Patent Publication Number: US-6216576-B1

Title: Plotters

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a plotter provided with a cutting head, and a cutter drive actuator is driven to lower a cutter, and the cutting head transfers in a horizontal direction relative to a paper to cut the paper on the cutting surface. 
     In a pen plotter that moves a pen vertically by means of a moving coil, in order to prevent a collision of the pen against a plotting, impressed voltage to the moving coil is controlled by a closed field system on the basis of a soft landing program, and. the soft landing of the pen is carried out against the plotting surface which has heretofore been known among those who are in the art. 
     Furthermore, in a plotter wherein a cutter is coupled with a solenoid, an open loop-type plotter has been known in which voltage sufficient to lower the cutter at a high speed is supplied to the solenoid, and after the cutter is collided with the cutter surface, the impressed voltage is lowered to switch to a predetermined cut voltage. 
     A mechanism of soft landing of the pen by the closed loop system had problems such as complicated control and numerous component parts as well as an expensive cost in case this mechanism is employed in a cutter mechanism. Moreover, a system of down controlling of the cutter by means of the open loop through the solenoid tends to cause a collision of the cutter against the paper surface at a high speed depending on the cutter mechanism on grounds of a fluctuation in the load of the cutter mechanism. For example, assuming that a fluctuation in the load of the cutter mechanism exists between 100 g to 450 g, the voltage that renders the down force sufficiently to the solenoid against the load of 500 g, but in this case, for the cutter mechanism with the load of 100 g or with the load of 200 g, the cutter down force becomes excessive, and as a result, the cutter tends to collide with the cutter receiving surface at a high speed, which causes wear and tear on the part of the cutter which was some of the problems. Furthermore, when the cutter is collided with the cutter receiving surface, a large vibrating force occurs on the machine of the plotter, which exerts an adverse influence on the shape of ink on the nozzle surface of an inkjet recording head, which was resulted in a deteriorated quality of picture in some cases. 
     The present invention has an object of providing a plotter that has solved the foregoing problems. 
     SUMMARY OF THE INVENTION 
     The present invention prevents the collision of the cutter against the surface of the paper at a high speed. When the cutter is lowered in order to cut the paper off, the controller initially minimizes the impressed voltage to the cutter drive actuator and impresses the voltage by stages thereafter. After the impressed voltage for lowering the cutter to the cutter drive actuator arrives at a maximum set voltage, the controller switches the voltage impressed to the cutter drive actuator to a predetermined voltage for cut. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an operation explanation drawing of the present invention. 
     FIG. 2 is a schematic cross sectional view of the plotter. 
     FIG. 3 is a block explanation view of the plotter. 
     FIG. 4 is a cross section explanation view showing a cutter mechanism of the plotter. 
     FIG. 5 is an A-A cross section. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION: 
     The mode of the embodiment of the present invention will be set forth in the following by referring to attached drawings. 
     Reference numeral  2  denotes a plotter of an inkjet type, and a Y rail  12  is mounted on a platen  4 . A carrier  6  is mounted on the Y rail  12  reciprocatingly along the Y rail  12  in a direction crossing a paper  10  on the platen  4 , namely, in a paper surface perpendicular direction in FIG. 2 by the drive of a carrier drive motor  8 . The paper  10  on the platen  4  is sandwiched between a drive roller  13  and a pressure roller  14 , and is carried in a direction of an arrow A in FIG. 2 on the platen  4  by an intermittent rotation of the drive roller  13  to be driven by a paper carrier motor  16 . A recording head  18  of inkjet type is mounted on the carrier  6 , and the. recording head  18  jets an ink droplet to the paper  10  on the platen  4  on the basis of a picture printing information to be supplied from a controller  20  of the plotter  2 , and performs a plotting on the paper  10 . Furthermore, a cutting head  22  is mounted on the carrier  6 , and the cutting head  22  is constructed in such a way that a predetermined position of the paper  10  that is already plotted is cut off by the transfer of the carrier  6  in a direction crossing the paper  10 , namely, Y axis direction on the cutting surface of a cutting mat  24  fixed to the platen  4 . A cylindrical cutter guide holder  26  is integrally fixed to the machine body of the cutting head  22  as shown in FIG. 4, and a cutter  28  is inserted and disposed liftably in the cutter.guide holder  26  in a perpendicular direction against the cutting mat  24 . The cutter  28  comprises a thin plate resin portion  28   a  formed by a resin molding and a blade portion  28   a  made of metal blade, and a part of the cutter  28  is slidably fitted with a friction into a guide hole  30  of rectangular cross section of an angular cylindrical guide portion  26   a  of the cutter guide holder  26 . On the upper part of the cutter guide holder  26 , the cylindrical holder portion  26   a ,is formed, and on the holder portion  26   b , a holder hole  32  of circular cross section is formed which is coaxial with the guide hole  30 , and a part of the cutter  28  is loosely disposed in the holder hole  32 . The cutter  28  is energized in a lifting direction with a lower end  36  of different level of the holder hole  32  as a fulcrum by a resilient force of a coil spring  34  compressed and disposed in the holder hole  32 , and an upper end of the cutter  28  is disposed in contact with the lower surface of an arm  40  connected to the cutter drive actuator  38  such as the solenoid and the like. A convex stripe  42  is formed on the resin portion  28   a  of the cutter  28  along its longitudinal direction, and the convex stripe  42  is fitted to a concave groove of the guide hole  30 , and thus, the cutter  28  is guided accurately along the guide hole  30 . The cutter resin portion  28   a  is curved, and a friction arises between the guide hole  30  and the cutter resin portion  28   a  by the curve. This friction force constitutes a load against the descendance of the cutter  28  by the cutter drive actuator  38 . When the voltage is impressed to the cutter drive actuator  38  by instruction from the controller  20 , and the coil is energized, an output shaft  44  is attracted to descend, and the arm is lowered. With the descendance, the cutter  28  is forced to lower by resisting the resilient force of the spring  34 , and the blade  28   a  of the tip of the cutter  28  comes to contact the cutting mat  24  under pressure with a predetermined pressure. In the pressure contact condition, when the carrier  6  transfers in the Y-axis direction along the Y rail  12 , the paper  10  on the cutting mat  24  is cut off by the cutter  2 . When the supply of voltage to the cutter drive actuator  38  is released, the cutter  28  rises by the resilient force of the coil spring  34 ,and lifts by a predetermined distance from the cutting mat  24 . The controller  20  prepares a plotter drive signal on the basis of a picture signal from a host computer  48  connected by means of an interface  46 , and a picture data is supplied to the recording head  18 , and controls the motors  8 ,  16  and the actuator  38 . 
     In the following, the down control of the cutter by the controller will be described by referring to FIG.  1 . 
     FIG. 1 shows an example where the descending force of the cutter drive actuator  38  is 500 g(operation rate 100%) and the load of the cutter mechanism is set at from 100 g to 450 g. The load of the cutter mechanism means concretely and primarily the friction force between the cutter  28  and the cutter guide holder  26 , and assumption is based on a fluctuation between 100 g and 450 g by the cutter mechanism of the plotter. The voltage for cutter down to be supplied to the cutter drive actuator  38  by the instruction from the controller  20  is set at 5 stages as shown in the following. 
     First stage: voltage (1st voltage) corresponding to cutter down force of 100 g 
     Second stage: voltage (2nd voltage) corresponding to cutter down force of 200 g 
     Third stage: voltage (3rd voltage) corresponding to cutter down force of 300 g 
     Fourth stage: voltage (4th voltage) corresponding to cutter down force of 400 g 
     Fifth stage: voltage (5th voltage) corresponding to cutter down force of 500 g 
     The voltage impressing time t1 of each stage is set at a time required to down the counter  28  from the lifting position from the standpoint of mechanism. 
     The voltage signal of 5 stages is transmitted from the first stage to the fifth stage sequentially to the cutter drive actuator  38  at the cutter down time by the control of the controller  20 .In the case where the cutter mechanism of the plotter is load 100 g, the cutter  28  downs with the [1st voltage]of the first stage. Furthermore, in the case where the cutter mechanism of load 250 g, the cutter ( 28 ) downs with [3rd voltage] of the third stage. Moreover, in the case of the cutter mechanism of load 450 g, the cutter  28  downs with[5th voltage] of the fifth stage. 
     The controller  20  switches to the cutter voltage applying signal for cutting the paper at a time of elapse of 5t 1 hours upon impression of the voltage for the descendance of the cutter,and sets the pressure of the cutter  28  against the cutting surface to a predetermined paper cut pressure. And, the cutting head  22  transfers in the Y axis direction along the cutting surface by the transfer of the carrier  6 , and the cut operation of the paper  10  is carried out. 
     The present invention has been constructed as explained in the foregoing, and therefore, has an effect of preventing the collision of the cutter with the surface of the paper at a high speed by a simple construction.