Patent Publication Number: US-9409346-B2

Title: Three-dimensional printing apparatus

Description:
This application claims priority to Patent Application No. 2013-166841 filed in Japan on Aug. 9, 2013, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to three-dimensional printing apparatuses. 
     2. Description of the Related Art 
     A three-dimensional printing apparatus is conventionally known in which a liquid photo-curable resin stored inside a tank is irradiated with light so as to cure the photo-curable resin, thus forming a three-dimensional object. A three-dimensional printing apparatus of this type includes a base, a tank, and a raisable and lowerable holder. The base is provided with an opening. The tank is placed on the base. The holder is disposed above the tank. An optical device including a light source and a mirror, for example, is disposed below the base. Light emitted from the light source is reflected by the mirror. A resin inside the tank is irradiated through the opening of the base with the light reflected by the mirror. A portion of the resin inside the tank which has been irradiated with the light is cured. By controlling a light irradiation position, a position at which the resin is to be cured is appropriately changed. Hence, the cured resin can form a desired cross-sectional shape. A desired cross-sectional shape is continuously formed downward by sequentially raising the holder. As a result, a desired three-dimensional object is formed by the cured resin. 
     In the above-described three-dimensional printing apparatus, the tank that stores a photo-curable resin in liquid form is placed on the base before a three-dimensional object is formed. After the three-dimensional object has been formed, the tank in which the photo-curable resin in liquid form remains is moved from a position on the base. In this case, the photo-curable resin might scatter from the tank. The scattered photo-curable resin might adhere to the optical device through the opening. A known solution to this problem is to close the opening with a transparent plate made of glass, for example, so that the scattered resin does not pass through the opening. 
     However, when the opening is closed with the transparent plate, the light emitted from the light source is undesirably attenuated through the transparent plate before being applied to the photo-curable resin, thus disadvantageously preventing the resin inside the tank from being efficiently cured. Furthermore, the resin scattered from the tank might adhere to the transparent plate. The resin adhered to the transparent plate might block the light emitted from the light source. 
     A proposed solution to these problems is to provide the opening with a shutter that is controllable so as to be opened and closed. JP 2012-187807 A discloses a three-dimensional printing apparatus that includes a sensor that detects whether or not a tank is placed on a base, and a motor that drives a shutter so that the shutter is opened and closed. The sensor includes a protrusion that can be protruded from and retracted into the base, and a spring that constantly urges the protrusion upward. Upon placement of the tank on the base, the protrusion is pushed down by a bottom wall of the tank. Thus, the protrusion is retracted into the base. Upon removal of the tank from a position on the base, the protrusion protrudes from the base due to a force of the spring. The sensor detects whether or not the tank is placed on the base on the basis of a state of the protrusion. In this three-dimensional printing apparatus, upon detection of placement of the tank on the base, the shutter is automatically opened by the motor. In contrast, upon detection of removal of the tank from the position on the base, the shutter is automatically closed by the motor. 
     The three-dimensional printing apparatus disclosed in JP 2012-187807 A is arranged so that the tank is placed on the base from above in such a way as to push down the protrusion. Therefore, when the tank is placed on the base, a gap might briefly be provided between the tank and the base, with the shutter opened. When the tank is moved away from the base, a gap might also be provided between the tank and the base, with the shutter opened. Thus, a photo-curable resin might enter through the gap. As a result, the photo-curable resin might adhere to an optical device. 
     SUMMARY OF THE INVENTION 
     Accordingly, preferred embodiments of the present invention provide a three-dimensional printing apparatus in which a photo-curable resin is unlikely to adhere to an optical device through an opening of a base. 
     A three-dimensional printing apparatus according to a preferred embodiment of the present invention includes a base, a tank, an optical device, a holder, a shutter, a slide guide, and an interlocking device. The base is provided with an opening. The tank is placed on the base, and stores a photo-curable resin in liquid form. The optical device is disposed below the base, and includes at least a light source that emits light. The optical device irradiates the photo-curable resin inside the tank with the light emitted from the light source through the opening. The holder is raisable and lowerable, and lifts the photo-curable resin that has been cured with irradiation of the light. The shutter covers the opening in an openable and closable manner. The slide guide guides sliding of the tank on the base so that the tank is slidable between a preparation position located outside of a region over the opening and an installation position located over the opening. The interlocking device opens and closes the shutter in conjunction with sliding of the tank on the base so that the shutter is opened when the tank is located over the entire opening, and the shutter is closed when the tank is not located over at least a portion of the opening. 
     In the above-described three-dimensional printing apparatus, the slide guide guides sliding of the tank on the base. The tank is moved between the preparation position and the installation position by sliding the tank on the base and along the slide guide. The shutter is opened and closed in conjunction with sliding of the tank so that the shutter is opened when the tank is located over the entire opening of the base, and the shutter is closed when the tank is not located over at least a portion of the opening. Therefore, unlike the apparatus disclosed in JP 2012-187807 A, no gap is provided between the tank and the base, with the shutter opened. As a result, the photo-curable resin scattered from the tank is prevented from adhering to the optical device through the opening. 
     According to one preferred embodiment of the present invention, the interlocking device is preferably arranged to move the shutter in conjunction with sliding of the tank so that the interlocking device starts opening the shutter after the tank has slid to a position at which the tank is located over the entire opening, and finishes closing the shutter before the tank slides to a position at which the tank is not located over at least a portion of the opening. 
     The tank moves from the preparation position to the installation position by sliding on the base. When the tank has moved to the position located over the entire opening, the opening is completely covered with the tank. Therefore, according to the above-described preferred embodiment, the shutter starts to open after the opening has been completely covered with the tank. The tank moves from the installation position to the preparation position by sliding on the base. The opening is completely covered with the tank until the tank is not located over at least a portion of the opening of the base. Therefore, according to the above-described preferred embodiment, the shutter finishes closing before the opening is not completely covered with the tank. As a result, the photo-curable resin scattered from the tank is more reliably prevented from adhering to the optical device through the opening. 
     According to another preferred embodiment of the present invention, the interlocking device preferably includes an engagement member, a connection member, and an elastic member. The engagement member preferably engages with the tank and moves in response to sliding of the tank. The connection member preferably connects the engagement member and the shutter to each other so that the shutter is opened and closed in response to the movement of the engagement member. The elastic member preferably applies an elastic force to the shutter so that the shutter is closed. 
     According to the above-described preferred embodiment, the shutter is mechanically and automatically opened and closed in response to sliding of the tank. Therefore, a tank detection sensor and a shutter driving motor are unnecessary. For example, when a tank detection sensor and a shutter driving motor are used, the tank is detected by the sensor, and then the motor is driven to open or close the shutter. In that case, a control time delay occurs between the detection by the sensor and opening or closing of the shutter. Thus, the shutter might remain open even though the opening of the base is not covered with the tank. However, according to the above-described preferred embodiment, such a control time delay does not occur. As a result, the photo-curable resin scattered from the tank is suitably prevented from adhering to the optical device through the opening. 
     According to still another preferred embodiment of the present invention, when the tank slides from the installation position toward the preparation position, the tank preferably slides forward, and when the tank slides from the preparation position toward the installation position, the tank preferably slides rearward. The interlocking device preferably includes a guide rod, a slider, a link member, a rotation shaft, and a tension spring. The guide rod preferably extends in a front-rear direction. The slider is preferably provided on the shutter so as to be movable together with the shutter. The slider is preferably provided with a guide groove that extends in a vertical direction. The slider is preferably slidably engaged with the guide rod. The link member preferably includes an abutting portion, an engagement portion, and a rod portion. The abutting portion preferably abuts against a rear portion of the tank. The engagement portion is preferably slidably engaged with the guide groove of the slider. The rod portion preferably connects the abutting portion and the engagement portion to each other. The rotation shaft preferably extends in a right-left direction and supports a portion of the link member which is located between the abutting portion and the engagement portion. The tension spring preferably includes an upper end portion disposed behind the slider, and a lower end portion locked to a portion of the link member which is located between the rotation shaft and the engagement portion. 
     According to the above-described preferred embodiment, the shutter is opened and closed in response to sliding of the tank by using a simple structure. 
     According to yet another preferred embodiment of the present invention, the three-dimensional printing apparatus preferably further includes a lock mechanism that locks the tank at the installation position. 
     According to the above-described preferred embodiment, the tank is locked at the installation position by the lock mechanism. Hence, even if a shock is given to the tank, the tank does not move out of the installation position. Accordingly, the tank is stably and reliably held at the installation position. 
     According to still yet another preferred embodiment of the present invention, when the tank slides from the installation position toward the preparation position, the tank preferably slides forward, and when the tank slides from the preparation position toward the installation position, the tank preferably slides rearward. The tank preferably includes a bottom wall, a left wall that extends vertically from a left portion of the bottom wall, and a right wall that extends vertically from a right portion of the bottom wall. The slide guide preferably includes a left guide member and a right guide member. The left guide member is preferably attached onto the base. The left guide member preferably includes a left longitudinal plate that extends in a front-rear direction, and a left upper plate that extends rightward from the left longitudinal plate. The left guide member preferably comes into sliding contact with the left wall of the tank. The right guide member is preferably attached onto the base. The right guide member preferably includes a right longitudinal plate that extends in the front-rear direction, and a right upper plate that extends leftward from the right longitudinal plate. The right guide member preferably comes into sliding contact with the right wall of the tank. 
     According to the above-described preferred embodiment, the slide guide allows the tank to stably slide on the base. 
     According to another preferred embodiment of the present invention, when the tank slides from the installation position toward the preparation position, the tank preferably slides forward, and when the tank slides from the preparation position toward the installation position, the tank preferably slides rearward. The shutter preferably includes a plate portion and a protruded portion. The plate portion is preferably slidable in a front-rear direction. The protruded portion preferably protrudes upward from a rear end of the plate portion. 
     For example, suppose that the shutter includes the plate portion slidable in the front-rear direction and the photo-curable resin in liquid form has adhered onto the plate portion. In that case, when the shutter is moved forward, the adhered photo-curable resin might fall down from the rear end of the plate portion. The photo-curable resin that has fallen down might adhere to the optical device. However, according to the above-described preferred embodiment, the rear end of the plate portion is provided with the protruded portion that protrudes upward therefrom. Therefore, when the shutter is moved forward, the photo-curable resin adhered onto the plate portion is stopped by the protruded portion. Thus, the photo-curable resin adhered onto the plate portion is prevented from falling down. Consequently, the photo-curable resin is prevented from adhering to the optical device. 
     According to still another preferred embodiment of the present invention, the tank preferably includes a bottom wall, and side walls located laterally of the bottom wall. A lower surface of the bottom wall is preferably located higher than lower surfaces of the side walls. 
     According to the above-described preferred embodiment, the lower surfaces of the side walls come into contact with a surface of the base, but the lower surface of the bottom wall does not come into contact with the surface of the base. Thus, the bottom wall of the tank does not come into sliding contact with the base when the tank slides between the preparation position and the installation position. Therefore, the bottom wall of the tank is prevented from being contaminated by sliding of the tank. As a result, the photo-curable resin inside the tank is efficiently irradiated with light through the opening of the base. 
     Various preferred embodiments of the present invention provide a three-dimensional printing apparatus in which a photo-curable resin is unlikely to adhere or preventing from adhering to an optical device through an opening of a base. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view illustrating a three-dimensional printing apparatus according to a preferred embodiment of the present invention. 
         FIG. 2  is a plan view illustrating a base on which a tank is placed. 
         FIG. 3  is a vertical cross-sectional view of the tank. 
         FIG. 4  is a plan view illustrating the tank and the base. 
         FIG. 5  is a side view illustrating the tank, the base, and an interlocking device. 
         FIG. 6  is a plan view illustrating the tank and the base. 
         FIG. 7  is a side view illustrating the tank, the base, and the interlocking device. 
         FIG. 8  is a plan view illustrating the tank and the base. 
         FIG. 9  is a side view illustrating the tank, the base, and the interlocking device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a three-dimensional printing apparatus according to preferred embodiments of the present invention will be described. Preferred embodiments described herein are naturally not intended to limit the present invention in any way. Components or elements having similar functions are identified by the same reference signs, and redundant description thereof will be omitted or simplified. 
       FIG. 1  is a side view illustrating a three-dimensional printing apparatus  1  according to the present preferred embodiment. Note that in the following description, right and left portions of  FIG. 1  correspond to front and rear portions of the three-dimensional printing apparatus  1 , respectively. In  FIGS. 1 to 9 , the reference signs “F”, “Rr”, “L” and “R” indicate front, rear, left and right, respectively. It is to be noted that directions indicated by the reference signs are defined merely for the sake of convenience of description. These directions are not intended to limit how the three-dimensional printing apparatus  1  is installed in any way. As illustrated in  FIG. 1 , the three-dimensional printing apparatus  1  preferably includes a base  11 , a tank  12 , and an optical device  13 . 
       FIG. 2  is a plan view illustrating the base  11  on which the tank  12  is placed. The base  11  is provided with an opening  21 . The opening  21  is not limited to any particular shape. In the present preferred embodiment, the opening  21  preferably has a rectangular shape in a plan view, for example. 
     As illustrated in  FIG. 1 , the tank  12  is placed on the base  11 . The tank  12  stores a photo-curable resin  23  in liquid form. The photo-curable resin  23  is a resin that is curable by being irradiated with light. The tank  12  is preferably made of a material that allows light to pass therethrough. For example, the tank  12  is preferably made of a material such as a transparent resin or glass. In the present preferred embodiment, the tank  12  is made of a transparent acrylic resin. Note that the tank  12  may be made of such a material as to allow light to pass through at least a portion of a bottom wall  12 B (see  FIG. 2 ) of the tank  12 . 
     The tank  12  is a receptacle preferably having a rectangular or substantially rectangular shape in the plan view. It is to be noted that the tank  12  is not limited to any particular shape. As illustrated in  FIG. 2 , in the present preferred embodiment, the tank  12  preferably includes the bottom wall  12 B, a front wall  12 F, a rear wall  12 Rr, a left wall  12 L, and a right wall  12 R. Note that each of the front wall  12 F, the rear wall  12 Rr, the left wall  12 L and the right wall  12 R is an example of a side wall located laterally of the bottom wall  12 B. In the present preferred embodiment, the bottom wall  12 B has a flat plate shape. It is to be noted that the bottom wall  12 B is not limited to any particular shape. In the plan view, the bottom wall  12 B is smaller than the base  11 . In the plan view, the bottom wall  12 B is larger than the opening  21  provided in the base  11 . Note that a surface of the bottom wall  12 B may be provided with a layer that prevents undesirable adhesion of the photo-curable resin  23 . For example, the surface of the bottom wall  12 B may be provided with a silicon layer. 
     The front wall  12 F extends vertically from a front portion of the bottom wall  12 B. The rear wall  12 Rr extends vertically from a rear portion of the bottom wall  12 B. The front wall  12 F and the rear wall  12 Rr each extend in a right-left direction. The left wall  12 L extends vertically from a left portion of the bottom wall  12 B. The left wall  12 L is continuous with the front wall  12 F and the rear wall  12 Rr. The right wall  12 R extends vertically from a right portion of the bottom wall  12 B. The right wall  12 R is continuous with the front wall  12 F and the rear wall  12 Rr. The left wall  12 L and the right wall  12 R each extend in a front-rear direction. The bottom wall  12 B, the front wall  12 F, the rear wall  12 Rr, the left wall  12 L and the right wall  12 R preferably are molded in one piece. Alternatively, the bottom wall  12 B, the front wall  12 F, the rear wall  12 Rr, the left wall  12 L and the right wall  12 R may be molded separately and then assembled to each other. 
       FIG. 3  is a vertical cross-sectional view of the tank  12 . In the present preferred embodiment, a lower surface  12 B 1  of the bottom wall  12 B is located higher than a lower surface  12 L 1  of the left wall  12 L and a lower surface  12 R 1  of the right wall  12 R. In other words, a lower portion of the left wall  12 L and a lower portion of the right wall  12 R protrude downward relative to the lower surface  12 B 1  of the bottom wall  12 B. Although not illustrated, the lower surface  12 B 1  of the bottom wall  12 B is located higher than a lower surface of the front wall  12 F and a lower surface of the rear wall  12 Rr. In other words, a lower portion of the front wall  12 F and a lower portion of the rear wall  12 Rr protrude downward relative to the lower surface  12 B 1  of the bottom wall  12 B. With the tank  12  placed on the base  11 , a space  12 S is provided between the bottom wall  12 B and the base  11 . The bottom wall  12 B is located away from the base  11 . In other words, the bottom wall  12 B does not come into contact with the base  11 . In this preferred embodiment, the front wall  12 F, the rear wall  12 Rr, the left wall  12 L and the right wall  12 R of the tank  12  come into contact with the base  11 . 
     As illustrated in  FIG. 1 , the optical device  13  irradiates the photo-curable resin  23  inside the tank  12  with light through the opening  21  of the base  11 . The optical device  13  is disposed below the base  11 . In the present preferred embodiment, the optical device  13  is contained in a case  25  provided under the base  11 . The optical device  13  preferably includes a light source  31  and a mirror  32 . 
     The light source  31  emits light. In the present preferred embodiment, the light source  31  is disposed below a front portion of the base  11 . The light source  31  emits light from front to rear. The light source  31  is not limited to any particular type. A light source such as a laser diode or a projector, for example, may be suitably used as the light source  31 . 
     In the present preferred embodiment, a control device  35  is connected to the light source  31 . The control device  35  is configured or programmed to control the light emitted from the light source  31 . More specifically, the control device  35  is configured or programmed to control, for example, a wavelength band of the light, a shape of the light, and timing of emission of the light emitted from the light source  31 . The control device  35  is not limited to any particular configuration. For example, the control device  35  may be a computer. The control device  35  may include a central processing unit (hereinafter referred to as a “CPU”), a ROM that stores, for example, a program to be carried out by the CPU, and a RAM or the like. 
     The mirror  32  reflects the light emitted from the light source  31 . In the present preferred embodiment, the mirror  32  is disposed below the opening  21  provided in the base  11 . The mirror  32  is disposed behind the light source  31 . The mirror  32  is disposed so that its mirror surface faces obliquely upward and forward. The light emitted from the light source  31  is reflected by the mirror  32 . Through the opening  21 , the photo-curable resin  23  inside the tank  12  is irradiated with the light reflected by the mirror  32 . Note that an angle of the mirror  32  is freely controllable. The angle of the mirror  32  is controlled, thus appropriately changing a light irradiation position for the photo-curable resin  23  stored in the tank  12 . By appropriately changing the light irradiation position, the photo-curable resin  23  is cured at a desired position. As a result, a desired cross-sectional shape is formed by the cured photo-curable resin  23 . 
     The three-dimensional printing apparatus  1  preferably further includes a holder  14 . The holder  14  lifts the photo-curable resin  23  that has been cured with irradiation of the light emitted from the light source  31 . The holder  14  is a raisable and lowerable member. In the present preferred embodiment, a rear portion of the base  11  is provided with a support column  41  that extends in an up-down direction. A slider  42  is attached to the support column  41 . The slider  42  is raisable and lowerable along the support column  41 . The slider  42  is driven to move upward or downward by a motor (not illustrated). In this preferred embodiment, the holder  14  is attached to the slider  42 . Thus, the holder  14  is driven to move upward or downward by the motor via the slider  42 . The holder  14  is disposed above the opening  21  of the base  11 . 
     The three-dimensional printing apparatus  1  preferably further includes a shutter  15 . The shutter  15  covers the opening  21  of the base  11  in an openable and closable manner. In the present preferred embodiment, the shutter  15  is disposed under the base  11 . The shutter  15  preferably includes a plate portion  51 , a protruded portion  52 , and an engagement plate  53 . 
     The shutter  15  is slidable in the front-rear direction. More specifically, the plate portion  51  is slidable in the front-rear direction. Upon rearward movement of the shutter  15 , the plate portion  51  is located under the opening  21  of the base  11 . In this case, the opening  21  is closed. Upon forward movement of the shutter  15 , the plate portion  51  moves out of a position under the opening  21 . In this case, the opening  21  is opened. In this manner, the plate portion  51  slides in the front-rear direction, and thus the shutter  15  opens and closes the opening  21 . The plate portion  51  has a shape and size which allows the plate portion  51  to cover the opening  21  in the plan view. In this preferred embodiment, similarly to the opening  21 , the plate portion  51  preferably has a rectangular or substantially rectangular shape in the plan view. It is to be noted that the plate portion  51  is not limited to any particular shape. For example, the plate portion  51  and the opening  21  may have the same shape in the plan view, or may have different shapes in the plan view. In this preferred embodiment, the plate portion  51  preferably has a horizontal plate shape. Alternatively, the plate portion  51  may have a bent plate shape, or may have any other shape. The protruded portion  52  protrudes upward from a rear end of the plate portion  51 . The protruded portion  52  extends in the right-left direction from a left end of the plate portion  51  to aright end thereof. The engagement plate  53  protrudes downward from a front end of the plate portion  51 . The engagement plate  53  is provided with a hole  53   a  (see  FIG. 5 ) that engages with a guide rod  71  (which will be described below). 
     As illustrated in  FIG. 2 , the three-dimensional printing apparatus  1  preferably further includes a slide guide  16 . Note that in the following description, a position at which the tank  12  is located outside of a region over the opening  21  of the base  11  will be referred to as a “preparation position A” (see  FIG. 4 ), and a position at which the tank  12  is installed over the opening  21  will be referred to as an “installation position B” (see  FIG. 2 ). The slide guide  16  is arranged so that the tank  12  is slidable between the preparation position A and the installation position B. The slide guide  16  guides a sliding operation of the tank  12  on the base  11 . In the present preferred embodiment, the slide guide  16  preferably includes a left guide member  61  and a right guide member  62 . 
     The left guide member  61  is attached to a left portion of an upper surface of the base  11 . The left guide member  61  extends in the front-rear direction. The left guide member  61  comes into sliding contact with the left wall  12 L of the tank  12 . In the present preferred embodiment, the left guide member  61  preferably includes a left longitudinal plate  63   a , a left upper plate  63   b , and a left attachment plate  63   c.    
     The left longitudinal plate  63   a  extends in the front-rear direction. The left longitudinal plate  63   a  is disposed in a direction perpendicular to the base  11 . The left upper plate  63   b  extends rightward from an upper end of the left longitudinal plate  63   a . In this preferred embodiment, the left wall  12 L of the tank  12  may be slidably disposed in a space located rightward of the left longitudinal plate  63   a  and under the left upper plate  63   b . The left attachment plate  63   c  extends leftward from a lower end of the left longitudinal plate  63   a . As illustrated in  FIG. 1 , the left attachment plate  63   c  is attached to the base  11  via screws  65   a  and  65   b  in this preferred embodiment. The screws  65   a  and  65   b  are attached to the base  11 . In the present preferred embodiment, the left guide member  61  is slidable in the up-down direction between the base  11  and a head portion  65   aa  of the screw  65   a  and between the base  11  and a head portion  65   ba  of the screw  65   b . A spring  66  is provided between the head portion  65   aa  of the screw  65   a  and the left attachment plate  63   c . The spring  66  urges the left guide member  61  downward. A fixation member  65   c  is attached to the left guide member  61 . The movement of the left guide member  61  in the up-down direction is restricted by the fixation member  65   c.    
     As illustrated in  FIG. 2 , the right guide member  62  is attached to a right portion of the upper surface of the base  11 . The right guide member  62  extends in the front-rear direction. The right guide member  62  comes into sliding contact with the right wall  12 R of the tank  12 . In the present preferred embodiment, the right guide member  62  preferably includes a right longitudinal plate  67   a , a right upper plate  67   b , and a right attachment plate  67   c.    
     The right longitudinal plate  67   a  extends in the front-rear direction. The right longitudinal plate  67   a  is disposed in a direction perpendicular to the base  11 . The right upper plate  67   b  extends leftward from an upper end of the right longitudinal plate  67   a . In this preferred embodiment, the right wall  12 R of the tank  12  may be slidably disposed in a space located leftward of the right longitudinal plate  67   a  and under the right upper plate  67   b . The right attachment plate  67   c  extends rightward from a lower end of the right longitudinal plate  67   a . In this preferred embodiment, the right attachment plate  67   c  is attached to the base  11  via a plurality of screws  68 . Although not illustrated, similarly to the left guide member  61 , at least one of the plurality of screws  68  may be provided with a spring that urges the right guide member  62  downward. The right guide member  62  is also slidable in the up-down direction. The movement of the right guide member  62  in the up-down direction is restricted by a fixation member  69 . 
     As illustrated in  FIG. 1 , the three-dimensional printing apparatus  1  preferably further includes an interlocking device  17 . The interlocking device  17  opens and closes the shutter  15  in conjunction with the sliding operation of the tank  12  on the base  11 . Specifically, when the tank  12  is located over the entire opening  21  of the base  11 , the interlocking device  17  opens the shutter  15  so that the opening  21  is opened. When the tank  12  is not located over at least a portion of the opening  21 , the interlocking device  17  closes the shutter  15  so that the opening  21  is closed. In the present preferred embodiment, the interlocking device  17  starts to open the shutter  15  after the tank  12  has slid rearward and has been located over the entire opening  21  of the base  11 . The interlocking device  17  finishes closing the shutter  15  before the tank  12  slides forward and is not located over at least a portion of the opening  21 . In this preferred embodiment, the interlocking device  17  is provided at a left portion of the base  11 . It is to be noted that the position at which the interlocking device  17  is provided is not limited to any particular position. For example, the interlocking device  17  may be provided at a right portion of the base  11 . The interlocking device  17  preferably includes the guide rod  71 , a slider  72 , a link member  73 , and a tension spring  74 . 
     The guide rod  71  extends in the front-rear direction. In the present preferred embodiment, the guide rod  71  is disposed below the base  11  so as to be in parallel or substantially in parallel with the base  11 . Specifically, attachment members  81  and  82  are disposed at front and rear portions of a lower surface of the base  11 , respectively. A front end of the guide rod  71  is attached to the attachment member  81 . A rear end of the guide rod  71  is attached to the attachment member  82 . The guide rod  71  is inserted through the hole  53   a  (see  FIG. 5 ) provided in the engagement plate  53  of the shutter  15 . Thus, the shutter  15  is slidable in the front-rear direction along the guide rod  71 . 
     The slider  72  is provided on the shutter  15  so as to be movable together with the shutter  15 . The slider  72  and the shutter  15  may be integral with each other. The slider  72  may be fixed to the shutter  15 . In the present preferred embodiment, the slider  72  is provided on a rear left end of a lower surface of the plate portion  51  of the shutter  15 . The slider  72  extends downward from the lower surface of the plate portion  51  so that the slider  72  is perpendicular or substantially perpendicular to the plate portion  51 . The slider  72  is provided with a guide groove  83 . The guide groove  83  extends in a direction perpendicular or substantially perpendicular to the guide rod  71 . The guide groove  83  extends along a longitudinal direction of the slider  72 . In other words, the guide groove  83  extends in a vertical direction. 
     The link member  73  transmits movement of the tank  12  to the shutter  15  so that the shutter  15  is opened or closed in response to the movement of the tank  12 . The link member  73  preferably includes an abutting portion  84 , an engagement portion  85 , and a rod portion  86 . The abutting portion  84  abuts against the tank  12  when the tank  12  has slid rearward. The abutting portion  84  that has abutted against the tank  12  moves in response to the sliding operation of the tank  12 . Note that the abutting portion  84  is an example of an engagement member. In the present preferred embodiment, the abutting portion  84  is arranged so as to abut against a rear portion of the tank  12 . Specifically, the abutting portion  84  is disposed above the base  11 . The abutting portion  84  is arranged so as to abut against a rear surface of the rear wall  12 Rr of the tank  12 . The engagement portion  85  is slidably engaged with the guide groove  83  of the slider  72 . The rod portion  86  connects the abutting portion  84  and the engagement portion  85  to each other. The abutting portion  84  bends from the rod portion  86  in the present preferred embodiment, but the abutting portion  84  may extend on an extension of the rod portion  86 . As illustrated in  FIG. 2 , in the present preferred embodiment, an insertion hole  88  that extends in the front-rear direction is provided in a region of the left portion of the base  11  which is located rearward relative to a center of the base  11 . With the rod portion  86  inserted into the insertion hole  88 , the rod portion  86  connects the abutting portion  84  and the engagement portion  85  to each other. 
     As illustrated in  FIG. 1 , the link member  73  is provided with a rotation shaft  87 . The rotation shaft  87  extends in the right-left direction. The rotation shaft  87  supports a portion of the link member  73  which is located between the abutting portion  84  and the engagement portion  85 . In the present preferred embodiment, the slider  72 , the engagement portion  85 , the rod portion  86  and the rotation shaft  87  constitute a connection member. 
     The tension spring  74  applies an elastic force to the shutter  15  so that the shutter  15  is closed. The tension spring  74  preferably includes a first end portion (upper end portion)  74   a  disposed behind the slider  72 , and a second end portion (lower end portion)  74   b  locked to a portion of the link member  73  which is located between the rotation shaft  87  and the engagement portion  85 . In the present preferred embodiment, the first end portion  74   a  of the tension spring  74  is attached to the attachment member  82  disposed at the rear portion of the lower surface of the base  11 . The second end portion  74   b  of the tension spring  74  is attached to the rod portion  86  of the link member  73 . The tension spring  74  is an example of an elastic member. 
     As illustrated in  FIG. 2 , the three-dimensional printing apparatus  1  preferably further includes a lock mechanism  18 . The lock mechanism  18  locks the tank  12  at the installation position B. In the present preferred embodiment, the lock mechanism  18  preferably includes a fixation rod  91  and a knob  92 . A first end of the fixation rod  91  is attached to a front portion of the right guide member  62 . A second end of the fixation rod  91  is attached to a front portion of the left guide member  61 . The fixation rod  91  extends from the front portion of the right guide member  62  to the front portion of the left guide member  61 . The fixation rod  91  is rotatable upward about the right guide member  62 . The fixation rod  91  moves together with the left guide member  61 . Therefore, the fixation rod  91  is rotatable upward until the left attachment plate  63   c  of the left guide member  61  reaches a position at which the left attachment plate  63   c  abuts against the head portion  65   aa  of the screw  65   a  or the head portion  65   ba  of the screw  65   b . The knob  92  is provided on the second end of the fixation rod  91 . A user lifts the knob  92 , thus rotating the fixation rod  91 . In this case, with the upward rotation of the fixation rod  91 , the left guide member  61  also moves upward. Note that the lock mechanism  18  according to the present preferred embodiment is provided merely by way of example, and any other lock mechanism  18  may naturally be used. 
     Next, a procedure for installing the tank  12  on the base  11  will be described. In the present preferred embodiment, when a three-dimensional object is formed, the tank  12  is slid along the slide guide  16 . Thus, the tank  12  is disposed over the opening  21  of the base  11 .  FIGS. 4, 6 and 8  are plan views each illustrating the tank  12  and the base  11 .  FIGS. 5, 7 and 9  are side views each illustrating the tank  12 , the base  11  and the interlocking device  17 .  FIGS. 4 and 5  each illustrate a state in which the tank  12  is disposed at the preparation position A.  FIGS. 6 and 7  each illustrate a state in which the tank  12  is on its way from the preparation position A to the installation position B, and the opening  21  is closed by the shutter  15 .  FIGS. 8 and 9  each illustrate a state in which the tank  12  is on its way from the preparation position A to the installation position B, and the opening  21  is being opened by the shutter  15 . Note that  FIGS. 1 and 2  each illustrate a state in which the tank  12  is disposed at the installation position B. 
     First, as illustrated in  FIG. 4 , the tank  12  is disposed at the preparation position A. In this case, as illustrated in  FIG. 5 , the rod portion  86  of the link member  73  is pulled rearward by the tension spring  74 . Hence, the slider  72  engaged with the engagement portion  85  of the link member  73  is pulled rearward. Accordingly, the slider  72  is positioned at its rearmost position. As illustrated in  FIG. 4 , with the tank  12  disposed at the preparation position A, the opening  21  provided in the base  11  is covered with the shutter  15  and is thus closed. Note that as illustrated in FIG.  5 , the engagement portion  85  of the link member  73  is located at a lower end of the guide groove  83  of the slider  72 . The abutting portion  84  of the link member  73  is inclined forward relative to the rotation shaft  87 . 
     From the state in which the tank  12  is disposed at the preparation position A, the tank  12  is slid rearward along the slide guide  16  until the rear surface of the rear wall  12 Rr of the tank  12  abuts against the abutting portion  84  of the link member  73  as illustrated in  FIG. 6 . In this case, the left wall  12 L of the tank is located within the space provided rightward of the left longitudinal plate  63   a  of the left guide member  61  of the slide guide  16  and under the left upper plate  63   b . The right wall  12 R of the tank  12  is located within the space provided leftward of the right longitudinal plate  67   a  of the right guide member  62  of the slide guide  16  and under the right upper plate  67   b . Accordingly, the tank  12  is guided along the slide guide  16  and thus moves rearward in a straight line. Note that as illustrated in  FIG. 7 , until the rear surface of the rear wall  12 Rr of the tank  12  abuts against the abutting portion  84 , the slider  72  is pulled rearward by the tension spring  74  via the link member  73 . Therefore, the shutter  15  remains closed. As illustrated in  FIG. 6 , a front end of the abutting portion  84  is located rearward relative to a rear end of the opening  21 . Hence, until the tank  12  covers the entire opening  21 , the tank  12  and the abutting portion  84  do not abut against each other. In other words, when the tank  12  abuts against the abutting portion  84 , the opening  21  provided in the base  11  is covered with the shutter  15 , and in addition, the opening  21  is covered with the bottom wall  12 B of the tank  12 . 
     Subsequently, after the rear wall  12 Rr of the tank  12  and the abutting portion  84  have abutted against each other, the tank  12  is slid further rearward along the slide guide  16 . In this case, the abutting portion  84  is pushed rearward by the tank  12 . Hence, as illustrated in  FIG. 9 , the link member  73  rotates about the rotation shaft  87 . In this case, the abutting portion  84  moves further rearward while abutting against the rear wall  12 Rr of the tank  12 . With the rotation of the rod portion  86 , the engagement portion  85  connected to the rod portion  86  moves obliquely upward and forward. The slider  72  is pushed forward by the engagement portion  85 , and is thus moved forward. The engagement portion  85  moves upward along the guide groove  83  of the slider  72 . The slider  72  is integral with the shutter  15 , and therefore, the shutter  15  slides forward along the guide rod  71  upon forward movement of the slider  72 . 
     As mentioned above, at a point in time when the tank  12  starts abutting against the abutting portion  84 , the entire opening  21  of the base  11  is covered with the tank  12 . Therefore, the shutter  15  starts to open after the tank  12  has been located over the entire opening  21 . As illustrated in  FIGS. 8 and 9 , when the tank  12  is slid further rearward, the shutter  15  moves further forward. In this case, the opening  21  is gradually opened. Then, when the engagement portion  85  of the link member  73  has reached an upper end of the guide groove  83  of the slider  72  as illustrated in  FIG. 1 , further rotation of the link member  73  is restricted, thus restricting further rearward movement of the tank  12 . In this case, as illustrated in  FIG. 2 , the tank  12  is positioned at the installation position B. Thus, the entire opening  21  is opened. When the tank  12  has reached the installation position B, the tank  12  is locked by the lock mechanism  18 . More specifically, the fixation rod  91  of the lock mechanism  18  is engaged with the front wall  12 F of the tank  12 , thus restricting forward movement of the tank  12 . 
     Thus, the tank  12  is installed at the installation position B. In this state, three-dimensional printing is started. 
     Next, a procedure for removing the tank  12  from the base  11  will be described. First, the knob  92  of the lock mechanism  18  is lifted to disengage the fixation rod  91  and the front wall  12 F of the tank  12  from each other. In this case, the link member  73  is pulled by the tension spring  74 . Upon disengagement of the fixation rod  91  and the front wall  12 F of the tank  12  from each other, the link member  73  rotates so that the abutting portion  84  moves forward. Thus, the tank  12  is pushed forward by the abutting portion  84 . In this case, the tank  12  slides forward until the rear wall  12 Rr of the tank  12  moves away from the abutting portion  84 . Upon rotation of the link member  73 , the slider  72  is pulled rearward by the engagement portion  85  of the link member  73 . The slider  72  is integral with the shutter  15 . Therefore, the slider  72  moves rearward, and in addition, the shutter  15  slides rearward along the guide rod  71 . Hence, the opening  21  of the base  11  is covered with the shutter  15 . When the abutting portion  84  has reached its foremost position (i.e., a position at which the rear wall  12 Rr of the tank  12  moves away from the abutting portion  84 ), the entire opening  21  is closed by the shutter  15 . 
     The position at which the rear wall  12 Rr of the tank  12  moves away from the abutting portion  84  corresponds to a position at which the rear wall  12 Rr of the tank  12  starts to abut against the abutting portion  84  at the time of installation of the tank  12 . As illustrated in  FIG. 6 , the position at which the tank  12  moves away from the abutting portion  84  is located rearward relative to the rear end of the opening  21 . Accordingly, the shutter  15  finishes closing before the tank  12  is not located over at least a portion of the opening  21 . After the tank  12  has moved away from the abutting portion  84 , the tank  12  is slid further forward. Then, the tank  12  is removed from the slide guide  16 . 
     As described above, according to the present preferred embodiment, the shutter  15  is opened while the tank  12  is located over the entire opening  21  of the base  11  as illustrated in  FIG. 1 . As illustrated in  FIG. 4 , the shutter  15  is closed while the tank  12  is not located over at least a portion of the opening  21 . Therefore, if the photo-curable resin  23  in liquid form has scattered from the tank  12 , the scattered photo-curable resin  23  is prevented from adhering to the optical device  13  through the opening  21 . Even if the photo-curable resin  23  scattered from the tank  12  has adhered to the shutter  15 , the shutter  15  is opened while the photo-curable resin  23  inside the tank  12  is irradiated with light. Hence, the photo-curable resin  23  that has adhered to the shutter  15  does not interfere with irradiation of the photo-curable resin  23  inside the tank  12  with light. 
     As illustrated in  FIG. 2 , the three-dimensional printing apparatus  1  preferably includes the slide guide  16  that guides sliding of tank  12  on the base  11 . The tank  12  is moved between the preparation position A and the installation position B by sliding the tank  12  on the base  11 . For example, suppose that an apparatus in which the shutter  15  is closed upon detection that the tank  12  is located over the opening  21  of the base  11  is used. In that case, when the tank  12  is placed on the base  11  from above, a gap might be provided between the tank  12  and the base  11 , with the shutter  15  opened. However, according to the present preferred embodiment, the tank  12  is moved to a position over the opening  21  by sliding the tank  12  on the base  11 , thus preventing a situation where a gap is provided between the tank  12  and the base  11 , with the shutter  15  opened. As a result, the photo-curable resin  23  scattered from the tank  12  is more reliably prevented from adhering to the optical device  13  through the opening  21 . 
     Note that in the present preferred embodiment, the user cannot install the tank  12  on the base  11  from above due to the existence of the slide guide  16 . Thus, the user is prevented from installing the tank  12  on the base  11  from above. 
     As illustrated in  FIG. 1 , the three-dimensional printing apparatus  1  preferably includes the interlocking device  17  that opens and closes the shutter  15  in conjunction with sliding of the tank  12 . The interlocking device  17  starts to open the shutter  15  after the tank  12  has been located over the entire opening  21  of the base  11 . In other words, the shutter  15  starts to open after the entire opening  21  of the base  11  has been covered with the tank  12 . The interlocking device  17  finishes closing the shutter  15  before the tank  12  is not located over at least a portion of the opening  21 . In other words, the shutter  15  finishes closing before a portion of the opening  21  is not covered with the tank  12 . Thus, the opening  21  of the base  11  is constantly closed with the tank  12  and/or the shutter  15 . Consequently, the photo-curable resin  23  scattered from the tank  12  is more reliably prevented from adhering to the optical device  13  through the opening  21 . 
     The interlocking device  17  according to the present preferred embodiment mechanically and automatically opens and closes the shutter  15  in response to sliding of the tank  12 . Therefore, a sensor for detection of the tank  12  is unnecessary. A motor by which the shutter  15  is driven is also unnecessary. Hence, cost for the three-dimensional printing apparatus  1  is reduced. For example, suppose that an apparatus in which a shutter driving motor is controlled on the basis of detection by a sensor is used. In that case, a control time delay occurs between the detection by the sensor and opening or closing of the shutter. Thus, in such an apparatus, the shutter  15  might remain open even though the opening  21  is not covered with the tank  12 . However, according to the present preferred embodiment, the above-mentioned control is unnecessary, and therefore, such a control time delay does not occur. Consequently, adhesion of the photo-curable resin  23  to the optical device  13  resulting from a control time delay is prevented. 
     The interlocking device  17  according to the present preferred embodiment opens and closes the shutter  15  in response to sliding of the tank  12  by using a simple and inexpensive structure. 
     As illustrated in  FIG. 2 , the three-dimensional printing apparatus  1  preferably includes the lock mechanism  18  that locks the tank  12  at the installation position B. Thus, even if a shock is applied to the tank  12  when a three-dimensional object is being formed, the tank  12  does not move out of the installation position B. Hence, the tank  12  is stably held at the installation position B. Via the link member  73 , the tank  12  constantly receives, from the tension spring  74 , a force exerted in a direction toward the preparation position A. However, the three-dimensional printing apparatus  1  includes the lock mechanism  18 , and therefore, the tank  12  is stably held at the installation position B even though the tank  12  constantly receives the force from the tension spring  74 . 
     The slide guide  16  preferably includes the left guide member  61  and the right guide member  62 . The left guide member  61  comes into sliding contact with the left wall  12 L of the tank  12 . The right guide member  62  comes into sliding contact with the right wall  12 R of the tank  12 . Thus, the tank  12  is slid on the base  11  by using a simple structure. The tank  12  is slid in a straight line. As a result, the tank  12  is easily installed at the installation position B. 
     For example, suppose that the photo-curable resin  23  in liquid form has adhered onto the plate portion  51  of the shutter  15 . In that case, when the shutter  15  moves forward, the photo-curable resin  23  might trickle down from the rear end of the plate portion  51 . The photo-curable resin  23  that has trickled down might adhere to the optical device  13 . However, according to the present preferred embodiment, the shutter  15  includes the protruded portion  52  that protrudes upward from the rear end of the plate portion  51  as illustrated in  FIG. 1 . Therefore, when the shutter  15  moves forward, the photo-curable resin  23  on the plate portion  51  is stopped by the protruded portion  52 . Hence, the photo-curable resin  23  on the plate portion  51  is prevented from trickling down from the plate portion  51 . Consequently, the photo-curable resin  23  is prevented from adhering to the optical device  13 . 
     As illustrated in  FIG. 3 , in the present preferred embodiment, the lower surface  12 B 1  of the bottom wall  12 B of the tank  12  is located higher than the lower surfaces of the other walls of the tank  12 , i.e., the lower surface of the front wall  12 F, the lower surface of the rear wall  12 Rr, the lower surface  12 L 1  of the left wall  12 L, and the lower surface  12 R 1  of the right wall  12 R. Thus, the bottom wall  12 B of the tank  12  does not come into contact with the base  11  when the tank  12  slides between the preparation position A and the installation position B. Therefore, the bottom wall  12 B of the tank  12  is prevented from being contaminated by the sliding operation of the tank  12 . A portion of the tank  12  which is to be located over the opening  21  of the base  11  is the bottom wall  12 B. The photo-curable resin  23  inside the tank  12  is irradiated with light through the bottom wall  12 B. According to the present preferred embodiment, the bottom wall  12 B is unlikely to be contaminated, thus efficiently irradiating the photo-curable resin  23  inside the tank  12  with light. 
     One preferred embodiment of the present invention has been described thus far. However, the foregoing preferred embodiment is merely illustrative, and the present invention may be embodied in various other forms. 
     As illustrated in  FIG. 1 , in the foregoing preferred embodiment, the tank  12  is placed over the opening  21  of the base  11  preferably by sliding the tank  12  from front to rear. However, the direction in which the tank  12  is slid is not limited to any particular direction. For example, the tank  12  may be placed over the opening  21  of the base  11  by sliding the tank  12  from left to right or from right to left. In that case, the slide guide  16  preferably extends in the right-left direction. 
     In the foregoing preferred embodiment, the slide guide  16  preferably includes the left guide member  61  and the right guide member  62 . Alternatively, the slide guide  16  may include only one of the left guide member  61  and the right guide member  62 . 
     As illustrated in  FIG. 3 , in the foregoing preferred embodiment, the lower surfaces of the front, rear, left and right walls of the tank  12 , i.e., the lower surface of the front wall  12 F, the lower surface of the rear wall  12 Rr, the lower surface  12 L 1  of the left wall  12 L, and the lower surface  12 R 1  of the right wall  12 R, are preferably located lower than the lower surface  12 B 1  of the bottom wall  12 B of the tank  12 . However, the lower surfaces of the walls of the tank  12  do not necessarily have to be located in this manner in order to prevent contact between the bottom wall  12 B of the tank  12  and the base  11 . For example, only the lower surfaces of the front and rear walls  12 F and  12 Rr of the tank  12  may be located lower than the lower surface  12 B 1  of the bottom wall  12 B. Alternatively, only the lower surface  12 L 1  of the left wall  12 L and the lower surface  12 R 1  of the right wall  12 R may be located lower than the lower surface  12 B 1  of the bottom wall  12 B. It is not necessary that the entire lower surface of the front wall  12 F, the entire lower surface of the rear wall  12 Rr, the entire lower surface  12 L 1  of the left wall  12 L, and the entire lower surface  12 R 1  of the right wall  12 R be located lower than the lower surface  12 B 1  of the bottom wall  12 B. For example, only lower surfaces of four corners of the tank  12  may be located lower than the lower surface  12 B 1  of the bottom wall  12 B. 
     As illustrated in  FIG. 1 , in the foregoing preferred embodiment, the tension spring  74  that pulls the shutter  15  rearward via the link member  73  and the slider  72  preferably is used as the elastic member that applies an elastic force to the shutter  15  so as to close the shutter  15 . However, the elastic member is not limited to the tension spring  74 . For example, a compression spring that pushes the shutter  15  rearward via the link member  73  and the slider  72  may be used as the elastic member. Alternatively, a torsion spring that applies a rotational force to the link member  73  with respect to the rotation shaft  87  may be used as the elastic member. 
     In the foregoing preferred embodiment, the abutting portion  84  of the link member  73  preferably is arranged to abut against the rear wall  12 Rr of the tank  12 . However, the abutting portion  84  does not necessarily have to abut against the rear wall  12 Rr. For example, the left wall  12 L of the tank  12  may be provided with a portion which extends leftward and against which the abutting portion  84  is to be abutted. This portion will be referred to as an “abutted portion”. The abutting portion  84  of the link member  73  may abut against the abutted portion. In that case, the abutting portion  84  and the abutted portion preferably abut against each other after the tank  12  has slid rearward and the entire opening  21  has been covered with the tank  12 . 
     In the foregoing preferred embodiment, the interlocking device  17  preferably opens and closes the shutter  15  mechanically in conjunction with sliding of the tank  12 . However, the interlocking device  17  may open and close the shutter  15  electrically in conjunction with the sliding operation of the tank  12 . The shutter  15  may be opened and closed by being controlled electrically. For example, the three-dimensional printing apparatus  1  may include an actuator such as a motor by which the shutter  15  is opened and closed, and a sensor that detects whether or not the tank  12  is installed at the installation position B. In that case, upon detection by the sensor that the tank  12  has been installed at the installation position B, the control device  35  may control the actuator, thus opening the shutter  15 . 
     The terms and expressions used herein are used for explanation purposes and should not be construed as being restrictive. It should be appreciated that the terms and expressions used herein do not eliminate any equivalents of features illustrated and mentioned herein, and allow various modifications falling within the claimed scope of the present invention. The present invention may be embodied in many different forms. The present disclosure is to be considered as providing examples of the principles of the present invention. These examples are described herein with the understanding that such examples are not intended to limit the present invention to preferred embodiments described herein and/or illustrated herein. Hence, the present invention is not limited to the preferred embodiments described herein. The present invention includes any and all preferred embodiments including equivalent elements, modifications, omissions, combinations, adaptations and/or alterations as would be appreciated by those skilled in the art on the basis of the present disclosure. The limitations in the claims are to be interpreted broadly based on the language included in the claims and not limited to examples described in the present specification or during the prosecution of the application. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.