JP2004195966A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To turn a cationic polymerization system ink of a high curing sensitivity which is cured by a light source of a relatively low output into practical use by improving the reliability through prevention of printing failures due to curing failures in an inkjet recording device which uses a photo-curing ink, to make the device compact and to reduce manufacturing costs of the device. <P>SOLUTION: The inkjet recording device consists of a light source 2 for emitting light to cure the ink discharged from an inkjet head 1 and adhered to a recording medium, a quantity of light measuring sensor 3 for measuring a quantity of light of the light source 2, and a light source control means 4 for controlling the quantity of light of the light source 2 according to the measured result by the measuring sensor 3. In addition, a light source scanning means, and a scanning means for the measuring sensor 3 are set to enable measurement of the quantity of light of many light sources by a small number of the measuring sensors 3. In the event that the quantity of light is insufficient, a display means 5 for notifying the user is set, or a process of prohibiting a recording operation is carried out. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an inkjet recording apparatus using a photocurable ink.

In general, many ink jet recording apparatuses are currently used because of relatively low noise during printing and good printing quality.
An ink jet recording apparatus uses, for example, a piezo element or a heater element, and discharges ink from a nozzle of a recording head as a fine droplet toward a recording medium such as paper, and allows the ink to permeate or fix the recording medium. An image is formed on the recording medium by moving the relative position of the recording head and the recording medium.
Ink jet recording apparatuses include, for example, a serial head type that forms an image by reciprocating a recording head on a recording medium and transporting the recording medium in a direction orthogonal to the scanning direction of the recording head, and a recording medium. There is a line head type which has a fixed recording head having a nozzle array over a recording width and forms an image by transporting a recording medium in a direction perpendicular to the recording width direction.

At present, in the field of printing products and packaging materials, there is a growing need for small-volume production, and small-volume production can be performed at lower cost compared to methods that require plate making, such as gravure printing and flexographic printing. Use of the ink jet system is expanding.
As is well known, materials that do not absorb ink, such as resins and metals, are often used for products and packaging materials for the products.
When such a non-absorbent material is used as a recording medium, a high-viscosity photocurable ink is ejected onto the recording medium and allowed to adhere to the recording medium in order to fix the ink on the recording medium. 2. Description of the Related Art A photocurable ink jet recording apparatus that cures and fixes ink by irradiating light such as ultraviolet rays has been developed.

Conventionally, as such a photo-curing type ink jet recording apparatus, an ultraviolet curable type ink jet recording apparatus having a configuration in which radical polymerization ink is used and a large amount of ultraviolet rays are collectively irradiated has been used. As a light source, it has been proposed to use a light source that emits directional light such as a laser beam (for example, see Patent Document 1). Specifically, semiconductor lasers, LEDs (light-emitting diodes), and the like are known as light sources that emit directional light.
By using a semiconductor laser or LED, the amount of heat generated during irradiation is reduced, and power consumption is reduced. Further, the size of the light source unit is smaller than that of a fluorescent tube or a high-pressure mercury lamp. Further, semiconductor lasers and LEDs have good stability and light intensity can be easily adjusted.
JP 2001-310454 A (page 4)

  However, the above prior art has the following problems.

When a radical polymerization type ink is used, a relatively large amount of ultraviolet irradiation is required. Therefore, there is a problem in that a high-output light source device is mounted, which leads to an increase in the length of the device and an increase in the manufacturing cost of the device.
In order to solve such a problem, it is conceivable to employ a cationic polymerization type ink which has not been practically used at present. However, the cationic polymerization type ink has unstable physical properties such as humidity dependency, and has physical properties that undergo a curing reaction by weak light such as reflected light, so that it is difficult to handle, making practical use difficult.
For example, the illuminance on the ink decreases due to deterioration due to long-term use of the light source, and the closer the light source is to the recording head due to a demand for miniaturization of the apparatus, the more the mist is affected by the ink mist. Under such circumstances, if a cationic polymerization type ink having the above-mentioned physical properties is used, curing failure is likely to occur, and the practical use range is not reached.

  The present invention has been made in view of the above-described problems in the prior art, and in an ink jet recording apparatus using a photocurable ink, improving the reliability of the apparatus by preventing printing failure due to curing failure, Accordingly, it is an object to reduce the size of the apparatus and reduce the manufacturing cost of the apparatus by enabling the practical use of ink with high curing sensitivity that is cured by a light source having a relatively low output.

The invention according to claim 1 for solving the above-described problems is directed to an ink-jet recording head that ejects ink from a plurality of ejection ports,
A light source that emits light that cures ink that is ejected from the recording head and adheres to the recording medium,
Light amount measuring means for measuring the light amount of the light source,
A control unit for controlling the light amount of the light source in accordance with a value measured by the light amount measurement unit.

  According to the first aspect of the present invention, it is possible to measure the light amount of the light source, and it is possible to detect in advance whether the light amount required for curing the ink is given to the ink on the recording medium. Thus, the light amount of the light source can be accurately controlled.

The invention according to claim 2 has a light source scanning unit that scans the light source on the recording medium by moving the light source in a direction perpendicular to a conveying direction of the recording medium,
A plurality of the light sources are provided at different positions in the vertical direction,
2. The ink jet recording apparatus according to claim 1, wherein the light source scanning unit sequentially moves different light sources to a measurement area of the light amount measurement unit so that the light amount measurement unit sequentially measures the light amounts of the plurality of light sources. It is.

  According to the second aspect of the present invention, different light sources are sequentially moved to the measurement area of the light amount measuring unit by the light source scanning unit, and the light amount measuring units sequentially measure the light amounts of the plurality of light sources. A measurement can be performed.

According to a third aspect of the present invention, there is provided a print head scanning unit that scans the print head on the print medium by moving the print head in a direction perpendicular to the transport direction of the print medium,
The inkjet recording apparatus according to claim 2, wherein the light source scanning unit is configured by moving the light source together with the recording head by the recording head scanning unit.

  According to the third aspect of the present invention, similarly to the above, different light sources are sequentially moved to the measurement area of the light quantity measuring means by the light source scanning means, and the light quantity measuring means sequentially measures the light quantities of the plurality of light sources. , All the light sources can be measured, and the light source and the recording head can be mounted on the same carriage.

The invention according to claim 4 is provided with a plurality of the light sources,
The inkjet recording apparatus according to any one of claims 1 to 3, further comprising a scanning unit configured to sequentially measure the plurality of light sources by the light amount measuring unit by moving the light amount measuring unit. is there.

  According to the fourth aspect of the invention, light sources at different positions in the main scanning direction and the recording medium conveyance direction can be measured by the same light amount measuring unit.

In the invention according to claim 5, a plurality of the light sources are provided at different positions in a transport direction of the recording medium,
5. The scanning device according to claim 1, further comprising a scanning unit configured to sequentially measure the plurality of light sources by the light amount measurement unit by moving the light amount measurement unit in a conveyance direction of the recording medium. 6. 2. The ink jet recording apparatus according to item 1.

  According to the fifth aspect of the invention, when a plurality of light sources are provided at different positions in the transport direction of the recording medium, the light amount measuring means can be moved in that direction to sequentially measure the light amount of the light sources. .

  The invention according to claim 6, wherein a recording medium supporting means for supporting the recording medium is arranged between the light source and the light amount measuring means, and a part of the recording medium supporting means is at least a part of light of the light source. The inkjet recording apparatus according to any one of claims 1 to 5, wherein the inkjet recording apparatus is configured by a member that transmits light.

  According to the sixth aspect of the present invention, a part of the recording medium supporting means disposed between the light source and the light quantity measuring means is constituted by a member transmitting at least a part of the light of the light source. , The light amount of the light source can be measured with the recording medium supporting means disposed therebetween.

The invention according to claim 7, wherein the storage means stores a target value of the light amount controlled by the control means,
The ink jet recording apparatus according to any one of claims 1 to 6, further comprising: display means for notifying a user of the measurement result when the measured value by the light quantity measuring means is less than the target value. Device.

  According to the invention described in claim 7, the user can be notified by the display means that the measured value of the light quantity of the light source by the light quantity measurement means is less than the target value of the light quantity stored in the storage means.

The invention according to claim 8 has storage means for storing a target value of the amount of light controlled by the control means,
8. The ink jet recording apparatus according to claim 1, wherein a recording operation by the recording head is prohibited when a value measured by the light quantity measuring unit is smaller than the target value. 9.

  According to the invention described in claim 8, when the measured value of the light amount of the light source by the light amount measuring unit is less than the target value of the light amount stored in the storage unit, the recording operation by the recording head is automatically stopped. it can.

  According to a ninth aspect of the present invention, in the method according to any one of the third to eighth aspects, the light amount is measured by the light amount measuring unit every time the recording head is scanned by the recording head scanning unit. Is an ink jet recording apparatus.

  According to the ninth aspect of the present invention, it is possible to measure the light amount by the light amount measuring means every time the recording head scans.

  According to a tenth aspect of the present invention, at the start of recording on the recording medium or at the end of recording, the light quantity measurement unit performs light quantity measurement. Is an ink jet recording apparatus.

  According to the tenth aspect, by measuring the light amount at the start of recording on the recording medium or at the end of recording, it is possible to accurately measure the amount of light actually irradiated on the recording medium.

  The invention according to claim 11 is the ink jet recording apparatus according to any one of claims 1 to 8, wherein the light amount is measured by the light amount measuring unit when the apparatus is activated or in a standby state. .

  According to the eleventh aspect of the present invention, the time until the light amount of the light source is stabilized at the time of starting the apparatus and the time while waiting for the input of the recording operation instruction, that is, the recording while the light source is turned on. The amount of light can be measured using the time when the medium is not irradiated with light.

  According to a twelfth aspect of the present invention, the light amount is measured by the light amount measuring means on condition that a predetermined total operation time of the device or a lapse of time after the device is started is set as a condition. An ink jet recording apparatus according to any one of claims 8 to 13.

  According to the twelfth aspect of the present invention, since the light amount measurement is performed after a fixed total operation time of the device or after a certain period of time after the device is started, it is possible to grasp a temporal change in the light amount of the light source.

  13. The inkjet recording apparatus according to claim 1, wherein the light source uses any one of a mercury lamp, a metal halide lamp, a semiconductor laser, and an LED. Device.

  According to the thirteenth aspect, it is possible to use, as the light source, a mercury lamp or a metal halide lamp capable of obtaining a relatively large amount of light, a semiconductor laser or an LED having directivity and a small amount of heat generation.

  The invention according to claim 14 is the ink jet recording apparatus according to any one of claims 1 to 13, wherein the light for curing the ink is ultraviolet light.

  According to the fourteenth aspect, it is possible to use ultraviolet light as light for curing the ink.

  The invention according to claim 15 is the ink jet recording apparatus according to any one of claims 1 to 14, wherein a cationic polymerization type ink is used as the ink.

  According to the invention as set forth in claim 15, as described above, since the light amount of the light source can be controlled with high accuracy, an ink having a high curing sensitivity that is cured by a relatively low output light source such as a cationic polymerization ink. Can be put to practical use.

  According to the first aspect of the present invention, it is possible to measure the light amount of the light source, and it is possible to detect in advance whether the light amount required for curing the ink is given to the ink on the recording medium. Thus, the light amount of the light source can be accurately controlled. Therefore, printing failure due to poor curing of the ink can be prevented, and the reliability of the inkjet recording apparatus can be improved. Further, since the light amount of the light source can be controlled with high accuracy, it is possible to commercialize an ink having a high curing sensitivity, such as a cationic polymerization ink, which is cured by a light source having a relatively low output. For this reason, since a high-output light source is not required, the light source device does not increase in size, and there is an effect that the inkjet recording device can be downsized and the manufacturing cost can be reduced.

  According to the second aspect of the present invention, different light sources are sequentially moved to the measurement area of the light amount measuring unit by the light source scanning unit, and the light amount measuring units sequentially measure the light amounts of the plurality of light sources. A measurement can be performed. Therefore, in addition to the effect of the invention described in claim 1, different light sources are measured by the same light quantity measuring means, so that the number of light quantity measuring means can be made smaller than the number of light sources. Simplification and downsizing can be achieved.

  According to the third aspect of the invention, the same effect as that of the second aspect can be obtained, and the light source and the recording head can be mounted on the same carriage. It can be incorporated in a space-saving manner, and it is possible to further reduce the size of the inkjet recording apparatus.

  According to the invention described in claim 4, since the light sources at different positions in the main scanning direction and the transport direction of the recording medium can be measured by the same light quantity measuring means, the light quantity measuring means is single. Thus, in addition to the effects of the invention described in the above claims, it is possible to further simplify and downsize the device.

  According to the fifth aspect of the invention, when a plurality of light sources are provided at different positions in the transport direction of the recording medium, the light amount measuring means can be moved in that direction to sequentially measure the light amount of the light sources. Therefore, it is possible to measure light sources located at different positions in the main scanning direction and the transport direction of the recording medium by the same light amount measuring means, and in addition to the effects of the invention described in the above claims, further simplifying the apparatus, It is possible to reduce the size.

  According to the sixth aspect of the present invention, a part of the recording medium supporting means disposed between the light source and the light quantity measuring means is constituted by a member transmitting at least a part of the light of the light source. The measurement of the light amount of the light source can be performed while the recording medium supporting means is arranged between the recording medium supporting means, so that the measurement area is not provided at a position adjacent to the recording medium supporting means, and is provided via the recording medium supporting means. The light amount of the light source can be measured immediately below the light source. Therefore, in addition to the effects of the invention described in the above claims, it is possible to further simplify and downsize the ink jet recording apparatus. Further, even in a line head type ink jet recording apparatus in which the position of the light source is fixed, the light amount of the light source can be easily measured, and the apparatus can be downsized.

  According to the invention described in claim 7, the user can be notified by the display means that the measured value of the light quantity of the light source by the light quantity measurement means is smaller than the target value of the light quantity stored in the storage means. It is possible to take appropriate measures such as replacing the light source, and it is possible to prevent poor printing due to poor curing of the ink. Therefore, in addition to the effects of the invention described in the above claims, the reliability of the ink jet recording apparatus can be further improved.

  According to an eighth aspect of the present invention, in addition to the effects of the above-mentioned invention, the recording head is provided when the measured value of the light amount of the light source by the light amount measuring unit is smaller than the target value of the light amount stored in the storage unit. , The printing operation is prohibited, so that it is possible to prevent the output of the printed matter in which the uncured ink remains, prevent the user from obtaining such misprints without knowing it, and improve the reliability of the ink jet printing apparatus. Can be achieved.

  According to the ninth aspect of the present invention, in addition to the effect of the above-mentioned aspect, it is possible to measure the light amount by the light amount measuring means every time the recording head scans. By measuring the light amount every time and frequently measuring the light amount, it is possible to immediately detect a relatively short-time change such as a decrease in the light irradiation amount due to the ink mist.

  According to the tenth aspect of the present invention, by measuring the amount of light at the start of recording on the recording medium or at the end of recording, the amount of light actually irradiated on the recording medium can be accurately measured. It is possible to accurately grasp the change in light amount over a long period of time. Therefore, in addition to the effects of the invention described in the above claims, the reliability of the ink jet recording apparatus can be further improved.

  According to the eleventh aspect of the present invention, in addition to the effect of the above-mentioned aspect, the light quantity measurement is performed by using the time when the recording medium is not irradiated with the light even when the light source is turned on. Therefore, the light amount can be measured without lowering the recording speed on the recording medium, and the power consumption of the ink jet recording apparatus can be further reduced.

  According to the twelfth aspect of the present invention, in addition to the effects of the above-described aspect, by measuring the light amount after a certain total operation time of the device or a certain time after the start of the device, the light amount of the light source over time can be measured. Since it is possible to accurately grasp the change, it is possible to predict in advance the time when the light amount of the light source becomes less than the target value, or it is possible to appropriately take measures such as removing dirt due to the ink mist. Therefore, printing failure due to poor curing of the ink can be reliably prevented, and the reliability of the inkjet recording apparatus can be improved.

  According to the invention described in claim 13, in addition to the effects of the invention described in the above claim, as a light source, a mercury lamp or a metal halide lamp capable of obtaining a relatively large light amount, a semiconductor laser or an LED having directivity and a small heat generation amount is used. Since it is possible to select from among these, it is possible to prevent printing failure due to curing failure and further enhance the reliability of the ink jet recording apparatus, and to use a relatively low output light source such as a cationic polymerization ink. Thus, it is possible to more accurately carry out the practical use of an ink that cures and has high curing sensitivity, or it is possible to further reduce the power consumption of the apparatus.

  According to the fourteenth aspect of the present invention, in addition to the effects of the above-described aspect, since ultraviolet light is used as light for curing the ink, the curability of the ink is further increased, and the power consumption is further reduced. Becomes possible.

  According to the fifteenth aspect, since the amount of light from the light source can be controlled with high accuracy, an ink having a high curing sensitivity, such as a cationic polymerization ink, which is cured by a light source having a relatively low output is used. be able to. For this reason, since a high-output light source is not required, the light source device does not increase in size, and there is an effect that the inkjet recording device can be downsized and the manufacturing cost can be reduced.

  An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

[First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing an ink jet recording apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, the ink jet recording apparatus of the present embodiment includes an ink jet head 1, a light source device 2, a light amount measuring sensor 3 as a light amount measuring unit, a control unit 4, a display unit 5, and a recording medium supporting unit. And a platen 6 as the above, and constitute a serial head type ink jet recording apparatus.

The ink jet head 1 is an ink jet type recording head that discharges ink from a plurality of discharge ports, and uses a well-known one. The inkjet head 1 is mounted on a carriage (not shown) and reciprocates in the main scanning direction A to scan on a recording medium such as paper or film conveyed along the platen 6.
Here, the direction perpendicular to the paper of FIG. 1 is the transport direction H of the recording medium (not shown).
Recording head scanning means (not shown) for moving the inkjet head 1 in a direction perpendicular to the transport direction H of the recording medium (= main scanning direction A) to scan the inkjet head 1 on the recording medium includes a carriage, It is configured using a well-known mechanism for linearly reciprocating this.

The light source device 2 includes one or more semiconductor lasers or LEDs as a light source that emits ultraviolet light that cures ink that is ejected from the inkjet head 1 and adheres to a recording medium. The light source device 2 moves together with the inkjet head 1 by being mounted on a carriage together with the inkjet head 1. As the ink, an ultraviolet curable cationic polymerization type ink is used. As a recording medium, a resin film having no ink absorption is used.
In this way, a light source scanning unit is configured to scan the light source on the recording medium by moving the light source device 2 in a direction perpendicular to the transport direction H of the recording medium (= main scanning direction A). That is, in the present embodiment, the light source scanning unit is configured by moving the light source device 2 together with the inkjet head 1 by the recording head scanning unit. In this case, a separate mechanism for moving the light source device 2 is not required.

The light amount measurement sensor 3 is an optical sensor that measures the light amount of a light source provided in the light source device 2 and uses a known sensor.
The control means 4 is configured to control the light amount of the light source provided in the light source device 2 according to the measurement value of the light amount measurement sensor 3, and includes, for example, a computer and a program executed on the computer. Use a well-known one. In this embodiment, as shown in FIG. 1, the light source device 2, the light amount measurement sensor 3, and the display unit 5 are electrically connected to the control unit 4. Although not shown, the control unit 4 is also electrically connected to a storage unit for storing control data such as a control program, a drive source for the carriage, an inkjet head, a transport mechanism for a recording medium, and the like. The control unit 4 is also configured to control the operation of the entire inkjet recording apparatus.

The display means 5 is configured by an image display device such as a liquid crystal display device for displaying an image, and is further configured by adding a loudspeaker for displaying a sound as needed. In the present embodiment, both image display and sound display can be implemented.
The platen 6 is a member for supporting the recording medium from below and keeping the conveyance position of the recording medium at a predetermined position, thereby making the distance between the recording medium and the recording head, that is, the ink flying distance constant, Use a well-known one. In the case where the platen 6 is interposed between the light source and the light amount measuring sensor 3, a part of the platen 6 is made of a transparent material such as a transparent glass or a resin that transmits at least a part of the light of the light source. It is composed of members.

Next, the light source control operation in the present embodiment will be described.
First, before the recording operation by the inkjet head 1 or during the recording operation, the control unit 4 moves the light source device 2 to the measurement area C adjacent to the recording area B as shown in FIG. The light quantity of the light source provided in 2 is arranged at a position where the light quantity measurement sensor 3 can measure the light quantity.
Next, the light intensity of the light source provided in the light source device 2 is measured by the light intensity measurement sensor 3.
Next, the control unit 4 controls the light amount of the light source provided in the light source device 2 according to the measurement value of the light amount measurement sensor 3. That is, control is performed so that the measured value of the light amount of the light source is maintained in a range that is equal to or larger than the target value. The target value is calculated in consideration of various conditions such as the curing characteristics of the cationic polymerization ink to be used and the amount of ink droplets landed on the recording medium, or is obtained experimentally, and the light amount required for curing the ink is obtained. And stored in the storage means. The control means 4 controls by reading the target value from the storage means.
For example, such control is performed according to the flowchart shown in FIG.
That is, as shown in FIG. 2, when the light quantity measurement is started, the control means 4 reads the target value P0 from the memory (step S1), and changes the light source drive value to obtain the measured value P1 by the light quantity measurement sensor 3 (step S1). Step S2).
Next, the target value P0 is compared with the measured value P1 (step S3). If the measured value P1 exceeds the target value P0, the light source drive value is determined so as to be equal to or more than the target value P0 (step S5). . Further, the processing is ended, and the operation proceeds to the printing operation (step S6).
On the other hand, if the measured value P1 is less than the target value P0 in step S3, error processing S4 is performed. As the error processing S4, the display unit 5 notifies the user that the measurement result, that is, the measured value P1 is less than the target value P0. For example, the loudspeaker generates a warning sound dedicated to insufficient light quantity, and displays the measured value on the image display device. At the same time, it may be displayed that the light quantity is insufficient. Thereby, the measurement result can be notified to the user.
Further, as the error processing S4, the recording operation by the inkjet head 1 is prohibited. That is, the start of the recording operation of the inkjet head 1 is prohibited, and if the measurement is performed during the recording operation, the recording operation is stopped, and the display unit 5 notifies the user. As a result, it is possible to prevent the output of the printed matter in which the uncured ink remains, prevent the user from obtaining such misprints without knowing it, and improve the reliability of the ink jet recording apparatus.

  The recording operation may be performed only by notifying the user of the measurement result by the display unit 5 without prohibiting the recording operation by the inkjet head 1. Even in this case, the user can know that the ink jet recording apparatus operates with an irradiation amount less than the ink curing energy, and necessary measures such as applying light from another light source can be performed.

This embodiment is an example in which four ink jet heads 1 are provided, and is an example in which the light source device 2 is single and the light source devices 2 are arranged outside the mounting range of the four ink jet heads 1.
When a plurality of light sources provided in the light source device 2 are provided at the same position in the recording medium transport direction H and at different positions in the main scanning direction A, the light sources are shared with the recording head scanning means of the inkjet head 1 as described above. The different light sources are sequentially moved to the measurement area of the light amount measurement sensor 3 by the light source scanning means, and the light amount measurement sensors 3 sequentially measure the light amounts of the plurality of light sources. Thereby, the measurement of all the light sources is performed. Therefore, since different light sources are measured by the same light quantity measuring sensor 3, the number of light quantity measuring sensors 3 can be smaller than the number of light sources, and the device can be simplified and downsized.

According to the above embodiment, it is possible to measure the light amount of the light source, and it is possible to detect in advance whether the light amount necessary for curing the ink is given to the ink on the recording medium, and to accurately detect the light amount. The light amount of the light source can be controlled. Since the light amount of the light source can be controlled with high accuracy, the reliability of the ink jet recording apparatus can be improved. Further, since the light amount of the light source can be controlled with high accuracy, it is possible to commercialize an ink having a high curing sensitivity, such as a cationic polymerization ink, which is cured by a light source having a relatively low output. Therefore, since a high-output light source is not required, the length of the light source device 2 does not increase, and the size and manufacturing cost of the inkjet recording apparatus can be reduced.
Further, since the light source device 2 is mounted on the same carriage together with the inkjet head 1, both can be integrated in a space-saving manner, and the size of the inkjet recording apparatus can be reduced.

[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a sectional view showing an ink jet recording apparatus according to a second embodiment of the present invention.
As shown in FIG. 3, the ink jet recording apparatus of the present embodiment has the same means (1 (1a to 1d), 2 (2a to 2e), 3, 4, 5, 6) as in the first embodiment. ing. Corresponding components have the same reference characters.
However, unlike the first embodiment, the ink jet recording apparatus of the present embodiment has five light source devices 2a to 2e, and four ink jet heads 1a to 1d have one light source device between the five light source devices. Are arranged one by one. When the carriage on which these are mounted moves in the main scanning direction A to the left in the drawing, the ink ejected onto the recording medium by the ink jet head 1a is irradiated with ultraviolet rays by the light source device 2a, and the ink is discharged by the ink jet head 1b. The ink ejected on the recording medium is irradiated with ultraviolet light by the light source device 2b, the ink ejected on the recording medium by the inkjet head 1c is irradiated with ultraviolet light by the light source device 2c, and is ejected on the recording medium by the inkjet head 1d. The light source device 2d irradiates the ink thus produced with ultraviolet rays. This is an effective configuration for quickly irradiating the ink that has landed on the recording medium with ultraviolet rays.

Conversely, when moving in the main scanning direction A to the right in the drawing, the ink ejected onto the recording medium by the inkjet head 1a is irradiated with ultraviolet rays by the light source device 2b, and the ink is discharged onto the recording medium by the inkjet head 1b. The ink ejected on the recording medium is irradiated with ultraviolet light by the light source device 2c, the ink ejected on the recording medium by the ink jet head 1c is irradiated with ultraviolet light by the light source device 2d, and the ink ejected on the recording medium by the ink jet head 1d is irradiated on the recording medium. Ultraviolet light is emitted from the light source device 2e.
As described above, the present embodiment is a recording apparatus of the type that performs a recording operation in a reciprocating manner. In the case of a recording apparatus that performs a recording operation only in one way, one of the light source devices 2a and 2e at both ends becomes unnecessary.

Next, the light source control operation in the present embodiment will be described.
First, before the recording operation by the inkjet heads 1a to 1d or during the recording operation, the control unit 4 moves the light source device 2a to the measurement area D, regardless of the order, and the light source provided in the light source device 2a, for example. Is disposed at a position where the light amount of the light can be measured by the light amount measurement sensor 3. As in the first embodiment, the light source devices 2a to 2e are provided on the same carriage as the inkjet heads 1a to 1d, and the above operation is performed by moving the carriage.
Next, the light intensity of the light source provided in the light source device 2a is measured by the light intensity measurement sensor 3.

  Similarly, the light source device 2b is moved to the measurement area D, and the light amount of the light source provided in the light source device 2b is arranged at a position where the light amount measurement sensor 3 can measure the light amount. Measure the amount of light from the light source.

  Similarly, the light source devices 2c to 2e are sequentially moved to the measurement region D, and the light amounts of the light sources provided in the light source devices 2c to 2e are sequentially arranged at positions where the light amount measurement sensor 3 can measure the light amounts. , The light amounts of the light sources provided in the light source devices 2c to 2e are sequentially measured.

Next, the control means 4 controls the light amounts of the light sources provided in the light source devices 2a to 2e according to the measured values of the light sources provided in the light source devices 2a to 2e by the light amount measurement sensor 3.
Other than that, it is carried out in the same manner as in the first embodiment.

As described above, in the second embodiment, even when a plurality of light sources are provided at different positions in the main scanning direction A, the light source scanning configured by mounting the light source devices 2a to 2e on the carriage that moves the inkjet head 1 is performed. By means of different means, different light sources are sequentially moved to the measurement area D of the light quantity measuring sensor 3 so that the light quantity measuring sensors 3 sequentially measure the light quantities of the plurality of light sources.
Therefore, since different light sources are measured by the same light quantity measuring sensor 3, the number of light quantity measuring sensors 3 can be smaller than the number of light sources, and the device can be simplified and downsized.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a bottom view of the ink jet recording apparatus according to the third embodiment of the present invention as viewed from the lower side of the platen.

This embodiment relates to the invention that can be added to the first embodiment or the second embodiment. FIG. 4 illustrates a case where the present embodiment is added to the second embodiment.
In the first embodiment or the second embodiment, a plurality of point light sources 11 each having a dot-shaped irradiation range are provided in a direction perpendicular to the main scanning direction A, that is, in the transport direction H of the recording medium. May be valid. This is the present embodiment. This is to cope with the case where a large number of ejection ports 10 are provided in a row in the transport direction of the recording medium. That is, when a large number of ejection ports 10 are provided in the conveying direction of the recording medium, one point light source cannot irradiate all the ink dots with ultraviolet rays. For this reason, in the present embodiment, a plurality of point light sources 11 are provided in the conveying direction of the recording medium. Here, the transport direction of the recording medium is the same as the arrow E in FIG.

However, as described in the first embodiment or the second embodiment, the light source scanning unit can move the light source only in the main scanning direction A. Since a plurality of light sources are provided at different positions in the direction E, one light amount measurement sensor 3 whose position is fixed cannot measure the light amounts of all the light sources independently. When a plurality of light quantity measuring sensors 3 are arranged in the direction E so that the light quantities of all the light sources can be measured, the number of light quantity measuring sensors 3 increases.
Therefore, in the present embodiment, the light quantity measuring sensor 3 is reciprocated in the direction E.
That is, a scanning means for sequentially measuring a plurality of light sources by the light quantity measuring sensor 3 by moving the light quantity measuring sensor 3 is provided. Specifically, a scanning unit (not shown) for sequentially measuring a plurality of light sources by the light quantity measuring sensor 3 by moving the light quantity measuring sensor 3 in the transport direction E of the recording medium is provided. This can be constituted by a well-known moving mechanism, drive source and control means. In this embodiment, the control means 4 is electrically connected to the scanning means, and the control means 4 also controls the movement of the light quantity measuring sensor 3 in the transport direction of the recording medium. Have been.

Next, the light source control operation in the present embodiment will be described. The sectional view is the same as FIG.
First, before the recording operation by the inkjet heads 1a to 1d or during the recording operation, the control unit 4 moves the light source device 2a to the measurement area D, regardless of the order, and the light source provided in the light source device 2a, for example. Is disposed at a position where the light amount of the light can be measured by the light amount measurement sensor 3. As in the first embodiment, the light source devices 2a to 2e are provided on the same carriage as the inkjet heads 1a to 1d, and the above operation is performed by moving the carriage.
Next, while moving the light amount measuring sensor 3 in the direction E, scanning for sequentially measuring the light amounts of the plurality of light sources 11 arranged in the direction E provided in the light source device 2a is performed.

  Similarly, the light source device 2b is moved to the measurement area D, the light amount of the light source provided in the light source device 2b is arranged at a position where the light amount measurement sensor 3 can measure the light amount, and the light amount measurement sensor 3 is moved in the direction E while moving. Scanning for sequentially measuring the light amounts of the plurality of light sources 11 arranged in the direction E provided in the light source device 2b is performed.

  Similarly, the light source devices 2c to 2e are sequentially moved to the measurement region D, and the light amounts of the light sources provided in the light source devices 2c to 2e are sequentially arranged at positions where the light amount measurement sensor 3 can measure the light amounts. While moving in the direction E, scanning for sequentially measuring the light amounts of the plurality of light sources 11 arranged in the direction E provided in the light source devices 2c to 2e is performed.

Next, the control means 4 controls the light quantity of each light source 11 according to the measurement value of each light source 11 provided in the light source devices 2a to 2e by the light quantity measurement sensor 3.
Other than that, it is carried out in the same manner as in the first embodiment.

  Therefore, according to the present embodiment, since the light sources located at different positions in the main scanning direction A and the recording medium transport direction E are measured by the same light quantity measuring sensor 3, the light quantity measuring sensor 3 may be a single. As a result, the device can be simplified and downsized.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a bottom view of the inkjet recording apparatus according to the fourth embodiment of the present invention, as viewed from the lower side of the platen.

As shown in FIG. 5, this embodiment relates to the case of the line head system. In the case of the line head system, since the inkjet head 1 is fixed, the light source device 2 is also fixedly provided.
In the case of the line head method, the ejection ports 10 provided in the inkjet head 1 form a line in a direction perpendicular to the recording medium conveyance direction F with the light quantity measurement sensor 3. Further, in the present embodiment, the plurality of light sources 11 are provided in the light source device 2 so as to form a row in the direction G parallel to the row of the discharge ports 10 for the same purpose as the third embodiment. In addition, for the purpose of simplifying the light quantity measuring sensor 3 similar to the third embodiment, in this embodiment, the light quantity measuring sensor 3 is moved in the direction G to sequentially measure a plurality of light sources by the light quantity measuring sensor 3. Scanning means is provided. This can be constituted by a well-known moving mechanism, drive source and control means. In the present embodiment, the control unit 4 is electrically connected to the scanning unit, and the control unit 4 is configured to also control the movement of the light amount measurement sensor 3 in the direction G. .

As shown in FIG. 5, when a plurality of rows in the direction of arrow G of the light source 11 are provided by providing a plurality of light source devices 2 or the like, one light quantity measuring sensor 3 is provided for each row, The following control operations are performed simultaneously. Each light quantity measuring sensor 3 is arranged at a position where the light quantity of the light source of the row in charge can be measured in the transport direction F of the recording medium.
Note that a platen 6 is disposed between the light quantity measurement sensor 3 and the light source 11. At least a portion of the platen 6 directly below the light source 11 is a light-transmitting through-hole or a transparent portion so that the light amount can be measured in the following control operation. In the case of the line head system, since the position of the light source 11 is fixed, the light quantity can be measured by providing a light transmitting hole or a transparent portion partially.

Next, the light source control operation in the present embodiment will be described.
First, before the recording operation by the inkjet head 1 or during the recording operation, the control unit 4 controls the plurality of light sources 11 arranged in the direction G provided in each light source device 2 while moving each light amount measurement sensor 3 in the direction G. A scan for sequentially measuring the light amount is performed.

Next, the control means 4 controls the light quantity of each light source 11 according to the measurement value of each light source 11 by each light quantity measurement sensor 3.
Other than that, it is carried out in the same manner as in the first embodiment.

  Therefore, according to the present embodiment, in the line head type ink jet recording apparatus, different light sources are measured by the same light quantity measuring sensor 3, so that the number of light quantity measuring sensors 3 can be made smaller than the number of light sources. Simplification and downsizing are achieved.

  In the first to third embodiments described above, the measurement area can be arranged in the recording area B. In this case and in the fourth embodiment, the light amount is measured when the recording medium does not enter between the light source and the light amount measurement sensor 3. That is, the amount of light during a period from the time when the rear end of a certain recording medium passes between the light source and the light intensity measurement sensor 3 to the time when the front end of the next recording medium enters between the light source and the light intensity measurement sensor 3 The light quantity of the light source can be measured by the measurement sensor 3.

In the first to third embodiments, the time interval at which the light amount measurement of the light source is performed by the light amount measurement sensor 3 can be performed for each scan of image formation as a minimum unit according to the above embodiment. If the light amount is measured every time the image formation is performed, it is possible to immediately detect a relatively short-term change such as a decrease in the irradiation amount due to the ink mist.
When there is a concern about a decrease in printing speed, or when a change over a relatively long period of time (for example, a decrease in the output of a light source due to deterioration of an electric system including the light amount measurement sensor 3) is mainly considered as a problem, when the apparatus is started or the recording medium is The light amount measurement sensor 3 measures the light amount at the start of recording on the, the paper interval, the standby time waiting for the input of a print job instruction, or the end of recording. At the same time, the light quantity measurement may be performed by the light quantity measurement sensor 3 on condition that a preset time has elapsed, that is, a preset total operation time of the apparatus or an elapsed time after the apparatus has been started.

Next, technical items that can be adopted as the embodiment of the present invention will be described separately.
<Injection volume>
The ejection amount per dot is 2 pl (picoliter) to 20 pl. It is preferably 4 pl to 10 pl. If it exceeds 20 pl per dot, high-definition printing is difficult, and if it is less than 2 pl per dot, the density of the formed image becomes low.

<Dot diameter>
The dot diameter formed on the recording medium is 50 μm to 200 μm. Preferably it is 50 μm to 150 μm, more preferably 55 μm to 100 μm. If it is less than 50 μm, the density of the formed image will be low, and if it is more than 200 μm, high-definition printing will be difficult.

<Does not contain water and organic solvents>
It is desirable that the ink used contains substantially no water and no organic solvent. Substantially free means that the content of water and the organic solvent is less than 1% by weight.

<Inkjet method>
As a driving force of the ink ejection of the ink jet printer, a method using a piezoelectric action of a piezoelectric material which has a wide application range to ink and can perform high-speed ejection is preferable. Specifically, as described in, for example, Japanese Patent Publication No. 4-48622, an ink flow in which an electrode film is formed inside a fine groove formed on a piezoelectric substrate and further covered with an insulating film. This is an ink jet head system which is used as a path.

<Irradiation source>
It is possible to use various radiation sources that irradiate ultraviolet rays, electron beams, X-rays, visible light, infrared light, and the like. preferable. As the ultraviolet ray source, a mercury lamp, a metal halide lamp, an excimer lamp, an ultraviolet laser, an LED, or the like can be used.
The basic irradiation method is disclosed in JP-A-60-132767. According to this, light sources are provided on both sides of the head unit, and the head and the light source are scanned in a shuttle system. Irradiation is performed at a fixed time after the ink has landed. Further, the curing is completed by another light source without driving. WO9954415 discloses a method using an optical fiber or a method in which a collimated light source is applied to a mirror provided on a side surface of a head unit to irradiate a recording unit with UV light. These irradiation methods can be used as an embodiment of the present invention.
Specifically, a strip-shaped metal halide lamp tube and an ultraviolet lamp tube are preferable. The radiation source can be made inexpensive by substantially fixing the radiation source to the ink jet printer and eliminating the operation unit.
Irradiation is preferably performed every time an image of each color is formed. In other words, one of the preferable modes is to prepare two types of radiation sources and complete the curing by the second radiation source in any exposure method. . This contributes to obtaining wettability of the second landing ink and adhesion between the inks, and inexpensively assembling the radiation source.
Note that it is preferable to change the exposure wavelength or the exposure illuminance between the first radiation source and the second radiation source. The irradiation energy of the first source is smaller than the irradiation energy of the second source, that is, the irradiation energy of the first source is 1 to 20%, preferably 1 to 10%, more preferably 1 to 10% of the total irradiation energy. To 5%. By performing irradiation with changed illuminance, the molecular weight distribution after curing becomes preferable. That is, when irradiation with high illuminance is performed at once, the polymerization rate is increased, but the molecular weight of the polymerized polymer is small, and the strength cannot be obtained.
In addition, the irradiation of the first radiation source has a longer wavelength than the irradiation of the second radiation source, so that the first irradiation cures the surface layer of the ink and suppresses the bleeding of the ink. In the irradiation, the ink near the recording medium to which the irradiation light is hardly reach can be cured, and the adhesion can be improved. The second irradiation wavelength is preferably a long wavelength in order to promote the curing inside the ink.

<Irradiation timing>
Using the above ink, the ink is heated to a constant temperature, and the time from landing to irradiation is 0.01 to 0.5 seconds, preferably 0.01 to 0.3 seconds, more preferably 0.01 to 0 seconds. Radiation can be applied after 15 seconds. By controlling the time from landing to irradiation in a very short time in this way, it is possible to prevent the landing ink from bleeding before curing. In addition, even if the porous recording medium is exposed before the ink penetrates to a deep portion where the light source cannot reach, the residual unreacted monomer can be suppressed, and the odor can be reduced. This results in a large synergistic effect by using a high viscosity ink. In particular, a great effect can be obtained by using an ink having an ink viscosity of 35 to 500 mPa · s at 25 ° C. By adopting such a recording method, the dot diameter of the landed ink can be kept constant even for various recording media having different surface wettabilities, and the image quality is improved. Note that in order to obtain a color image, it is preferable to superimpose the colors in order from the color with the lowest brightness. When ink with low lightness is overlaid, the irradiation rays hardly reach the ink at the lower portion, and the curing sensitivity is likely to be impaired, residual monomers are increased, odor is generated, and adhesion is deteriorated. In addition, irradiation can be performed by exposing all colors and exposing them collectively. However, it is preferable to expose each color individually from the viewpoint of accelerating curing.
Further, in a unit composed of a plurality of color heads, it is preferable that the space between the respective colors is substantially transparent to the radiation. More specifically, the structure is such that the members between the heads are made of a member that transmits radiation, or no members are arranged. With such a simple configuration, it is possible to quickly irradiate each color immediately after landing, and to prevent bleeding of the secondary color, and in particular, to prevent a dot bleeding difference between forward and backward in bidirectional drawing. This is preferable because it is possible to prevent the colors of the going and returning from being different.

<Ink heating, head temperature control>
It is preferred from the viewpoint of ejection stability that the ink is heated to 30 to 150 ° C. and ejected with the ink viscosity lowered. More preferably, it is 40 to 100 ° C. At 30 ° C. or lower and 150 ° C. or higher, injection becomes difficult. Irradiation-curable inks generally have higher viscosities than aqueous inks, and therefore have a large range of viscosity variation due to temperature variations. Fluctuations in viscosity directly affect the droplet size and droplet ejection speed as they are, causing deterioration in image quality. Therefore, it is necessary to keep the ink temperature as constant as possible. The control range of the ink temperature is the set temperature ± 5 ° C., preferably the set temperature ± 2 ° C., and more preferably the set temperature ± 1 ° C. The ink jet printer is provided with a means for stabilizing the ink temperature, but all the piping systems and members from the ink tank (the intermediate tank if there is an intermediate tank) to the nozzle ejection surface are targeted for the temperature to be kept constant.
In order to control the temperature, it is preferable to provide a plurality of temperature sensors at each of the piping sections and perform heating control according to the ink flow rate and the environmental temperature. Further, it is preferable that the head unit to be heated is thermally shielded or insulated so as not to be affected by the temperature from the apparatus body or the outside air. In order to shorten the printer startup time required for heating and to reduce the loss of thermal energy, it is preferable to insulate other parts and reduce the heat capacity of the entire heating unit.

<Recording medium without ink absorption>
As an embodiment of the present invention, a recording medium having no ink absorption or a recording medium having low ink absorption (or a non-ink-absorbing recording medium) can be used. A non-ink-absorbing recording medium or a low-ink-absorbing recording medium (or a non-ink-absorbing recording medium) refers to a non-ink-absorbing material or a low-ink-absorbing material (or non-ink-absorbing material). Recording medium having a surface layer (image forming layer) made of a material having no ink absorption or a material having low ink absorption (or a material having no ink absorption), and a material or ink having no ink absorption The low-absorbing material (or the ink non-absorbing material) is, for example, various resins and metals.

<Viscosity>
The ink according to the embodiment of the present invention is a liquid having a viscosity at 30 ° C. of 10 to 500 mPa · s. Preferably, it is 40 to 500 mPa · s. If it is less than 10 mPa · s, bleeding deteriorates, and if it exceeds 500 mPa · s, the smoothness of image quality is lost. The ink is preferably a liquid of 3 to 30 mPa · s at 60 ° C., more preferably 3 to 20 mPa · s. When the pressure is 3 mPa · s or less, high-speed injection is inconvenient, and when the pressure is 30 mPa · s, the injection property is deteriorated.

FIG. 1 is a cross-sectional view illustrating an inkjet recording apparatus according to a first embodiment of the present invention. (A) and (b) depict different operation time points. 6 is a flowchart illustrating an example of a process performed by a control unit. FIG. 5 is a cross-sectional view illustrating an inkjet recording apparatus according to a second embodiment of the present invention. FIG. 11 is a bottom view of the ink jet recording apparatus according to the third embodiment of the present invention, as viewed from a platen mask side. FIG. 14 is a bottom view of the inkjet recording apparatus according to the fourth embodiment of the present invention, as viewed from a platen mask side.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Ink-jet head 2 ... Light source device 3 ... Light quantity measurement sensor 4 ... Control means 5 ... Display means 6 ... Platen 10 ... Discharge port 11 ... Light source

Claims (15)

An inkjet recording head that ejects ink from a plurality of ejection ports,
A light source that emits light that cures ink that is ejected from the recording head and adheres to the recording medium,
Light amount measuring means for measuring the light amount of the light source,
Control means for controlling the light amount of the light source according to a measurement value of the light amount measuring means. Light source scanning means for scanning the light source on the recording medium by moving the light source in a direction perpendicular to the conveying direction of the recording medium,
A plurality of the light sources are provided at different positions in the vertical direction,
2. The ink jet recording apparatus according to claim 1, wherein the light source scanning unit sequentially moves different light sources to a measurement area of the light amount measurement unit so that the light amount measurement unit sequentially measures the light amounts of the plurality of light sources. . Recording head scanning means for scanning the recording head on the recording medium by moving the recording head in a direction perpendicular to the conveying direction of the recording medium,
The ink-jet recording apparatus according to claim 2, wherein the light source scanning unit is configured by moving the light source together with the recording head by the recording head scanning unit. A plurality of the light sources are provided,
4. The ink jet recording apparatus according to claim 1, further comprising a scanning unit that sequentially measures the plurality of light sources by moving the light amount measuring unit by the light amount measuring unit. 5. A plurality of light sources are provided at different positions in the transport direction of the recording medium,
5. The scanning device according to claim 1, further comprising a scanning unit configured to sequentially measure the plurality of light sources by the light amount measurement unit by moving the light amount measurement unit in a conveyance direction of the recording medium. 6. 3. The ink jet recording apparatus according to claim 1. A recording medium supporting unit that supports the recording medium is disposed between the light source and the light amount measuring unit, and a part of the recording medium supporting unit is configured by a member that transmits at least a part of the light of the light source. The inkjet recording apparatus according to any one of claims 1 to 5, wherein: Storage means for storing a target value of the amount of light controlled by the control means,
The ink jet recording apparatus according to any one of claims 1 to 6, further comprising: display means for notifying a user of the measurement result when the measured value by the light quantity measuring means is less than the target value. apparatus. Having a storage means for storing a target value of the light amount controlled by the control means,
8. The ink jet recording apparatus according to claim 1, wherein a recording operation by the recording head is prohibited when a value measured by the light quantity measuring unit is smaller than the target value. 9. 9. The ink-jet recording apparatus according to claim 3, wherein a light amount is measured by the light amount measuring unit every time the recording head is scanned by the recording head scanning unit. The ink jet recording apparatus according to any one of claims 1 to 8, wherein the light amount is measured by the light amount measuring unit when recording on the recording medium starts or when recording ends. 9. The ink jet recording apparatus according to claim 1, wherein the light quantity is measured by the light quantity measuring unit when the apparatus is activated or in a standby state. 9. The light quantity measurement unit according to claim 1, wherein the light quantity measurement unit performs the light quantity measurement on condition that a preset total operation time of the apparatus or a lapse of time after the apparatus is started. Ink jet recording device. The inkjet recording apparatus according to claim 1, wherein the light source uses one of a mercury lamp, a metal halide lamp, a semiconductor laser, and an LED. 14. The ink jet recording apparatus according to claim 1, wherein the light for curing the ink is ultraviolet light. The ink jet recording apparatus according to claim 1, wherein a cationic polymerization ink is used as the ink.

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