JPH0582306B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal printing device used as a printer such as a world processor or a typewriter.

FIG. 1 is a plan view of a thermal printing apparatus for explaining the prior art, and FIG. 2 is an equivalent circuit diagram thereof. In this thermal printing device, a large number of resistance heating elements 2 forming heating dots are formed in a row in the left-right direction in FIG. 1 on one surface of a flat substrate 1 made of an electrically insulating material such as ceramics or glass. has been done. A common conductor 3 is connected to the upper end of one end of the resistance heating element 2. Further, at the lower end of the other end of the resistive heating element 2, a plurality of individual drive signal lines generally indicated by reference numerals A1 to An are formed at intervals from each other. The individual drive signal lines A1 to An are collectively designated by the reference mark Da1 of the integrated circuit elements D1 to Dn.
A plurality of terminals Da1 to Dan indicated by ~Da2 are connected. The integrated circuit elements D1-Dn include a plurality of control signal lines, generally indicated by the references B1-B2, and the integrated circuit elements D1, indicated generally by the reference numerals E1-En.
The power feed paths E1 to En, which supply current to the respective resistance heating elements 2 through Dn, are connected to a plurality of terminals of the integrated circuit element D1, generally indicated by reference symbols Db1 to Dbn, and terminals De.
1 to Den, respectively.

The integrated circuit element D1 responds to a control signal input via the control signal line B1, and selectively connects the power supply line E1 and each of the individual drive signal lines A1 to conduction. Each of the individual drive signal lines A1 is individually connected to the resistance heating element 2. Note that the same applies to the remaining integrated circuit elements D2 to Dn.

In FIG. 1, the thermal recording paper is moved in a direction (vertical direction in FIG. 1) perpendicular to the extending direction of the resistance heating element 2 (horizontal direction in FIG. 1). Along with this movement,
A power supply path E is provided to the resistance heating element 2 constituting each heating dot.
1 to En, individual drive signal lines A1 to An, and the common conductor 3, voltages are applied to each heating dot to selectively generate heat, thereby printing dots on the sensitive recording paper.

However, in this prior art, as shown in an enlarged view in FIG. 3, the semiconductor element D1 is usually provided close to the common conductor 3 in order to downsize the thermal printing apparatus. A control signal line B1 for supplying various electric signals for selectively generating heat from each resistance heating element was also provided close to the common conductor 3. However, when each resistance heating element 2 generates heat and performs dot printing, a small current of about 5 to 15 mA flows through each control signal line B1, whereas a relatively large current of about 20 A flows through the common conductor 3. Therefore, noise is induced in the control signal line B1 by the electric field of the large current flowing through the common conductor 3.
As a result, an erroneous signal is supplied to the semiconductor element D1, causing the semiconductor element D1 to malfunction, resulting in printing defects.

The present invention has been devised in view of the above-mentioned drawbacks, and its purpose is to provide a thermal printing device that effectively prevents erroneous signals from being supplied to semiconductor elements and has extremely excellent printing quality.

The present invention provides a plurality of resistance heating elements on one surface of an electrically insulating substrate, a common conductor commonly connected to one end of the resistance heating element, and an individual drive signal connected to the other end of the resistance heating element. a switching integrated circuit element connected to the other end of the individual drive signal line, a control signal line connected to the integrated circuit element, and a power supply that supplies power to each resistive heating element through each of the integrated circuit elements. The thermal printing apparatus is characterized in that a shielding conductor is disposed between at least the common conductor and the control signal line.

Hereinafter, the present invention will be explained in detail based on the embodiment shown in FIGS. 4 and 5.

In the figure, the same parts as in the conventional product are given the same reference numerals.

FIG. 3 shows an enlarged view of the main parts of the thermal printing apparatus of the present invention, and the individual drive signal lines collectively indicated by the reference numeral A1 are individually indicated by the reference numeral A101 for each heating dot.
~A132, respectively. Similarly, the control signal line B1 is individually referred to as B101.
~B105. Also, integrated circuit element D
1 terminal Da1 is individually referenced Da101~
The terminals Db1 are individually indicated by reference symbols Db101 to Db105.

In manufacturing such a thermal printing device, first, a resistance heating element 2 is formed on the surface of an electrically insulating substrate 1 made of ceramic, glass, or the like. Next, the common conductor 31 and the power supply path EA1 are formed, and finally the individual drive signal lines A1 (A101 to A132) and the control signal lines B1 (B101 to B105) are formed.

The common conductor 31 and the power supply path EX1 are made of, for example, gold (Au), silver (Ag), copper (Cu), or a metal containing these as main components, and are formed by a conventionally well-known thick film method. . Since the common conductor 31 and the power supply path EX1 are formed of a good electrical conductor, the electrical resistance can be kept to an extremely low value even if the width of the conductive path is narrowed due to high-density wiring. Therefore, even if a relatively large current flows through the common conductor 31 and the power supply path EX1 during printing,
A large voltage drop does not occur in the common conductor 31 or the like, and the resistance heating element 2 can always generate heat at a predetermined temperature.

The individual drive signal lines A101 to A132 and control signal lines B101 to B105 are the same as in the conventional product.
It is made of metal such as Al or Ni, and is formed on the insulating substrate 1 by employing a conventionally well-known thin film method. These individual drive signal lines A101 to A132 and control signal lines B101 to B105 have a high resistance value because the width of the conductive path is narrowed due to high density wiring, but the current flowing through each signal line is a relatively small value. (40 to 50mA), and no voltage drop occurs in each signal line.
Note that each of the individual drive signal lines A101 to A132 is formed so as to overlap the resistance heating element 2 so that a portion thereof is connected to both ends of each resistance heating element 2.

Further, the individual drive signal lines A101 to A132,
The control signal lines B101 to B105 and the power supply line EX1 each have a terminal Da101 of the integrated circuit element D1.
~Da132, Db101~Db105 and De are electrically connected via a conductive adhesive etc.
The integrated circuit element D1 has control signal lines B101 to B1.
The power supply line EX1 and each of the individual drive signal lines A101 to A132 are selectively made conductive in response to a control signal inputted through the line EX1.

In the present invention, it is important to arrange a shielding conductor between the common conductor and the control signal line. Therefore, in the embodiment shown in FIGS. 4 and 5, a shielding conductor 4 is arranged between the common conductor 31 and the control signal lines B101 to B105 so as to cover the control signal lines B101 to B105. This shielding conductor 4 is connected to the common conductor 31 and the control signal line B101~
By providing it between B105, even if a relatively large current flows through the common conductor 31 during printing and an electric field is generated, the electric field is blocked by the shielding conductor 4 and induces noise in the control signal lines B101 to B105. There's nothing to do. Therefore, control signal line B
101 to B105 can always supply normal electrical signals to the semiconductor element D1.

Note that the shielding conductor 4 is connected to the control signal line B1.
01 to B105 are coated with an electrical insulating film 5 such as polyimide resin, and then a metal such as aluminum (Al) or silver (Ag) is coated on the surface by employing a conventionally well-known thin film method or thick film method. It is formed.

In the above description, only the semiconductor element D1 has been described, but the same applies to the semiconductor element Dn (see FIG. 1).

Thus, according to the thermal printing apparatus of the present invention, by disposing the shielding conductor between the common conductor and the control signal line, various electrical signals for selectively driving the resistive heating element in the semiconductor element are constantly transmitted. A small, highly reliable thermal printing device that can be stably supplied and has extremely excellent printing quality can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view for explaining the prior art, FIG. 2 is an equivalent circuit diagram of the thermal printing apparatus shown in FIG. 1, FIG. 3 is a partially enlarged sectional view for explaining the prior art, and FIG. Figure 4 is an enlarged cross-sectional view of the main part of the present invention;
The figure is a sectional view taken along the Y-Y line in FIG. 4. 1... Board, 2... Resistance heating element, 3... Common conductor, 4... Shielding conductor, B1, B101-B
105...Control signal line.

Claims (1)

[Claims] 1. On one surface of an electrically insulating substrate, a plurality of resistance heating elements, a common conductor commonly connected to one end of the resistance heating elements, and an individual drive signal line connected to the other end of the resistance heating elements. , a switching integrated circuit element connected to the other end of the individual drive signal line, a control signal line connected to the integrated circuit element, and a power supply line that conducts current to each resistive heating element through each of the integrated circuit elements. 1. A thermal printing device formed by attaching and forming a thermal printing device, characterized in that a shielding conductor is disposed between at least the common conductor and the control signal line.