Patent Description:
Conventionally, a printing apparatus using a screen plate as shown in, for example, <CIT> has been provided. The printing apparatus disclosed in <CIT> includes a conveyor belt for conveying a fabric, with the fabric attached to the surface thereof, drive rollers for driving the conveyor belt; a screen plate that is to be positioned on the surface of the fabric, and on which a pattern to be printed is formed; a printing unit having a squeegee; and a support base for supporting the conveyor belt from the lower surface during printing on the fabric by the printing unit. A plate-making area is formed on the screen plate. The plate-making area has an area where ink is shielded, and holes through which ink passes. By placing ink on the screen plate and moving the squeegee on the surface of the screen plate with the screen plate pressed against the fabric, the ink passes through the holes in the screen plate, thereby performing printing on the fabric under the screen plate. When the movement of the squeegee is completed, the fabric is intermittently conveyed by the drive rollers and the conveyor belt, a surface area of the fabric on which printing is to be performed next is positioned under the screen plate, and printing is performed on the surface of the fabric sequentially.

Further, a printing apparatus using an inkjet mechanism as shown in, for example, <CIT> is also known. The printing apparatus includes a plurality of nozzles housed in a printhead, and the nozzles eject ink of multiple colors. The conveyor belt conveys a fabric intermittently at the printing pitch of the printhead. Each time the fabric is intermittently conveyed, the printhead is moved along the direction (the width direction of the fabric) perpendicular to the fabric conveyance direction to eject ink from the nozzles, thus performing printing of a pattern on the surface of the fabric.

Another known printing apparatus according to the preamble of claim <NUM> is disclosed in <CIT>.

In printing apparatuses using a screen plate or an inkjet mechanism, conveyance errors may occur because of rough accuracy of intermittent feeding of a fabric. If the fabric is conveyed a distance shorter than the length of the printing pitch, the previously printed portion and the portion printed afterward may greatly overlap, causing color unevenness. If the fabric is conveyed a distance longer than the length of the printing pitch, a gap may be left between the previously printed portion and the portion printed afterward. Thus, if there are conveyance errors, printing cannot be performed on a fabric with high accuracy. Accordingly, there is demand for minimizing conveyance errors, and improving conveyance accuracy.

One of the causes of conveyance errors is the expansion and contraction of a conveyance belt itself. The conveyor belt of a printing apparatus is generally an endless belt, and is looped between a drive roller and a driven roller disposed on the upstream side and the downstream side in the fabric conveyance direction. A drive source such as a servomotor is connected to the drive roller. By causing the drive source to intermittently operate, the drive roller is rotated to intermittently convey the conveyor belt. Even in the case in which there are no errors when driving the drive roller, if the conveyor belt itself expands and contracts, the fabric conveyance position deviates from a desired position, resulting in a conveyance error. In particular, the central portion of the conveyor belt in the conveyance direction is not supported by the drive roller or the driven roller unlike both ends on the upstream side and the downstream side, and is thus likely to expand and contract. Moreover, when the conveyor belt is moved intermittently while the lower surface of the central portion of the conveyor belt is in contact with the support base and supported by the support base, a frictional force between the lower surface of the conveyor belt and the upper surface of the support base causes elongation in the central portion of the conveyor belt. Depending on the material of the conveyor belt, an error of about ±<NUM> may occur.

The present invention has been accomplished in view of the problems described above. An object of the present invention is to provide a printing apparatus having a function to suppress expansion and contraction of a conveyor belt during the intermittent feeding movement of the conveyor belt.

The aforementioned aims are reached by a printing apparatus according to the present invention as defined in claim <NUM>.

By means of the claimed printing apparatus, since the intermittent feeding movement of the conveyor belt is assisted by the belt feed assisting mechanism, expansion and contraction of the conveyor belt is suppressed, and printing on a fabric can be performed with high accuracy.

By using the printing apparatus according to the present invention, since the intermittent feeding movement of the conveyor belt is assisted by the belt feed assisting mechanism, the expansion and contraction of the conveyor belt can be suppressed, and fabric conveyance errors can be reduced, thereby performing printing with high accuracy.

Embodiments are described below with reference to drawings.

<FIG> show a printing apparatus <NUM> according to a first embodiment of the present invention. The printing apparatus <NUM> includes a conveyor belt <NUM> for supporting a printing object from below and conveying the object in a horizontal direction; a belt drive mechanism <NUM> that causes the conveyor belt <NUM> to perform an intermittent feeding movement; a printing mechanism <NUM> that is disposed in the travel path of the conveyor belt <NUM>, and performs printing on the object; a support base <NUM> for supporting the conveyor belt <NUM> from below during printing by the printing mechanism <NUM>; and a belt feed assisting mechanism <NUM> that assists the intermittent feeding movement of the conveyor belt <NUM> each time the belt drive mechanism <NUM> causes the conveyor belt <NUM> to perform the intermittent feeding movement. The intermittent feeding movement includes conveying the conveyor belt <NUM> a predetermined distance and stopping the conveyor belt <NUM>, and refers to a movement of repeating the conveying and the stopping.

The printing object is, for example, a fabric C. The material of the fabric C is not particularly limited; and various materials made of natural fibers such as cotton and silk, and artificial fibers such as polyester, rayon, and acetate, may be used. The fabric is conveyed from the left side to the right side in <FIG>. The direction in which the fabric is conveyed is referred to as the conveyance direction, and the direction perpendicular to the conveyance direction is referred to as the width direction of the fabric.

The belt drive mechanism <NUM> includes drive rollers 12a, 12a that are disposed on the upstream side and the downstream side in the conveyance direction, and that are rotationally driven; and a drive source (not shown), such as a servomotor, connected to the rotation shafts of the drive rollers 12a, 12a. The endless conveyor belt <NUM> is looped between the drive rollers 12a, 12a; and the drive rollers 12a, 12a are rotated by the drive source to causes the conveyor belt <NUM> to perform an intermittent feeding movement. A driven roller may be used instead of one drive roller 12a.

The conveyor belt <NUM> is formed from an elastic body such as urethane rubber, has an adhesive layer (not shown) on the upper surface thereof, and supports the fabric C. The long fabric C wound in a roll shape is disposed on the upstream side of the conveyor belt <NUM>, unwound by an unwinding roller 15a, and attached onto the conveyor belt <NUM> by an attaching roller 15b. After printing is performed on the surface of the fabric C conveyed by the conveyor belt <NUM>, the fabric C is wound by a winding roller 15c at the downstream side. Further, the surface of the conveyor belt <NUM> is washed with a washing device (not shown) disposed in the return path from the drive roller 12a on the downstream side to the drive roller 12a on the upstream side, and an adhesive layer is formed on the surface with a gluing device (not shown).

The printing mechanism <NUM> is for performing, for example, screen printing, and is attached to a frame <NUM> (<FIG>) of the printing apparatus <NUM> so that the printing mechanism <NUM> is above the fabric C attached to the conveyor belt <NUM> and so that the printing mechanism <NUM> vertically faces the support base <NUM>. The printing mechanism <NUM> includes a plate 13a, a printing unit 13b, and a movement mechanism (not shown) for moving the plate 13a and the printing unit 13b. The plate 13a has a screen (not shown) attached to the inside of a rectangular frame. The screen is perforated with minute holes according to a pattern to be printed. In the printing unit 13b, a pair of squeegee carriers reciprocate in the width direction along two guide frames between which the plate 13a is located and that extend along the width direction of the fabric C. A squeegee supported by the squeegee carriers applies squeegee pressure to the screen of the plate 13a during forward and backward movements. In printing by the printing mechanism <NUM>, the screen of the plate 13a is first pressed against the surface of the fabric C, and then the squeegee moves on the screen. Accordingly, ink on the screen passes through the minute holes of the screen and reaches the fabric C, thereby printing a desired pattern on the fabric C. One or more printing mechanisms <NUM> are provided according to the number of ink colors used. For example, when ten ink colors are used, ten printing mechanisms <NUM> are arranged in the conveyance direction. <FIG> shows only one printing mechanism <NUM>, for convenience of explanation. The printing mechanism <NUM> is not limited to the configuration of this embodiment, and may be, for example, an inkjet printing mechanism.

The support base <NUM> is provided under the conveyor belt <NUM> in the forward path, and supported by the frame <NUM> of the printing apparatus <NUM>. As shown in <FIG>, the support base <NUM> has a plurality of air holes <NUM> penetrating in the vertical direction. Ducts <NUM> that are opened on the upper side and communicate with the air holes <NUM> are attached to the lower surface of the support base <NUM>. The ducts <NUM> are connected to air supply mechanisms <NUM> each including, for example, a blower fan, via air pipes <NUM>. Air supplied from the air supply mechanisms <NUM> blows out of the air holes <NUM> through the ducts <NUM>, and is fed toward the lower surface of the conveyor belt <NUM>. The load of the conveyor belt <NUM> located above the support base <NUM> is supported by this air. The amount of air blowing per predetermined period of time and the speed of air blowing from each air hole <NUM> can be adjusted. By adjusting these, the conveyor belt <NUM> is floated upward from the support base <NUM> to form a gap between the lower surface of the conveyor belt <NUM> and the support base <NUM>; accordingly, the upper surface of the support base <NUM> is released from contact with the lower surface of the conveyor belt <NUM>. In <FIG> and <FIG>, the printing mechanism, the fabric, and the belt drive mechanism are not shown.

The air holes <NUM>, the air pipes <NUM>, and the air supply mechanisms <NUM> provided in the support base <NUM> constitute belt feed assisting mechanisms <NUM>. In this embodiment, each belt feed assisting mechanism <NUM> is a gap-forming mechanism for forming a gap between the lower surface of the conveyor belt <NUM> and the support base <NUM>. However, the belt feed assisting mechanism <NUM> is not limited to one for forming a gap. Depending on the amount of air supplied per predetermined period of time and the speed of air blowing from each air hole <NUM>, the conveyor belt <NUM> may be in contact with the support base <NUM>, without floating upward from the support base <NUM>.

In this embodiment, the support base <NUM> includes nine support plates 14A to 14I arranged continuously in the conveyance direction, each support plate having a length of <NUM> in the conveyance direction, a length of <NUM> in the direction (the width direction of the fabric C) perpendicular to the conveyance direction, and a thickness of <NUM>. However, the support base <NUM> is not limited to this configuration, and may be formed from a single flat plate. The number and size of the support plates may be freely set. In this embodiment, the diameter of each air hole <NUM> is set to be about <NUM>.

In this embodiment, as shown in <FIG>, four ducts <NUM> are attached, in the width direction of the fabric C, to each of the second, fifth, and eighth support plates 14B, 14E, <NUM>. The four ducts <NUM> are connected to an air supply mechanism <NUM> via an air pipe <NUM>. That is, in this embodiment, a total of three sets of one air supply mechanism <NUM> and four ducts <NUM>, each set consisting of one air supply mechanism <NUM> and four ducts <NUM>, are provided in the support base <NUM>. In each of the support plates 14B, 14E, <NUM>, seven air holes <NUM> in the conveyance direction multiplied by four air holes <NUM> in the width direction of the fabric C are provided in an area that corresponds to each duct <NUM>. That is, <NUM> air holes <NUM> are provided in each of the support plates 14B, 14E, and <NUM>.

The support plates in which the air holes <NUM> are formed, the number of air holes <NUM>, and the area in which the air holes <NUM> are provided are not limited to this embodiment, and may be suitably selected as long as the load of the conveyor belt <NUM> located over the support base <NUM> can be supported to reduce the frictional force between the conveyor belt <NUM> and the support base <NUM>. The air holes <NUM> may be formed in any area of the support base <NUM>. The size and number of ducts <NUM>, the number of air pipes <NUM>, and the number of air supply mechanisms <NUM> are not limited as long as air can be supplied to the air holes <NUM>. For example, a duct <NUM> may be provided for each of the support plates 14B, 14E, and <NUM>. Further, an air supply mechanism <NUM> may be provided for each of multiple ducts <NUM>. In this case, the amount of air supplied from the air holes <NUM> communicating with the ducts <NUM> can be adjusted for each supply mechanism <NUM>.

In this embodiment, the printing mechanisms <NUM> are provided directly above the first, third, fourth, sixth, seventh, and ninth support plates 14A, 14C, 14D, 14F, <NUM>, and 14I, in which no air holes <NUM> are provided. However, if the air holes <NUM> have a diameter that does not affect printing on the fabric C by the printing mechanisms <NUM>, the printing mechanisms <NUM> may be provided directly above the support plates 14B, 14E, <NUM>. In <FIG>, only the printing mechanism <NUM> directly above the support plate 14A is shown.

The drive source for driving the drive rollers 12a, 12a, the printing mechanisms <NUM>, and the air supply mechanisms <NUM> are connected to a control device (not shown), and their operations are controlled by the control device.

The printing operation of the printing apparatus <NUM> according to the first embodiment is as follows. First, the fabric C is conveyed under the printing mechanism <NUM> by the intermittent feeding movement of the conveyor belt <NUM>, and stopped. Then, the plate 13a of the printing mechanism <NUM> is pressed against the fabric C from above, and ink is transferred to the fabric C through the minute holes provided in the plate 13a by movement of a squeegee, thereby performing printing on the fabric C. At this time, the surface of the support plate 14A of the support base <NUM> is in contact with the lower surface of the conveyor belt <NUM>, and supports the fabric C. Next, the fabric C is conveyed and stopped by the intermittent feeding movement of the conveyor belt <NUM> so that an area of the fabric C on which printing is to be performed next is positioned under the printing mechanism <NUM>. Printing is then performed on the area conveyed under the printing mechanism <NUM>. Printing is performed on the fabric C by repeating these operations.

In the above printing operation, the air supply mechanisms <NUM> supply air to the air holes <NUM> in the support base <NUM> each time the belt drive mechanism <NUM> causes the conveyor belt <NUM> to perform the intermittent feeding movement. Specifically, during stopping immediately before the conveying movement of the conveyor belt <NUM>, air is supplied to the ducts <NUM> via the air pipes <NUM> by the air supply mechanisms <NUM>, as shown by arrow A1 in <FIG>; and supplied to the air holes <NUM> of the support base <NUM> (support plate 14E in the example of the drawing), as shown by arrows A2. Thereby, the air is fed from the air holes <NUM> toward the lower surface of the conveyor belt <NUM>, as shown by arrows A3, and the conveyor belt <NUM> is lifted from the support base <NUM> to form a gap between the conveyor belt <NUM> and the support base <NUM>; accordingly, the conveyor belt <NUM> is released from contact with the support base <NUM>. In this state, the conveyor belt <NUM> is conveyed by the belt drive mechanism <NUM>. After the conveyor belt <NUM> is moved a predetermined distance and stopped, the air supply by the air supply mechanisms <NUM> is stopped. Thereby, the conveyor belt <NUM> is lowered onto the support base <NUM>; accordingly, the conveyor belt <NUM> is brought into contact with the support base <NUM>. Thereafter, printing is performed on the fabric C by the printing mechanisms <NUM>. As described above, during the conveying movement of the conveyor belt <NUM>, air is fed from the air holes <NUM> toward the lower surface of the conveyor belt <NUM>, and the conveyor belt <NUM> is lifted from the support base <NUM> to form a gap between the conveyor belt <NUM> and the support base <NUM>; accordingly, the conveyor belt <NUM> is released from contact with the support base <NUM>.

According to the above configuration, since the air supply mechanisms <NUM> supply air to the air holes <NUM> of the support base <NUM>, the conveyor belt <NUM> is supported from below by the air while floating upward from the support base <NUM>, thereby reducing the frictional force generated between the lower surface of the conveyor belt <NUM> and the upper surface of the support base <NUM> during movement of the conveyor belt <NUM>. This prevents elongation from occurring in the central portion of the conveyor belt <NUM>, reducing conveyance errors. Thus, according to the printing apparatus <NUM> of this embodiment, the intermittent feeding movement of the conveyor belt <NUM> can be assisted.

The intermittent feeding movement of the conveyor belt <NUM> by the belt drive mechanism <NUM> may be performed while the conveyor belt <NUM> is in contact with the support base <NUM> without forming a gap between the conveyor belt <NUM> and the support base <NUM>. Even in this case, the conveyor belt <NUM> is supported from below by air, and the frictional force generated between the lower surface of the conveyor belt <NUM> and the upper surface of the support base <NUM> during movement of the conveyor belt <NUM> is reduced, thus preventing elongation from occurring in the central portion of the conveyor belt <NUM> and thereby reducing conveyance errors.

In this embodiment, the air supply mechanisms <NUM> operate in synchronization with the intermittent feeding movement of the conveyor belt <NUM>. During the conveying movement of the conveyor belt <NUM>, air is supplied toward the lower surface of the conveyor belt <NUM> by the belt feed assisting mechanisms <NUM>. While the conveyor belt <NUM> is stopped, and printing is performed by the printing mechanisms <NUM>, air is not supplied. However, if supplied air does not affect printing on the fabric C by the printing mechanisms <NUM>, the air may continue to be supplied toward the lower surface of the conveyor belt <NUM> by the belt feed assisting mechanisms <NUM>, even during the printing operation of the printing apparatus <NUM>. That is, during the intermittent feeding movement in which the conveyor belt <NUM> conveys the fabric C and the printing operation in which printing on a roll of the fabric C by the fabric printing apparatus <NUM> starts and ends, air may be continuously supplied toward the lower surface of the conveyor belt <NUM> by the belt feed assisting mechanisms <NUM>. In this case, it is not necessary to control the air supply mechanisms <NUM> during the operation of the printing apparatus <NUM>.

The belt feed assisting mechanism <NUM> is not limited to the configuration described above, and may have any configuration as long as the load of the conveyor belt <NUM> can be supported to reduce the frictional force between the lower surface of the conveyor belt <NUM> and the support base <NUM>. For example, the belt feed assisting mechanism <NUM> may be a gap-forming mechanism in which an air injection device is disposed on both sides of the support base <NUM> in the width direction at a height position that is aligned with the upper surface of the support base <NUM>, and air is injected by the air injection devices during the conveying movement of the conveyor belt to lift the conveyor belt <NUM>, thereby forming a gap.

<FIG> show a printing apparatus <NUM> according to a second embodiment that is not covered by the claims. In the printing apparatus <NUM> according to this embodiment, the same reference numerals as used in the first embodiment are used for elements that are the same as those in the first embodiment; a detailed description thereof is omitted.

In this embodiment, a support base <NUM> includes a set 14a of support plates 14A to 14C and a set 14b of support plates 14D to 14F, the set 14a and the set 14b being spaced apart in the conveyance direction. The set 14a and the set 14b are configured by arranging the support plates 14A to 14F that are similar to those in the first embodiment; i.e., three plates are arranged continuously in the conveyance direction in each set. However, the support base <NUM> is not limited to this configuration. Each set may be formed from a single flat plate or from an arbitrary number of flat plates, instead of the support plates 14A to 14F. The size of the support plates 14A to 14F may also be arbitrary.

A push-up mechanism <NUM> constituting a belt feed assisting mechanism is disposed between the sets 14a and 14b of the support plates. The push-up mechanism <NUM> pushes up a conveyor belt <NUM> to separate the conveyor belt <NUM> from the support base <NUM>. As shown in <FIG>, the push-up mechanism <NUM> includes a push-up member <NUM> that comes into contact with the lower surface of the conveyor belt <NUM> and pushes up the conveyor belt <NUM>, and elevating mechanisms <NUM> that raise and lower the push-up member <NUM> so that the top of the push-up member <NUM> protrudes from and retracts into the upper surface of the support base <NUM>.

The push-up member <NUM> includes two push-up rollers 31A, 31A having substantially the same length as the length of the support base <NUM> in the width direction. The push-up rollers 31A, 31A are placed along the direction perpendicular to the conveyance direction, i.e., the width direction of a fabric C, and spaced apart in the conveyance direction. Each of the push-up rollers 31A, 31A has a bearing or the like inside, is rotatably supported by a rotation shaft 31a, and comes into contact with the lower surface of the conveyor belt <NUM> to rotate by movement of the conveyor belt <NUM>. The number of push-up rollers 31A, 31A may be one or three or more. In order to reduce the frictional force between the conveyor belt <NUM> and the push-up rollers 31A, 31A during movement of the conveyor belt <NUM>, it is preferable that the number of push-up rollers is smaller; whereas in order to stably lift the conveyor belt <NUM>, it is preferable that the number of push-up rollers is larger. In this embodiment, the number of push-up rollers is two.

The elevating mechanisms <NUM> are provided on both longitudinal direction (fabric width direction) end sides of the push-up rollers 31A, 31A, one on each side. As shown in <FIG>, each elevating mechanism <NUM> includes a movable plate <NUM>; a pair of guide frames <NUM>, <NUM> fixed to, for example, a frame <NUM> or a base (not shown) of the printing apparatus <NUM>; and an actuator including, for example, a hydraulic cylinder <NUM>. The movable plate <NUM> has shaft support grooves 33a on its inner surface. Both ends of the rotation shaft 31a of each of the push-up rollers 31A and 31A are supported in the corresponding shaft support grooves 33a. The longitudinal direction (conveyance direction) ends of the movable plate <NUM> are slidably supported in guide grooves 34a provided in the guide frames <NUM>, <NUM>. The hydraulic cylinder <NUM> includes a cylinder body 35a and a rod 35b that protrudes from and retracts into the cylinder body 35a, and the tip of the rod 35b is connected to the lower surface of the movable plate <NUM>. The push-up rollers 31A, 31A attached to the movable plate <NUM> are raised and lowered along the guide frames <NUM>, <NUM> by the protruding and retracting movements of the rod 35b. In a state where the rod 35b retracts into the cylinder body 35a, the top of each of the push-up rollers 31A, 31Ais located below the upper surface of the support base <NUM>. In a state where the rod 35b is extended from the cylinder body 35a, the top of each of the push-up rollers 31A, 31A is located above the upper surface of the support base <NUM>. In a state where the push-up rollers 31A, 31A come into contact with the lower surface of the conveyor belt <NUM> and push up the conveyor belt <NUM> , the height from the upper surface of the support base <NUM> to the top of each of the push-up rollers 31A, 31A is set to about <NUM> to <NUM>; however, the height is not limited thereto.

A drive source for driving drive rollers 12a, 12a, one or more printing mechanisms <NUM>, and the actuators (hydraulic cylinders <NUM>) of the elevating mechanisms <NUM> are connected to a control device (not shown); and their operations are controlled by the control device.

The printing operation of the printing apparatus <NUM> according to the second embodiment is described below in terms of differences from the printing apparatus <NUM> according to the first embodiment.

In the printing operation, during stopping immediately before the conveying movement of the conveyor belt <NUM>, the rod 35b of the hydraulic cylinder <NUM> of each elevating mechanism <NUM> is extended to raise the movable plate <NUM>, and the top of each of the push-up rollers 31A, 31A is thus lifted above the upper surface of the support base <NUM> to thereby separate the conveyor belt <NUM> from the support base <NUM>. By raising the push-up rollers 31A, 31A, the conveyor belt <NUM> is lifted from the support base <NUM> to release the conveyor belt <NUM> from contact with the support base <NUM>. In this state, the conveyor belt <NUM> is conveyed by a belt drive mechanism <NUM> to move a predetermined distance. At this time, the push-up rollers 31A, 31A rotate with the movement of the conveyor belt <NUM>. This rotation reduces the frictional force between the push-up rollers 31A, 31A and the conveyor belt <NUM>, and prevents the conveyor belt <NUM> from expanding and contracting under the influence of the push-up rollers 31A, 31A. When the conveyor belt <NUM> stops after moving a predetermined distance, the rod 35b of the hydraulic cylinder <NUM> retracts into the cylinder body 35a to lower the movable plate <NUM>, and the push-up rollers 31A, 31A are thus located below the upper surface of the support base <NUM>. As a result, the conveyor belt <NUM> is lowered onto the support base <NUM> to be brought into contact with the support base <NUM>. Thereafter, printing on the fabric C is performed by the one or more printing mechanisms <NUM>. As described above, during the conveying movement of the conveyor belt <NUM>, the conveyor belt <NUM> is lifted from the support base <NUM> by the elevating mechanisms <NUM>; accordingly, the conveyor belt <NUM> is released from contact with the support base <NUM>.

According to the above configuration, since the push-up rollers 31A, 31A lift the conveyor belt <NUM> to separate the conveyor belt <NUM> from the support base <NUM> each time the intermittent feeding movement of the conveyor belt <NUM> is performed, no frictional force is generated between the lower surface of the conveyor belt <NUM> and the upper surface of the support base <NUM> when the conveyor belt <NUM> moves. This prevents elongation from occurring in the central portion of the conveyor belt <NUM>, and thus reduces conveyance errors. Thus, according to the printing apparatus <NUM> of this embodiment, the intermittent feeding movement of the conveyor belt <NUM> can be assisted.

The push-up rollers 31A, 31A may not rotate with movement of the conveyor belt <NUM>, and may be rod-shaped members. In this case, when the conveyor belt <NUM> is conveyed by the belt drive mechanism <NUM> to move a predetermined distance, the push-up rollers 31A, 31A come into contact with the lower surface of the conveyor belt <NUM>, but do not rotate. Even in this case, the frictional force between the push-up rollers 31A, 31A and the conveyor belt <NUM> is smaller than that in conventional techniques.

The configuration of the elevating mechanisms <NUM> is not limited to this embodiment, and the elevating mechanisms <NUM> may have any configuration as long as the push-up rollers 31A, 31A can be lifted. For example, as shown in <FIG>, the elevating mechanisms <NUM> may be rodless cylinders <NUM>. In each rodless cylinder <NUM>, for example, a cylinder tube 40b is disposed between upper and lower base portions 40a, 40a fixed to, for example, the frame <NUM> or the base (not shown) of the printing apparatus <NUM>, a piston (not shown) is housed in the cylinder tube 40b, and a slide body 40c is provided on the outer peripheral surface of the cylinder tube 40b, so as to be slidable along the cylinder tube 40b. The piston and the slide body 40c move integrally by a magnetic coupling force. For example, by moving the piston by air, the slide body 40c follows the movement of the piston.

A pair of rodless cylinders <NUM> are provided per one push-up roller 31A. The pair of rodless cylinders <NUM> are disposed on both end sides (in the width direction of the fabric C) of each push-up roller 31A, and the tips at both ends of the rotation shaft 31a of each of the push-up rollers 31A, 31A are each fixed to the corresponding slide body 40c. By raising and lowering the slide bodies 40c, the push-up rollers 31A, 31A are raised and lowered so that the top of each push-up roller 31A is between a position above the upper surface of the support base <NUM> and a position below the upper surface of the support base <NUM>. Moreover, a movable plate may be attached to each of the slide bodies 40c of a pair of rodless cylinders <NUM>, the tips at both ends of the rotation shaft 31a of each of two push-up rollers 31A, 31A may be fixed to the corresponding movable plates, and the two push-up rollers 31A, 31A may be moved simultaneously by the pair of rodless cylinders <NUM>.

The elevating mechanisms <NUM> may be cam mechanisms <NUM> shown in <FIG>. Each cam mechanism <NUM> includes a rotating body <NUM> as a driver cam that rotates by rotation of a motor (not shown), and a rod-shaped member <NUM> as a follower cam disposed on the upper side of the rotating body <NUM>. The rotating body <NUM> includes a circular disk portion 51a whose central portion is attached to an output shaft 51c of the motor, and a protrusion 51b that protrudes outward from the disk portion 51a. At the lower end of the rod-shaped member <NUM>, a roller 52a that is rotatable by rotation of the rotating body <NUM> is provided in order to reduce the frictional force between the rod-shaped member <NUM> and the rotating body <NUM>; and to the upper end of the rod-shaped member <NUM>, a tip of the rotation shaft 31a of a push-up roller 31A is fixed. When the protrusion 51b faces upward by rotation of the output shaft 51c of the motor, the rod-shaped member <NUM> is lifted, and the push-up rollers 31A, 31A fixed to the corresponding rod-shaped members <NUM> are raised. When the protrusion 51b faces in a direction other than the upward direction (for example, laterally or downward), the push-up rollers 31A, 31A fixed to the corresponding rod-shaped members <NUM> are lowered.

The push-up member <NUM> is not limited to the push-up rollers 31A, 31A, and may have any configuration as long as it can come into contact with the lower surface of the conveyor belt <NUM> and push up the conveyor belt <NUM> to release the conveyor belt <NUM> from contact with the upper surface of the support base <NUM>. For example, the push-up member <NUM> may be a spherical body rotatably supported by a base portion. The push-up member <NUM> may include a plurality of spherical bodies.

Claim 1:
A printing apparatus (<NUM>) comprising:
a conveyor belt (<NUM>) for supporting a printing object from below and conveying the object in a horizontal direction;
a belt drive mechanism (<NUM>) that causes the conveyor belt (<NUM>) to perform an intermittent feeding movement;
a printing mechanism (<NUM>) that is disposed in a travel path of the conveyor belt (<NUM>), and performs printing on the object;
a support base (<NUM>) for supporting the conveyor belt (<NUM>) from below during printing by the printing mechanism (<NUM>); and
a belt feed assisting mechanism that assists the intermittent feeding movement of the conveyor belt by the belt drive mechanism;
characterized in that
the belt feed assisting mechanism comprises
air holes (<NUM>) formed in the support base (<NUM>) and an air supply mechanism (<NUM>) that supplies air to be fed from the air holes (<NUM>) toward a lower surface of the conveyor belt (<NUM>).