JPH0735351Y2 - PTC heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a PTC heater having electrodes arranged in a comb-like shape.

(Prior Art) PT using the heat generation characteristics of a porcelain substrate with a positive temperature coefficient
As a C (Postive Temperaure Coefficient) heater,
As shown in FIG. 5, the substrate 1 is formed on the surface 1a of the PTC substrate 1.
From the side surface 1b to the first grooves 4 '(4'a, 4b', ...) And the side surfaces so as to be orthogonal to the length direction alternately along the length direction of the
The second groove 5 '(5'a, 5'b, ...) Is formed from 1c, and the first groove
Also, there is known a structure in which the first electrode 2 and the second electrode 3 are formed in the second grooves 4'and 5'to face each other in a comb shape. 2a, 2b, ... And 3a, 3b, ... Show the comb tooth portions of the first and second electrodes 2, 3, respectively. The first electrode 2 and the second electrode 3 are formed so as to extend to the side surfaces 1b and 1c of the substrate 1, respectively, and lead wires 8 and 9 are provided to the extended portions, respectively.
Are connected by spot welding or the like. Like this first
By forming the second electrodes 2 and 3 on the surface of the substrate 1 in the shape of a comb, it is possible to efficiently generate heat. FIG. 6 shows an enlarged view of a portion A in FIG. 5, and FIG. 7 shows a sectional view taken along the line VII-VII in FIG.

As is apparent from FIG. 5, the first and second grooves 4 ', 5'
The cross-sectional shape of is formed in a square shape along the length direction of the substrate 1, and as shown in FIG. 7, corners 4a, 5a are formed on the side surfaces of each groove 4 ', 5'. First and second electrodes 2 and 3 are formed so as to extend from the inside of each groove 4'and 5'to the side surface.

(Problems to be solved by the invention) By the way, in the conventional PTC heater, when the first and second electrodes 2 and 3 are formed by extending from each groove 4 ', 5'to the side surface, the side surface shown in FIG. As described above, since the corner portions 4a and 5a are formed in a square shape, there is a problem that each electrode is easily broken at the arc-shaped corner portion. In addition, since the cross-sectional shape of each groove is formed in a square shape in each groove as well, it is easy for each electrode to be similarly broken in this portion, which makes it difficult to form an electrode with a large area in each groove. . Further, even if the wire is not broken, the electrodes are thinly formed at these corners, so that the electrodes are easily burned when a large current is applied.

The present invention has been made to address the above problems,
An object of the present invention is to provide a PTC heater in which each electrode is formed with a uniform thickness.

[Means for Solving the Problems] (Means for Solving the Problems) In order to achieve the above object, the present invention is directed to a surface of a positive-characteristic porcelain substrate, which alternates along the length direction of the substrate in a direction orthogonal to the length direction. In a PTC heater having a first groove and a second groove and a first electrode and a second electrode formed in each groove, the first groove and the second groove are formed along the substrate length direction. The cross-sectional shape is formed in an arc shape, and the corners of the side surface of each groove are rounded.

(Operation) Since the cross-sectional shapes of the first groove and the second groove along the substrate length direction are formed in an arc shape, and the corner portions of the side surfaces of each groove are rounded, the first and second grooves are formed. The first and second electrodes are formed in the groove and at the corners of each groove with a uniform thickness. Therefore, disconnection of the first and second electrodes can be prevented.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a PTC heater according to the present invention, in which 1 is a positive-characteristic semiconductor substrate, and the surface 1a of the substrate 1 is orthogonal to the lengthwise direction of the substrate 1 alternately. Side 1b to make
To the first groove 4 (4a, 4b, ...) and the side surface 1c to the second groove 5
(5a, 5b, ...) are formed. Here, as shown in FIG. 2 which is an enlarged view of the A portion of the first and second grooves 4,5, each groove 4,5
The cross-sectional shape along the substrate length direction is formed in an arc shape, for example, a semicircular shape, and rounded portions 10 and 11 are formed at the corners of the side surfaces 1b and 1c of each groove. As an example, the depth of the first and second grooves 4,5 is formed to be 0.1 mm or more, and each roundness 8,
9 is formed to have a radius of curvature of 0.3 mm or more.

In the thus formed first and second grooves 4 and 5, first and second electrodes 2 and 3 are formed so as to extend to the side surfaces. The third is a cross-sectional view taken along the line III-III in FIG. 2, and since the rounded portions 10 and 11 are formed on the side surfaces 1b and 1c, the first and second electrodes 2 and 3 are uniform. It is formed in various thicknesses. Lead wires 8 and 9 are connected to the electrodes 2 and 3 extended to the side surfaces 1b and 1c by spot welding or the like.

FIG. 4 shows the manufacturing process of the PTC heater of this embodiment. First, in step (a), raw materials necessary for forming a PTC porcelain substrate are prepared, and in step (b), the raw materials are molded by a die to form the first and second arc-shaped cross-sectional shapes as described above. The PTC substrate 1 having the second grooves 4 and 5 and the rounded surfaces 10 and 11 formed on the side surfaces 1b and 1c is prepared. Subsequently, the substrate 1 is baked as in step (c), and then in step (d) an electrode material is attached to the entire surface of the substrate 1 by a method such as vapor deposition or sputtering to form the first electrode 2 and the second electrode 2. The electrode 3 is formed. Subsequently, in step (e), a lapping process is performed to remove unnecessary electrode material to flatten the surface.
Next, lead wires are connected to the electrodes on each side surface 1b, 1c.

Next, the operation of this embodiment will be described.

The first groove and the second groove 3 having an arcuate cross-section are formed alternately in the length direction of the surface 1a of the substrate 1, and roundnesses 10 and 11 are formed at the corners of the side faces 1b and 1c of the substrate 1. By being
First to extend from the surface 1a of the substrate 1 to each side surface 1b, 1c
When the electrode 2 and the second electrode 3 are formed, the first and second electrodes 2 and 3 are formed to have a uniform thickness throughout.

This makes it possible to prevent the occurrence of disconnection on the side faces 1b and 1c of the electrodes 2 and 3, respectively. The presence of the arcuate cross-sectional shape in the grooves 4 and 5 also prevents disconnection, so that the electrodes can be formed over the entire area of each groove, so that it is possible to form an electrode with a large area. . Therefore, even when a large current is applied, the electrode can be prevented from burning.

In this embodiment, an example was shown for the degree of depth or the degree of roundness of each groove, but these values can be arbitrarily selected according to the purpose, application, etc. The PTC heater according to this embodiment is effective not only for general-purpose heaters but also for various applications such as a dew condensation prevention heater for copying machines.

[Advantages of the Invention] As described above, according to the present invention, each groove having an arc-shaped cross section is formed, and the corners of each side surface are rounded to form the first and second electrodes. Therefore, each electrode can be formed to have a uniform thickness, and the disconnection of the electrode can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the PTC heater of the present invention, FIG. 2 is an enlarged view of a part of FIG. 1, and FIG. 3 is III-II of FIG.
A sectional view taken along line I, FIG. 4 is a block diagram showing a manufacturing process of the PTC heater of this embodiment, FIG. 5 is a perspective view of a conventional PTC heater, and FIG. 6 is an enlarged view of a part of FIG. , FIG. 7 is a sectional view taken along the line VII-VII in FIG. 1 ... Positive characteristic porcelain substrate, 2 ... First electrode, 3 ... Second
Electrodes, 4 ... first groove with an arc-shaped cross section, 5 ... second groove with an arc-shaped cross section, 10, 11 ... rounded corners on the side surface of the substrate.

Claims (1)

[Scope of utility model registration request] 1. A first groove and a second groove formed on a surface of a positive-characteristic porcelain substrate alternately along the length direction of the substrate and orthogonal to the length direction.
In a PTC heater having a groove formed in a groove and a first electrode and a second electrode formed in each groove, an arc-shaped cross section of the first groove and the second groove along the substrate length direction is formed. Formed and rounded at the corners of the sides of each groove
C heater.