EP3403834B1

EP3403834B1 - Printing apparatus

Info

Publication number: EP3403834B1
Application number: EP18173238.9A
Authority: EP
Inventors: Kenji Kojima; Sandro Robustelli
Original assignee: Seiko Epson Corp
Current assignee: Seiko Epson Corp
Priority date: 2017-05-19
Filing date: 2018-05-18
Publication date: 2021-03-10
Anticipated expiration: 2038-05-18
Also published as: JP6926669B2; CN108946235B; JP2018193199A; CN108946235A; EP3403834A1

Description

BACKGROUND

1. Technical Field

The present invention relates to a printing apparatus.

2. Related Art

Recently, in textile printing on fabrics such as cotton, silk, wool, chemical fiber, and mixed fabrics, an ink jet type printing apparatus which discharges ink toward a surface of fabrics and performs printing patterns or the like on fabrics is used. The printing apparatus used in textile printing is provided with a transport belt which mounts a medium and transports the medium in a transport direction to handle fabrics having flexibility as a medium. In this kind of printing apparatus, in order to improve transport accuracy of the transport belt, the printing apparatus provided with a mechanism for measuring a moving amount of the transport belt is known. For example, JP-A-2013-28143 discloses an ink jet type recording apparatus (printing apparatus) provided with a moving amount measuring unit configured with a scale portion which is engaged with the transport belt and moves therewith and a sensor unit which is fixed to a base and measures a moving amount of the scale portion.
However, in the printing apparatus described in JP-A-2013-28143 , a holding unit which makes the scale portion to be held (engaged) with the transport belt needs a rotation mechanism for switching the state thereof between a holding state and an unholding state. Since the rotation mechanism is configured with many members such as a rotation shaft, a support member which supports the rotation shaft, a base connected to the rotation shaft, and a rotation driving source which rotates the rotation shaft, the mechanism of a switching unit which switches the state thereof between the holding state and the unholding state is large and leads to an increase in size of the printing apparatus.
EP 2 679 391 discloses a recording medium transfer apparatus having an intermittently rotatable endless belt and a sliding unit used to determine a transfer quantity of a recording medium. The sliding unit engages with the endless belt at an initial belt position, then moves with the belt, and finally releases engagement with the endless belt.

SUMMARY

The invention can be realized in the following aspects or application examples. Application Example 1
According to this application example, there is provided a printing apparatus according to claim 1.
According to the application example, the printing apparatus includes a holding unit in which a state thereof is changeable between a holding state which holds the transport belt and an unholding state which does not hold the transport belt, and a switching unit which switches the state of the holding unit between the holding state and the unholding state. At least a part of the holding unit is configured with an elastic member, and the switching unit switches the state of the holding unit from one side to the other side between the holding state and the unholding state using elasticity of the elastic member, and thereby it is possible to simplify the configuration of the holding unit and the switching unit. In this way, the printing apparatus can be miniaturized.
According to the application example, the switching unit includes an electromagnet, and the holding unit includes a ferromagnetic material which is attracted to a magnet. The state of the holding unit is changed from the unholding state to the holding state by the simple configuration of the magnetic force generated in a case where current flows in the electromagnet of the switching unit and the ferromagnetic material of the holding unit, and thereby the configuration of the switching unit and the holding unit can be also miniaturized.

Application Example 2

In the printing apparatus of the application example, it is preferable that the elastic member be a carbon fiber or a composite material containing a carbon fiber.
According to the application example, the elastic member which configures at least a part of the holding unit is a carbon fiber or a composite material containing a carbon fiber, and the elasticity and strength required by the elastic member of the holding unit can be secured.

Application Example 3

It is preferable that the printing apparatus of the application example include a driving unit which rotationally moves the transport belt, in which the driving unit be provided on a downstream side from the printing unit in the transport direction, and the holding unit hold the transport belt on an upstream side from the printing unit in the transport direction.
According to the application example, the driving unit of the transport belt is provided on the downstream side from the printing unit and the holding unit holds the transport belt on the upstream side from the printing unit. In a case where the driving unit is rotationally driven in order to move the holding unit in the holding state in the transport direction along with the transport belt, there is a concern that loosening of the transport belt may occur between the driving unit and the holding unit in a rotational moving direction of the transport belt. However, since the printing unit of the application example is positioned between the holding unit and the driving unit, the influence from the loosening of the transport belt in the printing unit can be reduced.

Application Example 4

It is preferable that the printing apparatus of the application example include a control unit which stops the rotation of the transport belt and performs an adjusting operation of adjusting the position of the transport belt based on the moving amount measured by the measuring unit in a case where the holding unit in the holding state is moved from a first position to a second position positioned on a downstream side from the first position in a transport direction.
According to the application example, the printing apparatus includes a control unit which adjusts the position of the transport belt based on the actual moving amount of the transport belt measured by the measuring unit in a case where the driving unit moves the transport belt from the first position to the second position, and the position of the transport belt can be suitably adjusted.

Application Example 5

In the printing apparatus of the application example, it is preferable that the control unit determine whether or not to perform the adjusting operation.
According to the application example, depending on the required image quality, it is possible to suitably control the printing apparatus.

Application Example 6

It is preferable that the printing apparatus of the application example include a return portion which moves the holding unit in the unholding state in a reverse direction of the transport direction, in which the return portion be separated from the holding unit when the holding unit in the holding state is moved in the transport direction.
According to the application example, the printing apparatus includes a return portion which moves the holding unit in the reverse direction of the transport direction. In this way, the holding unit is returned to the upstream side of the transport direction, and it is possible to repeatedly move the holding unit in the holding state along with the transport belt. In addition, since the return portion is separated from the holding unit when the holding unit of the holding state is moving along with the transport belt, it is possible to prevent the return portion from giving a load to the rotational drive of the transport belt.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, wherein like numbers reference like elements.

Fig. 1 is a schematic view illustrating an entire schematic configuration of a printing apparatus according to an embodiment.
Fig. 2 is a plan view illustrating a main portion of the printing apparatus.
Fig. 3 is a perspective view illustrating a configuration of a belt moving amount measuring unit.
Fig. 4 is a cross-sectional view taken along line IV-IV of Fig. 2.
Fig. 5 is an electrical block diagram illustrating an electrical configuration of the printing apparatus.
Fig. 6 is a flowchart illustrating a printing method.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of the invention will be described with reference to drawings. Furthermore, in each drawing, scales of each layer and member are made different from the actual scales thereof to a size large enough to be recognized.
Also, in Figs. 1 to 4, for convenience of explanation, three axes, X axis, Y axis, and Z axis, orthogonal to each other are illustrated in the drawings, and the tip end side of the arrow illustrating the axial direction is set to" + side" and base end side to "- side". A direction parallel to the X axis is referred to as an "X axial direction", a direction parallel to the Y axis is referred to as a "Y axial direction", and a direction parallel to the Z axis is referred to as a "Z axial direction".

Embodiment

Schematic Configuration of Printing Apparatus

Fig. 1 is a schematic view illustrating an entire schematic configuration of a printing apparatus according to an embodiment. Fig. 2 is a plan view illustrating a main portion of the printing apparatus. First, a schematic configuration of a printing apparatus 100 according to the embodiment will be explained with reference to Figs. 1 and 2. Furthermore, in the embodiment, an ink jet type printing apparatus 100 which performs textile printing on a medium 95 with forming an image or the like on the medium 95 will be described as an example.
As illustrated in Fig. 1, the printing apparatus 100 includes a medium transport portion 20, a medium close contact portion 60, a printing unit 40, a drying unit 27, a belt moving amount measuring unit 70, and a cleaning unit 50. The printing apparatus also includes a control unit 1 which controls each of these parts. Each part of the printing apparatus 100 is attached to a frame portion 90.
The medium transport portion 20 transports the medium 95 in the transport direction. The medium transport portion 20 includes a medium supply portion 10, a transport roller 22, a transport belt 23, a belt rotating roller 24, a belt driving roller 25, transport rollers 26 and 28, and a medium collecting portion 30. First, a transport path of the medium 95 from the medium supply portion 10 to the medium collecting portion 30 will be described. In addition, in the embodiment, a direction along gravity is set as a Z axis, a direction to which the medium 95 is transported in the printing unit 40 as an X axis, and a width direction of the medium 95 that intersects with both Z axis and X axis as a Y axis. Furthermore, the positional relationship along the transport direction of the medium 95 or the moving direction of the transport belt 23 may be referred to as "upstream side" or "downstream side".
The medium supply portion 10 supplies the medium 95 for forming an image to the printing unit 40 side. Fabrics such as cotton, wool, and polyester are used as the medium 95. The medium supply portion 10 includes a supply shaft portion 11 and a bearing portion 12. The supply shaft portion 11 is formed in a cylindrical shape or a columnar shape, and is provided so as to be rotatable in a circumferential direction. On the supply shaft portion 11, a strip-shaped medium 95 is wound into a roll shape. The supply shaft portion 11 is detachably attached to the bearing portion 12. In this way, the medium 95 in a state wound around the supply shaft portion 11 in advance can be attached to the bearing portion 12 along with the supply shaft portion 11.
The bearing portion 12 rotatably supports both ends of the supply shaft portion 11 in an axial direction. The medium supply portion 10 includes a rotational driving unit (not illustrated) which rotationally drives the supply shaft portion 11. The rotational driving unit rotates the supply shaft portion 11 in a direction in which the medium 95 is sent out. The operation of the rotational driving unit is controlled by the control unit 1. The transport roller 22 relays the medium 95 from the medium supply portion 10 to the transport belt 23.
The transport belt 23 is held between at least two rollers which rotate the transport belt 23, and transports the medium 95 in the transport direction (+X axial direction) as the transport belt 23 rotationally moves. For details, both end portions of a strip-shaped belt of the transport belt 23 are connected to form an endless shape, and are set on and between two rollers of the belt rotating roller 24 and the belt driving roller 25. The transport belt 23 is held in a state in which a predetermined tension is applied, so as the part between the belt rotating roller 24 and the belt driving roller 25 become horizontal. On a surface (supporting surface) 23a of the transport belt 23, an adhesive layer 29 to which medium 95 is adhered is provided. The transport belt 23 supports (holds) the medium 95 supplied from the transport roller 22 and brought into close contact with the adhesive layer 29 at the medium close contact portion 60 described later. In this way, fabrics having flexibility or the like can be handled as the medium 95.
The belt rotating roller 24 and the belt driving roller 25 support an inner peripheral surface 23b of the transport belt 23. Furthermore, a supporting portion such as a roller for supporting the transport belt 23 may be provided between the belt rotating roller 24 and the belt driving roller 25.
The belt driving roller 25 is a driving unit that rotationally moves the transport belt 23 and includes a motor (not illustrated) that rotationally drives the belt driving roller 25. The belt driving roller 25 as the driving unit is provided on the downstream side from the printing unit 40 with respect to the transport direction of the medium 95 and the belt rotating roller 24 is provided on the upstream side from the printing unit 40. When the belt driving roller 25 is rotationally driven, the transport belt 23 rotates as the belt driving roller 25 rotates, and the belt rotating roller 24 rotates by the rotation of the transport belt 23. By the rotation of the transport belt 23, the medium 95 supported by the transport belt 23 is transported in the transport direction (+X axial direction), and an image is formed on the medium 95 at the printing unit 40 described later.
In the embodiment, medium 95 is supported on a side (+Z axial side) where the surface 23a of the transport belt 23 is opposite to the printing unit 40, and the medium 95 is transported from the belt rotating roller 24 side to the belt driving roller 25 side along with the transport belt 23. In addition, on a side (-Z axial side) where the surface 23a of the transport belt 23 is opposite to the cleaning unit 50, only the transport belt 23 moves to the belt rotating roller 24 side from the belt driving roller 25 side. Furthermore, it is noted that the transport belt 23 is provided with the adhesive layer 29 to which the medium 95 is adhered, but the invention is not limited thereto. For example, the transport belt may be an electrostatic adsorption type belt which electrostatically adsorbs a medium to a belt.
The transport roller 26 separates the medium 95 on which an image is formed from the adhesive layer 29 of the transport belt 23. The transport rollers 26 and 28 relay the medium 95 from the transport belt 23 to the medium collecting portion 30.
The medium collecting portion 30 collects the medium 95 transported by the medium transport portion 20. The medium collecting portion 30 includes a winding shaft portion 31 and a bearing portion 32. The winding shaft portion 31 is formed in a cylindrical shape or a columnar shape, and is provided so as to be rotatable in a circumferential direction. In the winding shaft portion 31, the strip-shaped medium 95 is wound in a roll shape. The winding shaft portion 31 is detachably attached to the bearing portion 32. In this way, the medium 95 in a state wound around the winding shaft portion 31 can be removed with the winding shaft portion 31.
The bearing portion 32 rotatably supports both ends of the winding shaft portion 31 in an axial line direction. The medium collecting portion 30 includes the rotational driving unit (not illustrated) which rotationally drives the winding shaft portion 31. The rotational driving unit rotates the winding shaft portion 31 in a direction on which the medium 95 is wound. The operation of the rotational driving unit is controlled by the control unit 1.
Next, each part of the medium close contact portion 60, the belt moving amount measuring unit 70, the printing unit 40, the drying unit 27, and the cleaning unit 50 provided along the medium transport portion 20 will be described.
The medium close contact portion 60 brings the medium 95 into close contact with the transport belt 23. The medium close contact portion 60 is provided on the upstream side (-X axial side) from the printing unit 40. The medium close contact portion 60 includes a pressing roller 61, a pressing roller driving unit 62 and a roller supporting portion 63. The pressing roller 61 is formed in a cylindrical shape or a columnar shape, and is provided so as to be rotatable in a circumferential direction. The pressing roller 61 is disposed so that the axial line direction thereof intersects with the transport direction to rotate in a direction along the transport direction. The roller supporting portion 63 is disposed on the inner peripheral surface 23b side of the transport belt 23 opposite to the pressing roller 61 with the transport belt 23 interposed therebetween.
The pressing roller driving unit 62 moves the pressing roller 61 in the transport direction (+X axial direction) and in a reverse direction of the transport direction (-X axial direction) while pressing the pressing roller 61 to a lower side (-Z axial side) in the vertical direction thereof. The medium 95 superimposed on the transport belt 23 is pressed against the transport belt 23 between the pressing roller 61 and the roller supporting portion 63. In this way, it becomes possible to firmly adhere the medium 95 to the adhesive layer 29 provided on the surface 23a of the transport belt 23, and thereby it is possible to prevent the occurrence of floating of the medium 95 on the transport belt 23.
The belt moving amount measuring unit 70 is provided between the medium close contact portion 60 and the printing unit 40. The belt moving amount measuring unit 70 will be described later.
The printing unit 40 is disposed above (+Z axial side) the arrangement position of the transport belt 23, and performs printing on the medium 95 mounted on the surface 23a of the transport belt 23. The printing unit 40 includes a head unit 42, a carriage 43 on which the head unit 42 is mounted, a carriage moving unit 45 that moves the carriage 43 to the width direction (Y axial direction) of the medium 95 which intersects with the transport direction, and the like. The head unit 42 of the embodiment is configured with four subunits 42a, and, in the subunit 42a, a plurality of discharge heads (not illustrated) for discharging ink (for example, yellow, cyan, magenta, black, and the like) supplied from an ink supply portion (not illustrated) to the medium 95 mounted on the transport belt 23 as liquid are provided.
The carriage moving unit 45 is provided above (+Z axial side) the transport belt 23. The carriage moving unit 45 includes a pair of guide rails 45a and 45b extending along the Y axial direction. The guide rails 45a and 45b are laid between frame portions 90a and 90b provided vertically on an outer side of the transport belt 23. The head unit 42 is supported by the guide rails 45a and 45b in a state reciprocable along the Y axial direction along with the carriage 43.
The carriage moving unit 45 is provided with a moving mechanism and a power source (not illustrated). As a moving mechanism, for example, a mechanism combining a ball screw with a ball nut, a linear guide mechanism, or the like can be adopted. Moreover, the carriage moving unit 45 includes a motor (not illustrated) as the power source for moving the carriage 43 along the guide rails 45a and 45b. As a motor, various types of motors such as a stepping motor, a servo motor, and a linear motor can be adopted. When the motor is driven by the control of the control unit 1, the head unit 42 moves in the Y axial direction along with the carriage 43.
The drying unit 27 is provided between the transport roller 26 and the transport roller 28. The drying unit 27 dries ink discharged on the medium 95. In the drying unit 27, for example, an IR heater is included, and it is possible to dry the ink discharged on the medium 95 in a short period of time by driving the IR heater. In this way, it is possible to wind the strip-shaped medium 95 on which an image or the like is formed around the winding shaft portion 31.
The cleaning unit 50 is disposed between the belt rotating roller 24 and the belt driving roller 25 in the X axial direction. The cleaning unit 50 includes a cleaning portion 51, a pressing portion 52 and a moving portion 53. The moving portion 53 moves integrally with the cleaning unit 50 along a floor surface 99 and fixes the cleaning unit at a predetermined position.
The pressing portion 52, for example, is a lifting device configured with an air cylinder 56 and a ball bush 57, and causes the cleaning portion 51 provided thereabove to abut and move away from the surface 23a of the transport belt 23. The cleaning portion 51 is set on and between the belt rotating roller 24 and the belt driving roller 25 in a state in which a predetermined tension is applied, and cleans the surface (supporting surface) 23a of the transport belt 23 moving from the belt driving roller 25 toward the belt rotating roller 24 from below (-Z axial direction).
The cleaning portion 51 includes a cleaning tank 54, a cleaning roller 58 and a blade 55. The cleaning tank 54 is a tank for storing a cleaning liquid used for cleaning ink or foreign matters adhered to the surface 23a of the transport belt 23, and the cleaning roller 58 and the blade 55 are provided inside the cleaning tank 54. As a cleaning liquid, for example, water or a water-soluble solvent (alcohol solution or the like) can be used, and a surfactant or an antifoaming agent may be added as necessary.
When the cleaning roller 58 rotates, the cleaning liquid is supplied to the surface 23a of the transport belt 23, and the cleaning roller 58 and the transport belt 23 slide on each other. In this way, the ink adhered to the transport belt 23, fibers of the fabrics serving as the medium 95, or the like are removed by the cleaning roller 58.
The blade 55, for example, can be made of a flexible material such as silicone rubber. The blade 55 is provided on the downstream side from the cleaning roller 58 in the transport direction of the transport belt 23. The remaining cleaning liquid on the surface 23a of the transport belt 23 is removed as the blade 55 and the transport belt 23 slide on each other.
Fig. 3 is a perspective view illustrating a configuration of a belt moving amount measuring unit. Fig. 4 is a cross-sectional view taken along line IV-IV of Fig. 2. Next, the configuration of the belt moving amount measuring unit 70 will be described with reference to Figs. 2 to 4.
The belt moving amount measuring unit 70 is provided on an upstream side of the printing unit 40 and provided along any one end between both ends of the transport belt 23 in the width direction (Y axial direction). The belt moving amount measuring unit 70 of the embodiment is provided on a +Y axial side of the transport belt 23. The belt moving amount measuring unit 70 includes a rectangular shaped base 71 long along the transport direction (X axial direction) of the medium 95, a scale pasting portion 73 provided above the base 71, a holding unit 80, which is provided on the base 71 and moves along a guide rail 72 extending in the X axial direction, a return portion 76 which moves the holding unit 80 to an upstream side of the transport direction, and the like.
The scale pasting portion 73 is laid between column portions 73a and 73b vertically provided on both ends of the base 71 in a longitudinal direction (X axial direction). The scale pasting portion 73 has a protruding portion protruding like eaves in the -Y axial direction, and a part thereof overlaps with the transport belt 23 in a plan view. On a lower surface (-Z axial side surface) of the protruding portion of the scale pasting portion 73, a scale portion 75 is provided along the transport direction of the medium 95. In the scale portion 75 of the embodiment, a magnetic scale in which magnets having different polarities are alternately arranged is used.
The holding unit 80 of the embodiment holds the transport belt 23 on the upstream side from the printing unit 40 in the transport direction. In a case where the belt driving roller 25 is rotationally driven in order to move the holding unit 80 in a holding state in the transport direction along with the transport belt 23, since the transport belt 23 has elasticity, there is a concern that loosening may occur in the transport belt 23 between the belt driving roller 25 and the holding unit in a rotational moving direction of the transport belt 23. The printing unit 40 is provided between the holding unit 80 and the belt driving roller 25 in the rotational moving direction of the transport belt 23, and thereby the influence from the loosening of the transport belt 23 in the printing unit 40 can be reduced. Consequently, the transport accuracy of the medium 95 is improved.
The holding unit 80 includes a holding substrate 81, a guide block 82, a measuring unit 85, and the like. The holding substrate 81 has a rectangular plate shape long in the width direction (Y axial direction) of the transport belt 23. An end portion 81c on a -Y axial side of the holding substrate 81 substantially coincides with a side wall 73c on the -Y axial side of the scale pasting portion 73 in a plan view, and overlaps with the transport belt 23. An end portion 81d on the +Y axial side of the holding substrate 81 protrudes in a +Y axial direction from a side wall 71d on the +Y axial side of the base 71 in a plan view. The guide block 82 is provided on a bottom surface of the holding substrate 81 (-Z axial side surface). On the guide block 82, a concave groove opened on the -Z axial side is formed following the shape of the convexly protruding guide rail 72. As the guide block 82 and the guide rail 72 are engaged with each other, the holding unit 80 is formed to move reciprocally along the transport direction (X axial direction).
At least a part of the holding unit 80 is formed of an elastic member 83. For details, the elastic member 83 is provided on an upper surface (+Z axial side surface) of the holding substrate 81. The elastic member 83 has a rectangular plate shape shorter than the holding substrate 81. An end portion 83d on the +Y axial side of the elastic member 83 is joined with the holding substrate 81 at substantially the center of the holding substrate 81. An end portion 83c on the -Y axial side of the elastic member 83 substantially coincides with the end portion 81c on the -Y axial side of the holding substrate 81 in a plan view. The end portion 81c of the holding substrate 81 and the end portion 83c of the elastic member 83 have a gap slightly larger than the thickness of the transport belt 23. The holding unit 80 is configured to sandwich the transport belt 23 between the end portion 81c of the holding substrate 81 and the end portion 83c of the elastic member 83 by the elastic force of the elastic member 83. The elastic member 83 is preferably a carbon fiber or a composite material containing a carbon fiber. Since the carbon fiber has specific gravity lower than a metal material and is excellent in strength, elastic modulus, and abrasion resistance, it is possible to secure the elasticity and the strength required for the elastic member 83 of the holding unit 80.
The state of the holding unit 80 is changeable between a holding state of holding the transport belt 23 and moving along with the transport belt 23 and an unholding state of not holding the transport belt 23. For details, the holding unit 80 has a ferromagnetic material 84. The ferromagnetic material 84 is provided on an upper surface (+Z axial side surface) of the elastic member 83 that does not overlap with the transport belt 23 in a plan view. As a ferromagnetic material 84, iron, nickel, cobalt, and the like can be used.
In addition, at a position that is a lower surface of the holding substrate 81 of the holding unit 80 and is opposite to the ferromagnetic material 84, a switching unit 74 that switches the state of the holding unit 80 between a holding state and an unholding state is provided. The switching unit 74 includes an electromagnet, and the ferromagnetic material 84 is attracted to the switching unit 74 (electromagnet) by the magnetic force generated in a case where current flows in the electromagnet. At this time, the elastic member 83 is elastically deformed toward the holding substrate 81 side, and the transport belt 23 is held between the holding substrate 81 and the elastic member 83 by the elastic force. In this way, the state of the holding unit 80 is changed from the unholding state to the holding state. Moreover, in a case where the current flowing in the electromagnet is blocked, the state of the holding unit 80 is changed from the holding state to the unholding state. Accordingly, the switching unit 74 has a function of switching the state of the holding unit 80 from between the holding state and the unholding state using the elasticity of the elastic member 83. The state of the holding unit 80 can be changed with a simple configuration of the electromagnet of the switching unit 74 and the ferromagnetic material 84, and thereby the switching unit 74 and the holding unit 80 can be miniaturized.
At a position that is an upper surface of the end portion 83c of the elastic member 83 and is opposite to the scale portion 75, the measuring unit 85 is provided. The measuring unit 85 is provided with an element for converting a change in a magnetic field into an electric signal (for example, hall element or MR element) and measures a relative moving amount with respect to the scale portion 75. The measuring unit 85 of the embodiment is provided on a pedestal for placing the measuring unit close to the scale portion 75. Since the measuring unit 85 is configured to move integrally with the holding unit 80, it is possible to measure a moving amount of the transport belt 23 when the holding unit 80 in the holding state is moving along with the transport belt 23.
The return portion 76 moves the holding unit 80 in the unholding state in a reverse direction of the transport direction. The return portion 76 includes a moving lever 78 and a lever moving portion 77 reciprocally moving the moving lever 78 along the transport direction. The lever moving portion 77 has a rectangular shape long in the transport direction, and is fixed to the side wall 71d on the +Y axial side of the base 71. On an upper surface (+Z axial side surface) and a lower surface (-Z axial side surface) of the lever moving portion 77, a concave guide groove extending in the transport direction is provided.
The moving lever 78 includes a pedestal 78a having a projection following the shape of the guide groove and an elongated portion 78b extending from the pedestal 78a in a vertical direction (+Z axial direction). The moving lever 78 is configured to move reciprocally along the guide groove of the lever moving portion 77. The lever moving portion 77 includes the moving mechanism (not illustrated) reciprocally moving the moving lever 78 in the transport direction. As the moving mechanism, for example, an air cylinder or the like can be adopted. When the moving lever 78 is moved to the upstream side of the transport direction by the lever moving portion 77, the elongated portion 78b of the moving lever 78 abuts on the holding substrate 81 of the holding unit 80, and the holding unit 80 in the unholding state is returned to an upstream side in the reverse direction of the transport direction. In this way, it is possible to repeatedly move the holding unit 80 in the holding state along with the transport belt 23, and repeatedly measure the moving amount of the transport belt 23 by the measuring unit 85.
Furthermore, in the embodiment, a configuration of the measuring unit 85 moving integrally with the holding unit 80 and the scale portion 75 being fixed is described, but the configuration may be such that the scale portion moves integrally with the holding unit and the measuring unit is fixed.
In addition, in the embodiment, a so-called magnetic encoder that obtains a relative moving amount between the scale portion 75 and the measuring unit 85 from a change in the magnetic field is exemplified, but an optical encoder that obtains the moving amount from optical change may be used.

Electrical Configuration

Fig. 5 is an electrical block diagram illustrating an electrical configuration of the printing apparatus. Next, the electrical configuration of the printing apparatus 100 will be described with reference to Fig. 5.
The printing apparatus 100 includes an input device 6 to which printing conditions or the like are input, the control unit 1 which controls each part of the printing apparatus 100, or the like. As the input device 6, a desktop type or a laptop type personal computer (PC), a tablet type terminal, a portable terminal, and the like can be used. The input device 6 may be provided separately from the printing apparatus 100.
The control unit 1 includes an interface (I/F) 2, a central processing unit (CPU) 3, a storage unit 4, a control circuit 5, and the like. The interface 2 transmits and receives data between the input device 6 and the control unit 1 for handling input signals and images. The CPU 3 is an arithmetic processing device for processing an input signal from various measuring device groups 7 including the first and the second measuring units 85a and 85b, and controlling a printing operation of the printing apparatus 100. For example, the CPU 3 calculates the moving amount of the transport belt 23 from the input signal output from the measuring unit 85 and input to the CPU 3.
The storage unit 4 is a storage medium for securing an area for storing a program of the CPU 3 or a work area, and has a storage element such as random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), and the like.
The control unit 1 controls driving of a discharge head provided in the head unit 42 by a control signal output from the control circuit 5 and discharges ink toward the medium 95. The control unit 1 controls driving of the motor provided in the carriage moving unit 45 by the control signal output from the control circuit 5 and reciprocally moves the carriage 43 mounted with the head unit 42 in a main scanning direction (Y axial direction). The control unit 1 controls driving of the motor provided in the belt driving roller 25 by the control signal output from the control circuit 5 and rotationally moves the transport belt 23. In this way, the medium 95 mounted on the transport belt 23 is moved in the transport direction (+X axial direction).
An image or the like is formed on the medium 95 by the alternately repeated printing operation of main scanning in which the control unit 1 controls the carriage moving unit 45 and the head unit 42 and moves the head unit 42 (carriage 43) while discharging ink from the discharge head, and sub-scanning in which the control unit controls the belt driving roller 25 and transports the medium 95 in the transport direction.
The control unit 1 controls the current flowing in the electromagnet provided in the switching unit 74 by the control signal output from the control circuit 5 and switches the state of the holding unit 80 between the holding state and the unholding state. The control unit 1 controls the moving mechanism of the lever moving portion 77 by the control signal output from the control circuit 5 and reciprocally moves the moving lever 78 along the transport direction. In addition, the control unit 1 controls each device (not illustrated).

Printing Method

Fig. 6 is a flowchart illustrating a printing method. Next, the printing method of the printing apparatus 100 will be described with reference to Fig. 6.
Step S1 is a print data receiving step for receiving print data. The control unit 1 receives the print data for recording an image on the medium 95 from the input device 6 and stores the print data in the storage unit 4.
Step S2 is a holding step for holding the holding unit 80 by the transport belt 23. The control unit 1 applies current to the electromagnet of the switching unit 74 and generates magnetic force to the electromagnet. In this way, the holding unit 80 is brought into the holding state and holds the transport belt 23.
Step S3 is a sub-scanning step for transporting the transport belt 23 in the transport direction. The control unit 1 controls the belt driving roller 25 and moves the holding unit 80 in the holding state along with the transport belt 23. Then, the control unit 1 stops the rotation of the transport belt 23 based on the moving amount measured by the measuring unit 85 in a case where the holding unit 80 is moved from a first position (initial position) to a second position positioned on a downstream side from the first position in the transport direction. Moreover, in the initial sub-scanning step, a distance between the first position and the second position is the transport amount up to a predetermined position for starting the printing operation. In the second and subsequent the sub-scanning steps, the distance between the first position and the second position is the line feed amount generated during the printing operation.
In step S4, it is determined whether a position deviation amount of the transport belt 23 is within an allowable range. Since the transport belt 23 has elasticity, there is a concern that slight position deviation may occur after the movement of the transport belt 23 is stopped. For this reason, the control unit 1 rechecks the actual moving amount of the transport belt 23 from the first position based on the measured result of the measuring unit 85 after the movement of the transport belt 23 is stopped. Then, the control unit 1 compares the distance between the first position and the second position and the actual moving amount of the transport belt 23 to calculate the position deviation amount of the transport belt 23, and determines whether the position deviation amount of the transport belt 23 is within a predetermined allowable range. In a case where the position deviation amount of the transport belt 23 is within the allowable range (Yes in step S4), the process proceeds to step S6. In a case where the position deviation amount of the transport belt 23 is out of allowable range (No in step S4), the process proceeds to step S5.
Step S5 is a belt position adjusting step for adjusting the position of the transport belt 23. The control unit 1 controls the belt driving roller 25 based on the position deviation amount calculated in step S4 and performs a feeding operation or a returning operation of the transport belt 23 to correct the position of the transport belt 23. Here, the feeding operation is an operation of moving the transport belt 23 in the transport direction and the returning operation is an operation of moving the transport belt 23 in the reverse direction of the transport direction. Moreover, the moving amount of the transport belt 23 in the feeding operation and the returning operation is often slightly smaller than the moving amount the transport belt 23 in the sub-scanning in the printing operation. By steps S4 and S5, the control unit 1 performs an adjusting operation of adjusting the position of the transport belt 23 based on the moving amount measured by the measuring unit 85. In this way, the position deviation of the transport belt 23 is corrected, and accuracy of the position where ink to be discharged in next step lands on the medium 95 is improved.
Step S6 is a main scanning step for discharging ink toward the medium 95. The control unit 1 controls the head unit 42 and the carriage moving unit 45 to perform the main scanning of discharging ink toward the medium 95 from the head unit 42 while moving the carriage 43 mounted with the head unit 42 in the width direction (Y axial direction) of the medium 95 intersecting with the transport direction.
Step S7 is an unholding step for changing the state of the holding unit 80 holding the transport belt 23 to the unholding state. The control unit 1 blocks current flowing in the electromagnet of the switching unit 74 to demagnetize the magnetic force of the electromagnet. In this way, the holding unit 80 is in the unholding state.
Step S8 is a returning step for returning the return portion 76 to the upstream side of the transport direction. The control unit 1 controls the lever moving portion 77 and moves the moving lever 78 waiting at a predetermined position on the downstream side of the transport direction to the upstream side from the holding unit 80 in the transport direction. In this way, the holding unit 80 abuts on the moving lever 78, and the holding unit 80 in the unholding state positioned at the second position is returned to the first position. In this way, it is possible to repeatedly move the holding unit 80 in the holding state from the first position to the second position along with the transport belt 23. Next, the moving lever 78 is moved to the downstream side from the second position in the transport direction and waits at a predetermined position. Accordingly, in step S3, when the holding unit 80 in the holding state moves along with the transport belt 23, the moving lever 78 of the return portion 76 is separated from the holding unit 80, and thereby it is possible to prevent the return portion 76 from giving a load to the rotational drive of the transport belt 23. Furthermore, for convenience of explanation, the steps from the main scanning step for step S6 to the returning step for step S8 are explained in different steps, but, step S7 and step S8 are performed substantially simultaneously with step S6.
In step S9, it is determined whether there is print data for the next line. The control unit 1 determines whether there is the print data for the next line with reference to the print data stored in the storage unit 4. In a case where there is the print data for the next line (Yes in step S9), the process returns to step S2 and step S2 to step S9 are repeated. In this way, the main scanning and the sub-scanning are repeated and an image or the like is printed on the medium 95. In a case where there is no print data for the next line (No in step S9), the control unit 1 ends the printing operation of the printing apparatus 100.
Furthermore, in the embodiment, the printing method capable of performing adjusting operation of adjusting the position of the transport belt 23 based on the moving amount measured by the measuring unit 85 is described by steps S4 and S5. However, whether to perform the adjusting operation or not (ON/OFF) may be determined by the control unit 1 depending on the received print data (print quality). In addition, the printing apparatus 100 may be configured to have a function of allowing a user to select ON/OFF of the adjusting operation. By performing the adjusting operation, the image quality improves but the print speed decreases. It is possible to suitably control the printing apparatus 100 by determining whether or not to perform the adjusting operation depending on the required image quality. In summary, the control unit 1 may be configured to determine whether or not to perform the adjusting operation. Then, the determination of whether or not to perform the adjusting operation may be performed automatically by the control unit 1, or manually by a user. In this way, it is possible to suitably control the printing apparatus 100 depending on the required image quality.
In the embodiment, the flow of performing the returning step for each sub-scanning step and main scanning step is described, but a flow of returning the moving amount of the holding unit 80 moved in a plurality of times by a single returning step after repeatedly performing the sub-scanning step and the main scanning step a plurality of times may be adopted.
In addition, in the embodiment, a configuration of performing steps S4 and S5 after step S3 is described, but steps S4 and S5 may be performed in parallel while performing step S3. That is, while transporting the transport belt 23 in the transport direction, determining whether the position deviation amount of the transport belt 23 is within the allowable range or not and adjusting the position of the transport belt 23 may be performed. Accordingly, the moving amount of the transport belt 23 can be adjusted in real time while the transport belt 23 is moving.
As described above, the following effects can be obtained according to the printing apparatus 100 of the embodiment.
The belt moving amount measuring unit 70 of the printing apparatus 100 includes the holding unit 80 holding the transport belt 23 and the switching unit 74 that changes the state of the holding unit 80 between the holding state and the unholding state. Since a part of the holding unit 80 is configured with the elastic member 83 and the switching unit 74 changes the state of the holding unit 80 using the elasticity of the elastic member 83, it is possible to simplify the configuration of the holding unit 80 and the switching unit 74. In this way, the printing apparatus 100 can be miniaturized.
The elastic member 83 is formed with a carbon fiber or a composite material containing a carbon fiber. Since the carbon fiber has specific gravity lower than a metal material and is excellent in strength, elastic modulus, and abrasion resistance, it is possible to secure the elasticity and the strength required for the elastic member 83 of the holding unit 80.
The holding unit 80 includes the ferromagnetic material 84 which is attracted to a magnet on the elastic member 83, the switching unit 74 including the electromagnet is provided at a position opposite to the ferromagnetic material 84 via the elastic member 83 and the holding substrate 81. The holding unit 80 holds the transport belt 23 by the ferromagnetic material 84 being attracted to the switching unit 74 (electromagnet) by the magnetic force generated in a case where current flows in the electromagnet. The state of the holding unit 80 can be changed with a simple configuration of the electromagnet of the switching unit 74 and the ferromagnetic material 84, and thereby the switching unit 74 and the holding unit 80 can be miniaturized.
The belt driving roller 25 of the transport belt 23 is provided on the downstream side from the printing unit 40 and the holding unit 80 holds the transport belt 23 on the upstream side from the printing unit 40. In a case where the belt driving roller 25 is rotationally driven in order to move the holding unit 80 in the holding state in the transport direction along with the transport belt 23, there is a concern that loosening may occur in the transport belt 23 between the belt driving roller 25 and the holding unit 80 in the rotational moving direction of the transport belt 23. Since the printing unit 40 is provided between the holding unit 80 and the belt driving roller 25 in the rotational moving direction of the transport belt 23, the influence from loosening of the transport belt 23 in the printing unit 40 is reduced, and the transport accuracy of the medium 95 is improved.
The control unit 1 performs the adjusting operation of adjusting the position of the transport belt 23 based on the moving amount measured by the measuring unit 85. In this way, the position deviation of the transport belt 23 is corrected, and accuracy of the position where the ink lands on the medium 95 is improved.
The belt moving amount measuring unit 70 includes the return portion 76 that moves the holding unit 80 in the unholding state to the upstream side of the transport direction. The holding unit 80 in the unholding state is returned to the upstream side from the downstream side by the return portion 76. In this way, it is possible to repeatedly move the holding unit 80 in the holding state along with the transport belt 23 and the moving amount of the transport belt 23 can be repeatedly measured by the measuring unit 85.
When the holding unit 80 in the holding state moves along with the transport belt 23, the moving lever 78 of the return portion 76 is separated from the holding unit 80, and thereby it is possible to prevent the return portion 76 from giving a load to the rotational drive of the transport belt 23.

Claims

A printing apparatus (100) comprising:
a printing unit (40) configured to perform printing on a medium (95);

a transport belt (23) configured to rotationally move to transport the medium in a transport direction;

a scale portion (75) which is provided along the transport direction;

a measuring unit (85) configured to measure a relative moving amount with respect to the scale portion;

a holding unit (80) which is configured to move integrally with the scale portion or the measuring unit and in which a state thereof is changeable between a holding state of holding the transport belt and moving along with the transport belt and an unholding state of not holding the transport belt; and

a switching unit (74) configured to switch the state of the holding unit between the holding state and the unholding state,

characterized in that

at least a part of the holding unit is configured with an elastic member (83),

wherein the switching unit is configured to switch the state of the holding unit between the holding state and the unholding state using elasticity of the elastic member,

wherein the switching unit (74) includes an electromagnet, and

wherein the holding unit includes a ferromagnetic material (84) and the state thereof is changed from or to the unholding state to or from the holding state by magnetic force generated in a case where current flows in the electromagnet.
The printing apparatus according to Claim 1,
wherein the elastic member is a carbon fiber or a composite material containing a carbon fiber.
The printing apparatus according to any one of the preceding claims, further comprising:
a driving unit (25) configured to rotationally move the transport belt,

wherein the driving unit is provided on a downstream side from the printing unit in the transport direction, and

wherein the holding unit is configured to hold the transport belt on an upstream side from the printing unit in the transport direction.
The printing apparatus according to any one of the preceding claims, further comprising:
a control unit (1) configured to stop the rotation of the transport belt and perform an adjusting operation of adjusting the position of the transport belt based on the moving amount measured by the measuring unit in a case where the holding unit in the holding state is moved from a first position to a second position positioned on a downstream side from the first position in a transport direction.
The printing apparatus according to Claim 4,
wherein the control unit is configured to determine whether or not to perform the adjusting operation.
The printing apparatus according to any one of the preceding claims, further comprising:
a return portion (76) configured to move the holding unit in the unholding state in a reverse direction to the transport direction,

wherein the return portion is separated from the holding unit when the holding unit in the holding state is moved in the transport direction.