JPH11311863A - Plotting device and method for attaching balance weight - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent forced vibration caused by the centrifugal unbalance at the time of rotating. SOLUTION: One balance weight 7 is disposed at both end surfaces of a recording drum 1 rotated and driven. The balance weight 7 consists of a magnet, and is attracted by magnetic attraction to the end surface of the recording drum 1. Each balance weight 7 is arranged by having a specified attaching angle at a specified position in a radial direction so as to negate unbalancing caused by the centrifugal force of a printing plate 2 and a moving clamp 5 or the like. The position of the balance weight 7 is adjusted each time the size and mass of the printing plate 2 are changed, so that the forced vibration of the recording drum 1 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawing apparatus for drawing on a photosensitive material such as a printing plate mounted on a drum, and a method of attaching a counterweight for adjusting a counterweight when the drum rotates. .

[0002]

2. Description of the Related Art A drawing apparatus is used to perform drawing by irradiating various photosensitive materials with light. In a drum type drawing apparatus, a photosensitive material is mounted on a recording drum rotatable in a main scanning direction, and a recording head equipped with a laser diode or the like moves in a sub-scanning direction parallel to a rotation axis of the recording drum, so that the photosensitive material is moved. Draw on.

FIG. 10 is a schematic perspective view of a recording drum of a conventional drawing apparatus. The recording drum 1 in FIG. 10 is configured such that a printing plate 2 made of aluminum as a photosensitive material can be mounted. A fixed clamp 4 for fixing one end of the printing plate 2 and a movable clamp 5 for fixing the other end of the printing plate 2 are provided on the outer peripheral surface of the recording drum 1. The movable clamp 5 is formed to be movable on the outer peripheral surface of the recording drum 1 according to the size of the printing plate 2. The recording drum 1 on which the printing plate 2 is mounted is driven to rotate at a relatively low speed about the rotation shaft 3, and drawing is performed on the surface of the printing plate 2.

[0004]

Recently, there has been a demand for improving the efficiency of drawing processing on the printing plate 2. Therefore, it has been studied to perform a drawing operation by rotating the recording drum 1 on which the printing plate 2 is attached at a high speed.

However, the printing plate 2 made of aluminum is heavier than a film material or the like, and is mounted unevenly on a part of the outer peripheral surface of the recording drum 1. For this reason, when the recording drum 1 is rotated at a high speed, an unbalanced force is generated on the rotating shaft 3 of the recording drum 1 due to the centrifugal force of the printing plate 2. A fixed clamp 4 and a movable clamp 5 are provided on the outer peripheral surface of the recording drum 1, and the fixed clamp 4 and the movable clamp 5 each have a considerable mass. For this reason, when the recording drum 1 is rotated at a high speed similarly to the plate 2, an unbalanced force is generated by each centrifugal force.

[0006] When an unbalanced force is generated on the recording drum 1 by the printing plate 2, the fixed clamp 4 and the moving clamp 5, when the recording drum 1 rotates at a high speed, a forced vibration is generated in a bearing supporting the rotating shaft 3 of the recording drum 1. May cause a failure. The generation of such an unbalanced force does not cause a problem when the recording drum 1 is rotated at a low speed as in the related art, but becomes a serious problem as the recording drum 1 is rotated at a high speed for improving the efficiency of the drawing operation. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a drawing apparatus and a method of attaching a counterweight which do not generate forced vibration due to unbalance of centrifugal force during rotation.

[0008]

Means for Solving the Problems and Effects of the Invention (1)
A drawing apparatus according to a first invention is a drawing apparatus that irradiates a photosensitive material with light to perform drawing, and has a rotation axis and a cylindrical drum on which a photosensitive material is mounted on an outer peripheral surface. A driving means for driving the drum to rotate around the rotation axis, a fixing member provided on the outer peripheral surface of the drum and fixing the photosensitive material to the outer peripheral surface of the drum, A pair of counterweights are provided one at each end so as to be movable and fixable in the radial direction.

In the drawing apparatus according to the first aspect, the photosensitive material is attached to the outer peripheral surface of the cylindrical drum by the fixing member, and is driven to rotate by the driving means. Then, drawing is performed by irradiating the photosensitive material rotating with the drum with light. The fixing member and the photosensitive material provided on the outer peripheral surface of the cylindrical drum generate centrifugal forces in different directions when the drum rotates. Therefore, an unbalanced force due to the centrifugal force of the photosensitive material and the fixing member acts on the rotating shaft of the drum.

On the other hand, a pair of counterweights are provided at both ends of the drum. Each counterweight produces a centrifugal force due to the rotation of the drum. The counterweight is arranged so that the combined force of the centrifugal force of the pair of counterweights balances the unbalance force generated by the photosensitive material and the fixing member.
Thus, even when the drum is rotated, an unbalanced force is prevented from being generated on the rotating shaft, and a failure due to forced vibration occurring on the rotating shaft of the drum can be prevented. Further, by providing a pair of counterweights provided on both ends of the drum so as to be movable and fixed in the circumferential and radial directions, even when the weight or size of the photosensitive material changes, each counterweight can be used. Is changed in the radial direction and the circumferential direction to cancel the unbalance force generated by the photosensitive material and the fixing member.

(2) Second invention A drawing apparatus according to a second invention is the drawing apparatus according to the first invention, wherein a pair of counterweights is provided on each end face of the drum. It is.

In this case, by providing one counterweight on each end face of the drum so as to be movable and fixed in the circumferential direction and the radial direction, even if the weight or size of the photosensitive material changes, each counterweight can be provided. By changing the position of the weight in the radial direction and the circumferential direction, the unbalance force generated by the photosensitive material and the fixing member can be canceled.

(3) Third invention A drawing apparatus according to a third invention is the drawing apparatus according to the second invention, wherein each of the pair of counterweights is formed of a magnet which can be attracted to both end surfaces of the drum. It becomes.

By forming the counterweight from a magnet, the counterweight can be easily moved and fixed on both end faces of the drum without using a special structure.

(4) Fourth invention A drawing apparatus according to a fourth invention is the drawing apparatus according to the third invention, wherein the configuration of the drum is based on information on a photosensitive material and a fixing member mounted on the drum. Position calculating means for calculating the position of the pair of counterweights to cancel the unbalance force generated by the centrifugal force of the fixed member and the photosensitive material during rotation; and moving means for moving the pair of counterweights to the position calculated by the position calculating means. It is provided with.

In this case, since the position calculating means calculates the position of the counterweight based on the information on the photosensitive material and the fixing member, even if the type of the photosensitive material is different, the optimum position of the counterweight can be calculated. Thereby, the moving means can move the pair of counterweights. Thereby, regardless of the type of the photosensitive material, the recording drum can be driven to rotate at a high speed without forcibly vibrating the rotating shaft of the recording drum.

(5) Fifth invention The drawing apparatus according to the fifth invention is the drawing apparatus according to the fourth invention, wherein the position calculating means is arranged such that the position calculating means is arranged so that the rotation axis of each counterweight on each end face of the drum is centered. The moving means engages with each counterweight provided on each end face of the drum and moves along the radial direction around the rotation axis of the drum. The counterweight is moved by the engaging means to the possible engaging means and the radial position calculated by the position calculating means, and the drum is rotated by the driving means while the counterweight is engaged with the engaging means. Moving means for moving the counterweight to the circumferential position calculated by the position calculating means.

In this case, the engaging means defines the radial position of the counterweight by engaging with and moving in the radial direction of each counterweight. Further, the driving means rotates the drum in a state where the engaging means is engaged with the counterweight, thereby defining the circumferential position of the counterweight, whereby the counterweight moves to a predetermined position on the end face of the drum. Thus, the unbalance force generated when the drum rotates can be canceled.

(6) Sixth Invention The drawing apparatus according to the sixth invention is the drawing apparatus according to the fifth invention, further comprising storage means for storing the position of each counterweight on the end surface of the drum. The control means moves the engagement means in the radial direction around the rotation axis to a position at which the engagement means engages with the counterweight, based on the position of the counterweight stored in the storage means, and drives the control means. The drum is rotated by the means.

In this case, the storage means stores the positions of the pair of counterweights on the end face of the drum. For this reason, the control means retrieves the position information of the counterweight from the storage means and refers to the position to move the engaging means in the radial direction and rotate the drum, thereby easily engaging the engaging means with the counterweight. Can be combined.

(7) Seventh Invention The drawing apparatus according to the seventh invention is the drawing apparatus according to any one of the fourth to sixth inventions, further comprising an input means for inputting information relating to a photosensitive material. The position calculating means calculates the position of the pair of counterweights based on information input from the input means.

Information on various photosensitive materials is input using input means. Then, the position calculating means calculates the position of the pair of counterweights based on the information input from the input means. Thus, when the type of the photosensitive material is different, by inputting the information, the pair of counterweights can be arranged at the optimum positions regardless of the type of the photosensitive material.

(8) Eighth Invention In the drawing apparatus according to the eighth invention, in the configuration of the drawing apparatus according to any one of the fourth to seventh inventions, the position calculating means may include:
Based on the information on the photosensitive material and the fixed member, the product of the position vector of the center of gravity of the photosensitive material with respect to the rotation center of the drum and the mass of the photosensitive material, and the position vector of the center of gravity of the fixed member with reference to the rotation center of the drum By calculating the unbalance amount by synthesizing the product of the mass of the fixing member and the mass of the fixing member, by synthesizing the product of the position vector of the pair of counterweights based on the rotation center of the drum and the mass of the corresponding counterweight respectively. The position of a pair of counterweights is calculated so that the resultant vector is balanced with the unbalance amount.

Thus, the positions of the pair of counterweights can be easily calculated so as to be balanced with the unbalance amount caused by the rotation of the fixing member and the photosensitive material.

(9) Ninth Invention A method for mounting a counterweight according to a ninth invention is to draw by irradiating light to the photosensitive material while rotating a cylindrical drum on which the photosensitive material is mounted by a fixing member. A method of attaching a counterweight to the drum to counterbalance the imbalance caused by the centrifugal force of the photosensitive material and the fixing member during rotation of the drum. Calculating the mounting position of a pair of counterweights, one for each end of the drum, so as to generate a large centrifugal force;
Attaching a pair of counterweights to the calculated attachment position.

In the method for mounting a counterweight according to the ninth aspect, a pair of counterweights can be mounted on both ends of the drum so as to cancel the unbalance force generated by the fixing member and the photosensitive material. Thus, drawing can be performed by rotating the drum at high speed without causing forced vibration on the rotation axis of the drum.

(10) Tenth invention A method for mounting a counterweight according to the tenth invention is described in the ninth invention.
In the method of attaching a counterweight according to the invention, a pair of counterweights is provided on each end face of the drum.

In this case, a pair of counterweights can be attached to both end faces of the drum one by one so as to cancel the unbalance force generated by the fixing member and the photosensitive material.
Thus, drawing can be performed by rotating the drum at high speed without causing forced vibration on the rotation axis of the drum.

(11) Eleventh Invention The method for attaching a counterweight according to the eleventh invention is described in ninth invention.
Alternatively, in the method for mounting a counterweight according to the tenth aspect, the step of calculating the mounting position of the counterweight includes:
Based on the information on the photosensitive material and the fixed member, the product of the position vector of the center of gravity of the photosensitive material with respect to the rotation center of the drum and the mass of the photosensitive material, and the position vector of the center of gravity of the fixed member with reference to the rotation center of the drum Determining the amount of unbalance by combining the product of the weight of the counterweight and the mass of the fixed member, and combining the product of the position vectors of the pair of counterweights with respect to the rotation center of the drum and the corresponding weights of the counterweights. Calculating the position of the pair of counterweights so that the resultant vector obtained by the above-mentioned operation is balanced with the unbalance amount.

In this way, the unbalance amount of the photosensitive material and the fixing member is obtained for each of the drawing processes of various photosensitive materials, and the position of a pair of balance weights is calculated so as to be balanced with the unbalance amount. Then, based on the calculated position of the counterweight, the counterweight is attached to both end surfaces of the drum, whereby it is possible to prevent forced vibration from occurring on the rotating shaft of the recording drum.

[0031]

FIG. 1 is a schematic diagram of a drawing apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic view of a main part of the drawing apparatus of FIG.

Referring to FIG. 1, the drawing apparatus includes a cylindrical recording drum 1. The recording drum 1 is rotatably supported on a rotating shaft 3 whose both ends are supported by bearings. A pair of pulleys 9 and 11 and a belt 1 are provided at one end of the rotating shaft 3.
0 and a drive mechanism composed of a motor 12 are connected. The drive mechanism controls the rotation of the motor 12 by a pair of pulleys 9,
The recording drum 1 is driven to rotate by transmitting it to the rotating shaft 3 via the belt 11 and 11.

In FIG. 2, a recording head 120 is provided at a position facing the outer peripheral surface of the recording drum 1. The recording head 120 includes a plurality of laser diodes 100. The recording head 120 is movably attached to the guide 130, and moves in the sub-scanning direction B in synchronization with the rotation of the recording drum 1.

The current position of the printing plate 2 in the main scanning direction A is detected based on a detection signal output from a rotation angle detector 13 attached to the rotation shaft 3 of the recording drum 1. The current position of the recording head 120 in the sub-scanning direction B is detected based on a detection signal output from the linear encoder 150.

The plurality of laser diodes 100 of the recording head 120 are driven by a laser diode drive circuit section 160. The laser diode drive circuit section 160 includes a plurality of laser diode drive circuits 110 corresponding to the plurality of laser diodes 100 of the recording head 120.

The image signal generating circuit 180 generates a serial image signal VDS. Serial / parallel converter 1
Reference numeral 70 designates the serial image signal VDS generated by the image signal generation circuit 180 as a parallel image signal
n, and supplies the image signals VD1 to VDn to the plurality of laser diode driving circuits 110 of the laser diode driving circuit unit 160, respectively. Thus, each laser diode 100 of the recording head 120 is driven by the corresponding laser diode drive circuit 110, and irradiates the plate 2 with laser light.

FIG. 3 is a perspective view of the recording drum, and FIG. 4 is a side view of the recording drum. On the outer peripheral surface of the recording drum 1, a fixed clamp 4 and a movable clamp 5 for attaching the printing plate 2 are arranged. The fixed clamp 4 is fixed to the outer peripheral surface of the recording drum 1, and the movable clamp 5 is formed so as to be movable on the outer peripheral surface of the recording drum 1 according to the size of the printing plate 2. A fixed clamp balance member 8 is attached to the outer peripheral surface of the recording drum 1 opposite to the fixed clamp 4. The fixed clamp balance member 8 is formed to have substantially the same weight as the fixed clamp 4. Thus, when the recording drum 1 rotates, a centrifugal force that balances with the centrifugal force of the fixed clamp 4 is generated, thereby preventing an unbalanced force from being generated.

One counterweight 7 is disposed on each of both end surfaces 1a of the recording drum 1. The counterweight 7 is made of a permanent magnet, and is attracted to the end surface 1a of the metal recording drum 1 by magnetic force. The surface of the counterweight 7 is formed with a hole 7a into which the engaging pin 17 of the weight position adjusting unit 15 is inserted. The counterweight 7 is disposed at a position on the end face 1a where the centrifugal force of each member acting on the rotating shaft 3 of the recording drum 1 can rotate in a balanced state. The operation of arranging the counterweight 7 will be described later in detail.

A pair of weight position adjusters 15 are arranged to face both end surfaces 1a of the recording drum 1. FIG. 5 is a side view (a) and a front view (b) of the weight position adjusting unit.
1 and 5, the weight position adjusting unit 15 has an engaging pin 17 that can move forward and backward with respect to the end surface 1 a of the recording drum 1. The engaging pin 17 is provided with a counterweight 7 by a cylinder 16.
Is moved forward and backward. The cylinder 16 has a support member 18
It is supported by. The support member 18 engages with a feed screw 19 extending in parallel with the end face 1a of the recording drum 1, and
With the rotation of No. 9, the recording drum 1 reciprocates in the direction C parallel to the end surface 1a. The feed screw 19 is formed of a ball screw, and both ends thereof are supported by bearings 20. A motor 21 is connected to one end of the feed screw 19. The motor 21 can rotate forward and reverse, and the rotation of the motor 21 rotates the feed screw 19, whereby the cylinder 16 and the engaging pin 17 supported by the support member 18 are parallel to the end surface 1 a of the recording drum 1. It reciprocates in the direction C.

The control unit 23 receives the detection signal from the rotation angle detector 13 and controls the operations of the motor 12 for driving the recording drum 1 to rotate and the pair of weight position adjustment units 15.

The input section 24 inputs information such as the size and weight of the printing plate 2. In addition, the position calculation unit 25 includes the input unit 24
The arrangement position of the counterweight 7 is calculated on the basis of the physical characteristic data of the printing plate 2 input from. Further, the storage unit 26
Stores the arrangement position of the counterweight 7.

In this embodiment, the recording drum 1 corresponds to the drum of the present invention, the driving mechanism corresponds to the driving means, the movable clamp 5 corresponds to the fixed member, and the counterweight 7 corresponds to the counterweight. Further, the position calculation unit 25 corresponds to a position calculation unit, the control unit 23 corresponds to a control unit, the weight position adjustment unit 15 corresponds to an engagement unit, the storage unit 26 corresponds to a storage unit, and the input unit 24 Corresponds to the input means.

Next, the operation of adjusting the position of the counterweight 7 in the drawing apparatus will be described. The position adjustment operation of the counterweight 7 is performed by a control process of the unbalance force, a counterweight arrangement position calculation process, and a counterweight position adjustment process based on the control of the control unit 23.

When drawing a new printing plate having a different size and weight from the pre-processed printing plate, information such as the size and weight of the printing plate is input from the input unit 24 in advance. After that, the following steps are performed.

(1) Calculation Step of Unbalance Force When the recording drum 1 rotates at a high speed, a fixed clamp 4, a movable clamp 5, and a printing plate 2 disposed on the outer peripheral surface of the recording drum 1.
In the balance member 8 for fixed clamp, a centrifugal force is generated from the position of the center of gravity toward the outside of the recording drum 1 in the radial direction. Usually, these members are not arranged in consideration of the balance of each centrifugal force. For this reason, an unbalanced force is generated due to a variation in the acting direction and the magnitude of the centrifugal force of each member. The direction of action of this unbalance force changes periodically as the recording drum 1 rotates. For this reason, forced vibration is applied to the rotating shaft 3 of the recording drum 1, which causes a failure.

Therefore, the position calculating unit 25 calculates the unbalance force generated on the recording drum 1 based on the input information on the size and mass of the printing plate 2 in addition to the information on the position and mass of each member described above. Is calculated as follows.

FIG. 6 is a schematic diagram (a) showing the unbalance force due to the centrifugal force of the moving clamp of the recording drum and the printing plate, and a vector diagram (b) of the unbalance force. In the following description, the expression of the centrifugal force, the unbalance force, and the balance force for canceling the unbalance force generated in the recording drum 1 includes a term of the rotational angular velocity which is originally common. Therefore,
In the following, the common rotation angular velocity term will be omitted. Thus, the unbalanced force and the balance force from which the term of the rotational angular velocity is omitted are referred to as the unbalance amount D and the balance amount B, respectively.

The fixed clamp 4 and the fixed clamp balance member 8 are arranged such that their centrifugal forces are balanced. Therefore, it is excluded from the calculation target of the following unbalance amount D.

Further, in the following description, the rotation axis 3 is set as the center of rotation, and the direction passing through the center of rotation and the fixed clamp 4 is defined as Y.
An XY coordinate system having an X-axis in a direction orthogonal to the axis and the Y-axis is fixed on the end surface of the recording drum 1. The circumferential direction counterclockwise from the Y axis is defined as the θ direction.

As shown in FIG. 6A, when the recording drum 1 rotates at a high speed, a centrifugal force Fg is generated at the center of gravity G of the printing plate 2. The angle of the centrifugal force Fg of the printing plate 2 in the circumferential direction is defined as θg.

In the moving clamp 5, a centrifugal force Fc is generated at the center of gravity of the moving clamp 5. The angle of the centrifugal force Fc of the moving clamp 5 in the circumferential direction is θc.

Therefore, the combined amount of the centrifugal force Fg of the printing plate 2 and the centrifugal force Fc of the moving clamp 5 acts on the rotating shaft 3 of the recording drum 1 as an unbalanced amount D.

In FIG. 6B, if the component of the unbalance amount D in the X-axis direction is Dx and the component in the Y-axis direction is Dy, D
x and Dy are obtained from the centrifugal forces Fg and Fc by the following equations.

[0054]

(Equation 1)

Note that Fgx, Fg in the equations (1) and (2)
y indicates the X-axis direction component and the Y-axis direction component of the centrifugal force Fg, respectively, and Fcx and Fcy respectively indicate the X-axis component of the centrifugal force Fc.
An axial component and a Y-axis component are shown.

Further, assuming that the angle in the circumferential direction at which the unbalance amount D acts is θ _D , the magnitude of the unbalance amount D and the angle θ _{D in the} circumferential direction are expressed by the following equations.

[0057]

(Equation 2)

[0058]

(Equation 3)

As a result, the magnitude of the unbalance amount D and the action direction are obtained.

(2) Calculation Step of Arrangement Position of Balance Weight Once the magnitude of the unbalance amount D and the action direction are obtained,
The position calculation unit 25 calculates a balance amount B that cancels out the unbalance amount D as follows.

FIG. 7 is a schematic diagram showing the balancing force of the recording drum due to the centrifugal force of the balancing weight. In FIG. 7, the balance B is set to be equal in magnitude to the unbalance D and to have the direction of action opposite. The balance amount B is the centrifugal force F of the two balance weights 7 at both end surfaces of the recording drum 1.
w.

The mass of each counterweight 7 is predetermined. Assuming that the mass of each counterweight 7 is Mw and the distance from the center of the rotating shaft 3 to the center of gravity of each counterweight 7 is Rw, the centrifugal force Fw of each counterweight 7 is

[0063]

(Equation 4)

Is obtained. Therefore, the combined amount of the centrifugal force Fw by the two balance weights 7 arranged on both end surfaces of the recording drum 1, that is, the magnitude of the balance amount B is:

[0065]

(Equation 5)

Is obtained. What is necessary is that the magnitude of the balance B is equal to the magnitude of the unbalance D obtained earlier. Therefore, when the mass of the counterweight 7 is constant, the radial distance Rw of the counterweight 7 that satisfies the relationship of Expression (7) may be obtained by the following equation.

[0067]

(Equation 6)

The circumferential angle (attachment angle) θ _w of the counterweight 7 can be obtained by the following equation.

[0069]

(Equation 7)

(3) Step of Adjusting Position of Balance Weight By the steps (1) and (2), two balance weights 7
Radial position Rw and circumferential mounting angle θ
_{When w} is determined, the counterweight 7 is moved to the determined radial and circumferential positions.

In FIG. 1, a counterweight 7 on the end face of the recording drum 1 at the end of the previous drawing process is stored in the storage unit 26.
Radial position Rw and circumferential mounting angle θ _w
I remember. Therefore, the control unit 23 drives the motor 12 based on the current rotation position information of the recording drum 1 and the arrangement position information of the counterweight 7 from the rotation angle detector 13 to rotate the recording drum 1 to rotate the counterweight 7. The vertical position of the hole 7a is made to coincide with the vertical position of the engaging pin 17 of the weight position adjusting unit 15. Further, the motor 21 is driven, the feed screw 19 is rotated, and the support member 18 is moved in the radial direction of the end surface 1a of the recording drum 1, and the counterweight 7
The horizontal position of the hole 7a and the engaging pin 17 is made to coincide.

In this state, the engaging pin 17 is extended, and the engaging pin 17 is inserted into the hole 7a of the counterweight 7. Then, by driving the feed screw 19 and moving the engaging pin 17 in the radial direction, the counterweight 7 is moved to the radial position Rw obtained in the step (2).

Further, with the engagement pin 17 inserted into the hole 7a of the counterweight 7, the recording drum 1 is rotated to attach the counterweight 7 in the circumferential direction obtained in the step (2). relatively moving the position of the angle theta _w. Thereafter, the engaging pin 17 is retracted. Thereby, the position adjustment of the counterweight 7 is completed. The position adjustment of the counterweight 7 is performed simultaneously on both end surfaces 1a of the recording drum 1.

Through the above steps, the four counterweights 7 are arranged so as to balance the centrifugal force of the printing plate 2 and the moving clamp 5. Accordingly, the recording drum 1 can be rotated at high speed without forcible vibration occurring in the bearing of the rotating shaft 3.

The end surface 1a of the recording drum 1 and the suction surface of the counterweight 7 may be provided not only with a flat surface but also with concave and convex grooves extending in the circumferential direction around the rotating shaft 3. In this case, the concave and convex grooves on the suction surface of the end face 1a and the counterweight 7 are engaged with each other, thereby preventing the counterweight 7 from moving or detaching in the radial direction due to the high speed rotation of the recording drum 1. be able to.

The drawing apparatus according to the above-described embodiment is configured to adjust the position of the counterweight 7 using the weight position adjusting unit 15. The counterweight 7 may be directly mounted on the recording drum 1 at a position on both end faces thereof. In this case, the weight position adjusting unit 15 becomes unnecessary, and the configuration of the drawing apparatus is simplified.

Further, the counterweight 7 is not limited to a magnet, but may have a structure to be mechanically attached to the end face of the recording drum 1.

FIGS. 8 and 9 are views showing another example of a method of attaching a counterweight, in which (a) is a front view and (b) is a side view.

In the example of FIG. 8, disk-shaped auxiliary members 62 are fixed to both ends of the rotating shaft 3 of the recording drum 1, respectively. One counterweight 7 is provided on one surface of each auxiliary member 62 so as to be movable and fixed in the circumferential and radial directions. The auxiliary member 62 is made of metal. Each counterweight 7 is made of a permanent magnet and is attracted to the auxiliary member 62 by magnetic force.

Each counterweight 7 is formed with a hole 7a into which the engaging pin 17 of the weight position adjusting section 15 in FIG. 1 can be inserted. When the engaging pin 17 is moved in the radial direction around the rotating shaft 3 in a state where the engaging pin 17 is inserted into the hole 7a of the counterweight 7, the counterweight 7 moves on the auxiliary member 62 in the radial direction. . When the auxiliary member 62 rotates together with the recording drum 1 in this state, the counterweight 7 moves on the auxiliary member 62 in the circumferential direction around the rotation shaft 3. After the position adjustment, the counterweight 7 is fixed to the auxiliary member 62 by a magnetic force.

In the example of FIG. 9, one arm member 65 is provided at each end of the rotating shaft 3 of the recording drum 1.
Is mounted so as to be rotatable and fixable with respect to.
The arm member 65 includes a cylindrical mounting portion 65a fitted to the rotating shaft 3, a long arm 65b, and a short arm 65c.
It consists of. The counterweight 7 is movably and fixedly attached to the long arm 65b.
A balancer 66 is provided at an end of the point c. Balancer 6
6 keeps the balance of the arm member 65 when there is no counterweight 7. The mounting portion 65a of the arm member 65 is made of a permanent magnet, and is attracted to the metal rotating shaft 3 by magnetic force. The long arm 65b of the arm member 65 is made of metal. Each counterweight 7 is made of a permanent magnet,
5 is attracted to the long arm 65b by magnetic force.

Each counterweight 7 is formed with a hole 7a into which the engaging pin 17 of the weight position adjusting section 15 in FIG. 1 can be inserted. When the engaging pin 17 is moved in the radial direction around the rotation shaft 3 in a state where the engaging pin 17 is inserted into the hole 7a of the counterweight 7, the counterweight 7 has a radius on the long arm 65b of the arm member 65. Move in the direction. When the rotating shaft 3 rotates together with the recording drum 1 in this state, the arm member 65 rotates with respect to the rotating shaft 3, and the counterweight 7 attached to the arm member 65 moves in the circumferential direction with respect to the recording drum 1. Moving. After the position adjustment, the arm member 65 is fixed to the rotating shaft 3 by a magnetic force.

The mounting portion 65a of the arm member 65
Instead of using a permanent magnet, the arm member 65 may be rotatably and fixedly mounted on the rotating shaft 3 by providing a ratchet structure in the mounting portion 65a of the arm member 65.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a drawing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a main part of the drawing apparatus of FIG. 1;

FIG. 3 is a perspective view of a recording drum.

FIG. 4 is a side view of the recording drum of FIG. 2;

FIGS. 5A and 5B are a side view and a front view of a weight position adjusting unit of the drawing apparatus. FIGS.

FIGS. 6A and 6B are a schematic diagram showing an unbalance force due to a centrifugal force of a moving clamp of a recording drum and a printing plate, and a vector diagram of an unbalance force, respectively, FIG.

FIG. 7 is a schematic diagram showing the balancing force of the recording drum due to the centrifugal force of the balancing weight.

FIG. 8 is a front view and a side view showing another example of a method of attaching a counterweight.

FIG. 9 is a front view and a side view showing another example of a method of attaching a counterweight.

FIG. 10 is a perspective view of a recording drum of a conventional drawing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording drum 2 Printing plate 3 Rotating shaft 4 Fixed clamp 5 Moving clamp 7 Counterweight 7a hole 8 Balance member for fixed clamp 13 Rotation angle detector 15 Weight position adjustment unit 17 Engagement pin 23 Control unit 24 Input unit 25 Position calculation unit 26 storage unit 62 auxiliary member 65 arm member

Continuation of the front page (72) Inventor Toru Kawada 4-chome Tenjin, Kitamachi 1-chome, Horikawa-dori Teranouchi, Kamigyo-ku, Kyoto Dainippon Screen Manufacturing Co., Ltd.

Claims (11)

[Claims] 1. A drawing apparatus for irradiating a photosensitive material with light to perform drawing, comprising: a cylindrical drum having a rotating shaft, the photosensitive material being mounted on an outer peripheral surface; Driving means for driving the drum to rotate; a fixing member provided on the outer peripheral surface of the drum for fixing the photosensitive material to the outer peripheral surface of the drum; and a circumferential direction and a radius around the rotation axis of the drum. A drawing device comprising: a pair of counterweights, one at each end, which is movable and fixed along a direction. 2. The apparatus according to claim 1, wherein the pair of counterweights are provided one at each end surface of the drum.
The drawing apparatus described in the above. 3. The drawing apparatus according to claim 2, wherein each of said pair of counterweights comprises a magnet which can be attracted to both end surfaces of said drum. 4. A pair of balances for canceling an unbalance force generated by a centrifugal force of the fixing member and the photosensitive material when the drum rotates, based on information on the photosensitive material and the fixing member mounted on the drum. The drawing apparatus according to claim 3, further comprising: a position calculating unit that calculates a position of the weight; and a moving unit that moves the pair of counterweights to the position calculated by the position calculating unit. 5. The position calculating means calculates a radial position and a circumferential position of each counterweight on each end face of the drum centering on the rotation axis, and the moving means includes Engaging means which engages with each counterweight provided on each end face and is movable along a radial direction about the rotation axis of the drum; and the radial position calculated by the position calculating means. The counterweight is moved by the engaging means, and the drum is rotated by the driving means in a state where the counterweight is engaged with the engaging means to calculate the counterweight by the position calculating means. 5. The drawing apparatus according to claim 4, further comprising control means for moving the selected position in the circumferential direction. 6. A storage unit for storing a position of each of the counterweights on the end face of the drum, wherein the control unit controls the engagement of the counterweight based on the position of the counterweight stored in the storage unit. 6. The drum according to claim 5, wherein the engagement means is moved in a radial direction about the rotation axis until the engagement means is engaged with the counterweight, and the drum is rotated by the drive means. Drawing device. 7. An input unit for inputting information on the photosensitive material, wherein the position calculating unit calculates the position of the pair of counterweights based on information input from the input unit. The drawing apparatus according to any one of claims 4 to 6. 8. The method according to claim 1, wherein the position calculating unit calculates a product of a position vector of a center of gravity of the photosensitive material with respect to a rotation center of the drum and a mass of the photosensitive material based on information on the photosensitive material and the fixing member. And the unbalance amount is obtained by synthesizing the product of the position vector of the center of gravity of the fixed member and the mass of the fixed member based on the rotation center of the drum, and the pair of the pair based on the rotation center of the drum. The position of the pair of counterweights is calculated so that a composite vector obtained by synthesizing a product of the position vector of the counterweight and the mass of the corresponding counterweight is balanced with the unbalance amount. Item 8. The drawing apparatus according to any one of Items 4 to 7. 9. A drawing apparatus for drawing by irradiating light to said photosensitive material while rotating a cylindrical drum on which said photosensitive material is mounted by a fixing member, wherein said photosensitive material and said fixing member are rotated when said drum is rotated. A method of attaching a counterweight to the drum, the counterweight for canceling the unbalance force generated by the centrifugal force of the member, wherein the drum has a centrifugal force that cancels the unbalance force of the drum. A step of calculating an attachment position of a pair of counterweights, one for each end, and a step of attaching the pair of counterweights to the calculated attachment position. installation method. 10. The method according to claim 9, wherein the pair of counterweights is provided on each end face of the drum. 11. The step of calculating the mounting position of the counterweight includes, based on information on the photosensitive material and the fixing member, a position vector of a center of gravity of the photosensitive material with respect to a rotation center of the drum and the photosensitive element. Determining the amount of unbalance by combining the product of the mass of the material and the product of the mass of the fixed member and the position vector of the center of gravity of the fixed member with respect to the center of rotation of the drum; and The positions of the plurality of counterweights are adjusted so that a composite vector obtained by synthesizing a product of the position vector of the plurality of counterweights with respect to the center and the mass of the corresponding counterweight is balanced with the unbalance amount. 10. A calculating step.
Or the mounting method of the counterweight according to 10.