JPH05325697A - Detector - Google Patents

Abstract

PURPOSE:To improve switching reliability upon a detector by establishing the contact condition of a contact brush with a pattern formed in a switch substrate, always close to that of the contact brush established in its early stage of use, with the aid of plural segment-shaped portions formed in the head of the contact brush in such structure that the heads of brush segments may differ in position from one another. CONSTITUTION:A switch substrate is in the shape of a disc composed of an electrically conductive portion 1 and an electrically non-conductive portion 2. A contact brush 4 is formed in its head in such structure as to have plural contacts so as to calculate upon a chattering preventive effect. Although such a contact brush 4 has no problem in the early stage of use, it is worn away at its head to cause the incomplete detection of a pulse by a detector during long use from the viewpoint of durability. In order to solve that problem, the contact brush 4 is reformed in such structure that the plural segment-shaped contact portions formed in the head of the contact brush 4 may be shifted in the vertical direction of the contact brush 4 little by little from one another. This structure enables another brush segment adjacent to one brush segment to establish the contact condition thereof with a pattern formed in the switch substrate, close to that of the contact brush 4 in its early stage of use, so that the detector may secure the ability enough to detect a pulse even if the one brush segment is worn away at its head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact brush type detector which slides on and off a switch substrate such as is used for detecting the position of a printing wheel of a printer or detecting the number of revolutions of a counter.

[0002]

2. Description of the Related Art An example of a conventional detector of this type is Jikken Shinsho 6
Although disclosed in 3-1386, the contact mechanism portion of the detector generally used for detecting the position of the type wheel of the printer is
It is required to have extremely good wear resistance. FIG. 4 shows a switch of this type, that is, a rotary shaft 6 for driving the type wheel 5.
A disk-shaped substrate 7 is attached to the rotary shaft 6, and a contact brush 4 made of a metal piece having good conductivity is elastically contacted on a switch pattern 8 on the substrate 7 which rotates at a high speed together with a rotary shaft 6 to rotate the type wheel 5. An example of a high speed detector for detecting is shown.

[0003]

However, the rotation detector used for detecting the position of the type wheel of the printer, detecting the number of rotations in the counter, etc., is a contact brush and a brush for high speed rotation (several thousands rpm). Friction of the switch substrate is remarkable, both the contact brush and the switch substrate pattern portion are worn, and conduction failure such as chattering due to wear becomes a problem in terms of durability.

As a countermeasure against this wear, lubricating oil is applied to the switch substrate or the contact load of the contact brush is reduced. However, for the endurance, the change of the contact state and the harmful effect of the abrasion powder due to the abrasion of the switch substrate and the contact brush are not caused. It always occurred, and a sufficient pulse detection effect was not obtained.

The present invention has been made to solve the above drawbacks, and an object thereof is to improve the reliability of switching between a contact brush and a switch substrate.

[0006]

SUMMARY OF THE INVENTION The present invention provides a contact mechanism having a switch substrate having a plurality of switch patterns formed of a conductor portion and a non-conductor portion, and a contact brush for elastically sliding on the switch pattern. At this point, the contact portion of the contact brush that makes elastic contact with the switch substrate is divided into a plurality of parts, and at least one of the contact portions slides on the switch substrate in the initial state,
The other contact portion has a gap with the switch substrate.

[0007]

According to the above configuration of the present invention, the position of the tip of the contact brush that comes into contact with the switch substrate moves downward with time, and the contact point between the contact brush and the switch substrate is always close to the initial state. Therefore, the reliability of pulse detection is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, a rotation detector used for detecting the position of a printing wheel of a printer, detecting the number of rotations of a counter, etc. will be described with reference to FIGS. FIG. 1 is a front view of the switch board, FIG. 2 shows a contact position of the contact brush, and FIG. 3 is a view showing a contact state of the switch board and the contact brush.

FIG. 1 shows a disk-type switch substrate composed of a conductive part 1 with plating and a non-conductive part 2 without plating. Reference numeral 3 is a central hole in which the switch substrate is fixed to a shaft that is rotationally driven. The conduction pattern is formed by embossing a protrusion corresponding to the conduction pattern of the conduction part 1 with a copper material, and then insert-molded so as to be formed into a sandwich shape with a synthetic resin of polyacetal, and further exposed to the surface of the protrusion. It is formed by applying a metal of good conductivity such as gold or silver. Reference numeral 4 is a contact brush made of nickel silver and elastically contacting the switch substrate 7, and the inside is a common brush.
The switch substrate constructed as described above is rotated at high speed around the center hole 3.

FIG. 3 (a) shows an elastic contact state between the contact brush and the switch substrate. Generally, the tip of the contact brush has a plurality of contact structures for the purpose of preventing chattering. However, although there is no problem in the initial stage, since the brush slides in contact with the same pattern part of the switch board, the tip of the brush or the pattern of the switch board wears for durability, and the contact state changes due to abrasion powder or pulse detection. Defects occur. Therefore, as shown in FIG. 3 (b), the plural shaped portions at the tip of the brush are gradually shifted in the vertical direction. With this structure, even if one brush tip wears,
Adjacent brushes make initial contact with the pattern on the switch substrate, ensuring sufficient pulse detection capability.
FIG. 3 (c) shows a brush contact state during durability. The left brush has worn tips, but the central brush creates the initial contact and the right brush is non-contact. As the durability further increases, the right end brush creates the initial contact state.

Thus, from the point of view of the present invention, it is the intent of the present invention if the tip of the contact brush is of any shape and its position is vertically displaced.

[0012]

As described above, according to the present invention, the contact state between the contact brush and the pattern on the switch substrate can be always close to the initial state by the plurality of shape portions having different positions of the contact brush tip. Therefore, the reliability of switching can be significantly improved by the effect of preventing the pulse detection failure due to the abrasion powder. As described above, the effect of the present invention is great, and the present invention can be utilized in a contact-type detector that performs switching by sliding with a contact brush in an electronic device.

[Brief description of drawings]

FIG. 1 is a front view of a switching board according to the present invention.

FIG. 2 is a diagram showing a contact position of the contact brush of the present invention.

FIG. 3 is a view showing a contact state between a switch substrate and a contact brush of the present invention.

FIG. 4 is a diagram showing an example of a conventional high-speed detector.

[Explanation of symbols]

 1 Conducting Part 2 Non-Conducting Part 3 Center Hole 4 Contact Brush 5 Type Wheel 6 Rotating Axis 7 Switch Board 8 Switch Pattern

Claims (1)

[Claims] 1. A switch substrate comprising a plurality of switch patterns formed of a conductor portion and a non-conductor portion, and a contact mechanism having a contact brush that elastically slides on the switch pattern. The contact part of the contact brush that makes elastic contact is divided into a plurality of parts, and in the initial state, at least one of the contact parts slides on the switch board, and the other contact parts have a gap between them. A detector characterized in that