JP3044123B2 - Ink amount detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink amount detecting device, and more particularly to an ink amount detecting device for detecting the amount of ink in an ink supply section of a stencil printing machine in a capacitive manner.

[0002]

2. Description of the Related Art As an ink amount detecting device for detecting an ink amount in an ink supply portion of a stencil printing machine for controlling ink supply, a detection electrode member and a ground electrode member opposed to each other across an ink reservoir portion are provided. An ink amount detecting device for detecting a change in the amount of ink in the ink reservoir based on a change in the capacitance between the two electrode members due to a change in the amount of ink between the two members has already been proposed. And Japanese Patent Publication No. 1-33352 and JP-A-62-146632.

[0003]

In the above-described capacitance type ink amount detecting apparatus, a circuit board constituting an ink amount detecting circuit, particularly a circuit board, is provided on the circuit board in order to stabilize the detecting operation. In order to minimize the stray capacitance between the oscillation circuit and the detection electrode member, the detection electrode member is preferably mounted directly on the ink amount detection circuit board.

When the detection electrode member is directly mounted on the ink amount detection circuit board, the position of the ink amount detection by the detection electrode member is limited in space due to the size of the ink amount detection circuit board. As a result, the degree of freedom in designing the ink supply unit of the stencil printing apparatus is reduced.

When the detecting electrode member is directly mounted on the ink amount detecting circuit board, the detecting electrode member must be disposed close to the ink reservoir, and the ink amount detecting circuit board is also mounted on the ink reservoir section. Therefore, there is an increased danger that the printing ink scatters on the circuit board for ink amount detection and adheres to the printing ink.
This is more noticeable as the printing ink is softer, and is particularly problematic for soft printing inks having a penetration value of 350 or more as measured by the JIS-K-2524 test method.

When the printing ink adheres to the circuit board for detecting the amount of ink, the electrical characteristics of the circuit board for detecting the amount of ink fluctuate, and the stability of the detecting operation is impaired. Therefore, conventionally, the printing ink is prevented from adhering to the circuit board for detecting the amount of ink by coating the circuit board for detecting the amount of ink with a mylar film or the like.

However, the coating of the circuit board for detecting the amount of ink with a mylar film or the like requires a coating material such as a mylar film and a coating operation, which further increases space restrictions.

The present invention has been made in view of the above-mentioned problems in the conventional ink amount detecting apparatus, and has been described in detail. It is an object of the present invention to provide an ink amount detecting device which does not impose any space restrictions on the ink jet head and does not need to cover the ink amount detecting circuit board with a mylar film or the like in order to prevent ink adhesion.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided an ink jet recording apparatus comprising: a detection electrode member sandwiching an ink reservoir inside a plate cylinder and a ground electrode member; In an ink amount detection device that detects a change in the amount of ink in the ink reservoir from a change in capacitance between members,
An input connected to the detection electrode member and the ground electrode member.
The circuit board for detecting the amount of ink comes from the ink reservoir inside the plate cylinder.
The detection electrode member is electrically connected to a circuit board for detecting the amount of ink by a center conductor of a coaxial cable, and the ground electrode member is connected to an outer conductor of the coaxial cable.
This is achieved by an ink amount detecting device which is connected to the ground.

[0010]

According to the above construction, the detecting electrode member and the ink amount detecting circuit board can be individually arranged, whereby the detecting electrode member can be reduced in size of the ink amount detecting circuit board. It is arranged close to the ink reservoir without being affected, whereas the circuit board for ink amount detection is
Apart from the detection electrode member, the printing ink is not scattered away from the ink reservoir portion, and can be arranged in a place excellent in assembling workability.

In this case, the detecting electrode member is electrically installed at a position distant from the ink amount detecting circuit board. However, the detecting electrode member has an outer conductor grounded to the ink amount detecting circuit board. Since the connection is made conductive by the center conductor of the coaxial cable, the stray capacitance between the oscillation circuit on the ink amount detection circuit board and the detection electrode member does not become so large as to cause a problem.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 1 shows an embodiment of an ink supply unit of a stencil printing machine equipped with an ink amount detecting device according to the present invention. In FIG. 1, reference numeral 1 indicates a cylindrical plate cylinder. The cylindrical plate cylinder 1 is made of an ink-permeable material such as a perforated metal plate, a mesh structure, or the like. The stencil paper (not shown) is wound around the outer peripheral surface.

The cylindrical plate cylinder 1 is rotationally driven clockwise in FIG. 1 around its own central axis by a plate cylinder rotation driving means (not shown). Is supplied to the press roller 3 while being moved from right to left in the figure in synchronization with the rotation of the cylindrical plate cylinder 1. Plate printing is performed on printing paper by being pressed against the base paper.

A squeegee device 5 for supplying ink is provided inside the cylindrical plate cylinder 1. The ink supply squeegee device 5 has left and right squeegee support side plates 7, and the left and right squeegee support side plates 7 are connected at one end to the cylindrical plate cylinder 1.
Are connected to each other by a connecting shaft 9 extending along the axial direction. A swing lever 11 is provided on the connecting shaft 9.
Is pivotally connected at one end thereof, and the swing lever 11 is rotatably supported at an intermediate portion by a support shaft 15 attached to a fixed frame (not shown), and rotates a cam follower roller 17 at the other end. We support as much as possible.

The cam follower roller 17 includes the swing lever 1
1 is urged in the counterclockwise direction in the figure by a spring (not shown) attached to the connection shaft 9 so that the cam shaft 21 is rotatably supported by the fixed frame body.
Of the cam 23. The camshaft 21 is rotated by a gear 25 in a one-to-one transmission relationship in synchronization with the rotation of the cylindrical plate cylinder 1.

The other end of the squeegee support side plate 7 is urged upward from the tension coil spring 31 in the figure, whereby the squeegee support plate 7 is fixed to the fixed frame 13 at the other end so that the mounting angle can be adjusted. Is in contact with

A squeegee support board 35 and a squeegee support mounting plate 39 fixedly mounted on the left and right squeegee support side plates 7 by screws 37 are laid between the left and right squeegee support side plates 7 in parallel with the axial direction of the cylindrical plate cylinder 1. It is attached in a manner as described above. The squeegee support board 35 and the squeegee support mounting plate 39 sandwich and support the base side of a squeegee blade 41 extending in parallel with the axial direction of the cylindrical plate cylinder 1.

The squeegee blade 41 is made of a rubber-like elastic material such as urethane rubber.
The cantilever is supported by the squeegee support mounting plate 39, and the leading edge, which is a free end, is pressed against the inner peripheral surface of the cylindrical plate cylinder 1 at a predetermined squeegee angle.

A spring plate 43 made of stainless steel is mounted on a back surface, that is, an upper surface of the squeegee blade 41 as a backup plate. The spring plate 43 is sandwiched between the squeegee support board 35 and the squeegee support mounting plate 39 together with the squeegee blade 41 on the base side, and is cantilevered by these.

The squeegee blade 41 is driven by the printing ink supplied from the ink supply pipe 45 to the cylindrical plate cylinder 1.
As a result, the ink reservoir P is formed on the side of the cylindrical plate cylinder 1 that is delayed from the contact position with the cylindrical plate cylinder 1 in the rotation direction, that is, in the triangular area on the right side of the contact position as viewed in FIG. The ink reservoir P is supported between the left and right side plates 47 of the squeegee support mounting plate 39 so as to be rotatable by a support shaft 49 extending parallel to the axial direction of the cylindrical plate cylinder 1. The arranged ink stirring pipe 51 is disposed.
The printing ink used here is JIS-K-2524
A soft printing ink having a penetration value of 350 or more as measured by the test method may be used.

The printing ink is supplied to the ink reservoir P through an ink supply pipe 45, and the printing ink dropped from the ink supply pipe 45 onto the inner peripheral surface of the cylindrical plate cylinder 1 is transferred to the cylinder plate 1 as shown in FIG. The rotation in the clockwise direction as seen in 1 shifts to the ink reservoir P and accumulates here. The printing ink in the ink reservoir P is rotated in the clockwise direction as viewed in FIG. Creates a vortex. The printing ink is laterally moved while being stirred by the eddy current around the ink stirring pipe 51 so that the volume in the horizontal direction (the axial direction of the ink stirring pipe 51) becomes uniform, and the squeegee blade 41 converts the printing ink into a cylinder. The cylindrical plate cylinder 1 is pushed into the cylindrical plate cylinder 1 from a leading edge portion which comes into sliding contact with the inner peripheral surface of the plate cylinder 1.

The control of ink supply to the ink reservoir P by the ink supply pipe 45 is performed in accordance with the amount of ink in the ink reservoir detected by an ink amount detector generally indicated by reference numeral 53 in FIG. It has become.

The ink amount detector 53 includes a mounting plate 59 fixed to a fixing member 57 by screws 55. The mounting plate 59 includes a horizontal portion 59a fixed to the fixing member 57 at a position sufficiently distant from the ink reservoir P, and a bent downward from one end of the horizontal portion 59a toward the vicinity of the ink reservoir P. And has a hanging portion 59b which is grounded via a screw 55 and a fixing member 57.

A circuit board 65 for detecting the amount of ink is fixedly mounted on the horizontal portion 59a of the mounting plate 59 with a screw 63 via a metal spacer 61 in a grounding conductive state. The position of the circuit board 65 for detecting the amount of ink is
This is a place where the ink is sufficiently scattered upward and the ink does not scatter, and the assembling workability is excellent. Various electric elements 67 and 69 constituting an oscillation circuit and the like are attached to the ink amount detection circuit board 65.

In the vicinity of the lower end of the hanging portion 59b of the mounting plate 59, an electrode mounting board 75 is fixedly mounted in an electrically insulated state by screws 73 made of an electrically insulating material via a spacer 71 made of an electrically insulating material such as plastics. ing. A needle-shaped detection electrode member 77 is attached to the electrode mounting board 75, and the detection electrode member 77 faces the plate cylinder 1 forming a ground electrode member with the ink reservoir P interposed therebetween, A change in capacitance between the plate cylinder 1 and the plate cylinder 1 due to a change in the amount of ink between the plate cylinder 1 is sensed.

The detection electrode member 77 is connected to a center conductor (core wire) 81 of the coaxial cable 79 by a circuit board 65 for detecting the amount of ink.
The coaxial cable 79 is electrically connected to the ground conductor of the ink amount detection circuit board 65, and the outer conductor (shield conductor) 83 is grounded.
The capacitance is about f / m.

In the case where the oscillation frequency of the ink amount detection by the capacitance is in the frequency band of 50 to 150 MHz, if the capacitance of the coaxial cable 79 is 64 pf / m, if the length of the coaxial cable 79 is 30 cm, Since the capacitance thereof is 21 pf, the maximum safe length of the coaxial cable 79 which does not substantially affect the oscillation circuit is 30 cm.
About.

Therefore, in this case, the ink amount detection circuit board 65 and the detection electrode member 77 can be arranged at individual positions separated from each other within a range of 30 cm, and if there is an allowance of 30 cm, In either case,
As shown in the figure, the detection electrode member 77 is disposed at a position appropriately approaching the ink reservoir P for detecting the amount of ink without being affected by the size of the circuit board 65 for detecting the amount of ink. The detection circuit board 65, apart from the detection electrode member 77, is located at a place sufficiently separated from the ink reservoir P as described above so that ink does not scatter from this part and the assembly workability is excellent. Will be different.

FIG. 2 shows another embodiment of the ink supply unit of the stencil printing machine equipped with the ink amount detecting device according to the present invention. In FIG. 2, parts corresponding to those in FIG. 1 are indicated by the same reference numerals as those in FIG. In the embodiment shown in FIG. 2, the horizontal portion 59a and the hanging portion 59b of the mounting plate 59 are formed by different members,
The horizontal portion 59a and the hanging portion 59b are separably connected by bolts 85.

In this case, when attaching the ink amount detecting device 53 to the inside of the cylindrical plate cylinder 1, the horizontal portion 59a of the mounting plate 59 is mounted on the fixing member 57 with the hanging portion 59b separated, and thereafter the mounting plate 59 is mounted. Hanging part 5 on horizontal part 59a
9b can be attached by bolts 85,
The degree of freedom of the assembling procedure is improved, and the workability of assembling is improved.

The horizontal portion 59a and the hanging portion 59b of the mounting plate 59
Is formed of a separate member, the horizontal portion 59a
The horizontal portion 59a is made of a grounded conductive material because of the stability of the high frequency circuit of the ink amount detection circuit board 65. The hanging part 59b can be made of an electrically insulating material such as plastics in order to avoid malfunction due to ink adhesion to the hanging part 59b.

The horizontal portion 59a and the hanging portion 5 of the mounting plate 59
9b may be individually fixedly arranged in the cylindrical plate cylinder 1. Further, the hanging portion 59b of the mounting plate 59 is omitted, and the detecting electrode member 77 is connected to the center conductor 81 of the coaxial cable 79 by the ink amount detecting circuit board. It may be directly fixedly arranged in a state where it is electrically connected to 65.

Further, as shown in FIGS.
The electrode mounting board 75 may also be omitted, and the detection electrode member 77 may be directly formed by the center conductor 81 of the coaxial cable 79, and may be directly disposed in the ink reservoir P. In this case, an end portion of the outer conductor 83 of the coaxial cable 79 on the detection electrode side is insulated and coated with an insulating material or the like as indicated by reference numeral 87 in the figure.

[0035]

As will be understood from the above description, according to the ink amount detecting device of the present invention, the detecting electrode member is conductively connected to the ink amount detecting circuit board by the coaxial cable, and the detecting electrode member is connected to the ink detecting member. Since the circuit boards for detecting the amount of ink are individually arranged, the detection electrode member does not increase in the amount of ink without causing the stray capacitance between the oscillation circuit on the circuit board for detecting the amount of ink and the detection electrode member to become a problem. The ink amount detecting circuit board is arranged close to the ink reservoir without being affected by the size of the detection circuit substrate, and the ink is not separated from the ink reservoir and separated from the ink reservoir. Since it is arranged in a place excellent in assembling workability, even if a softer ink is used than before, there is no possibility that the ink amount detecting circuit is soiled by the ink. From these facts, the stability of the detection operation, the degree of freedom in designing the arrangement position of the detection electrode member and the ink supply unit, and the assemblability are improved.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of an ink supply unit of a stencil printing machine equipped with an ink amount detection device according to the present invention.

FIG. 2 is a side view showing another embodiment of the ink supply unit of the stencil printing machine equipped with the ink amount detecting device according to the present invention.

FIG. 3 is a side view showing a main part of another embodiment of the ink amount detecting device according to the present invention.

FIG. 4 is a side view showing a main part of another embodiment of the ink amount detecting device according to the present invention.

FIG. 5 is a side view showing another embodiment of the ink amount detection device according to the present invention, concerning a main part thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical plate cylinder 3 Press roller 5 Ink supply squeegee device 41 Squeegee blade 53 Ink amount detection device 65 Ink amount detection circuit board 75 Electrode mounting board 77 Detection electrode member 79 Coaxial cable P Ink reservoir

Claims (1)

(57) [Claims] 1. A plate cylinder internal in the ink to the ink reservoir from the change in capacitance between the two electrode members due to ink amount changes between the ink reservoir and the detection electrode member sandwiching the ground electrode member In an ink amount detecting device for detecting an amount change, an ink connected to the detection electrode member and the ground electrode member.
The circuit board for detecting the amount of ink comes from the ink reservoir inside the plate cylinder.
The detection electrode member is electrically connected to a circuit board for detecting the amount of ink by a center conductor of a coaxial cable, and the ground electrode member is connected to an outer conductor of the coaxial cable.
Ink amount detecting apparatus characterized by being ground connection to.