JP7002891B2 - Inkjet recording device - Google Patents

Description

The present invention relates to an inkjet recording device.

In Patent Document 1, a developing solution stored in a tank is mixed with a diluting solution at a certain ratio to generate a developing solution for detecting a toner concentration, which is diluted to a concentration within a measurable range of the amount of transmitted light. A method of measuring the amount of transmitted light in the transparent cell portion is disclosed.

Japanese Unexamined Patent Publication No. 11-198398

However, when the density of the ink used for image formation in the inkjet recording apparatus is measured by the measurement method of Patent Document 1, the diluted solution is mixed with the ink actually used for image formation, so that the density detection is performed. Therefore, two concentration detection errors may occur: a mixing error of the diluted solution and a conversion error of the amount of transmitted light between the ink and the diluted solution. As a result, the density of the ink itself actually used is not measured, and there is a possibility that sufficient accuracy cannot be obtained in the measurement. Further, in the method of Patent Document 1, there is a possibility that the ink used for density detection is wasted.

Therefore, an object of the present invention is to measure the ink density with high accuracy.

In order to solve the above problems, the present invention has the following configurations. That is, it is an inkjet recording device including a tank for storing ink supplied to a recording head for ejecting ink and a density measuring unit for measuring the density of the ink, via the density measuring unit. , A first flow path for circulating the ink stored in the tank, and a second flow path for circulating the ink stored in the tank without going through the concentration measuring unit and the recording head . And a control unit that switches between the first flow path and the second flow path to circulate the ink, and the flow rate in the second flow path is larger than the flow rate in the first flow path. ..

INDUSTRIAL APPLICABILITY According to the present invention, the density of ink used for image formation can be measured with high accuracy.

It is a schematic diagram of a recording system. It is a perspective view of a recording unit. It is a block diagram of the control system of the recording system of FIG. It is a block diagram of the control system of the recording system of FIG. It is a perspective view which shows the structural example of a recording head. It is a figure for demonstrating the mechanism by which ink circulates in a recording head. It is a figure which shows the ink circulation mechanism between a recording head and a buffer tank. It is a figure explaining the circulation direction of ink in a recording head. It is a figure which shows the schematic structure of the concentration measuring part which concerns on this invention. It is a figure for demonstrating the structural example around the cell part of the concentration measuring part which concerns on this invention. It is a figure for demonstrating the flow path of ink which concerns on 1st Embodiment. It is a figure for demonstrating the switching of the ink flow path which concerns on 1st Embodiment. It is a flowchart which concerns on the concentration measurement processing which concerns on this invention. It is a figure which shows the schematic structure of the concentration measuring part which concerns on 2nd Embodiment. It is a figure for demonstrating the switching of the ink flow path which concerns on 2nd Embodiment.

An embodiment of the present invention will be described with reference to the drawings. In each figure, the arrows X and Y indicate the horizontal direction and are orthogonal to each other. The arrow Z indicates the vertical direction.

<Recording system>
FIG. 1 is a front view schematically showing a recording system 1 according to an embodiment of the present invention. The recording system 1 is a single-wafer inkjet printer that produces a recording material P'by transferring an ink image to a recording medium P via a transfer body 2. The recording system 1 includes a recording device 1A and a transport device 1B. In the present embodiment, the X direction, the Y direction, and the Z direction indicate the width direction (total length direction), the depth direction, and the height direction of the recording system 1, respectively. The recording medium P is conveyed in the X direction.

In "recording", not only when significant information such as characters and figures is formed, but also images, patterns, patterns, etc. are widely formed on a recording medium, or the medium is processed, regardless of whether it is significant or unintentional. Cases are also included, and it does not matter whether or not it is manifested so that it can be visually perceived by humans. Further, in the present embodiment, a sheet-shaped paper is assumed as the "recording medium", but a cloth, a plastic film, or the like may be used.

The components of the ink are not particularly limited, but in the present embodiment, it is assumed that a water-based pigment ink containing a pigment, water, and a resin as coloring materials is used.

<Recording device>
The recording device 1A includes a recording unit 3, a transfer unit 4, peripheral units 5A to 5D, and a supply unit 6.

<Recording unit>
The recording unit 3 includes a plurality of recording heads 30 and a carriage 31. See FIGS. 1 and 2. FIG. 2 is a perspective view of the recording unit 3. The recording head 30 ejects liquid ink to the transfer body 2 and forms an ink image of a recorded image on the transfer body 2.

In the case of the present embodiment, each recording head 30 is a full-line head extended in the Y direction, and nozzles are arranged in a range covering the width of the image recording area of the maximum usable recording medium. There is. The recording head 30 has an ink ejection surface through which a nozzle is opened on the lower surface thereof, and the ink ejection surface faces the surface of the transfer body 2 through a minute gap (for example, several mm). In the case of the present embodiment, since the transfer body 2 is configured to move cyclically on the circular orbit, the plurality of recording heads 30 are arranged radially.

Each nozzle is provided with a discharge element. The ejection element is, for example, an element that generates pressure in the nozzle to eject the ink in the nozzle, and a technique of an inkjet head of a known inkjet printer can be applied. As the ejection element, for example, an element that ejects ink by causing a film to boil in the ink by an electrothermal converter to form bubbles, an element that ejects ink by an electromechanical converter, and an element that ejects ink by using static electricity. Elements and the like can be mentioned. From the viewpoint of high-speed and high-density recording, a discharge element using an electric heat converter can be used.

In the case of this embodiment, nine recording heads 30 are provided. Each recording head 30 ejects different types of ink from each other. The different types of ink are, for example, inks having different coloring materials, such as yellow ink, magenta ink, cyan ink, and black ink. Although one recording head 30 ejects one type of ink, one recording head 30 may be configured to eject a plurality of types of ink. When a plurality of recording heads 30 are provided in this way, ink (for example, clear ink) in which some of them do not contain a coloring material may be ejected.

The carriage 31 supports a plurality of recording heads 30. The end of each recording head 30 on the ink ejection surface side is fixed to the carriage 31. As a result, the gap between the ink ejection surface and the surface of the transfer body 2 can be maintained more precisely. The carriage 31 is configured to be displaceable while mounting the recording head 30 by the guidance of the guide member RL. In the case of the present embodiment, the guide members RL are rail members extending in the Y direction, and are provided in pairs separated in the X direction. A slide portion 32 is provided on each side portion of the carriage 31 in the X direction. The slide portion 32 engages with the guide member RL and slides in the Y direction along the guide member RL.

<Transfer unit>
The transfer unit 4 will be described with reference to FIG. The transfer unit 4 includes a transfer drum (transfer cylinder) 41 and an impression cylinder 42. These bodies are rotating bodies that rotate around a rotation axis in the Y direction, and have a cylindrical outer peripheral surface. In FIG. 1, the arrows shown in the figures of the transfer drum 41 and the impression cylinder 42 indicate the rotation directions thereof, and the transfer drum 41 rotates clockwise and the impression cylinder 42 rotates counterclockwise.

The transfer drum 41 is a support that supports the transfer body 2 on its outer peripheral surface. The transfer body 2 is continuously or intermittently provided on the outer peripheral surface of the transfer drum 41 in the circumferential direction. When continuously provided, the transfer body 2 is formed in an endless band shape. When intermittently provided, the transfer body 2 is formed by dividing it into a plurality of segments in an endless band shape, and each segment can be arranged on the outer peripheral surface of the transfer drum 41 in an arc shape at equal pitches.

Due to the rotation of the transfer drum 41, the transfer body 2 moves cyclically on the circular orbit. Depending on the rotation phase of the transfer drum 41, the position of the transfer body 2 can be distinguished into a discharge pre-processing region R1, a discharge region R2, a discharge post-processing region R3 and R4, a transfer region R5, and a transfer post-processing region R6. The transcript 2 cyclically passes through these regions.

The ejection pre-processing region R1 is an region in which the transfer body 2 is preprocessed before the ink is ejected by the recording unit 3, and is a region in which the peripheral unit 5A performs the processing. In the case of this embodiment, the reaction solution is applied. The ejection region R2 is a forming region in which the recording unit 3 ejects ink to the transfer body 2 to form an ink image. The post-ejection processing areas R3 and R4 are processing areas for processing the ink image after the ink is ejected, the post-ejection processing area R3 is an area for processing by the peripheral unit 5B, and the post-ejection processing area R4 is the peripheral unit 5C. This is the area where the processing is performed. The transfer region R5 is a region in which the ink image on the transfer body 2 is transferred to the recording medium P by the transfer unit 4. The post-transcriptional processing region R6 is a region for post-treating the transfer body 2 after transcription, and is a region for processing by the peripheral unit 5D.

In the case of the present embodiment, the discharge region R2 is a region having a certain section. The sections of the other regions R1 and R3 to R6 are narrower than those of the discharge region R2. In the case of the present embodiment, the discharge pre-processing area R1 is approximately 10 o'clock, the discharge area R2 is approximately 11 o'clock to 1 o'clock, and the discharge post-processing area R3 is approximately 10 o'clock. It is the position at 2 o'clock, and the discharge post-processing area R4 is the position at about 4 o'clock. The transfer region R5 is at approximately 6 o'clock, and the post-transcriptional treatment region R6 is approximately 8 o'clock.

The transfer body 2 may be composed of a single layer, or may be a laminated body having a plurality of layers. When composed of a plurality of layers, for example, a surface layer, an elastic layer, and a compression layer may be included. The surface layer is the outermost layer having an image forming surface on which an ink image is formed. By providing the compression layer, the compression layer can absorb the deformation, disperse the fluctuation with respect to the local pressure fluctuation, and maintain the transferability even at the time of high-speed recording. The elastic layer is the layer between the surface layer and the compression layer.

As the material of the surface layer, various materials such as resin and ceramic can be appropriately used, but a material having a high compressive elastic modulus can be used in terms of durability and the like. Specific examples thereof include an acrylic resin, an acrylic silicone resin, a fluorine-containing resin, and a condensate obtained by condensing a hydrolyzable organosilicon compound. The surface layer may be subjected to surface treatment in order to improve the wettability of the reaction solution, the transferability of the image, and the like. Examples of the surface treatment include frame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray irradiation treatment, ozone treatment, surfactant treatment, silane coupling treatment and the like. A plurality of these may be combined. Further, any surface shape can be provided on the surface layer.

Examples of the material of the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, silicone rubber and the like. At the time of molding such a rubber material, a predetermined amount of a vulcanizing agent, a vulcanization accelerator, etc. are blended, and further, a filler such as a foaming agent, hollow fine particles, or sulfur is blended as necessary, and the porous rubber material is blended. May be. As a result, since the bubble portion is compressed with a volume change due to various pressure fluctuations, deformation in directions other than the compression direction is small, and more stable transferability and durability can be obtained. Porous rubber materials include those having a continuous pore structure in which each pore is continuous with each other and those having an independent pore structure in which each pore is independent, but any structure may be used, and these structures may be used in combination. You may.

As the member of the elastic layer, various materials such as resin and ceramic can be appropriately used. Various elastomer materials and rubber materials can be used in terms of processing characteristics and the like. Specific examples thereof include fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, urethane rubber, nitrile rubber and the like. Examples thereof include ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, ethylene / propylene / butadiene copolymer, and nitrile butadiene rubber. In particular, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are advantageous in terms of dimensional stability and durability because they have a small compression set. In addition, the change in elastic modulus with temperature is small, which is advantageous in terms of transferability.

Various adhesives or double-sided tape can also be used between the surface layer and the elastic layer, and between the elastic layer and the compression layer to fix them. Further, the transfer body 2 may include a reinforcing layer having a high compressive elastic modulus in order to suppress lateral elongation when mounted on the transfer drum 41 and to maintain elasticity. Further, the woven fabric may be used as a reinforcing layer. The transfer body 2 can be produced by arbitrarily combining the layers made of the above materials.

The outer peripheral surface of the impression cylinder 42 is pressed against the transfer body 2. At least one grip mechanism for holding the tip of the recording medium P is provided on the outer peripheral surface of the impression cylinder 42. A plurality of grip mechanisms may be provided so as to be separated from each other in the circumferential direction of the impression cylinder 42. The recording medium P is conveyed in close contact with the outer peripheral surface of the impression cylinder 42, and when it passes through the nip portion between the impression cylinder 42 and the transfer body 2, the ink image on the transfer body 2 is transferred.

A drive source such as a motor for driving the transfer drum 41 and the impression cylinder 42 is common to these, and the driving force can be distributed by a transmission mechanism such as a gear mechanism.

<Peripheral unit>
Peripheral units 5A to 5D are arranged around the transfer drum 41. In the case of the present embodiment, the peripheral units 5A to 5D are an application unit, an absorption unit, a heating unit, and a cleaning unit in this order.

The applying unit 5A is a mechanism for applying the reaction liquid onto the transfer body 2 before ejecting the ink by the recording unit 3. The reaction liquid is a liquid containing a component that increases the viscosity of the ink. Here, increasing the viscosity of the ink means that the coloring material or resin constituting the ink chemically reacts or is physically adsorbed by coming into contact with the component that increases the viscosity of the ink, thereby causing the ink to become highly viscous. An increase in the viscosity of the ink is observed. The increase in viscosity of the ink is not only when an increase in the viscosity of the entire ink is observed, but also when a part of the components constituting the ink such as a coloring material or a resin aggregates to cause a local increase in the viscosity. Is also included.

The component that increases the viscosity of the ink is not particularly limited, such as metal ions and polymer flocculants, but a substance that causes a change in the pH of the ink and aggregates the coloring material in the ink can be used, and an organic acid can be used. Can be used. Examples of the reaction liquid application mechanism include rollers, recording heads, die coating devices (die coaters), blade coating devices (blade coaters), and the like. If the reaction solution is applied to the transfer body 2 before the ink is ejected to the transfer body 2, the ink that has reached the transfer body 2 can be immediately fixed. This makes it possible to suppress bleeding in which adjacent inks are mixed with each other.

The absorption unit 5B is a mechanism for absorbing a liquid component from the ink image on the transfer body 2 before transfer. By reducing the liquid component of the ink image, bleeding of the image recorded on the recording medium P can be suppressed. Explaining the decrease of the liquid component from a different viewpoint, it can be expressed as concentrating the ink constituting the ink image on the transfer body 2. Concentrating the ink means that the liquid component contained in the ink decreases, so that the content ratio of the solid content such as the coloring material and the resin contained in the ink to the liquid component increases.

The absorption unit 5B includes, for example, a liquid absorption member that comes into contact with the ink image to reduce the amount of the liquid component of the ink image. The liquid absorbing member may be formed on the outer peripheral surface of the roller, or the liquid absorbing member may be formed in the shape of an endless sheet and may be circulated. In terms of protecting the ink image, the liquid absorbing member may be moved in synchronization with the transfer body 2 by making the moving speed of the liquid absorbing member the same as the peripheral speed of the transfer body 2.

The liquid absorbing member may include a porous body that comes into contact with the ink image. In order to suppress the adhesion of ink solids to the liquid absorbing member, the pore size of the porous body on the surface in contact with the ink image may be 10 μm or less. Here, the pore diameter indicates an average diameter, and can be measured by a known means such as a mercury intrusion method, a nitrogen adsorption method, SEM image observation, or the like. The liquid component is not particularly limited as long as it does not have a certain shape, has fluidity, and has a substantially constant volume. For example, water, an organic solvent, etc. contained in ink or a reaction liquid can be mentioned as liquid components.

The heating unit 5C is a mechanism for heating the ink image on the transfer body 2 before transfer. By heating the ink image, the resin in the ink image is melted, and the transferability to the recording medium P is improved. The heating temperature can be equal to or higher than the minimum film forming temperature (MFT) of the resin. MFT can be measured by generally known methods such as JIS K 6828-2: 2003 and ISO2115: 1996 compliant devices. From the viewpoint of transferability and image fastness, it may be heated at a temperature higher than MFT by 10 ° C. or higher, and further, it may be heated at a temperature higher than 20 ° C. or higher. As the heating unit 5C, known heating devices such as various lamps such as infrared rays and hot air fans can be used. Infrared heaters can be used in terms of heating efficiency.

The cleaning unit 5D is a mechanism for cleaning the transfer body 2 after transfer. The cleaning unit 5D removes ink remaining on the transfer body 2, dust on the transfer body 2, and the like. For the cleaning unit 5D, for example, a known method such as a method of bringing a porous member into contact with the transfer body 2, a method of rubbing the surface of the transfer body 2 with a brush, a method of scraping the surface of the transfer body 2 with a blade, or the like is appropriately used. Can be done. Further, as the cleaning member used for cleaning, a known shape such as a roller shape or a web shape can be used.

As described above, in the present embodiment, the imparting unit 5A, the absorbing unit 5B, the heating unit 5C, and the cleaning unit 5D are provided as peripheral units, but some of these units are provided with the cooling function of the transfer body 2 or are provided. , A cooling unit may be added. In the present embodiment, the temperature of the transfer body 2 may rise due to the heat of the heating unit 5C. If the ink image exceeds the boiling point of water, which is the main solvent of the ink, after the ink is ejected to the transfer body 2 by the recording unit 3, the absorption performance of the liquid component by the absorption unit 5B may deteriorate. By cooling the transfer body 2 so that the ejected ink is maintained below the boiling point of water, the absorption performance of the liquid component can be maintained.

The cooling unit may be a blowing mechanism that blows air to the transfer body 2 or a mechanism that brings a member (for example, a roller) into contact with the transfer body 2 and cools the member by air cooling or water cooling. Further, it may be a mechanism for cooling the cleaning member of the cleaning unit 5D. The cooling timing may be the period after transfer and before the reaction solution is applied.

<Supply unit>
The supply unit 6 is a mechanism for supplying ink to each recording head 30 of the recording unit 3. The supply unit 6 may be provided on the rear side of the recording system 1. The supply unit 6 includes a storage unit TK for storing ink for each type of ink. The storage unit TK may be composed of a main tank and a sub tank. Each storage unit TK and each recording head 30 communicate with each other through a flow path 6a, and ink is supplied from the storage unit TK to the recording head 30. The flow path 6a may be a flow path for circulating ink between the storage unit TK and the recording head 30, and the supply unit 6 may include a pump or the like for circulating ink. A degassing mechanism for degassing air bubbles in the ink may be provided in the middle of the flow path 6a or in the storage portion TK. A valve for adjusting the hydraulic pressure of the ink and the atmospheric pressure may be provided in the middle of the flow path 6a or in the storage portion TK. The heights of the storage unit TK and the recording head 30 in the Z direction may be designed so that the ink liquid level in the storage unit TK is lower than the ink ejection surface of the recording head 30.

<Transporting device>
The transport device 1B is a device that feeds the recording medium P to the transfer unit 4 and discharges the recorded material P'to which the ink image is transferred from the transfer unit 4. The transport device 1B includes a feed unit 7, a plurality of transport cylinders 8, 8a, two sprockets 8b, a chain 8c, and a recovery unit 8d. In FIG. 1, the arrow inside the figure of each configuration of the transport device 1B indicates the rotation direction of the configuration, and the arrow outside indicates the transport path of the recording medium P or the recorded object P'. The recording medium P is transported from the feeding unit 7 to the transfer unit 4, and the recorded material P'is transported from the transfer unit 4 to the recovery unit 8d. The feeding unit 7 side may be referred to as an upstream side in the transport direction, and the recovery unit 8d side may be referred to as a downstream side.

The feeding unit 7 includes a loading unit on which a plurality of recording media P are loaded, and also includes a feeding mechanism for feeding the recording media P one by one from the loading unit to the most upstream transport cylinder 8. Each of the transport cylinders 8 and 8a is a rotating body that rotates around a rotation axis in the Y direction, and has a cylindrical outer peripheral surface. At least one grip mechanism for holding the tip of the recording medium P (or the recording object P') is provided on the outer peripheral surface of each of the transport cylinders 8 and 8a. The gripping operation and the releasing operation of each grip mechanism are controlled so that the recording medium P is passed between the adjacent transport cylinders.

The two transport cylinders 8a are transport cylinders for reversing the recording medium P. When recording on both sides of the recording medium P, after the transfer to the surface, the recording medium P is not passed from the impression cylinder 42 to the transport cylinder 8 adjacent to the downstream side, but is passed to the transport cylinder 8a. The recording medium P is turned upside down via the two transport cylinders 8a, and is passed to the impression cylinder 42 again via the transport cylinder 8 on the upstream side of the impression cylinder 42. As a result, the back surface of the recording medium P faces the transfer drum 41, and the ink image is transferred to the back surface.

The chain 8c is wound between the two sprockets 8b. One of the two sprockets 8b is the driving sprocket and the other is the driven sprocket. The rotation of the drive sprocket causes the chain 8c to travel cyclically. The chain 8c is provided with a plurality of grip mechanisms separated in the longitudinal direction thereof. The grip mechanism grips the end of the recorded object P'. The recorded material P'is passed from the transport cylinder 8 located at the downstream end to the grip mechanism of the chain 8c, and the recorded material P'gripped by the grip mechanism is transported to the recovery unit 8d by the traveling of the chain 8c, and the grip is released. To. As a result, the recorded material P'is loaded in the recovery unit 8d.

<Post-processing unit>
The transport device 1B is provided with post-processing units 10A and 10B. The post-processing units 10A and 10B are arranged on the downstream side of the transfer unit 4 and are a mechanism for performing post-processing on the recorded material P'. The post-processing unit 10A processes the front surface of the recorded material P', and the post-processing unit 10B performs the processing on the back surface of the recorded material P'. As the content of the processing, for example, the image recording surface of the recorded object P'can be coated with a coating for the purpose of protecting the image, polishing the image, and the like. Examples of the content of the coating include application of a liquid, welding of a sheet, laminating and the like.

<Inspection unit>
The transport device 1B is provided with inspection units 9A and 9B. The inspection units 9A and 9B are arranged on the downstream side of the transfer unit 4 and are a mechanism for inspecting the recorded material P'.

In the case of the present embodiment, the inspection unit 9A is a photographing device that captures an image recorded on the recorded object P', and includes, for example, an image pickup element such as a CCD sensor or a CMOS sensor. The inspection unit 9A captures a recorded image during a continuous recording operation. Based on the image taken by the inspection unit 9A, it is possible to confirm the change with time such as the tint of the recorded image and determine whether or not the image data or the recorded data can be corrected. In the case of the present embodiment, the inspection unit 9A has an imaging range set on the outer peripheral surface of the impression cylinder 42, and is arranged so that the recorded image immediately after transfer can be partially captured. The inspection unit 9A may inspect all recorded images, or may inspect every predetermined number.

In the case of the present embodiment, the inspection unit 9B is also a photographing device that captures an image recorded on the recorded object P', and includes, for example, an image pickup element such as a CCD sensor or a CMOS sensor. The inspection unit 9B captures a recorded image in the test recording operation. The inspection unit 9B can capture the entire recorded image and make basic settings for various corrections related to the recorded data based on the image captured by the inspection unit 9B. In the case of the present embodiment, it is arranged at a position where the recorded object P'carried by the chain 8c is photographed. When the recorded image is taken by the inspection unit 9B, the running of the chain 8c is temporarily stopped and the whole is taken. The inspection unit 9B may be a scanner that scans on the recorded object P'.

<Control unit>
Next, the control unit of the recording system 1 will be described. 3 and 4 are block diagrams of the control unit 13 of the recording system 1. The control unit 13 is communicably connected to the host device (DFE) HC2, and the host device HC2 is communicably connected to the host device HC1.

In the host device HC1, the original data that is the source of the recorded image is generated or stored. The manuscript data here is generated in the form of an electronic file such as a document file or an image file. This manuscript data is transmitted to the higher-level device HC2, and the higher-level device HC2 converts the received manuscript data into a data format (for example, RGB data expressing an image in RGB) that can be used by the control unit 13. The converted data is transmitted from the host device HC2 to the control unit 13 as image data, and the control unit 13 starts the recording operation based on the received image data.

In the case of the present embodiment, the control unit 13 is roughly classified into a main controller 13A and an engine controller 13B. The main controller 13A includes a processing unit 131, a storage unit 132, an operation unit 133, an image processing unit 134, a communication I / F (interface) 135, a buffer 136, and a communication I / F 137.

The processing unit 131 is a processor such as a CPU, executes a program stored in the storage unit 132, and controls the entire main controller 13A. The storage unit 132 is a storage device such as a RAM, ROM, hard disk, SSD, etc., stores programs and data executed by the processing unit 131, and provides a work area to the processing unit 131. The operation unit 133 is, for example, an input device such as a touch panel, a keyboard, and a mouse, and receives a user's instruction.

The image processing unit 134 is, for example, an electronic circuit having an image processing processor. The buffer 136 is, for example, a RAM, a hard disk or an SSD. The communication I / F 135 communicates with the host device HC2, and the communication I / F 137 communicates with the engine controller 13B. In FIG. 3, the broken line arrow illustrates the flow of image data processing. The image data received from the host device HC2 via the communication I / F 135 is stored in the buffer 136. The image processing unit 134 reads image data from the buffer 136, performs predetermined image processing on the read image data, and stores the read image data in the buffer 136 again. The image data after image processing stored in the buffer 136 is transmitted from the communication I / F 137 to the engine controller 13B as recorded data used by the print engine.

As shown in FIG. 4, the engine controller 13B includes the control units 14, 15A to 15E, and acquires and controls the drive of the detection results of the sensor group and the actuator group 16 included in the recording system 1. Each of these control units includes a processor such as a CPU, a storage device such as RAM or ROM, and an interface with an external device. It should be noted that the division of the control units is an example, and some controls may be executed by a plurality of further subdivided control units, or conversely, a plurality of control units may be integrated to combine the control contents. It may be configured to be performed by one control unit.

The engine control unit 14 controls the entire engine controller 13B. The recording control unit 15A converts the recorded data received from the main controller 13A into a data format suitable for driving the recording head 30, such as raster data. The recording control unit 15A controls the ejection of each recording head 30.

The transfer control unit 15B controls the application unit 5A, the absorption unit 5B, the heating unit 5C, and the cleaning unit 5D.

The reliability control unit 15C controls the supply unit 6, the recovery unit 12, and the drive mechanism for moving the recording unit 3 between the discharge position POS1 and the recovery position POS3.

The transfer control unit 15D controls the drive of the transfer unit 4 and the transfer device 1B. The inspection control unit 15E controls the inspection unit 9B and the inspection unit 9A.

Among the sensor group and the actuator group 16, the sensor group includes a sensor for detecting the position and speed of a movable portion, a sensor for detecting temperature, an image pickup element, and the like. The actuator group includes a motor, a solenoid solenoid, a solenoid valve and the like.

Next, in the recording system having the above configuration, the ink circulation mechanism between the recording head 30 and the ink tank will be described.

<Detailed explanation of the ink circulation mechanism>
[Detailed configuration of recording head]
FIG. 5 is a perspective view showing the configuration of the recording head 30.

FIG. 5A is a perspective view of the recording head 30 viewed from diagonally below, and FIG. 5B is a perspective view of the recording head 30 viewed from diagonally above.

The recording head 30 arranges 15 element substrates 10 capable of ejecting one color of ink on one element substrate 10 in a straight line (arranged in-line), and has a recording width corresponding to the width of the recording medium for full-line recording. The head.

As shown in FIG. 5A, the connection portions 111 provided at both ends of the recording head 30 are connected to the ink supply mechanism of the recording device. As a result, the ink is supplied from the ink supply mechanism to the recording head 30, and the ink that has passed through the recording head 30 is collected by the ink supply mechanism. In this way, the ink can be circulated through the path of the ink supply mechanism and the path of the recording head 30.

As shown in FIG. 5B, the recording head 30 includes a signal input terminal 91 and a power supply terminal 92 electrically connected via each element board 10, a flexible wiring board 40, and an electrical wiring board 90. .. The signal input terminal 91 and the power supply terminal 92 are electrically connected to the recording control unit 15A of the recording device, and supply the power required for the drive signal and the discharge to the element substrate 10, respectively. By consolidating the wiring by the electric circuit in the electric wiring board 90, the number of signal input terminals 91 and power supply terminals 92 can be reduced as compared with the number of element boards 10. As a result, the number of electrical connections that need to be removed when the recording head 30 is attached to the recording unit 3 or when the recording head 30 is replaced can be reduced.

[Ink circulation flow path of recording head]
FIG. 6 is a diagram illustrating a mechanism in which ink circulates in the recording head 30.

FIG. 6A is a side view of the recording head 30 including the liquid discharge unit 300, the liquid supply unit 220, and the negative pressure control unit 230. FIG. 6B is a schematic diagram showing the flow of the liquid. 6 (c) is a perspective view showing a cross section in the GG line portion of FIG. 6 (a).

As shown in FIG. 6A, the negative pressure control unit 230 is integrally formed below the liquid supply unit 220. Further, a flow path member 60 is attached to the liquid supply unit 220, and another flow path member 50 is attached below the flow path member 60. These two flow path members 50 and 60 form a part of the liquid discharge unit 300. Further, as shown in FIG. 6B, a connection portion 111 and a filter 221 are provided in the liquid supply unit 220. With such a configuration, the distance between the negative pressure control unit 230 and the element substrate 10 in the height direction is shortened.

Further, since the water head difference between the negative pressure control unit 230 and the formation surface of the ink ejection port is relatively small, recording such that the tilt angle of the recording head 30 as shown in FIGS. 1 and 2 differs for each recording head. It can be suitably used for the unit 3. This is because the water arithmetic progression can be reduced, and even if a plurality of recording heads 30 are used at different tilt angles, the negative pressure difference applied to the ink ejection port of each element substrate can be reduced. In addition, as the distance from the negative pressure control unit 230 to the element substrate 10 becomes smaller, the flow resistance between them becomes smaller, and the pressure loss difference due to the change in the flow rate of the liquid (ink) becomes smaller, so that stable negative pressure control can be performed. preferable.

Further, FIG. 6B shows the actual ink flow inside the recording head 30. A set of a common flow path (common supply flow path) 211 and a common flow path (common recovery flow path) 212 extending in the longitudinal direction of the recording head 30 are provided in the long flow path member 60. .. The common flow path 211 and the common flow path 212 are configured so that liquid (ink) flows in directions facing each other, and a filter 221 is provided on the upstream side of each flow path and penetrates from a connection portion 111 or the like. Trap foreign objects.

In this way, the common flow path 211 and the common flow path 212 flow the liquid in the directions facing each other, so that the temperature gradient in the longitudinal direction in the recording head 30 is reduced.

Negative pressure control units 230 are connected to the common flow path 211 and the downstream side of the common flow path 212, respectively. Further, there is a branch portion to a plurality of individual flow paths (individual supply flow paths) 213a in the middle of the common flow path 211, and to a plurality of individual flow paths (individual recovery flow paths) 213b in the middle of the common flow path 212. There is a branch of. The individual flow paths 213a and the individual flow paths 213b are formed in a plurality of flow path members 50, and each individual flow path communicates with an opening (not shown) provided on the back surface of the element substrate 10. ..

In FIG. 6B, the negative pressure control unit 230 shown by H and L is a negative pressure control unit on the high pressure side (H) and a negative pressure control unit on the low pressure side (L). Each negative pressure control unit 230 is a back pressure type pressure adjusting mechanism set to control the pressure on the upstream side of the negative pressure control unit 230 with relatively high (H) and low (L) negative pressures. Is. The common flow path 211 is connected to the negative pressure control unit 230 (high pressure side), and the common flow path 212 is connected to the negative pressure control unit 230 (low pressure side), thereby between the common flow path 211 and the common flow path 212. A differential pressure is generated. Due to the differential pressure, the liquid flows from the common flow path 211 through the individual flow path 213a, each ink ejection port (not shown) in the element substrate 10, and the individual flow path 213b in this order to the common flow path 212.

Further, as can be seen from the configuration shown in FIG. 6A, the recording head 30 has a modular configuration including a plurality of units and members. As shown in FIG. 6C, each module is composed of a flow path member 50, an element board 10, and a flexible wiring board 40. In this embodiment, the element substrate 10 is directly connected to the flow path member 50. The common flow path 211 provided in the flow path member 60 is supplied from the communication port 61A formed on the upper surface thereof to the individual flow path 213a via the individual communication port 53 formed on the lower surface of the flow path member 50. Ru. After that, the liquid is recovered to the common flow path 212 via the individual flow path 213b, the individual communication port 53, and the communication port 61A in order via the pressure chamber (not shown) of the element substrate 10.

Here, the individual communication port 53 on the lower surface of the flow path member 50 (the surface on the flow path member 60 side) has a sufficiently large opening with respect to the communication port 61A formed on the upper surface of the flow path member 50. With this configuration, even if the position of each module is displaced when mounted on the flow path member 60, communication is reliably performed between the two flow path members 50, 60, so that the yield at the time of head manufacturing is improved. Cost reduction is planned.

[Ink circulation mechanism between the recording head and the buffer tank]
FIG. 7 is a diagram showing an ink circulation mechanism between the recording head 30 and the buffer tank. In FIG. 7, the same reference numbers and reference symbols as those already described with reference to FIG. 6 are assigned the same reference numbers and reference symbols, and the description thereof will be omitted. In addition, this ink circulation mechanism may be referred to as an ink supply device.

As shown in FIG. 7, five pumps 61 to 65 are used for the ink supply mechanism in this embodiment. In this embodiment, the storage unit TK for storing ink is composed of two tanks (main tank TK1 and buffer tank TK2), the buffer tank TK2 is connected to the recording head 30, and the buffer tank TK2 and the recording head 30 are connected. Ink circulates between them. On the other hand, a pump 61 is provided in the flow path between the main tank TK1 and the buffer tank TK2, and the pump 61 appropriately replenishes the buffer tank TK2 from the main tank TK1 with ink. The capacities of the main tank TK1 and the buffer tank TK2 are not particularly limited, and the relationship between the sizes is not particularly limited.

As shown in FIG. 7, the flow path 6a referred to in FIG. 1 has a flow path 71 between the main tank TK1 and the buffer tank TK2, and four flow paths 72 between the buffer tank TK2 and the recording head 30. It is composed of ~ 75. Pumps 62 to 65 are provided in the flow paths 72 to 75, respectively.

The ink circulation mechanism can switch the ink circulation direction by controlling the drive of the four pumps 62 to 65.

FIG. 8 is a diagram illustrating circulation of ink in the recording head. When the ink is circulated, the pump 62 and the pump 65 are driven as described above, and the pump 63 and the pump 64 are stopped. In this case, the pressure reducing valve that operates as the negative pressure control unit 230 on the flow path 74 side is closed, and the pressure reducing valve that operates as the negative pressure control unit 230 on the flow path 75 side is opened. Therefore, as shown in FIG. 8, the ink passes through the flow path 72, passes through the filter 221 and reaches the common flow path 211, is supplied to each nozzle of the element substrate 10 via the individual flow path 213a, and is supplied to each nozzle of the individual flow path 213b. From the common flow path 212 to the flow path 75.

Similarly, the pump 63 and the pump 64 are driven, and the pump 62 and the pump 65 are stopped. In this case, the pressure reducing valve that operates as the negative pressure control unit 230 on the flow path 75 side is closed, and the pressure reducing valve that operates as the negative pressure control unit 230 on the flow path 74 side is opened. As a result, the ink passes through the flow path 73, passes through the filter 221 and reaches the common flow path 212, passes through the individual flow path 213b, enters each nozzle of the element substrate 10, and passes through the individual flow path 213a from the common flow path 211. Return to the flow path 74.

In this way, the ink is circulated in the recording head 30. In the above, an example of a recording head having a configuration in which ink circulates in two directions has been shown, but the present invention is not limited to this, and a recording head that can circulate in only one direction may be used.

<First Embodiment>
Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.

[Concentration measurement unit]
Hereinafter, a configuration example of a density measuring unit for measuring the density of ink provided in the inkjet recording apparatus according to the present invention will be described with reference to the drawings.

FIG. 9 is a diagram showing a schematic configuration of a concentration measuring unit according to the present embodiment. A plurality of concentration measuring units are provided according to the number of storage units TK shown in FIG.

The cell portion 901 is a portion made of a transparent member in which a flow path for passing ink for measuring density is formed. The cell portion 901 is made of, for example, quartz. The light emitting element 902 is a light source that irradiates light. The light emitting element 902 irradiates light with a predetermined amount of light based on the instruction from the measuring unit 909. The light emitting element 902 is composed of, for example, an LED or the like. The light receiving element 903 is a light receiving element that receives light transmitted through the cell portion 901, and is arranged at a position corresponding to the light emitting element 902 with the cell portion 901 interposed therebetween. Information (signal) of the amount of light received by the light receiving element 903 is passed to the measuring unit 909. The light receiving element 903 is composed of, for example, a photodiode.

The flow paths 904 and 905 are connected to the cell portion 901 and the tank 906 so that the ink can be circulated. The tank 906 is a storage unit in which ink used for image formation is stored, and corresponds to the storage unit TK shown in FIG. More specifically, it corresponds to the buffer tank TK2 shown in FIG. 7. The bypass flow path 907 is a flow path connecting the flow path 904 and the flow path 905, and ink can flow by opening and closing the installed valve. The bypass flow path 907 is used, for example, for the purpose of shortening the ink replacement time in the cell portion 901 and eliminating the negative pressure at the time of density measurement. The pump 908 is controlled to circulate the ink in the flow path and the tank 906.

The measuring unit 909 functions as a control unit that controls the light emitting element 902 when measuring the density of the ink and emits light at a predetermined amount of light. Further, the measuring unit 909 also functions as a derivation unit that acquires the amount of light received by the light receiving element 903 in response to the light emitted by the light emitting element 902 and derives the ink density based on the value. It is assumed that the information is retained in advance by associating the amount of light emitted by the light emitting element 902, the amount of light received by the light receiving element 903, and the density of the ink. The correspondence here is defined for each ink color, for example, by a look-up table or the like.

FIG. 10 is a diagram showing a configuration example around the cell portion 901 according to the present embodiment.

The cell portion 901 is configured by using a transparent member, and a flow path 1001 through which ink flows is formed inside. Here, an example is shown in which ink flows from the lower side to the upper side of the figure. The light from the light emitting element 902 is irradiated to a predetermined position through which the ink flows as incident light. Then, the transmitted light transmitted through the predetermined position is configured to reach the light receiving element 903. In the flow path through which the ink of the cell portion 901 flows, a narrow portion is configured so that the predetermined position is narrower than the other portions. Here, it is assumed that the relationship between the width L1 (optical path length) at a predetermined position (narrow portion) in the cell portion 901 and the width L2 at other positions is defined according to the color and component of the ink. .. For example, the width L1 can be configured to be about 20 μm. The amount of light emitted by the light emitting element 902 at the time of density measurement is also defined in relation to the width L1 and the color (transmittance) of the ink. Here, the widths L1 and L2 refer to the diameter in the flow path through which the ink passes, but the cross section thereof is not limited to a circular shape and may have other shapes.

FIG. 11 is a diagram for explaining the overall concept of the ink flow path according to the present embodiment. As described above, since the cell portion 901 according to the present embodiment is configured so that a part of the flow path is narrowed, it takes time to circulate the ink, and the ink stays and the foreign matter is clogged. It may occur. Therefore, in the present embodiment, this problem is solved by providing two flow paths for the concentration measuring unit 1101 so that the flow paths can be switched. Although FIG. 11 shows the components for one color for the sake of simplification of the description, the set of components shown in FIG. 11 depends on the number of colors (types) of the inks supported by the recording device. Shall be provided.

The recording head 30 is a recording head that ejects ink to form an image. The ink used for image formation is supplied from the tank 906. Further, the recording head 30 and the tank 906 are configured so that ink circulates. As described above, the tank 906 corresponds to the buffer tank TK2 shown in FIG.

The tank 906 is a storage unit in which ink used for image formation is stored. The inside of the tank 906 may be provided with a stirring unit (not shown) for stirring ink, a detecting unit (not shown) for detecting the amount of ink stored (remaining amount), and the like.

An ink supply tank for supplying ink to the tank 906, a diluted water supply tank 1103 for supplying diluted water to the tank 906, and pumps 1104 and 1105 are provided around the tank 906. Pump 1104 corresponds to pump 61 shown in FIG.

Further, the tank 906 is provided with an ink flow path between the recording head 30 and the pumps 1106 and 1107 for circulating ink between the tank 906 and the recording head 30 on the flow path. It will be provided. Two pumps 1106 and 1107 are shown here for brevity, but they correspond to pumps 62-65 shown in FIG. The circulation of ink between the recording head 30 and the tank 906 is as shown in FIGS. 6 to 8.

The ink supply tank 1102 is a supply unit in which the ink supplied to the tank 906 is stored when the amount of ink stored in the tank 906 decreases or the concentration of the ink in the tank 906 decreases. .. The ink supply from the ink supply tank 1102 to the tank 906 may be performed based on an instruction from the control unit (not shown), or may be performed when the ink supply tank 1102 is replaced. Ink is supplied from the ink supply tank 1102 to the tank 906 by driving the pump 1104 by the control unit (not shown). Further, the inside of the ink supply tank 1102 may be provided with a stirring unit (not shown) for stirring the ink, a detecting unit (not shown) for detecting the amount of ink stored, and the like. The ink in the ink supply tank 1102 is replenished by a user or the like in a timely manner.

The diluted water supply tank 1103 is a supply unit in which diluted water for adjusting the concentration of the ink in the tank 906 is stored when the concentration of the ink in the tank 906 increases. As the diluted water, for example, pure water or the like is used. Since the density of the ink in the tank 906 fluctuates depending on the external environment, image forming operation, etc., the concentration is maintained at an appropriate level by supplying diluted water. The supply of the diluted water from the diluted water supply tank 1103 to the tank 906 may be performed based on an instruction from the control unit (not shown). By driving the pump 1105 by the control unit (not shown), the diluted water is supplied from the diluted water supply tank 1103 to the tank 906. Further, a detection unit (not shown) for detecting the stored amount of the diluted water may be provided inside the diluted water supply tank 1103. The diluted water in the diluted water supply tank 1103 is replenished by a user or the like in a timely manner.

The density measuring unit 1101 is a portion for detecting the density of the ink inside the tank 906. The concentration measuring unit 1101 corresponds to the configurations of 901 to 903 and 909 shown in FIG. The flow path 1108 is a flow path through which the ink whose density is measured by the density measuring unit 1101 passes. The flow path 1109 is a flow path through which the ink whose density is not detected by the density measuring unit 1101 passes. The flow path 1109 corresponds to the bypass flow path 907 shown in FIG. The pump 908 is controlled to circulate the ink in the tank 906 and the concentration measuring unit 1101 or the flow path 1109.

[Switching flow path]
FIG. 12 is a diagram for explaining switching of the ink flow path around the density measuring unit 1101 according to the present embodiment. In FIG. 12, the dashed line means that there is no ink flow.

FIG. 12A shows a state in which ink is flowing to the density measuring unit 1101 (that is, the cell unit 901) in the configuration shown in FIG. In other words, the ink in the density measuring unit 1101 is replaced. In this case, the flow rate of the ink in a predetermined time unit will be described as Q1.

FIG. 12B shows a state in which ink is flowing through the flow path 1109 (that is, the bypass flow path 907) instead of the inside of the concentration measuring unit 1101 in the configuration shown in FIG. In other words, the ink in the flow path 1109 has been replaced. In this case, the flow rate of the ink in a predetermined time unit will be described as Q2.

As described with reference to FIG. 10, a part of the cell portion 901 is provided with a narrow portion on the flow path 1001 for ink measurement. Therefore, when the ink is circulated by the pump 908 with the same force, the flow rate is larger in the flow path shown in FIG. 12 (b). in short,
Q2> Q1
The relationship is established. In other words, the time required to circulate the same amount of ink is different. Specifically, the flow path shown in FIG. 12A takes longer to circulate the same amount of ink. Here, for the sake of simplicity, it is assumed that the length of each flow path is the same.

In the present embodiment, by switching the ink flow path, the ink density is appropriately measured and the time required for circulation is shortened.

[Concentration measurement processing flow]
FIG. 13 shows a flow chart of control related to ink density measurement according to the present embodiment. This processing is realized by the control unit (for example, the main controller 13A) included in the recording device reading and executing the program stored in the storage unit. This process may be executed at a predetermined timing, or may be executed when a measurement instruction is received from a user or the like. Further, it may be performed in parallel during image formation.

In S1301, the control unit controls a valve (not shown) so that the ink flow path in the tank 906 becomes the flow path 1109. That is, it is controlled so as to be in the state of FIG. 12 (b). At the same time, by controlling the pumps 1104 and 1105, the ink supply tank 1102 and the diluted water supply tank 1103 can control the supply of ink and diluted water to the tank 906 within a range that does not affect the concentration of the ink in the tank 906. You may go. For example, only one may be supplied or the supply amount may be controlled.

In S1302, the control unit controls the pump 908 so that the ink in the tank 906 flows through the flow path 1109. As described above, the flow rate of the ink at this time is Q2. As a result, the ink in the flow path 1109 is replaced, and the density of the ink in the tank 906 becomes the same (or substantially the same).

In S1303, the control unit controls a valve (not shown) so that the ink flow path in the tank 906 is in the density measurement unit 1101. That is, it is controlled so as to be in the state of FIG. 12 (a). At the same time, by controlling the pumps 1104 and 1105, the ink supply tank 1102 and the diluted water supply tank 1103 can control the supply of ink and diluted water to the tank 906 within a range that does not affect the concentration of the ink in the tank 906. You may go.

In S1304, the control unit controls the pump 908 so that the ink in the tank 906 flows in the density measuring unit 1101. As described above, the flow rate of the ink at this time is Q1. As a result, the ink in the density measuring unit 1101 is replaced, and the density is the same as (or substantially the same as) the ink in the tank 906.

In S1305, the control unit controls the density measurement unit 1101 to measure the density of the ink passing through the density measurement unit 1101. That is, the density is measured by using the light emitting element 902 and the light receiving element 903 shown in FIG.

In S1306, the control unit determines whether or not the concentration measured in S1305 is within a predetermined range. It is assumed that the predetermined range here is defined in advance and is held in a storage unit or the like. Further, the predetermined range here shall be defined for each type (color) of ink. If it is determined to be within the predetermined range (YES in S1306), the process proceeds to S1307, and if it is determined to be not within the predetermined range (NO in S1306), the process proceeds to S1308.

In S1307, the control unit stops the supply of diluted water from the diluted water supply tank 1103 by controlling the pump 1105. At this time, since the ink density is appropriate, when the ink is being supplied from the ink supply tank 1102, the ink supply is also stopped by controlling the pump 1104 at the same time. Then, this processing flow is terminated.

In S1308, the control unit controls the pump 1105 to supply the diluted water from the diluted water supply tank 1103. At this time, if the diluted water has already been supplied, the supply amount may be controlled to be increased. Further, when both ink and diluted water are supplied, the supply ratio may be controlled to be changed. Then, this processing flow is terminated.

As described above, according to the present embodiment, by directly measuring the density of the ink used for image formation, it is possible to measure the density with higher accuracy without causing an error in detection. Further, by providing two flow paths for circulating the ink, it is possible to shorten the time required for circulation for measurement.

<Second embodiment>
Hereinafter, the configuration according to the second embodiment of the present invention will be described. The description of the configuration overlapping with the first embodiment will be omitted.

FIG. 14 is a diagram for explaining the overall concept of the ink flow path according to the present embodiment. Although FIG. 14 shows one set of components for the sake of simplicity, it is assumed that the set of components shown in FIG. 14 is provided according to the number of inks supported by the image forming apparatus. do.

In the first embodiment, the concentration measuring unit 1101 is provided at a portion different from that of the recording head 30. On the other hand, in the present embodiment, the concentration measuring unit 1101 is provided in the flow path between the recording head 30 and the tank 906. The same components are indicated by the same reference numbers. Further, in the first embodiment, the circulation of ink between the tank 906 (buffer tank TK2) and the recording head 30 has been described with reference to FIGS. 6 to 8. In the present embodiment, the circulation is similarly performed, and for example, the concentration according to the present invention may be measured at a timing other than the timing of image formation.

FIG. 15 is a diagram for explaining switching of ink flow paths according to the present embodiment.

FIG. 15A shows a state in which ink is flowing to the density measuring unit 1101 (that is, the cell unit 901) in the configuration shown in FIG. In this case, the flow rate of the ink in a predetermined time unit will be described as Q1.

FIG. 15B shows a state in which ink is flowing through the flow path 1109 (that is, the bypass flow path 907) instead of the concentration measuring unit 1101 in the configuration shown in FIG. The flow rate of the ink in this case in a predetermined time unit will be described as Q2.

Similar to the first embodiment, a part of the cell unit 901 included in the density measuring unit 1101 is provided with a narrow portion for measuring ink. Therefore, when the ink is circulated by the pump 1106 with the same force, the flow rate is larger in the flow path shown in FIG. 15 (b). in short,
Q2> Q1
The relationship is established. In other words, the time required to circulate the same amount of ink is different. Specifically, the flow path shown in FIG. 15A takes longer to circulate the same amount of ink.

As described above, the same effect as that of the first embodiment can be obtained by the configuration of the present embodiment. Furthermore, since the ink density can be measured at a position closer to the recording head, the ink density used for image formation can be measured with higher accuracy.

<Other embodiments>
In the above embodiment, two flow paths are formed as flow paths around the concentration measuring unit. However, the present invention is not limited to this, and more channels may be provided and controlled so as to be switchable.

In the above embodiment, the recording unit 3 has a plurality of recording heads 30, but may have one recording head 30. The recording head 30 does not have to be a full-line head, and even if it is a serial system in which ink is ejected from the recording head 30 while the carriage on which the recording head 30 is detachably mounted is moved in the Y direction to form an ink image. good.

The transport mechanism of the recording medium P may be another method such as a method of sandwiching and transporting the recording medium P by a pair of rollers. In a method of transporting the recording medium P by a pair of rollers or the like, a roll sheet may be used as the recording medium P, or the roll sheet may be cut after transfer to produce a recorded material P'.

In the above embodiment, the transfer body 2 is provided on the outer peripheral surface of the transfer drum 41, but another method such as a method in which the transfer body 2 is formed in an endless band shape and is circulated to run may be used.

The present invention also supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

901 ... cell unit, 902 ... light emitting element, 903 ... light receiving element, 904, 905 ... flow path, 906 ... tank, 908 ... pump, 909 ... measuring unit

Claims (8)

A tank that stores ink supplied to the recording head that ejects ink, and a tank that stores ink.
An inkjet recording apparatus including a density measuring unit for measuring the density of the ink.
A first flow path for circulating the ink stored in the tank through the concentration measuring unit, and
A second flow path for circulating the ink stored in the tank without going through the density measuring unit and the recording head .
A control unit for switching between the first flow path and the second flow path to circulate ink is provided.
An inkjet recording apparatus characterized in that the flow rate in the second flow path is larger than the flow rate in the first flow path. A recording head that ejects ink and
A tank for storing ink supplied to the recording head,
An inkjet recording apparatus including a density measuring unit for measuring the density of the ink.
A first flow path of ink from the tank to the recording head via the concentration measuring unit, and
A second flow path of ink from the tank to the recording head without going through the concentration measuring unit, and
A control means for switching between the first flow path and the second flow path is provided.
A flow path is formed between the recording head and the tank so that ink can be circulated.
An inkjet recording apparatus characterized in that the flow rate in the second flow path is larger than the flow rate in the first flow path. An adjusting means for adjusting the density of the ink stored in the tank is provided.
The inkjet recording apparatus according to claim 1 or 2, wherein the adjusting means adjusts the density of the ink in the tank based on the density measured by the density measuring unit. The adjusting means is
A first supply unit that supplies ink to the tank,
A second supply unit that supplies diluted water for diluting the concentration of the ink stored in the tank, and
3. The inkjet recording apparatus according to claim 3. The concentration measuring unit is
The cell part, which is composed of transparent members and has an ink flow path,
A light emitting element that irradiates the ink passing through the cell portion with light,
A light receiving element that receives light transmitted through the cell portion and
A derivation unit that derives the density of the ink based on the amount of light emitted by the light emitting element and the amount of light received by the light receiving element.
The inkjet recording apparatus according to any one of claims 1 to 4, wherein the inkjet recording apparatus comprises the above. The fifth aspect of the present invention is characterized in that, in the flow path configured in the cell portion, the position where the light is irradiated by the light emitting element is formed so that the diameter through which the ink passes is smaller than the other positions. The inkjet recording device described. The sixth aspect of claim 6, wherein the amount of light emitted by the light emitting element and the diameter of the position where the light is irradiated by the light emitting element are defined according to the type of ink stored in the tank. Inkjet recording device. The second flow path is characterized in that it branches from the first flow path on the upstream side of the concentration measuring unit and joins the first flow path on the downstream side of the concentration measuring unit. The inkjet recording apparatus according to claim 1 .

Images