JPH037176Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention relates to an etching processor for etching a printing plate used in a lithographic offset printing machine, and in particular to an etching processor that automatically moves the printing plate back and forth within an etchant. .

(Background Art) There are various types of plate materials used in lithographic offset printing machines. For example, there are those in which the surface of an aluminum plate material is coated with a photosensitive resin, those in which a silver salt compound is coated on paper as a photosensitive material, and those in which zinc oxide is coated on the surface of paper as a photosensitive material. Among these, plate materials using zinc oxide as a photosensitive material (hereinafter referred to as zinc oxide photosensitive plate materials) are superior in cost to other plate materials and are widely used in the light printing industry.

FIG. 1 is a diagram showing the structure of a zinc oxide photosensitive plate material. Zinc oxide photosensitive plate material has zinc oxide resin photosensitive layer 1
01, a conductive barrier layer 102, a base paper 103,
The conductive back layer 104 is made up of a conductive back layer 104.
The zinc oxide resin photosensitive layer 101 is made by adsorbing a sensitizing dye to zinc oxide (ZnO) and dispersing it in an acrylic resin, which is then coated and dried. This is because zinc oxide does not show sensitivity in the visible light region as it is, so visible light is absorbed by dye sensitization.
The conductive barrier 102 contains a conductive treatment agent that contains moisture and provides conductivity, adsorption of moisture due to changes in relative humidity,
It is made of kaolin and water-based resin to prevent desorption. The base paper 103 is made of a material that is water resistant and mechanically strong so that the plate does not stretch as much during printing. The conductive treated back layer 104 is made of the same material as the conductive barrier layer 102, but has a lower electrical resistance than the treated layer on the photosensitive layer side.

The zinc oxide photosensitive plate material is further made into a printing plate by a plate making machine using an image forming method using photoelectric effect and electrostatic phenomenon.

FIG. 2 is a block diagram showing the plate making process using a plate making machine. The plate making process includes a charging process 201, an exposure process 202, a developing process 203, and a fixing process 204. The charging step 201 is a step of applying a charge to the surface of the photosensitive layer of the plate material by applying corona discharge from a corona wire to the photosensitive layer in a dark place.
The exposure step 202 is a step in which a light image formed by an optical system is applied to the surface of the photosensitive layer for exposure, and electrical energy stored in the photosensitive layer in the form of electrostatic charges is canceled out by the energy of the exposure to form a latent image. It is. The developing step 203 is a step in which colored charged particles (toner) having a polarity opposite to that of the latent image are attached onto the latent image using electrostatic attraction. The fixing step 204 is a step in which the toner particles adhering to the photosensitive layer of the plate material by electrostatic attraction are fused to the photosensitive layer by heating or pressure, and the resins of the toner particles melt with each other to form a resin layer in the image area. It is. The resin layer in the image area that has passed through the charging step 201, the exposure step 202, and the developing step 203 is made of an acrylic or polystyrene thermoplastic resin, or a pigment such as carbon black, and thus exhibits lipophilicity. Further, the resin on the surface of the zinc oxide resin photosensitive layer is essentially lipophilic. Therefore, the entire surface of the plate made will exhibit lipophilic properties. Therefore, it cannot be used as a printing plate as it is, and requires etching treatment as described below.

In order to make the zinc oxide resin photosensitive layer in the non-image area of the printing plate hydrophilic, an etching process is performed by immersing it in a processing liquid called an etchant. The etch solution is a processing solution containing acidic salts such as phosphates, ferrocyanide salts, ferricyanide salts, etc. and a wetting agent as an auxiliary component. Ink does not adhere to non-image areas that have been rendered hydrophilic by the etchant. The reason is explained as follows. The zinc oxide photosensitive layer is made up of randomly laminated dot-like protrusions of a few micrometers in which zinc oxide particles aggregate and columnar zinc oxide particles with an average size of 0.3 micrometers.
It is in a state where there are many voids where particles are attached to each other with resin. The zinc oxide particles in the surface layer that adsorb a thin layer of resin react with the phosphoric acid of the etchant and dissolve, forming a kind of cavity. The resin around this cavity contains OH groups and COOH groups necessary for dispersing zinc oxide.
Since it has a portion of hydrophilic groups such as hydroxyl groups, it can easily hold the etchant through capillary action. In this way, the originally existing voids and the cavities created by the hydrophilic treatment retain the etchant, so that ink does not adhere. If ink directly adheres to the zinc oxide photosensitive layer, it will adhere to the resin and cannot be removed. Since the printing plate with the zinc oxide photosensitive layer has the above-mentioned properties, it is necessary to make the surface hydrophilic with an etchant after the plate is made and before it is installed in a printing machine.

Conventionally, the etching process has been carried out by hand etching, in which absorbent cotton or the like is impregnated with an etchant and manually applied to the surface of the printing plate. In hand etching, the etchant is manually pushed onto the surface of the printing plate, so the etching process can be carried out satisfactorily, but the amount of etchant used for one printing plate is large, and it is difficult to apply it evenly. This method has disadvantages such as difficult etching, which causes uneven etching, and the operator's hands become dirty.
For this reason, automatic etching has come to be performed by an etching processor, which will be described later.

(Prior Art) FIG. 3 is a schematic sectional view showing a conventional example of an etching processor.

A liquid dish 1 contains an etch liquid 2. A replenishment bottle (not shown) is provided in the liquid tray 1 to keep the etchant 2 at a constant level at all times. The guide plates 3 and 4 are plates for guiding the printing plate 12 to the liquid tray 1. The surfaces of the guide plates 3 and 4 are made of a material and shaped so as not to damage the surface of the printing plate 12 and not to interfere with the conveyance of the printing plate 12. The feed rollers 5 and 6 are rollers that are driven by a motor (not shown) to convey the printing plate 12. The rubbing roller 7 serves to rub the etchant 2 onto the surface of the printing plate 12.
The contact plate 13 is a plate for providing sufficient contact force between the rubbing roller 7 and the printing plate 12. Backing plate 13
also serves as a guide plate for guiding the printing plate 12 within the liquid tray 1 and aiding its conveyance. Feed roller 10,1
Like the feed rollers 5 and 6, the rollers 1 are driven by a motor (not shown) and rotate at the same rotation speed. The feed rollers 10 and 11 also have the function of squeezing out the etchant 2 adhering to the surface of the printing plate 12. Guide plates 8 and 9 are also provided on the discharge side, and the same considerations as for guide plates 3 and 4 are taken.

Printing plate 12 inserted between guide plates 3 and 4
is fed into the etchant 2 in the liquid tray 1 by feed rollers 5 and 6. Inside the liquid dish 1, the backing plate 1
The etching liquid 2 is rubbed into the printing plate 12 by the rubbing roller 7 and the rubbing roller 7, and the etching process is performed.
Thereafter, the printing plate 12 is conveyed by the feed rollers 10 and 11 while squeezing the etchant 2, and is guided by the guide plates 9 and 10 and discharged.

Such an etching processor has a drawback in that when the rubbing roller 7 rubs the etching liquid 2 onto the surface of the printing plate 12, the frictional force is insufficient, so that the etching process cannot be completed completely.
In order to compensate for this, the printing plate 12 that has been sent out from the guide plates 8 and 9 on the outlet side after the etching process must be inserted again through the guide plates 3 and 4 on the inlet side and the etching process must be performed again. Therefore, it took time and effort to perform a sufficient etching process.

(Purpose of the invention) An object of the invention is to provide an etching processor that can efficiently carry out sufficient etching processing by reciprocating a printing plate once inserted within the apparatus without having to take it out.

(Structure of the invention) In order to achieve the above object, the etching processor according to the invention includes an inlet-side feed roller for conveying a printing plate, and a roller for rubbing an etchant into the printing plate conveyed by the inlet-side roller. an etching processing section consisting of a rubbing roller and a backing plate; a discharge side feed roller that conveys the etched printing plate to the discharge side; a motor that rotates each of the rollers; and a motor drive circuit that drives the motor. An etching processor comprising: a plate detection switch that detects and outputs the passing of the printing plate at the inlet side; and a plate detection switch that detects the passing of the printing plate at the entrance side and outputs a signal for a set period of time when the plate detection switch detects the passing of the trailing edge of the printing plate. a first timer circuit that operates, a second timer circuit that operates for a set time after the first timer circuit finishes operating, and a latch that controls the plate detection switch to activate or deactivate the motor drive circuit. and a motor reversal relay that is operated for the time set by the second timer circuit.

According to the above structure, the object of the present invention can be completely achieved.

(Embodiment) FIG. 4 is a schematic sectional view showing an embodiment of the etching processor according to the present invention. Note that parts having the same functions as those of the conventional example described above are given the same reference numerals.

A liquid dish 1 contains an etch liquid 2. A replenishment bottle (not shown) is provided in the liquid tray 1 to keep the etchant 2 at a constant level at all times. The guide plates 3 and 4 are plates for guiding the printing plate 12 to the liquid tray 1. The surfaces of the guide plates 3 and 4 are made of a material and shaped so as not to damage the surface of the printing plate 12 and not to interfere with the conveyance of the printing plate 12. The feed rollers 5 and 6 are rollers that are driven by a motor (not shown) to convey the printing plate 12. The rubbing roller 7 serves to rub the etchant 2 onto the surface of the printing plate 12.
The contact plate 13 is a plate for providing sufficient contact force between the rubbing roller 7 and the printing plate 12. Backing plate 13
also serves as a guide plate for guiding the printing plate 12 within the liquid tray 1 and aiding its conveyance. Feed roller 10,1
Like the feed rollers 5 and 6, the rollers 1 are driven by a motor (not shown) and rotate at the same rotation speed. The feed rollers 10 and 11 also have the function of squeezing out the etchant 2 adhering to the surface of the printing plate 12. Guide plates 8 and 9 are also provided on the discharge side, and the same considerations as for guide plates 3 and 4 are taken.

The printing plate detection switch 14 is a switch for detecting that the printing plate 12 is inserted.
It turns on when the leading edge of the terminal contacts the terminal, and turns off after the rear end passes through.

FIG. 5 is a block diagram showing an embodiment of a control circuit for controlling an etching processor according to the present invention;
FIG. 6 is a waveform diagram for explaining the operation when reciprocating the printing plate.

The output of the printing plate detection switch 14 is the latch circuit 1.
7, connected to timer circuits 18, 19 and motor drive circuit 21.

The changeover switch 15 is a switch for selecting one-way feeding of the printing plate 12 as in the conventional case.
The changeover switch 16 is a switch for selecting the reciprocating feed operation according to the present invention. The reason why it is possible to perform one-way feeding is to allow the user to select which operation to perform, since there may be cases where it is not desirable to have two-way feeding depending on the printing plate 12, etchant 2, etc. . The output of the changeover switch 15 is connected to the timer circuit 18, and the output of the changeover switch 15 is connected to the timer circuit 18.
The output of 6 is connected to a timer circuit 19.

The timer circuit 18 is a circuit that operates for a set time when the one-way feed operation is selected by the changeover switch 15 and the printing plate detection switch 14 is turned off, and its output is sent to the motor drive circuit 2.
Connected to 1.

The latch circuit 17 regulates the operation of the motor drive circuit 21 when the changeover switch 16 is selected.
It is connected to the.

The timer circuit 19 is a circuit that operates for a set time when the reciprocating operation is selected by the changeover switch 16 and the printing plate detection switch 14 is turned off. The output of the timer circuit 19 is branched, one side is connected to the motor drive circuit 21,
The other end is connected to the timer circuit 20. The timer circuit 20 is a circuit that is activated when the set time of the timer circuit 19 ends. The output of the timer circuit 20 is branched and connected to a reset terminal of the latch circuit 17, a motor drive circuit 21, and a motor reversal relay 23.

The motor drive circuit 21 is a circuit that drives and stops the motor 22 based on the above-mentioned signals. The motor 22 is a motor for rotating the feed rollers 5, 6, 10, 11 and the rubbing roller 7. The motor reversing relay 23 is a relay for reversing the rotation of the motor 22 based on the output of the timer circuit 20.

Next, the operation of an embodiment of the etching processor according to the present invention will be explained.

It is assumed that the reciprocating feed operation is selected by the changeover switch 16 at time _t1 (FIG. 6b).

The printing plate 12 is placed on the guide plate 3 on the insertion side, and the leading end is fed to the feed rollers 5 and 6. At this time, at time _t2 , the leading edge of the printing plate 12 is detected by the printing plate detection switch 1.
4 (Figure 6a). Also, latch circuit 1
7 enters the set state at the time (t ₀ ) when a power switch (not shown) is turned on (FIG. 6i). Since the on signal of the printing plate detection switch 14 and the latch circuit 17 are in the set state, the motor drive circuit 21
The motor 22 starts rotating in the forward direction via (FIG. 6f, h). As a result, the feed roller 5,
6, 10, 11 and the rubbing roller 7 rotate, and the printing plate 12 is fed into the etchant 2 in the liquid tray 1. The printing plate 12 passes between the rubbing roller 7 and the backing plate 13 and is subjected to an etching process. Since the backing plate 13 also serves as a guide plate, the leading edge of the printing plate 12 is guided to the feed rollers 10 and 11 on the discharge side. Since the feed rollers 10 and 11 are rotating, the printing plate 12 is discharged onto the guide plate 8 on the discharge side.

The plate detection switch 14 is turned off at time _t3 after the rear end of the plate 12 has passed (FIG. 6a).
The timer circuit 19 is activated (FIG. 6d). The timer circuit 19 operates for a set time _T1 . The set time _T1 of the timer circuit 19 is such that the rear end portion of the printing plate 12 can pass between the rubbing roller 7 and the backing plate 13, and the rear end portion of the printing plate 12 can pass between the feed roller 1 on the discharge side.
It is set to a time that does not pass through 0 and 11.

When the set time T ₁ of the timer circuit 19 has elapsed, t ₄
The timer circuit 20 starts operating at the falling edge of the time point (FIG. 6e). Also, at this time, the latch circuit 17 is reset (FIG. 6c). When the motor reversing relay 23 is energized by the operating signal of the timer circuit 20 (FIG. 6g), the motor 22 rotates in the opposite direction (FIG. 6h). Therefore, the feed rollers 10, 11, 5, 6 and the rubbing roller 7 are rotated in the reverse direction. The printing plate 12 is again exposed to the etchant 2 in the liquid tray 1.
The printing plate 12 is fed into the rubbing roller 7.
The etching process is completely performed by passing between the plate 13 and the backing plate 13. The printing plate 12 is conveyed by the feed rollers 5 and 6, and the printing plate detection switch 14 is turned on and off at time _t5 (Fig. 6a), but since the latch circuit 17 has been reset (Fig. 6c). ), the motor drive circuit 21 does not operate even when the printing plate detection switch 14 is turned on (FIG. 6 f, g,
h).

When the set time _T2 of the timer circuit 20 has elapsed at time _t7 (Fig. 6 e), the motor reversal relay 23 is turned off (Fig. 6 g), and the motor 22 stops (Fig. 6 f, h). ).

The latch circuit 17 is set by this signal since the plate detection switch 14 is turned off when the plate 12 is removed from the guide plate 3 on the insertion side (FIG. 6c).

When the one-way operation is selected by the changeover switch 15, the printing plate detection switch 14 detects the printing plate 12.
The motor drive circuit 21 is activated to rotate the motor 22 in the forward direction. Printing plate 12
When the printing plate detection switch 14 is turned off due to the passing of the rear edge, the timer circuit 18 is activated, and after the set time has elapsed, the motor drive circuit 21 is deactivated, and the motor 2 is turned off.
Stop the rotation of 1.

(Effects of the invention) As explained in detail above, according to the invention,
The printing plate is automatically reciprocated within the etchant in a single operation similar to the conventional method, eliminating the problem of insufficient etching.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of a zinc oxide photosensitive plate. FIG. 2 is a block diagram showing the plate-making process using a plate-making machine. FIG. 3 is a schematic sectional view showing a conventional example of an etching processor. FIG. 4 is a schematic sectional view showing an embodiment of the etching processor according to the present invention, FIG. 5 is a block diagram showing an embodiment of a control circuit for controlling the etching processor according to the present invention, and FIG. 6 is a printing plate. FIG. 4 is a waveform diagram for explaining the operation when reciprocating the . 1... Liquid dish, 2... Etch liquid, 3, 4, 8, 9
... Guide plate, 5, 6, 10, 11 ... Feed roller, 7 ... Rubbing roller, 12 ... Printing plate, 13
...Passing plate, 14...Plate detection switch, 15,
16... Selector switch, 17... Latch circuit, 1
8, 19, 20...Timer circuit, 21...Motor drive circuit, 22...Motor, 23...Relay for motor reversal.

Claims (1)

[Scope of utility model registration request] an etching processing section consisting of an entrance side feed roller for conveying the printing plate, a rubbing roller and a patch plate for rubbing etching liquid onto the printing plate conveyed by the entrance side roller, and the printing plate that has been subjected to the etching process. a discharge side feed roller that conveys the
The etching processor includes a motor that rotates each of the rollers and a motor drive circuit that drives the motor, and includes a plate detection switch that detects and outputs passage of the plate at an inlet side; a first timer circuit that operates for a set time when detecting passage of the trailing edge of the printing plate; a second timer circuit that operates for a set time after the operation of the first timer circuit is completed; An etching processor characterized in that the printing plate detection switch is composed of a latch circuit that controls the motor drive circuit to be activated or inactivated, and a motor reversal relay that is activated for the time set by the second timer circuit. Setusa.