JPH0516320A - Semiconductor laser plate making device - Google Patents

Abstract

PURPOSE:To reduce time required for an ON-state current to reach a predetermined value to reduce a power loss of a semiconductor laser when it is driven on ON/OFF signals by a method wherein during an OFF period in which recesses are not formed on a plate by the semiconductor laser, an electric current up to the vicinity of the threshold of exciting the semiconductor laser is passed to the semiconductor laser. CONSTITUTION:When a status signal 31 of an input operation part 30 is inputted to a CPU 32, the CPU 32 respectively supplies normal or reverse rotation pulses to motor drivers 33, 35 to control a laser block travel motor 24 and a plate cylinder rotating motor 7. Simultaneously, the CPU 32 supplies image data 41 to a laser driver 43 through a gray scale conversion circuit 42 to control a semiconductor laser 10. In this manner, the semiconductor laser 10 forms recesses 15 corresponding to data of the video input signals on a plate sheet 2 set on the peripheral surface of a plate cylinder 1. In this case, in the laser driver 43, an electric current to be passed during an OFF period of the semiconductor laser 10 is set up to the vicinity of the threshold thereof through a threshold setting circuit 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser plate making apparatus which uses a semiconductor laser to form a recessed plate corresponding to the density of image data.

[0002]

2. Description of the Related Art The applicant of the present invention has previously disclosed Japanese Patent Laid-Open No. 2-139238.
Japanese Patent Laid-Open Publication No. 2003-242242 proposes a plate making apparatus for obtaining a plate cylinder of an intaglio plate in which a plate made of a thermoplastic resin is irradiated with a laser beam using a laser to form a recess corresponding to the shade of an image.

The outline of the configuration disclosed in the above publication will be described with reference to FIG. FIG. 5 is a conceptual diagram of an optical system showing a pattern forming method of the plate 2 wound around the plate cylinder 1. The plate cylinder 1 is a metal cylinder, and a plate made of synthetic resin along the outer shape of the plate cylinder 1. 2 is wound and fixed to a mother screw drilled in the plate cylinder 1 with a flat head screw or the like. Any appropriate fixing method can be selected as the fixing method, and for example, the back surface of the plate 2 can be coated with an adhesive and fixed to the plate cylinder.

As a material for the plate 2, a thermoplastic resin having a relatively narrow melting point distribution range, having a hardness during curing, and a resin that scatters or sublimes at a low temperature during melting is preferable. For example, polyethylene resin, acrylic resin, polypropylene. A resin containing about 20% carbon is used.
The thickness of the plate 2 is selected to be about 200 μm.

The plate cylinder 1 is connected to a plate cylinder rotation motor which will be described later, and the plate cylinder 1 is rotated in the direction of arrow B.

FIG. 5 shows a conceptual diagram for forming the recess 15 in the plate 2 by using the semiconductor laser 10 of about 1 W.

The video input signal 16 captured by an image scanner or the like is supplied to the semiconductor laser 10, and the drive current is directly turned on / off by the PCM video input signal 16. Therefore, the laser beam emitted from the semiconductor laser 10 blinks in synchronization with the image input signal 16. The laser beam emitted from the semiconductor laser 10 is collimated by the collimating optical system 12 and is irradiated through the focusing lens 13 so as to focus on the surface position of the plate 2.

Semiconductor laser 10 and collimating optical system 1
2. The laser block 14 including the focusing lens 13 is initially focused on a predetermined position on the leftmost end side of the plate cylinder 1.
Since the plate cylinder 1 is rotated in the direction of the arrow B by a plate cylinder rotating motor described later, when the plate cylinder 1 is rotated once, the depression 15 for one track along the circumference is scattered by the laser beam. Then, the depression 15 for one predetermined track is formed. Next, the laser block 14 is moved in the axial direction of the plate cylinder 1 for one pixel, and the synthetic resin material is scattered to form a predetermined recess 15 in two tracks. When such scanning is sequentially performed over the entire surface of the plate cylinder 1, the synthetic resin material forms the depression 15 corresponding to the shade of the image input signal 16.

That is, the plate cylinder 1 is irradiated with a laser beam through a focusing lens 13 to focus on the surface of the synthetic resin plate 2 to melt the plate surface and scatter or sublime the synthetic resin. In this case, the semiconductor laser 10 is provided with a signal as shown in FIG. 6A, which is an ON / OFF signal modulated by the video input signal 16 as described above, and has a duration of ON periods t ₁ , t ₂ , and t ₃ . The shade is determined by changing the area and depth of the depression 15. In this case, as shown in FIG. 6B, the current flowing through the semiconductor laser 10 is ideally zero during the off period, and the predetermined current I during the on periods t ₁ , t ₂ and t _3.
Platemaking was performed by pouring.

[0010]

According to the above conventional configuration, ideally, a current as shown in FIG. 6B should be applied to the semiconductor laser 10 by the semiconductor current. However, in practice, a laser power of about 1 W is to be obtained. It is necessary to pass a current of about 1.5 A through the semiconductor laser 10 during the on periods t ₁ , t ₂ , and t ₃ . In order to pass a large current in this way, when the state changes from the off state to the on state, the on / off signal of FIG. 7A causes a delay Δt until the current reaches a predetermined current value I from zero in the semiconductor laser as shown in FIG. 7B. However, there is a problem that the predetermined laser power is not reached, and the area and depth of the depression 15 at the time of plate making are reduced by that much, and the shading cannot be made to be a predetermined value. Further, in a plate making apparatus using a semiconductor laser, the semiconductor laser power is small, and thus plate making time is long. Therefore, it is necessary to compensate for this by various methods, and it is necessary to minimize the loss of the laser power.

The present invention has been made in order to solve the above problems, and an object thereof is to provide a semiconductor laser plate making apparatus in which the loss of the semiconductor laser power is minimized. ..

[0012]

As shown in FIG. 1, the plate making apparatus of the present invention uses a semiconductor laser 10 to form a recess in a plate 2 in accordance with the density of image data. In the semiconductor laser plate making apparatus, the semiconductor laser 10
In the off period in which the plate recess is not formed, the current is caused to flow near the threshold value at which the semiconductor laser 10 oscillates to reduce the power loss.

[0013]

In the plate making apparatus of the present invention, the current during the off period of the on / off signals not involved in the plate making is made to flow to near the threshold value at which the semiconductor laser 10 oscillates. When the on / off current is turned on. Since the time required to reach the predetermined value can be shortened, it is possible to obtain a semiconductor laser power loss that can be reduced when the on / off signal is driven.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor laser plate making apparatus of the present invention is shown in FIG.
4 to FIG.

FIG. 1 shows a perspective view of a semiconductor laser plate making apparatus used in this embodiment. Reference numeral 11 denotes a base of the semiconductor laser plate making apparatus, in which a plate cylinder rotating portion 62 and a laser block moving portion 63 are formed in a substantially rectangular steel plate shape. It is provided. The plate cylinder rotating portion 62 is configured such that the substantially cylindrical plate cylinder 1 is rotatably pivoted between the left and right side walls 64L and 64R formed in a substantially V shape, and the plate cylinder rotating motor 7 disposed on the base 11 The laser block 14 is driven so as to include the semiconductor laser 10 and move along a guide portion 22 arranged along the axial direction of the plate cylinder 1.

A plate 2 made of synthetic resin is wound and fixed along the outer circumference of the cylindrical portion of the plate cylinder 1. Metal caps 3L and 3R are fitted to the left and right of the plate cylinder 1, and left and right caps 3L and 3R
Shafts 4L and 4R formed integrally with the left and right side walls 64L and 64
It is rotatably attached to R. The shaft 4R is connected to a plate cylinder rotating motor 7 fixed on a base 11 via a plurality of pulleys 6 ... And a belt 5 ... And wound around the plate cylinder 1 via these pulleys 6 and a belt 5. Version 2 is arrow A or B
Rotate in the direction.

In the laser block moving portion 63, a substantially rectangular sub base 65 is mounted on a dogleg-shaped step formed on the left and right side walls 64L and 64R of the base 11.
A guide part 22 is formed on the upper part 5.

Further, on the sub base 65, the bearing portion 23L,
23R is established, the ball screw 26 of the laser block moving unit 63 is bridged between the bearings 23L and 23R,
The ball screw 26 is rotationally driven by the laser block moving motor 24. That is, the ball screw 26 is the shaft of the laser block moving motor 24 and the shaft coupling 25 for coupling.
To drive the ball screw 26.

A mover 27 is screwed onto the ball screw 26, the mover 27 and a laser block mount 28 are fixed by an arm 29, and the laser block 14 is placed on the laser block mount 28. Laser block 14
Is moved in the axial direction of the plate cylinder 1 along the guide portion 22, so that the laser beam emitted from the semiconductor laser 10 in the laser block 14 is X and Y of the plate 2 wound around the plate cylinder 1.
The depressions 15 can be formed so as to face each other in all directions of the shaft.

Using such a semiconductor laser plate making apparatus,
A method of forming the gravure plate 2 will be described with reference to the system diagram of FIG.

In FIG. 2, the input operation unit 30 sends a status signal 31 such as stop or reset to a microcomputer (hereinafter C
It is referred to as PU) 32. The CPU 32 supplies a normal rotation or reverse rotation pulse to the laser block moving motor driver 33 and the plate cylinder rotating motor driver 35 to rotate the laser block moving motor 24 and the plate cylinder rotating motor 7. The plate cylinder driving motor 7 rotates the plate cylinder 1, the semiconductor laser 10 forms a recess 15 corresponding to the data of the image input signal 16 on the plate surface, and when the plate cylinder 1 rotates, the laser block moving motor 24 is turned on. The pixel data is moved by the amount corresponding to the shade of the screen 15 along the circumference of the plate cylinder 1
The CPU 32 controls to make the.

The data RAM 38 stores digital image data 41 captured by an image scanner or the like. The CPU 32 reads the image data of the pixel to be plate-made from the data RAM 38 and sends it to the gray scale conversion circuit 42. The gray scale conversion circuit 42 has a role of converting light and shade of an image into long and short laser irradiation time. The output of the gray scale conversion circuit 42 drives the semiconductor laser 10 via the laser driver 43.

The laser driver 43 has a threshold setting circuit 44.
The semiconductor laser 10 is configured to be able to set the current to be applied when it is off.

FIG. 3 shows the operation of this example in the system diagram of the above configuration.
And FIG. 4 will be described. For example, the characteristic curve diagram of the driving current (mA) of the SLD-304 (Sony semiconductor laser) and the laser power output (mW) for outputting the laser power of about 1 W described above shows the characteristic 45 as shown in FIG. There is. That is, the laser power output is zero until the drive current is about 200 mA, and the output gradually rises from the drive current of about 250 mA. This semiconductor laser 1
The threshold current I _{S at} which 0 starts oscillating has a different value depending on the type of the semiconductor laser 10, so that the threshold setting circuit 44 can set the threshold current I _S according to the type of the semiconductor laser 10.

In the present example, the ON / OFF signal (see FIG. 3A) supplied from the gray scale conversion circuit 42 to the laser driver 43 is kept in the OFF signal period during the OFF signal period without turning off the drive current, as shown in FIG. The threshold current I _S at which the semiconductor laser 10 starts oscillating is passed during the OFF period shown.

In this way, since there is almost no laser power as shown in FIG. 4, the recess 15 is not formed in the plate 2 similarly to the case where the drive current is set to zero so that the drive current does not flow during the OFF period. The swing width of the flow amount is the same as in the conventional
As shown in FIG. 3B, the time Δt ₁ required for rising the current up to the predetermined current setting value I is shorter than Δt, and the semiconductor laser power loss is small.

In the circuit of the laser driver 43, the drive current had to be changed up to about 1.5 A in the past, but it can be reduced to about 1 A. Therefore, the circuit configuration should be small in capacity. You can also

Further, if the ON period t ₃ of the OFF / OFF signal is short as shown in FIG. 7B, it may become I ₁ which does not reach the predetermined set value current I. Since the threshold current I _S , which is a current offset, is applied,
A large amount of current flows at the time of turning on, and it is possible to obtain the one that can reach the predetermined set value I even if the on period t ₃ is short.

In the above-mentioned embodiment, the method of setting the current value at the time of OFF to about the threshold current I _S of the semiconductor laser 10 has been described. This is because it is sufficient that the recess 15 is not formed in the plate 2 at the time of the OFF. A semiconductor laser may be oscillated as long as the laser power is such that it is not possible.

[0030]

According to the semiconductor laser plate making apparatus of the present invention, since the amount of change in current when the semiconductor laser is switched on and off is small, the time Δt ₁ required for switching from off to on is shortened. You will get less loss. In addition, since the current swing width of the laser driver circuit for driving the semiconductor laser is also small, a circuit having a small capacity power can be obtained accordingly.

[Brief description of drawings]

FIG. 1 is a perspective view of a semiconductor laser plate making apparatus according to the present invention.

FIG. 2 is a system diagram of a semiconductor laser plate making apparatus according to the present invention.

FIG. 3 is an explanatory diagram of waveforms of the semiconductor laser plate making apparatus of the present invention.

FIG. 4 is an emission-current characteristic diagram of a semiconductor laser used in the semiconductor laser plate making apparatus of the present invention.

FIG. 5 is a conceptual diagram of an optical system showing a conventional laser scanning system.

FIG. 6 is an ideal waveform explanatory diagram of a semiconductor laser used in a conventional semiconductor laser plate making apparatus.

FIG. 7 is an explanatory diagram of actual waveforms of a semiconductor laser used in a conventional semiconductor laser plate making apparatus.

[Explanation of symbols]

 1 plate cylinder 2 plate 10 semiconductor laser 43 laser driver 44 threshold setting circuit

[Procedure amendment]

[Submission date] March 24, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

The present invention relates to a semiconductor laser plate making apparatus which was set to form the Mino plate recess corresponding to the shade of image <br/> image data by using a semiconductor laser.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007] images input signal 16 taken in by an image scanner or the like is supplied to the semiconductor laser 10, on the drive current images input signal 16 has been turned into PCM, directly modulated off. Therefore the laser beam emitted from the semiconductor laser 10 flashes in synchronization with the images input signal 16. The laser beam emitted from the semiconductor laser 10 is collimated by the collimating optical system 12 and is irradiated through the focusing lens 13 so as to focus on the surface position of the plate 2.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Semiconductor laser 10 and collimating optical system 1
2. The laser block 14 including the focusing lens 13 is initially focused on a predetermined position on the leftmost end side of the plate cylinder 1.
Since the plate cylinder 1 is rotated in the direction of the arrow B by a plate cylinder rotating motor described later, when the plate cylinder 1 is rotated once, the depression 15 for one track along the circumference is scattered by the laser beam. Then, the depression 15 for one predetermined track is formed. Next, the laser block 14 is moved in the axial direction of the plate cylinder 1 for one pixel, and the synthetic resin material is scattered to form a predetermined recess 15 in two tracks. Such recesses 15 corresponding to the shade of by performing scanning sequentially over the entire surface of the plate cylinder 1 is a synthetic resin material images input signal 16 is formed.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

That is, the plate cylinder 1 is irradiated with a laser beam through a focusing lens 13, focuses on the surface of the synthetic resin plate 2 and melts the plate surface to scatter or sublime the synthetic resin.
In this case, on the modulated by images input signal 16 as described above in the semiconductor laser 10, Fig. 6A was made off signal
Is given, and the shade is determined by changing the area and depth of the depression 15 by the duration of the ON periods t ₁ , t ₂ , and t ₃ . In this case, the semiconductor laser 10
As shown in FIG. 6B, ideally, the current flowing in the zero period is zero during the off period, and a predetermined current I is passed during the on periods t ₁ , t ₂ , and t ₃ for plate making.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

[0015] Figure 1 shows a perspective view of a semiconductor laser plate making apparatus used in this example, 11 is a plate cylinder rotating unit 62 and the laser block moving unit 63 in a substantially rectangular shape on a steel sheet at the base of the semiconductor laser plate making apparatus It is provided. The plate cylinder rotating portion 62 is configured such that the substantially cylindrical plate cylinder 1 is rotatably pivoted between the left and right side walls 64L and 64R formed in a substantially V shape, and is rotated by the plate cylinder rotation motor 7 disposed on the right side wall 64R . The laser block 14 includes the semiconductor laser 10 and is moved along a guide portion 22 arranged along the axial direction of the plate cylinder 1.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

A plate 2 made of synthetic resin is wound and fixed along the outer circumference of the cylindrical portion of the plate cylinder 1. Metal caps 3L and 3R are fitted to the left and right of the plate cylinder 1, and left and right caps 3L and 3R
Shafts 4L and 4R formed integrally with the left and right side walls 64L and 64
It is rotatably attached to R. The shaft 4R is connected to a plate cylinder rotating motor 7 fixed on the right side wall 64R via a plurality of pulleys 6 ... And a belt 5 ..., and is wound around the plate cylinder 1 via these pulleys 6 and a belt 5. The printed plate 2 rotates in the direction of arrow A or B.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

In FIG. 2, the input operation unit 30 sends a status signal 31 such as stop or reset to a microcomputer (hereinafter C
It is referred to as PU) 32. The CPU 32 supplies a normal rotation or reverse rotation pulse to the laser block moving motor driver 33 and the plate cylinder rotating motor driver 35 to rotate the laser block moving motor 24 and the plate cylinder rotating motor 7. In the plate cylinder moving motor 7 to rotate the plate cylinder 1, the recesses 15 corresponding to the data of the images input signal 16 is formed on the plate surface with a semiconductor laser 10, the plate cylinder 1 is a laser block moving motor 24 After rotation is moved one pixel data content, depression corresponding to the shade of images along the circumference of the plate cylinder 1 15
The CPU 32 controls to make the. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 24, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (1)

Claim: What is claimed is: 1. A semiconductor laser plate making apparatus, wherein a semiconductor laser is used to form a recess in a plate in accordance with the density of image data, wherein the semiconductor laser forms the recess in the plate. A semiconductor laser plate making apparatus characterized in that a power loss is reduced by causing a current to flow near a threshold value of the oscillation of the semiconductor laser during an off period when the semiconductor laser is not oscillated.