JP2001228619A - Method for driving motor for rotary drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time of rising and falling by using a motor for a rotary drum of low output so as to allow efficient image recording. SOLUTION: A main scanning motor is made larger in the output torque of an instantaneous use region than a continuous use region where output torque T is rated torque T0. This motor is so controlled that the output torque T attains the maximum output torque TMAX at the respective numbers N of revolutions when the revolutions of the main scanning motor are risen in order to rotate the rotary drum at the prescribed number of resolutions at which a printing plate is subjected to scanning exposure. As a result, the rising time (t) before the numbers N of revolutions of the main scanning motor attains the numbers N0 of revolutions is shortened and the scanning exposure of the printing plate may be efficiently executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer drum type image exposure apparatus which winds a photosensitive material such as a printing plate around a cylindrical rotating drum and scans and exposes the photosensitive material while rotating the rotating drum. More particularly, the present invention relates to a method for driving a rotary drum motor when a rotary drum is driven to rotate using a servomotor as the rotary drum motor.

[0002]

2. Description of the Related Art In general, a photosensitive printing plate (hereinafter, referred to as a "printing plate"), which is a photosensitive material in which a photosensitive layer is formed on a sheet-like support such as a thin aluminum plate, is used for printing. An image exposure apparatus that performs image exposure on the printing plate includes winding the printing plate around a cylindrical rotating drum, and irradiating the printing plate with a light beam corresponding to image data while rotating the printing plate integrally with the rotating drum. There is an outer drum type that performs scanning exposure according to the above.

In an outer drum type image exposure apparatus, the rotating drum is stopped at a predetermined position and the leading end of the printing plate is fixed to the rotating drum. Then, the rotating drum is rotated at a low speed to wind the printing plate around the rotating drum. Further, the rear end of the printing plate is fixed to a rotating drum. In the image exposure apparatus, the printing plate mounted on the rotating drum is scanned and exposed while the rotating drum is rotated at a high speed (for example, 1000 rpm or more) after the printing plate is mounted on the peripheral surface of the rotating drum.

Further, in the image exposure apparatus, when the scanning exposure of the printing plate is completed, the rotating drum is temporarily stopped, one end of the printing plate is detached from the rotating drum, and then the rotating drum is rotated at a low speed. The printing plate is removed from the rotating drum.

[0005] As described above, a servomotor (hereinafter referred to as "motor") is used to rotationally drive the rotary drum to stop at a predetermined position while rotating at a high speed or at a low speed, and to accurately rotate the rotary drum. To control.

On the other hand, the size (vertical and horizontal dimensions) of a printing plate is
It is determined by the size of the printed matter. In an image exposure apparatus that performs image exposure on printing plates of a plurality of sizes, the size of the rotating drum is determined according to the printing plate of the maximum size. For this reason, some rotating drums used in the image exposing apparatus have a weight of 70 kg, and the image exposing apparatus uses a motor capable of obtaining an output (torque) required for rotating the rotating drum. Can be

It is a general characteristic of a motor that the torque is large at low speed rotation, but the torque decreases as the rotation speed increases. Further, the motor requires a predetermined torque even at the maximum rotation speed.
For this purpose, the motor is usually selected and used so as to generate the maximum torque up to the maximum rotational speed used. That is, the motor is selected so as to obtain a desired rotation speed and a desired torque in the continuous use region.

On the other hand, when performing the scanning exposure of the printing plate, if the number of rotations of the rotating drum is increased, the exposure time can be shortened.

[0009] However, if the rotation speed is to be doubled when rotating the rotating drum, the rising time and the falling time until the rotating drum reaches the rotation speed are each approximately doubled. In the period from when the rotating drum is stopped to when the exposure process is performed and the rotating drum is stopped, the ratio of the rising time and the falling time of the rotation of the rotating drum increases. The start-up time and the fall-down time of such a motor become a substantial work interruption time, and the increase of the start-up time and the start-up time greatly affects the productivity of the image exposure apparatus.

In order to improve the productivity, it is possible to select a motor so as to shorten the start-up time and the fall time. However, in order to shorten the fall time and the start-up time by half. Requires an expensive motor whose output (torque) is approximately doubled, which increases the size of the image exposure apparatus and affects the product cost.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and proposes a method of driving a motor for a rotary drum which can shorten an exposure time by using a relatively inexpensive motor. With the goal.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of rotating a rotary drum having a sheet-shaped recording material wound around its outer peripheral surface at a predetermined number of revolutions without contacting the recording material. A method for controlling a rotating drum motor used for rotating the rotating drum when forming an image, wherein the rotating drum motor is driven within an instantaneous use area where a higher output is obtained than a continuous use area where a rated output is obtained. A motor is driven to increase the rotation speed until the rotating drum reaches a predetermined rotation speed and to decrease the rotation speed from the predetermined rotation speed to a substantially stopped state.

According to the present invention, the rotary drum motor is driven in the instantaneous use area where an output torque larger than the continuous use area is obtained. Even if the same motor is used, a large output torque is obtained, so that the rate of change in the number of revolutions is increased, and the time for starting and falling the number of revolutions can be reduced.

Further, the invention according to claim 2 is characterized in that the predetermined rotation speed of the rotary drum is a maximum rotation speed of a rotary drum motor.

According to the present invention, the rotary drum is driven to rotate at the maximum rotation speed at which the output torque becomes lowest. That is, the motor for the rotating drum is selected such that the rotating speed of the motor for the rotating drum at the time when the rotating drum reaches the predetermined rotating speed becomes the maximum rotating speed.

At the rotation speed when performing the scanning exposure, the rotating drum is in a non-contact state with the rotating drum, and the rotating drum motor is substantially in a no-load state, so that a large output torque is not required. Therefore, an inexpensive and compact motor having a low output torque can be used. Further, even when the same motor is used, the number of rotations of the rotary drum can be increased, so that the exposure time can be reduced.

Therefore, with an image exposure apparatus using a rotating drum, it is possible to reduce the cost and size while shortening the exposure time.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an image exposure apparatus 10 applied to the present embodiment. The image exposure apparatus 10 is a photosensitive lithographic printing plate (hereinafter, referred to as a sheet-shaped photosensitive material) in which a photosensitive layer is formed on a rectangular thin plate-shaped (for example, about 0.3 mm thick) support formed of aluminum or the like. The printing plate 12 is scanned and exposed by irradiating the printing plate 12 with a light beam modulated based on image data. The printing plate 12 that has been subjected to image exposure by the image exposure device 10 is subjected to development processing and the like by an automatic developing device (not shown) or the like.

In the image exposure apparatus 10, a cassette loading section 18, a plate feeding section 20, a recording section 22, a discharge buffer section 24 and the like are provided in a machine frame 14. The cassette loading section 18 is disposed in the machine frame 14 at the lower right side in FIG. 1, and a plurality of cassettes 16 each accommodating a large number of printing plates 12 are inclined at a predetermined angle. Will be loaded.

The image exposure apparatus 10 can process a plurality of sizes of printing plates 12 having different vertical and horizontal dimensions.
The printing plate 12 of any size is accommodated in the cassette 16 with the photosensitive layer facing upward and one end positioned at a predetermined position. Further, the cassette loading section 18 is loaded with a plurality of cassettes 16 at a predetermined interval and one end of the printing plate 12 accommodated in each cassette 16 has a substantially constant height.

The plate feeding section 20 is arranged above the cassette loading section 18, and the recording section 22 is arranged at the lower center of the apparatus adjacent to the cassette loading section 18. The plate feeder 20 is provided with a pair of side plates 26 (only one is shown in FIG. 1).
8 and a single-wafer unit 30 are attached.

The reversing unit 28 includes a reversing roller 32 having a predetermined outer diameter, and a plurality of small rollers (in the present embodiment, as an example, the small roller 3 is provided around the reversing roller 32).
4A, 34B, 34C, and 34D). The small rollers 34 </ b> A to 34 </ b> D are arranged from the cassette loading section 18 to above the reversing roller 32 and to the recording section 22, and the endless transport belt 36 is wound around the small rollers 34 </ b> A to 34 </ b> D. Thereby, the small roller 34A is attached to the reversing roller 32.
The conveyor belt 36 extends approximately half way between the roller and the small roller 34D.
Is wrapped around.

On the other hand, the single wafer unit 30 is
A plurality of suction cups 38 for sucking the upper end portion of the printing plate 12 therein are provided.
The printing plate 12 is sucked to face the upper end of the printing plate 12 in the cassette 16 loaded in the cassette 8. Further, the sheet-feeding unit 30 pulls out the leading end of the printing plate 12 from the cassette 16 by moving the suction cup 38 on which the printing plate 12 is sucked substantially upward, and inserts the leading end between the reversing roller 32 and the transport belt 36. In FIG. 1, the outline of the moving position of the suction cup 38 is indicated by a two-dot chain line.

The reversing unit 28 rotates the reversing roller 32 and the transport belt 36 in the direction in which the printing plate 12 is pulled out from the cassette 16 (the direction of arrow A in FIG. 1). As a result, the printing plate 12 is pulled out of the cassette 16 while being sandwiched between the reversing roller 32 and the transport belt 36, and
It is inverted while being curved by being wound around the peripheral surface of No. 2. Note that the radius of the reversing roller 32 is a dimension (for example, 100 mm or more) that does not cause the printing plate 12 to bend or bend when the printing plate 12 is curved.

As shown by a solid line and a two-dot chain line in FIG. 1, the side plate 26 moves horizontally in accordance with the position of the cassette 16 from which the printing plate 12 is taken out. Thereby, the sheet unit 30 is moved together with the reversing unit 28, and the suction cup 38 of the sheet unit 30 is opposed to the printing plate 12 in the selected cassette 16.

The side plate 26 is provided with a guide 40 below the small roller 34D, and the printing plate 12 inverted by the reversing roller 32 moves between the reversing drum 32 and the transport belt 36 on the small roller 34D side. From this guide 40
Sent out to. In addition, above the recording unit 22,
A transport conveyor 42 is provided, and the reversing unit 28
The printing plate 12 sent out of the printer is guided to a conveyor 42 by a guide 40.

The guide 40 swings with the movement of the side plate 26 so that the guide direction of the printing plate 12 is always directed to the conveyor 42, and the small roller 34D of the recording unit 22 side.
Moves so as to change the sending direction of the printing plate 12 from the reversing unit 28 with the movement of the side plate 26. As a result, the printing plate 12 sent out from the reversing unit 28 is gently curved by the guide 40. The small roller 34C moves so as to apply a substantially constant tension to the transport belt 36 when the small roller 34D moves.

On the conveyor 42, a conveyor belt 48 is wound around a roller 44 adjacent below the plate feeding unit 20 and a roller 46 adjacent above the recording unit 22.
The roller 46 is inclined so that the roller 46 side faces downward.

As shown in FIGS. 1 and 2, a roller 50 is disposed on the conveyor 42 so as to face the roller 46, and the printing plate 12 sent onto the conveyor 42 is transported by the conveyor belt 48. Rollers 46, 5
0 pinched.

On the other hand, a rotary drum 54 and a recording head section 56 are mounted on a gantry 52 in the recording section 22.
A puncher 58 is arranged above the rotating drum 54. The puncher 58 is formed with a mouth opening 60.

The transport conveyor 40 holding the printing plate 12 between the rollers 46 and 50 first sends the printing plate 12 toward the mouth 60 of the puncher 58 and inserts the leading end of the printing plate 12 into the mouth 60 of the puncher 58. I do. The puncher 58 operates when the printing plate 12 is inserted into the mouth opening 60, and cuts out a positioning notch at a predetermined position at the leading end of the printing plate 12.

The conveyor 42 is provided with a swinging means (not shown).
The roller 46 side is the rotating drum 5 of the recording unit 22 with the side as an axis.
4 (shown in phantom lines in FIGS. 1 and 2). As a result, the printing plate 12 is sent to the recording unit 22 with the leading end of the printing plate 12 facing a predetermined position on the peripheral surface of the rotating drum 54.

When the notch is formed in the printing plate 12 by the puncher 58, the conveyor 42 is driven in reverse to pull out the printing plate 12 from the opening 60 of the puncher 58, and then rotate the printing plate 12. The printing plate 12 is sent out toward the recording unit 22 by swinging downward so as to face the drum 54.

The rotating drum 5 provided in the recording unit 22
Reference numeral 4 denotes a mounting plate exposure direction (the direction of arrow B in FIGS. 1 and 2) of the printing plate 12 and a printing plate 12 that is opposite to the mounting exposure direction.
In the removal direction (the direction of arrow C in FIGS. 1 and 2).

As shown in FIG. 2, the rotary drum 54 provided in the recording section 22 has a tip chuck 62 mounted at a predetermined position on the outer peripheral surface. Rotating drum 54
When the printing plate 12 is mounted, first, the front end chuck 62 is stopped at a position (printing plate mounting position) opposed to the front end of the printing plate 12 fed by the conveyor 42.

The recording section 22 is provided with a mounting cam 64 opposed to the front end chuck 62 at the printing plate mounting position of the rotary drum 54. The tip chuck 62 is attached to the mounting cam 6.
The printing plate 12 can be inserted between the rotating plate 4 and the peripheral surface of the rotating drum 54 by pressing one end side.

The printing plate 12 sent to the recording section 22 by the conveyor 42 has a tip chuck 62
And the peripheral surface of the rotary drum 54, and the mounting cam 64 is rotated in this state, whereby it is sandwiched and fixed between the tip chuck 62 and the rotary drum 54. At this time, the printing plate 12 is inserted into the notch formed by the puncher 58 so that a positioning pin (not shown) protruding at a predetermined position on the peripheral surface of the rotating drum 54 enters the notch. Is positioned.

In the recording section 22, when the leading end of the printing plate 12 is fixed to the rotating drum 54, the rotating drum 54 rotates in the mounting exposure direction. As a result, the printing plate 12 sent from the conveyor 42 is wound around the peripheral surface of the rotating drum 54.

In the vicinity of the peripheral surface of the rotating drum 54, a squeeze roller 66 is provided downstream of the mounting cam 64 in the mounting exposure direction.
Is arranged. When the printing plate 12 is wound around the rotating drum 54, the squeeze roller 66 moves toward the rotating drum 54, and moves between the rotating plate 54 and the printing plate 1.
Hold 2 As a result, the printing plate 12 is brought into close contact with the peripheral surface of the rotating drum 54.

The recording unit 22 includes a squeeze roller 6.
6, a rear end chuck attaching / detaching unit 68 is disposed on the upstream side in the mounting / exposure direction, and the removal cam 7
0 is arranged. In the rear-end chuck attaching / detaching unit 68, a rear-end chuck 74 is detachably disposed at a front end of a shaft 72 that moves toward the rotary drum 54.

In the recording section 22, the rear end of the printing plate 12 wound around the rotating drum 54 is connected to the rear end chuck attaching / detaching unit 6.
8, the shaft 72 is made to protrude, and the rear end chuck 74 is mounted at a predetermined position on the rotating drum 54. As a result, the rear end chuck 74 clamps and fixes the rear end of the printing plate 12 with the rotating drum 54.

In the recording section 22, when the rotating drum 54 holds the leading and trailing ends of the printing plate 12, the squeeze roller 66
While rotating the rotating drum 54 at a high speed at a predetermined rotational speed, the recording head 56 irradiates a light beam modulated based on image data in synchronization with the rotation of the rotating drum 54, and Is scanned and exposed according to the image data.

In the recording unit 22, when the scanning exposure on the printing plate 12 is completed, the rotating drum 54 is temporarily stopped at a position where the trailing end chuck 74 faces the trailing end chuck attaching / detaching unit 68, and the trailing end chuck 74 is moved to the rotating drum. 54, the rear end of the printing plate 12 is opened, and the squeeze roller 6
6, the printing plate 12 is pressed toward the rotating drum.
In this state, when the rotating drum 54 rotates in the removing direction, the printing plate 12 is moved from the rear end side to the discharge buffer unit 2.
It is sent out to 4. In addition, the tip chuck 62
The rotating drum 54 rotates in the removal direction, and the removal cam 7
When the printing plate 12 is opposed to 0, it is pressed by the removal cam 70 to open the leading end of the printing plate 12.

As shown in FIG. 1, the discharge buffer unit 2
4 is provided above the squeeze roller 66.
The discharge buffer unit 24 includes a discharge roller 78 disposed inside a discharge port 76 formed in the machine frame 14. A plurality of small rollers (for example, small rollers 80A, 80B, 80C, 80
D, 80E) and these small rollers 80
An endless transport belt 82 is wound around A to 80E. As a result, the discharge roller 78 is attached to the small roller 8.
The transport belt 82 is wound around a range of 周 to ／ between 0A and the small roller 80E.

The small roller 80A is provided on the squeeze roller 66 side of the recording unit 22, and the roller 84 is opposed to the small roller 80A. The printing plate 12 sent from the recording unit 22 is guided between the small rollers 80A and the rollers 84, and
0A and the roller 84.

In the discharge buffer section 24, the discharge rollers 78
Is rotated in the direction in which the printing plate 12 is pulled in (in the direction of arrow D), so that the printing plate 12 sandwiched between the small rollers 80A and the rollers 84 is guided between the discharge roller 78 and the transport belt 82 while being pulled out from the recording unit 22. , Discharge roller 78
, And wound around the discharge roller 78. At this time, in the discharge buffer unit 24, the leading end of the printing plate 12 (the rear end side of the printing plate 12 sent from the recording unit 22) is sandwiched between the small rollers 80 </ b> A and the rollers 84, so that the printing plate 12 is wound around the discharge rollers 78. Printing plate 12 is temporarily held.

On the other hand, as shown by a two-dot chain line in FIG.
In the discharge buffer section 24, the small roller 80A and the roller 84
Moves to a position facing the outlet 76. This allows
The leading end of the printing plate 12 wound around the discharge roller 78 is directed to the discharge port 76. The small roller 80B above the small roller 80A moves following the movement of the small roller 80A, and applies a constant tension to the transport belt 82.

In the discharge buffer section 24, when the leading end of the printing plate 12 is directed to the discharge port 76, the discharge roller 78 is moved to the printing plate 12 by a processing device such as an automatic developing device arranged adjacent to the discharge port 76. The printing plate 12 is driven to rotate in the direction in which the printing plate 12 is sent out (the direction opposite to the direction of arrow D) at a rotation speed corresponding to the transfer speed of the printing plate 12, and the printing plate 12 is sent out from the outlet 76.

By the way, as shown in FIG. 3, the rotary drum 54 provided in the recording section 22 is formed in a substantially cylindrical shape. At both ends along the axial direction of the rotating drum 54, rotating shafts 54A are provided, and the rotating shafts 54A are supported by side plates 90 erected on the gantry 52 in pairs. The rotating drum 54 has, for example, a dimension along the axial direction of about 1200 mm and an outer diameter of about 350 mm.
mm and weight are about 70 kg.

The gantry 52 is provided with a base 92, on which a pair of guide rails 94 is provided along the axial direction of the rotary drum 54.
The recording head 56 is attached to the guide rail 94. The recording head 56 includes a sub-scanning motor 96.
The recording head unit 56 is driven by the sub-scanning motor 96 to move along the axial direction of the rotary drum 54 which is the sub-scanning direction when exposing the printing plate 12. .

On the other hand, the main scanning motor 100 is attached to the gantry 52 via a bracket (not shown). The main scanning motor 100 is provided with a pulley 102 on a drive shaft. A pulley 104 is attached to the rotating shaft 54A of the rotating drum 54 protruding from the side plate 90. An endless timing belt is provided between the pulley 104 and the pulley 102 attached to the main scanning motor 100. 106 is wound. This allows
When the main scanning motor 100 is driven, the rotating drum 54
Are driven to rotate at a rotation speed corresponding to the rotation speed of the main scanning motor 100.

The rotating drum 54 is formed in a cylindrical shape, and the recording head 56 and the like are in a non-contact state. Therefore, when the rotating drum 54 is rotated at a constant rotational speed such as during scanning exposure, the load of the main scanning motor 100 is reduced. Is extremely low (almost no load)
It is becoming. That is, when the rotation speed of the rotary drum 54 becomes constant when exposing the printing plate 12, the main scanning motor 100 is driven in a substantially no-load state.

As shown in FIG. 4, the recording unit 22 includes:
A controller 108 including a microcomputer in which memories such as a ROM and a RAM, a CPU, input / output ports, and the like are connected by a bus is provided. The controller 108 is connected to the recording head unit 56 and drives the main scanning motor 10 via driving circuits 110 and 112.
0 and the sub-scanning motor 94 are connected.

The controller 108 includes the main scanning motor 10
By operating the recording head unit 56 while controlling the 0 and sub-scanning motors 96, the printing plate 12 wound around the rotating drum 54 is scanned and exposed. Note that the driving circuits 110 and 112 can use a conventionally known configuration corresponding to a motor (electric motor) used as the main scanning motor 100 and the sub-scanning motor 96, and a detailed description thereof is omitted in the present embodiment. .

A servo motor is used as the main scanning motor 100, and the controller 108 controls the number of rotations of the main scanning motor 100 per unit time (hereinafter referred to as "number of rotations") and the rotation angle, thereby Rotating drum 54
At a predetermined number of rotations, and the rotating drum 54 can be stopped at a preset rotation angle. The stop position of the rotating drum 54 may be measured by measuring the rotation angle of the rotating drum 54 from a reference position, and a conventionally known method such as detecting whether or not the rotating drum 54 has reached a predetermined rotation angle by a sensor. Various methods can be used,
Detailed description is omitted in the present embodiment.

FIG. 5A schematically shows the relationship between the number of revolutions of the main scanning motor 100 and the output torque. The main scanning motor 100 outputs the output torque T at a rotation speed N ₀ at which the rotating drum 54 reaches a predetermined rotation speed during scanning exposure of the printing plate 12.
Is low. In addition, the main scanning motor 100 has a constant rated output T _{0 in the} rotation speed region lower than the rotation speed N ₁ , and the region where the rated output T ₀ is obtained for each rotation speed N is continuous. It is used area.

On the other hand, in the main scanning motor 100, an output torque larger than the rated output can be obtained at each rotational speed N in the instantaneous use area beyond the continuous use area. The controller 108 controls the rotation speed of the rotary drum 54 to a predetermined rotation speed at the time of scanning exposure of the printing plate 12, and at the time of startup to reduce the rotation speed of the rotation drum 54, With main scanning motor 1
00 is driven.

In general, if the output torque T of the motor is large, the rate of increase of the number of revolutions N also increases, and the braking torque increases when the number of revolutions N falls. Therefore, as shown in FIG. 5B, when the main scanning motor 100 is started up in the continuous use area, the main scanning motor 100
0 than the time to reach the rotation speed N ₀ (start-up time t _2),
The startup time t ₁ when the startup is performed in the instantaneous use area is reduced.

In FIG. 5B, the rotation speed N with respect to the elapsed time t when the main scanning motor 100 is controlled along the locus (instantaneous use area) at which the maximum torque T _MAX is obtained at each rotation speed N. changes are shown by solid lines are indicated by broken lines the change in the rotational speed N when the control of the main scanning motor 100 in the output torque T ₁ which is a maximum continuous use regions in the predetermined rotational speed N _0.

The controller 108 includes, in a memory (not shown), a parameter for driving the main scanning motor 100 in the continuous use area, and also stores the main scan motor 1 in the instantaneous use area.
The parameters for the start-up and the fall of 00 are stored. The controller 108 controls the rotating drum 5
4 when the scanning exposure to be rotated at a predetermined rotation speed, start-up and fall for a continuous use area for example, the output torque T drives the main scanning motor 100 so that the rated output T _0, performs scanning exposure sometimes, the instantaneous use area for example, the output torque T driving the main scanning motor 100 such that the maximum torque T _MAX.

The operation of the present embodiment will be described below.

In the image exposure apparatus 10, image data to be exposed on the printing plate 12 is input, and the printing plate 12 for performing image exposure is input.
When the size and the number of exposures are set and the start of image exposure is instructed, the image exposure processing on the printing plate 12 is started. Note that these processes may be performed by providing an operation panel in the image exposure apparatus 10 and instructing the same by operating a switch on the operation panel. A signal from an image processing apparatus or the like that outputs image data to the image exposure apparatus 10 may be used. May be used to instruct the image exposure apparatus 10 to start processing.

When the start of the processing is instructed, the image exposure apparatus 10 moves the sheet-feeding unit 30 together with the reversing unit 28 to a position corresponding to the cassette 16 accommodating the printing plate 12 of the designated size. The suction plate 38 sucks and removes the printing plate 12 in the corresponding cassette 16, and sends the printing plate 12 between the reversing roller 32 of the reversing unit 28 and the transport belt 36. Thus, the printing plate 12 is inverted while being taken out of the cassette 16 and sent to the transport conveyor 42.

The printing plate 12 sent to the conveyor 42
When the front end is inserted into the mouthpiece 60 of the puncher 58 and a notch is formed, the cutout is pulled out from the puncher 58 and sent out toward the peripheral surface of the rotating drum 54 of the recording unit 22.

In the recording unit 22, when the leading end of the printing plate 12 is held on the rotating drum 54 by the leading end chuck 62 and is wound around the peripheral surface of the rotating drum 54, the trailing end of the printing plate 12 is rotated by the trailing end chuck 74. Fix to 54. Thereafter, the recording unit 22 scans and exposes the printing plate 12 with a light beam emitted from the recording head unit 56 while rotating the rotating drum 54 at a predetermined rotation speed.

The printing plate 12 on which the scanning exposure has been completed is sent out to the discharge buffer section 24 while being detached from the rotary drum 54, and is sent out from the discharge buffer section 24 toward the discharge port 76 at a predetermined speed to be discharged. .

On the other hand, in the recording section 22, when the printing plate 12 is mounted on the rotary drum 54, the main scanning motor 100 is driven so that the leading end chuck 62 moves to the printing plate mounting position facing the mounting cam 64. To rotate. Thereafter, when the leading end of the printing plate 12 is fixed to the rotating drum 54 by the leading end chuck 62, the main scanning motor 100 is operated to rotate the rotating drum 54 at a low speed in the mounting exposure direction. 12 is wound. Also,
When the rear end of the printing plate 12 wound around the rotary drum 54 reaches a position facing the rear end chuck attaching / detaching unit 68 by a sensor (not shown), the rotary drum 54 is stopped, and the rear end chuck 74 is mounted on the rotary drum 54. Then, the rear end of the printing plate 12 is fixed to the rotating drum 54.

When the image exposure on the printing plate 12 is completed, the controller 108 rotates the main scanning motor 100 at a low speed so that the rear end chuck 74 mounted on the rotary drum 54 is moved to the rear end chuck attaching / detaching unit 68. Stop at the position facing. Thereafter, the trailing end chuck 74 is removed from the rotating drum 54, so that the trailing end of the printing plate 12 is opened. When the rear end of the printing plate 12 is opened, the controller 108 drives the main scanning motor 100 to
The rotating drum 54 is rotated in the printing plate removing direction, and the printing plate 12 wound around the rotating drum 54 is sent out to the discharge buffer unit 24.

By the way, the controller 108 drives the main scanning motor 100 in the continuous use area when the printing plate 12 is mounted on the rotating drum 54 and when the printing plate 12 is removed from the rotating drum 54.

On the other hand, in the recording section 22, when the printing plate 12 is wound and mounted on the rotating drum 54, the rotating drum 54 is rotated at a high speed (for example, 1000
rpm to 3000 rpm) to perform scanning exposure of the printing plate 12. The controller 108 drives the main scanning motor 100 so that the rotating drum 54 has a predetermined number of rotations, and drives the sub-scanning motor 96 in synchronization with the rotation of the rotating drum 54 that is rotationally driven by the main scanning motor 100. I do.

At this time, the controller 108 is driven within the instantaneous use area (see FIG. 5A) so that the main scanning motor 100 rotates while generating the maximum torque _TMAX . As a result, as shown in FIG. 5B, the main scanning motor 100 is driven in the continuous use area and the predetermined rotation speed N
₀ than the start-up time t ₂ according to reach in a short start-up time t ₁ can perform startup of the main scanning motor 100.

The controller 108 controls the printing plate 12
When the image exposure to the main scanning motor 100 is completed and the rotation speed N of the main scanning motor 100 is lowered, the main scanning motor 100 is controlled to be driven within the instantaneous use area.

Thus, the recording unit 2 of the image exposure apparatus 10
In 2, the fall time can be shortened even when the main scanning motor 100 is turned down, as compared with the case where the main scanning motor 100 is driven within a generally used continuous use area.

FIGS. 6A and 6B show specific examples of the case where the main scanning motor 100 is used to be driven in the continuous use area and the case where it is used to be driven in the instantaneous use area. An example is shown. FIG. 6A shows the main scanning motor 1.
6B shows a change in the output torque T with respect to the rotation speed N of 00, and FIG. 6B shows a change in the rotation speed N with respect to the elapsed time (time t) when the main scanning motor 100 starts up.

As shown in FIG. 6A, in Experimental Examples 1 and 3, the driving force of the main scanning motor 100 is transmitted to the rotary drum 54 at a reduction ratio of 3: 1 to drive the rotary drum 54. It was done. In Experimental Example 3, the main scanning motor 100 was set to 3000 rpm (rotating drum 100 was set to 1000 rpm).
(rpm) until the output torque T becomes constant at the torque T ₃ (approximately 4 N · m). The motor is driven up to 3000 rpm in the instantaneous use area so as to follow the locus where the output torque T becomes the maximum.

In Experimental Example 2, the reduction ratio was set to 2.5: 1.
The main scanning motor 100 is rotated so that the output torque T becomes a constant torque T ₄ (about 20 N · m) up to 2500 rpm.
4 rotates up to 1000 rpm.

As shown in FIG. 6B, in Experimental Examples 2 and 3, since the output torque T of the main scanning motor 100 is constant, the rotation speed N of the main scanning motor 100 is
Is rising linearly. In the third experimental example, the output torque T is lower than that in the second experimental example. Therefore, the start-up time t ₃ (about 16.2 sec) until the rotating drum 54 reaches a predetermined rotation speed (1000 rpm) is different from the second experimental example. Rise time t ₄
(About 4.8 sec).

On the other hand, in Experimental Example 1, the main scanning motor 100 is driven along the locus where the output torque T becomes maximum at each rotation speed N to perform the start-up processing. The rising time t ₅ (about 3 sec) is shorter than the rising time t ₄ of Experimental Example 2.

As described above, by performing the start-up process while maintaining the main scanning motor 100 so that the output torque T is maximized, the main scanning motor 100 is driven until the rotation speed N reaches the predetermined rotation speed (the rotation drum 54 is rotated to the predetermined rotation speed). The start-up time t, which is the time (until the rotation speed is reached), can be shortened. Further, at the time of falling, the output torque T of the main scanning motor 100 acts as a braking torque when the rotation speed of the main scanning motor 100 is reduced, so that the falling time can be shortened, and the exposure time of the printing plate 12 can be reduced. The start-up time and the ratio of the start-up time in which the printing plate 12 is in a standby state for performing the processing of the printing plate 12 can be reduced with respect to the required time, and the scanning exposure of the printing plate 12 can be performed efficiently.

As shown in FIG. 6A, in Experimental Example 1, the rotation speed N of the main scanning motor 100 was 2000 rp.
When m exceeds m, the output torque T gradually decreases. For this reason, as shown in FIG. 6B, in Experimental Example 1, when the rotation speed N of the main scanning motor 100 exceeds 2000 rpm, the degree of increase in the rotation speed N becomes gentle. Therefore, it is more preferable to pay attention to the rotation speed control of the main scanning motor 100.

On the other hand, although there is no large difference in the rise time t between Experimental Example 1 and Experimental Example 2, the main scanning motor 100
Since the reduction ratio at the time of transmitting the rotational force to the rotary drum 54 is changed, the load inertia ratio with respect to the main scanning motor 100 is changed. For this reason, the load inertia ratio of Experimental Example 2 having a low reduction ratio is higher (about 1.5 times) than the load inertia ratio of Experimental Example 1 having a high reduction ratio. This also facilitates control of the number of rotations of the main scanning motor 100.

As described above, by using the entire available rotational speed range of the main scanning motor 100 and controlling the main scanning motor 100 so that the output torque T is maximized at each rotational speed N, the start-up is achieved. And to shorten the fall time,
Scanning exposure to the printing plate 12 can be performed efficiently.

On the other hand, as shown in FIG. 5A, when the rotation speed N reaches a predetermined rotation speed N ₀ , the main scanning motor 100 maintains the rotation speed N _{0 and} keeps the rotating drum 54 constant. It rotates at the number of rotations. Further, in the recording unit 22, the scanning exposure is performed in a non-contact manner on the printing plate 12 wound around the rotating drum 54. When the scanning exposure is performed on the printing plate 12, the rotating drum 54 can be rotated by an inertial force. It has become.

For this reason, when the rotating drum 54 reaches the predetermined number of revolutions, the main scanning motor 100 does not need a large output torque, and the main scanning motor 100 turns the rotating drum 54 to the predetermined number of revolutions. The output torque T at the time is small. That is, even if the output torque T is low at the rotation speed N _0, the motor can be used as the main scanning motor 100.

Therefore, the motor having a low rated output and a low output torque at the maximum rotation speed is
By using 0, scanning exposure of the printing plate 12 can be performed efficiently.

In addition, a low-cost, low-cost, small-sized motor (servo motor) can be used for scanning exposure of the printing plate 12, so that the manufacturing cost of the recording unit 22 (image exposure apparatus 10) can be suppressed. Both can be made compact.

Note that the present embodiment described above does not limit the configuration of the present invention. In the present embodiment, the printing plate 12 is used as the recording material. However, the present invention is not limited to the printing plate 12 and is not limited to the printing plate 12, and may be any configuration in which various recording materials such as other photosensitive materials are wound around the rotating drum to perform scanning exposure. Can be used for controlling a servomotor that drives the rotary drum to rotate.

[0088]

As described above, according to the present invention, when raising and lowering the rotation speed of the motor for a rotary drum, the instantaneous use area where the output torque is larger than the continuous use area is used. In addition, the start-up time and the fall time can be reduced.

As a result, an excellent effect is obtained that an image can be efficiently formed on a recording material even when a small-sized and low-cost motor for a rotary drum having a small rated output is used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image exposure apparatus applied to the present embodiment.

FIG. 2 is a schematic configuration diagram of a recording unit provided in the image exposure apparatus.

FIG. 3 is a schematic perspective view showing the vicinity of a rotary drum provided in a recording unit.

FIG. 4 is a schematic block diagram illustrating connection of a main scanning motor and the like to a controller provided in a recording unit.

FIG. 5A is a diagram schematically showing an output torque with respect to the number of revolutions of the main scanning motor, and FIG. 5B is a diagram showing a change in the number of revolutions with respect to the time when the main scanning motor starts up.

FIGS. 6A and 6B are diagrams illustrating an experimental example of a change in the rotation speed with respect to a change in the output torque; FIG. 6A illustrates a change in the output torque with respect to the rotation speed of the main scanning motor;
(B) shows the change in the number of revolutions with respect to the time when the main scanning motor starts up.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image exposure apparatus 12 Printing plate (recording material) 22 Recording part 54 Rotary drum 56 Recording head part 100 Main scanning motor (rotary drum motor) 108 Controller 110 Drive circuit

Claims (2)

[Claims] 1. A rotating drum having a sheet-shaped recording material wound around its outer peripheral surface is used for rotating the rotating drum when an image is formed in a non-contact manner while rotating the drum at a predetermined number of revolutions. A method for controlling a motor for a rotating drum, wherein the motor for the rotating drum is driven in an instantaneous use area in which a higher output is obtained than in a continuous use area in which a rated output is obtained, so that the rotating drum has a predetermined rotation speed. A method for driving a motor for a rotating drum, comprising: starting up the rotation speed until the rotation speed of the motor is reduced, and lowering the rotation speed from the predetermined rotation speed until the vehicle is substantially stopped. 2. The method for driving a rotating drum motor according to claim 1, wherein the predetermined rotating speed of the rotating drum is a maximum rotating speed of the rotating drum motor.