JPH056515B2 - - Google Patents

Description

Detailed Description of the Invention - Field of Industrial Application - The present invention relates to a printer used as an output device for an information processing system. This invention relates to a printer that is particularly characterized by its forming method.

-Summary of the Invention- The printer of the present invention presses a surface of a print medium having a large number of minute conical protrusions facing the printing surface onto the printing surface by utilizing expansion due to the local piezoelectric effect of a piezoelectric plate. This device forms dots on the printing surface consisting of a collection of minute images with an area corresponding to the pressing area of the pyramidal protrusions acting on the printing surface. By changing the voltage value, it is possible to make the dots formed on the printing surface have shading.

-Prior Art- Printers currently commonly used as output devices for information processing systems use dots as image elements, and by controlling the printing position of the dots on the printing surface, a desired image can be printed on the printing surface. Characters and figures are formed by a collection of dots.

-Problems to be Solved by the Invention- However, when printing graphic information with shading, such as a photograph, using such a conventional printer, the shading of the printed figure is determined by the number of dots formed per unit area. must be expressed by numbers,
Since it was not possible to change the density of the dots themselves, in order to express smooth gradations of light and shade, it was necessary to increase the number of dots printed per unit area. For example, wire dot printers require thinner wires and densely arranged wires, while inkjet printers and laser printers require smaller ink droplets and laser beam irradiation spots to more precisely control their trajectory and irradiation angle. Not only does the structure of the printing head and its control become complicated, which reduces the printing speed, but there are also physical limitations to reducing the size of the dots, which limits the ability to express light and shade. There was a drawback.

Furthermore, with conventional printers that cannot change the printing density of the dots themselves, it has been completely impossible to create shading in lines expressed by arranging dots in a row.

This invention was made for the purpose of obtaining a technical means that can change the printing density of the dots themselves, which are image elements when printing characters and figures. The present invention provides a printer that can continuously change the density gradation of printed characters and figures.

-Means for Solving the Problems- FIG. 1 is a diagram showing the principle of image element forming means in an embodiment of the present invention. The technical means adopted by the present invention to solve the above problems will be explained below with reference to FIG.

In the printer of the present invention, a flexible piezoelectric plate 2 in which piezoelectric ceramics are dispersed in a piezoelectric polymer or a carrier is arranged opposite to the printing surface of the print medium 1.
Electrodes 3 and 4 are provided to locally apply an operating voltage to the piezoelectric plate 2. This piezoelectric plate 2 is formed into an endless shape, is wound around between pulleys 11 and 12, and is rotated at the same speed as the moving speed of the carrier 18, that is, the relative moving speed of the printing medium 1. On the surface of this piezoelectric plate 2 facing the printing medium 1,
A hard surface 6 is formed with a large number of minute conical projections 5, 5a, etc., and when a voltage is applied between the electrodes 3 and 4, the expanded portion is caused by local expansion of the piezoelectric plate 2. The conical protrusions 5a...5a are pressed against the printing surface of the printing medium 1, and minute images 7a..., 7b..., produced by the pressing of the tips of the conical protrusions 5a against the printing surface of the printing medium 1. Image elements (dots) 8a, 8 consisting of a set of 7... (see Figure 2)
b, 8c are formed.

In the one shown in FIG. 1, an ink layer 9 is interposed between the printing medium 1 and the surface 6 on which the conical projections 5, 5a, . . .
The structure is such that the image elements 8a to 8c are formed by pressing the ink onto the printing medium 1 and transferring the ink to the printing medium 1. However, by using a pressure-sensitive coloring type printing medium, the ink layer 9 can be transferred to the printing medium 1. It is also possible to have a structure without it.

- Effect - Piezoelectric plate 2 by voltage applied from electrodes 3 and 4
The amount of expansion varies depending on the voltage value. Therefore, if a large voltage is applied, the conical protrusions 5a...5a at the voltage applied portions will apply a large force to the printing medium 1.
As a result, the tip of the conical protrusion 5a digs into the print medium 1 that much more. That is, the area of the conical protrusion 5a that is pressed against the print medium 1 changes depending on the value of the applied voltage, and when a weak voltage is applied, a collection of minute images 7a with a small area as shown in FIG. 2a is created. When a strong voltage is applied, an image element 8a consisting of an image element 8c becomes an image element 8c consisting of a set of relatively large-area minute images 7c as shown in c in the same figure.
is formed on the print medium 1. This image element 8a,
8b and 8c form dots of a size determined by the size of the tip of the electrode 3, and a desired character or figure is formed on the printing surface by a collection of these dots.

The piezoelectric plate 2 is rotated at the same speed as the relative movement speed of the printing medium 1, and therefore no relative slippage occurs between the protrusion forming surface 6 of the piezoelectric plate 2 and the printing medium 1, so that the conical protrusion 5a The leading edge of the printing medium does not scratch the surface of the printing medium, and therefore, it is possible to form dots consisting of clear, point-like minute images 7a, 7b, and 7c on the printing surface.

That is, in the printer of the present invention, the density of the dots themselves, which are elements of characters or figures, can be continuously changed by the voltage value applied between the electrodes 3 and 4, and the dots can be continuously printed at a relatively coarse density. This makes it possible to print characters and figures with different density gradations.

-Embodiment- Figures 1 to 4 are diagrams showing an embodiment of the printer of the present invention, and in Figure 3, 1 is a print medium;
2 is a flexible piezoelectric plate, and the piezoelectric plate 2 is formed into an endless shape and is wound between pulleys 11 and 12. Reference numeral 13 denotes a pulley that faces the pulley 11 and holds the piezoelectric plate 2 therebetween, and the pulley 11 is rotationally driven by a drive mechanism (not shown) to rotate the piezoelectric plate 2 in the direction of arrow A in the figure. 14 is a head unit for locally applying an operating voltage to the piezoelectric plate 2; 15;
1 is an ink ribbon interposed between the piezoelectric plate 2 and the print medium 1, and 16 and 17 are ribbon guides.

The head unit 14, pulleys 11 to 13, and ink ribbon 15 are mounted on a carrier 18, and this carrier 18 is structured to move in the direction of arrow B in the figure at a speed synchronized with the rotation speed of the piezoelectric plate 2. .

The piezoelectric plate 2 is provided with a large number of fine conical projections 5...5 as shown in FIG. 1 on the entire surface of the outer surface 6 in the figure.

Inside the head unit 14, a large number of electrode pins 3...3 are arranged as shown in FIG.
Its tip is in sliding contact with the inner surface of the piezoelectric plate 2. 4
is an electrode plate on the ground side that covers the entire outer surface of the piezoelectric plate 2, and this electrode plate 4 has an end that is connected to the piezoelectric plate 2.
It is bent to the outside and exposed, and the electrode pin 4p is in sliding contact with this. And electrode pin 4p
As shown in FIG. 1, the structure is such that the piezoelectric plate 2 is locally expanded by applying an operating voltage between the piezoelectric plate 2 and a desired one of the electrode pins 3...3. The electrode pins 3 . . . 3 may be arranged, for example, in the same manner as the wires of a known wire dot type printing head. Of course, the electrode pins 3...3 are not driven in the axial direction like the wires of a wire dot printer, but voltage is simply applied to selected ones.

In the above structure, when the carrier 18 is moved in the direction of arrow B in synchronization with the rotational speed of the piezoelectric plate 2, the piezoelectric plate 2 moves opposite to the printing medium 1. At this time, there is no relative velocity difference between the piezoelectric plate 2 and the printing medium 1. During this movement, a voltage is applied to desired ones of the electrode pins 3...3 of the head unit 14, and by controlling the voltage value, minute images 7a... to 7c... as shown in FIGS. 2a to 2c are created. Dots 8a to 8c consisting of a set of
can be formed on the print surface of the print medium 1, and by a collection of these dots 8a to 8c, characters and figures can be printed in the same way as with conventional printers. Printed dots 8a to 8
Since the concentration of c changes in an analog manner as shown in Figure 2 a to c by controlling the voltage value applied to the electrode pins 3... It is possible to print characters and figures that have stepwise density gradations.

In the above embodiment, the ink of the ink ribbon 15 is transferred to the print medium 1 by pressing the conical projection 5, but for example, an ink supply roller is used to transfer the ink that has been attached to the conical projection 5 in advance to the conical projection 5. It is also possible to have a structure in which the images are transferred to the printing medium 1 by pressing the conical projections 5. If a pressure-sensitive coloring type medium is used as the printing medium, the minute images 7a to 7c can be transferred only by the pressing of the conical projections 5. can be formed.
In addition to the quadrangular pyramid shape shown in the drawing, the conical projection 5 may have a conical shape, a triangular pyramid shape, a hexagonal pyramid shape, or the like.

5 and 6 show other electrode configurations that can be adopted to apply a local voltage to the piezoelectric plate 2. The one shown in FIG. The ground side electrode is a large number of vertical strip-shaped electrodes 4a.
...4a, and the electrode on the voltage application side is formed by attaching a large number of horizontal strip-shaped electrodes 3a...3a to the inside of the piezoelectric plate 2, and these electrodes 3a...3a and 4a...4a are Brushes 23...23 and 24 are in sliding contact. Thin strip electrodes 3a...3a and 4a...4
a cross within the plane of the piezoelectric plate 2, and an operating voltage is locally applied to the piezoelectric plate 2 at the intersection of selected vertical and horizontal electrodes.

Furthermore, in the one shown in FIG. 6, the ground side electrode 4 is a flat electrode attached to the outside of the piezoelectric plate 2, and a large number of voltage application electrodes 3b...3b are arranged inside the piezoelectric plate 2. A brush 24 is in sliding contact with the electrode 4, and voltage is supplied from the brushes 23 to the electrodes 3b at a predetermined timing to print dots.

-Effects of the Invention- As explained above, according to the printer of the present invention, it is possible to change the density of the dots themselves, which are the forming elements of characters and figures, in continuous gradations, and therefore the dots can be It is possible to print characters and figures with continuous density gradation regardless of roughness.
Since halftones can be expressed freely, a printer that is extremely suitable for printing photographic information and the like can be obtained.

[Brief explanation of the drawing]

Figures 1 to 4 are diagrams showing one embodiment of the present invention. Figure 1 is a diagram schematically showing the principle structure, Figure 2 is an enlarged view of printed dots, and Figure 3 is a diagram of the printer. FIG. 4 is a perspective view schematically showing the main structure, and FIG. 4 is a perspective view showing the electrode structure. FIGS. 5 and 6 are perspective views showing second and third embodiments of a structure for locally applying a voltage to a piezoelectric plate. In the figure, 1: printing medium, 2: flexible piezoelectric plate, 3,
3a, 3b: electrode, 4, 4a: electrode, 5: pyramidal projection, 6: protrusion formation surface, 7a to 7c: minute image, 8
a to 8c: image element, 9: ink layer.

Claims (1)

[Claims] 1 An endless flexible piezoelectric plate 2 provided with electrode pairs 3 and 4 to which an operating voltage can be applied locally is wound between pulleys 11 and 12, and its outer peripheral surface is used as a printing medium 1.
is rotated at the same speed as the relative movement speed of the printing medium 1, and a surface on which fine conical projections 5, 5a are arranged is provided on the outer peripheral surface facing the printing medium 1,
The pressing force of the conical protrusions 5, 5a generated by local biasing of the piezoelectric plate 2 is applied to the printing surface of the printing medium 1, and the area corresponding to the pressing area of the conical protrusions 5, 5a applied to the printing surface is A pressure transfer printer characterized in that dots 8a, 8b, 8c consisting of a set of minute images 7a, 7b, 7c are formed on a printing surface.