Further, the transport drive unit 51 supplies a drive signal to the motor for operating the medium supply unit 12, the delivery unit 22, and the delivery unit 26 based on the control signal supplied from the control unit 40, and supplies the drive signal to the recording medium P. Supply to the transport drum 21 and discharge from the transport drum 21.

The input / output interface 52 mediates the transmission and reception of data between the external device 2 and the control unit 40. The input / output interface 52 is composed of, for example, any of various serial interfaces, various parallel interfaces, or a combination thereof.

The external device 2 is, for example, a personal computer, and supplies an image recording command (print job), image data, and the like to the control unit 40 via the input / output interface 52.

According to the above configuration, the recording medium P stored in the paper feeding unit 10 is conveyed to the image recording unit 20, an image is recorded by the ink ejected from the nozzle in the image recording unit 20, and the delivery unit 26 records the image. It is sent out to the paper ejection unit 30. However, ink may not be ejected to a predetermined region on the recording medium P due to nozzle clogging or failure of the ejection mechanism. Nozzle clogging or the like causes deterioration of image quality, so it is necessary to inspect whether or not ink is reliably ejected from the nozzle (nozzle missing inspection).

Next, the nozzle missing inspection will be described. Here, a case where the recording medium P is a blank sheet and white ink is ejected on the blank sheet will be described. The white ink contains a component (for example, titanium oxide) that absorbs light having a wavelength λ _sw in a short wavelength region which is shorter than the wavelength λ _r in the visible light region. Here, the wavelength λ _r in the visible light region is set to 400 [nm] or more. Further, the wavelength λ _sw in the short wavelength region is set to 365 [nm] or more and less than 400 [nm]. The area where dots are recorded when the white ink discharged from the nozzle lands on a blank sheet of paper is referred to as a "landing portion".

The nozzle shortage inspection is performed by the discharge state detection device. The discharge state detection device according to the present embodiment includes a detection unit 27A and a control unit 40. The detection unit 27A includes an irradiation unit 27 and a light receiving unit 28.

The irradiation unit 27 and the light receiving unit 28 are arranged so as to face the transfer surface of the transfer drum 21 from the arrangement position of the fixing unit 25 in the transfer direction to the arrangement position of the delivery drum 261 (delivery unit 26).

The irradiation unit 27 operates under the control of the control unit 40 and irradiates the landing unit with the irradiation light.

The irradiation unit 27 irradiates the landing unit with irradiation light having one wavelength in the wavelength λ _{sw in} the short wavelength region.

The light receiving unit 28 is arranged so that it can receive light through the landing unit based on the irradiation light.

The light receiving unit 28 has an optical sensor 281 that receives light from a short wavelength region to a visible light region. As the optical sensor 281, for example, an in-line sensor is used. The in-line sensor is composed of an image line sensor such as CCD or CMOS.

The light receiving unit 28 operates the optical sensor 281 under the control of the control unit 40. As a result, the optical sensor 281 detects the intensity of the light passing through the landing portion based on the irradiation light at the timing when the irradiation light is irradiated to the landing portion by the irradiation unit 27.

When the irradiation unit 27 irradiates the landing portion with irradiation light having a predetermined wavelength and the optical sensor 281 detects the light having a predetermined wavelength, the intensity of the irradiated irradiation light having a predetermined wavelength and the detected predetermined intensity are determined. The ratio of the wavelength to the intensity of light is called "spectral reflectance".

Due to poor ejection of white ink, the white ink may not land on the blank paper, or the ejected white ink may not land on the predetermined landing portion. The spectral reflectance when the white ink lands on the landing portion is the spectral reflectance of the white ink, which is the ratio of the intensity of the irradiation light applied to the white ink to the intensity of the received light. On the other hand, the spectral reflectance when the white ink does not land on the landing portion is the spectral reflectance of the blank paper, which is the ratio of the intensity of the irradiation light applied to the blank paper (the background of the blank paper) to the intensity of the received light. Is. The spectral reflectance of white ink and the spectral reflectance of blank paper are different. Therefore, it is possible to determine whether or not the white ink is poorly ejected based on the spectral reflectance.

Next, the spectral reflectance of the white paper and the spectral reflectance of the white ink will be described with reference to FIG. FIG. 3 is a diagram showing the spectral reflectance of white paper and the spectral reflectance of white ink. In the following description, Maricoat and Invarcoat (registered trademark) manufactured by Hokuetsu Kishu Paper Co., Ltd. are given as examples of blank paper. The horizontal axis of FIG. 3 shows the wavelength [nm] of the light received by the light receiving unit 28, and the vertical axis of FIG. 3 shows the spectral reflectance [%]. In FIG. 3, the spectral reflectance of Maricoat is shown by a solid line, the spectral reflectance of Invercoat is shown by a chain line, and the spectral reflectance of white ink is shown by a chain double-dashed line. Further, in FIG. 3, the difference between the spectral reflectance of Maricoat and the spectral reflectance of white ink is shown by a broken line, and the difference between the spectral reflectance of inverse coat and the spectral reflectance of white ink is shown by a dotted line.

First, the difference between the spectral reflectance of the maricoat shown by the broken line in FIG. 3 and the spectral reflectance of the white ink (spectral reflectance difference) will be described. When the wavelength of the irradiation light is 380 [nm], the spectral reflectance difference is 18%. When the wavelength of the irradiation light is 390 [nm], the spectral reflectance difference is 23%. When the wavelength of the irradiation light is 400 [nm], the spectral reflectance difference is 32%. When the wavelength of the irradiation light is 410 [nm], the spectral reflectance difference is 20%. On the other hand, when the wavelength range of the irradiation light is 420 [nm] or more and 470 [nm] or less, the spectral reflectance difference is 4% or less. From this, it can be seen that the difference in spectral reflectance when the wavelength range of the irradiation light is 380 [nm] or more and 410 [nm] or less is relatively large.

Next, the difference between the spectral reflectance of the inverse coat shown by the dotted line in FIG. 3 and the spectral reflectance of the white ink (spectral reflectance difference) will be described. When the wavelength of the irradiation light is 380 [nm], the spectral reflectance difference is 15%. Further, when the wavelength of the irradiation light is 390 [nm], the spectral reflectance difference is 12%. When the wavelength of the irradiation light is 400 [nm], the spectral reflectance difference is 8%. When the wavelength of the irradiation light is 410 [nm], the spectral reflectance difference is 2%. From this, it can be seen that the difference in spectral reflectance when the wavelength range of the irradiation light is 380 [nm] or more and less than 400 [nm] is relatively large.

From the above, it can be said in common that when the wavelength range of the irradiation light is a short wavelength range of 380 [nm] or more and less than 400 [nm], the spectral reflectance of blank paper (maricoat, inverse coat) and the spectroscopy of white ink It can be seen that the difference from the reflectance is relatively large.

In the present embodiment, the irradiation unit 27 irradiates light of one predetermined wavelength (for example, ultraviolet light of 380 [nm]) in the wavelength λ _{sw in} the short wavelength region as irradiation light, and the optical sensor 281 is short. It receives light with a wavelength of λ _{sw in} the wavelength range. The control unit 40 calculates the spectral reflectance based on the intensity of the received light, and whether the spectral reflectance is the spectral reflectance of white ink or the spectral reflectance of blank paper (blank background). It has a function as a detection unit for detecting a ejection failure of the nozzle.

By the way, when white ink containing a fluorescent dye is irradiated with light having a wavelength of λ _{sw in} a short wavelength region, a fluorescent light emitting action occurs. Similarly, when a blank sheet containing a fluorescent whitening agent is irradiated with light having a wavelength of λ _sw in the short wavelength region, a fluorescent light emitting action occurs. The wavelength range of light generated by the fluorescence emission action is 400 [nm] or more and 450 [nm] or less. On the other hand, it is possible to discriminate between the spectral reflectance of white paper and the spectral reflectance of white ink based on the spectral reflectance of the wavelength λ _sw in the short wavelength region. However, the optical sensor 281 detects not only the intensity of light having a wavelength λ _{sw in} the short wavelength region but also the intensity of light having a wavelength λ _{r in} the visible light region. Therefore, the detection accuracy of the light intensity of the wavelength λ _{sw in} the short wavelength region is lowered. As a result, it becomes difficult to distinguish between the spectral reflectance of white paper and the spectral reflectance of white ink.

The light receiving unit 28 in the present embodiment has a bandpass filter 282. The bandpass filter 282 is arranged between the transport surface of the transport drum 21 and the optical sensor 281. The bandpass filter 282 transmits light having a wavelength λ _{sw in} the short wavelength region and blocks light having a wavelength λ _r (400 [nm] or more) in the visible light region. As a result, the bandpass filter 282 blocks light having a wavelength of λ _{f in} the fluorescence emission region.

If fluorescence effect caused by irradiation with light of wavelength lambda _sw of short wavelength landing portion, band-pass filter 282 blocks light of wavelength lambda _f of the fluorescent region. Since the optical sensor 281 detects the light having the wavelength λ _{sw in} the short wavelength region and does not detect the light having the wavelength λ _{f in} the fluorescence emission region, the detection accuracy of the light intensity having the wavelength λ _{sw in} the short wavelength region is lowered. Can be suppressed.

The optical sensor 281 detects the intensity of light having a wavelength of λ _sw in the short wavelength region under the control of the control unit 40. The control unit 40 (detection unit) detects the ejection state of the white ink based on the intensity of the detected light having a wavelength of λ _{sw in} the short wavelength region.

Control unit 40, specifically, the intensity of light of wavelength lambda _sw of short wavelength region to be irradiated to the landing portion from the irradiation portion 27, the short wavelength region detected by the light sensor 281 of the wavelength lambda _sw of light The spectral reflectance of a predetermined wavelength is calculated from the intensity. When the spectral reflectance of the predetermined wavelength is close to the spectral reflectance of the blank paper, the control unit 40 determines that the spectral reflectance of the predetermined wavelength is the spectral reflectance of the blank paper and that the white ink is poorly ejected. Further, when the difference in the spectral reflectance of the predetermined wavelength is close to the spectral reflectance of the white ink, the control unit 40 determines that the spectral reflectance of the predetermined wavelength is the spectral reflectance of the white ink and that the ejection of the white ink is not defective. In other words, the white paper and the white ink are discriminated by the reading contrast difference between the white paper and the white ink due to the spectral reflectance.

More specifically, when the recording medium P is a maricoat, the control unit 40 determines the intensity of ultraviolet light having a wavelength of 380 [nm] irradiated to the landing unit and the intensity of 380 [nm] detected by the optical sensor 281. The spectral reflectance is calculated from the intensity of ultraviolet light of the wavelength. When the spectral reflectance is closer to the spectral reflectance of Maricoat than the white ink, the control unit 40 determines that the spectral reflectance is a blank sheet of paper (see FIG. 3) and that the white ink is poorly ejected. Further, when the spectral reflectance difference is closer to the spectral reflectance of the white ink than that of the maricoat, the control unit 40 determines that the spectral reflectance of the white ink is not (see FIG. 3) and that the ejection of the white ink is not defective. ..

Further, when the recording medium P is an inverse coat, the control unit 40 has an intensity of ultraviolet light having a wavelength of 380 [nm] irradiated to the landing part and ultraviolet light having a wavelength of 380 [nm] detected by the optical sensor 281. The spectral reflectance is calculated from the light intensity. When the spectral reflectance is closer to the spectral reflectance of the inverse coat than the white ink, the control unit 40 determines that the spectral reflectance is a blank sheet of paper (see FIG. 3) and that the white ink is poorly ejected. Further, when the light reflectance difference is closer to the spectral reflectance of the white ink than the inverse coat, the control unit 40 determines that it is the spectral reflectance of the white ink (see FIG. 3) and that the ejection of the white ink is not defective. To do.

Next, the discharge state detection process will be described with reference to FIG. FIG. 4 is a flowchart showing an example of the discharge state detection process. Here, it is assumed that the irradiation unit 27 irradiates the landing unit with light having a wavelength of λ _{sw in} the short wavelength region as irradiation light. Further, band-pass filter 282, of the light through the landing section based on the irradiation light, blocks the light of the wavelength lambda _r of the visible light region (including the fluorescence emission region), the optical sensor 281, the short wavelength region It is assumed that light having a wavelength of λ _sw is received. This flow is started when the print job is executed.

First, in step S100, the control unit 40 (detection unit) acquires the intensity of light through the landing unit based on the irradiation light. The control unit 40 calculates the spectral reflectance of a predetermined wavelength based on the acquired light intensity.

Next, in step S110, the control unit 40 determines whether the spectral reflectance of the predetermined wavelength is close to the spectral reflectance of the white ink or close to the spectral reflectance of the blank paper. When the spectral reflectance of the predetermined wavelength is close to the spectral reflectance of the white ink (step S110: YES), the process proceeds to step S120. When the spectral reflectance of the predetermined wavelength is close to the spectral reflectance of the white paper instead of the spectral reflectance of the white ink (step S110: NO), the process proceeds to step S130.

In step S120, the control unit 40 determines that the white ink is not defective in ejection. After that, the process shown in FIG. 4 ends.

In step S130, the control unit 40 determines that the white ink is poorly ejected. After that, the process shown in FIG. 4 ends.

According to the ejection state detection device according to the above embodiment, the white ink that absorbs the ultraviolet light of a predetermined wavelength is visible to the irradiation unit 27 that irradiates the white paper ejected from the recording head 242 with the ultraviolet light as the irradiation light. Recording is performed based on the light receiving unit 28, which has a higher sensitivity to light having a wavelength in the ultraviolet light region than light having a wavelength λ _{r in} the light region, and receives light through a blank sheet of light based on the irradiation light, and the intensity of the received light. A control unit 40 for detecting the ejection state of white ink from the head 242 is provided. As a result, it is not necessary to apply colored ink as a base, so that it is possible to accurately detect white paper and white ink without increasing the consumption of colored ink. As a result, it becomes possible to determine the ejection defect of the white ink.

Further, according to the ejection state detection device according to the above embodiment, when the white ink emits ultraviolet light to the blank paper ejected from the recording head 242 to cause a fluorescence emission effect, the bandpass filter 282 is visible. _Blocks light with a wavelength of λ _{r in} the optical region. As a result, since the optical sensor 281 does not detect the light generated by the fluorescence emission action, the influence of the fluorescence emission action on the intensity of the light received by the light receiving unit 28 can be reduced. As a result, it is possible to suppress a decrease in the detection accuracy of the white ink ejection state.

In addition, the above-described embodiments are merely examples of implementation of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

For example, in the above embodiment, the detection of the ink ejection state is performed based on the intensity of the light passing through one landing portion based on the irradiation light, but the present invention is not limited to this, and for example, a plurality of landings are performed. It may be performed based on the average value of the intensity of the light passing through the part. The plurality of landing portions may be provided, for example, along the transport direction of the recording medium P. By averaging the light intensities, the SN ratio can be increased, so that the accuracy of detecting the ink ejection state can be improved.

Further, for example, in the above embodiment, the ejection state is detected for the white ink, but the present invention is not limited to this, and the reading density difference with the recording medium P is low and the spectral reflection with the recording medium P is small. Any ink that causes a difference in rate may be used. For example, transparent ink may be used.

Further, for example, in the above embodiment, the yellow, magenta, may comprise a second irradiation unit which irradiates light of a wavelength lambda _r in the visible light region to the landing portion of the colored inks cyan, and black. The control unit 40 so that the landing portion of the white ink is irradiated with light having a wavelength λ _sw in the short wavelength region, and the landing portion of the colored ink is irradiated with light having a wavelength λ _r in the visible light region. , The irradiation unit 27 and the second irradiation unit are controlled in time division. This makes it possible, for example, to discriminate between the spectral reflectance of white paper and the spectral reflectance of white ink with a single in-line sensor, and also to determine the spectral reflectance of colored paper and the spectral reflectance of colored ink. It becomes possible to discriminate.

Further, in the above embodiment, the irradiation light irradiating the landing portion is ultraviolet light, but the present invention is not limited to this, and any light that absorbs a component (for example, titanium oxide) contained in the white ink is used. Often, light having a wavelength of λ _{sw in} the short wavelength region, such as 390 [nm], may be used.

Further, in the above embodiment, the band-pass filter 282, but is intended to cut off the wavelength lambda _r of the visible light region, the present invention is not limited thereto. For example, it may be any one that blocks light having a wavelength λ _{f in} the fluorescence emission region. As a result, the influence of the fluorescence light emitting action on the intensity of the light received by the light receiving unit 28 can be reduced.

1 Inkjet recording device 2 External device 10 Paper feed unit 11 Paper feed tray 12 Media supply unit 20 Image recording unit 21 Transport drum 22 Delivery unit 23 Heating unit 24 Head unit 25 Fixing unit 26 Delivery unit 27A Detection unit 27 Irradiation unit 28 Light receiving unit 30 Paper ejection unit 40 Control unit 242 Recording head 281 Optical sensor 282 Bandpass filter

Claims (10)

Irradiation that irradiates a recording medium ejected from an ejection unit with ink that absorbs light having a wavelength in a short wavelength region, which is shorter than the wavelength in the visible light region, with light having a wavelength in the short wavelength region as irradiation light. Department and
A light receiving unit that has higher sensitivity to light having a wavelength in the short wavelength region than light having a wavelength in the visible light region and receives light via the recording medium based on the irradiation light.
A detection unit that detects the ink ejection state by the ejection unit based on the intensity of the received light, and a detection unit.
Discharge state detection device including. The light receiving part is
An optical sensor that detects light with a wavelength extending from the short wavelength region to the visible light region,
A bandpass filter, which is arranged between the recording medium and the optical sensor, transmits light having a wavelength in the short wavelength region, and blocks light having a wavelength in the visible light region.
The discharge state detecting device according to claim 1. The bandpass filter blocks light having a wavelength in at least a fluorescent light emitting region in the visible light region.
The discharge state detecting device according to claim 2. The intensity of the light received by the light receiving unit is the intensity of each light received by the light receiving unit when the irradiation light is irradiated to a plurality of locations provided along the transport direction of the recording medium. Is the average value of
The discharge state detecting device according to any one of claims 1 to 3. The ink is a white ink.
The discharge state detecting device according to any one of claims 1 to 4. The ink is a transparent ink.
The discharge state detecting device according to any one of claims 1 to 4. A second irradiation unit that irradiates a recording medium on which colored ink is discharged with light having a wavelength in the visible light region, and a second irradiation unit.
The irradiation unit is controlled so as to irradiate the recording medium on which the white ink is discharged with light having a wavelength in the short wavelength region, and the recording medium on which the colored ink is discharged has a wavelength in the visible light region. A control unit that controls the second irradiation unit so as to irradiate light is provided.
The discharge state detecting device according to any one of claims 1 to 6. The control unit controls the irradiation unit and the second irradiation unit in a time-division manner.
The discharge state detecting device according to claim 7. A recording medium ejected from an ejection unit is irradiated with light having a wavelength in the short wavelength region as irradiation light, and an ink absorbing light having a wavelength in the short wavelength region, which is a wavelength region shorter than the wavelength in the visible light region, is irradiated to the recording medium ejected from the ejection unit.
The sensitivity to the light having a wavelength in the short wavelength region is made higher than the light having a wavelength in the visible light region, and the light is received through the recording medium based on the irradiation light.
The ink ejection state by the ejection unit is detected based on the intensity of the received light.
Discharge state detection method. An inkjet recording device including the ejection state detection device according to any one of claims 1 to 8 and the ejection unit.

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