JPH054673Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a mechanical switch that detects the paper surface or paper edge of paper through an actuator, which is mainly used in office machines such as office automation equipment. (hereinafter simply referred to as "paper detection switch").

``Prior Art'' Conventionally, this type of paper detection switch has been constructed by installing an actuator in a mechanical switch and opening and closing the switch depending on the operating angle of the actuator, or by using a photo-interrupter. The presence or absence of paper was detected by reading the movement of the actuator or the edge of the paper directly.

On the other hand, some improved paper detection switches are known in which a magnet is set at the tip of the actuator, and the movement of the magnet opens and closes a reed switch provided at the contact point. In addition, methods for detecting the presence or absence of paper without using an actuator or direct contact with the paper surface include an optical method that uses photoelectric elements to detect light reflected from the paper surface, and an optical method that uses air pressure. The air micrometer method was used.

``Problems to be solved by the invention'' This type of paper detection switch requires that its actuator operate at low torque in order to prevent paper jams and tears, and that the contact point Regarding opening and closing, high reliability is also an essential condition, so it is strongly required to satisfy the conflicting demands of high reliability with low operating force. Another important condition is that the angle of the actuator at the time of attaching and detaching the edge of the paper must be the same, or the error thereof must be minute.

Therefore, when operating a mechanical switch via an actuator in each of the above methods,
Fluctuations occur in the actuator's operating force when the contacts open and close, and if the torque is large at that time, the paper surface or paper edges are likely to fold, bend, or twist, and dust may adhere to the conductive material of the contacts. An oxide film was often generated, reducing reliability. On the other hand, in the case of low torque, the contacts will not open and close accurately, and if, for example, a snap-action structure is adopted for the purpose of increasing the reliability of the contact opening/closing operation, a hysteresis phenomenon will occur in the operating angle of the actuator. The problem was that the opening and closing angles were different.

On the other hand, the paper detection switch, which combines an actuator with a magnet and a reed switch, has a low operating force but has the disadvantage of a large hysteresis phenomenon; Although this method can prevent the above-mentioned drawbacks, it is easily affected by dust because the signal is transmitted by light.

Furthermore, the light reflection method against the paper surface is often affected by dust, and other air micrometers are also ideal as a detection method, but they require a large number of attached parts such as compressors and pressure sensors. As a result, the device itself becomes large and expensive, making it difficult to use in office equipment.

[Means for solving problems]

Therefore, in the present invention, an actuator lever (hereinafter simply referred to as "lever") that is sufficiently long compared to the radius of the rotor cam is fixed to the non-conductive rotor cam, and the actuator lever (hereinafter simply referred to as "lever") is fixed to the non-conductive rotor cam. The above-mentioned conventional method is improved by arranging contact plates facing each other, forming a semicircular portion having contact points that come into close contact with each other in the middle of the contact plates, and making the contact points move toward and away from each other via the rotor cam. This method solves at once the various problems seen in the various detection methods.

[Effect]

The present invention is capable of sufficiently increasing the contact pressure of the contacts and rotating the lever with low torque, and also allows the contacts to self-clean by opening and closing the contacts while sliding against each other. It has a special effect.

``Embodiment'' Hereinafter, the configuration will be described in more detail according to one embodiment shown in the drawings.
is a non-conductive rotor cam rotatably supported via shafts 2 at both ends, and is molded from a resin with a low coefficient of friction, such as polyacetal resin, for example.
Its cross-sectional shape consists of a short diameter part 1' and a long diameter part 1'' opposite to this, and the long diameter part 1'' gradually reduces in diameter in the direction of rotation (in the direction of the arrow) and becomes the short diameter part 1' on the other side. It is constructed in a continuous manner.

Reference numeral 3 denotes a lever integrally connected to one end surface of the rotor cam 1 so as to be perpendicular to the shaft 2, and the lever 3 has a sufficient length compared to the radius of the rotor cam 1.

Furthermore, reference numerals 4 and 4' denote a pair of contact plates made of elastic metal plates placed oppositely across the rotor cam 1, and semicircular portions 6 and 6' whose intermediate portions are curved inward.
Contact points 5 and 5' are formed in close contact with each other.

In the figure, 7 and 7' indicate lead wires connected to the lower ends of the contact plates 4 and 4'.

Next, the operating principle of the proposed switch will be described. As shown in FIG. rotor cam 1
Since this does not act on any of the contact plates, the contacts 5 and 5' are brought into close contact with each other by the elasticity of the contact plates 4 and 4', and a energized state is obtained.

Thus, the rotor cam 1 is
When the rotor cam 1 starts to rotate, the long diameter portion 1'' on the other side touches the contact plate 4' while maintaining a gap between one side of the rotor cam 1 and the contact plate 4, as shown in FIG. The contact points 5 and 5' are in close contact with each other, so that they are pressed (see a to b in the same figure).
As the contact plate 4' moves, the other contact plate 4 is inclined from its original position (dotted chain line in Figure b) by the above-mentioned gap amount and comes into contact with the outer periphery of the short diameter portion 1' of the rotor cam 1. . At the same time, the contact 5 slides a certain distance l from its original position along the curved surface of the semicircular portion of the contact plate 4', which is moving at an incline, so that dust adhering to the contact and an oxide film formed on the surface are removed. Thus, a self-cleaning effect can be obtained at the contacts 5 and 5'.

When the rotor cam 1 further rotates and spreads out the contact plate 4', the contacts 5 and 5' are completely separated and the current flow between the lead wires 7 and 7' is cut off. This completes a series of contact opening/closing operations (see Figure 2c).

In addition, when the lever 3 returns to its original position,
The contacts 5, 5' are closed by an operation opposite to that described above, but the self-cleaning action at the contacts also takes place at this time.

In the switch of this invention, since the rotor cam 1 only needs to contribute to the opening and closing of the contacts 5 and 5', its diameter can be set sufficiently small, and the lever 3
This makes it possible to increase the ratio between the length and the length of the lever 3, thereby significantly reducing the driving torque of the lever 3.
Since the contact pressure of the contacts 5 and 5' can also be increased, the contact resistance of the contacts 5 and 5' can be greatly reduced.

In addition, the present switch has a cam shape that allows the contact plate 4' to be quickly pushed after the rotor cam 1 comes into contact with the contact plate 4'.
Since the contacts 5 and 5' open quickly, bouncing and chattering are suppressed, and the contacts 5 and 5'
The design is such that the radius of the cam does not change after the lever 5' is opened, so there is no further movement of the contact plate 4' and only the torque of the return spring (not shown) of the lever 3 is applied. The torque characteristics change linearly and can prevent hysteresis.

In the above embodiment, in order to maintain a constant gap between at least the short diameter part 1' of the rotor cam 1 and the contact plate 4, the short diameter part 1' and the long diameter part 1 on the side of the contact plate 4 are Although a stepped portion is formed between the cam and the cam, the cam is not limited to a cam with a stepped portion, and a normal plate cam may be used as long as the above-mentioned operating principle can be obtained. It is.

Further, the rotor cam 1 may have its long diameter portion 1'' in contact with one of the contact plates 4 and 4' when the lever 3 is not activated (the state shown in FIG. 1a).
Preferably, the structure is such that they do not come into contact with each other.

[Effect of idea]

As mentioned above, the low-torque contact switch of the present invention solves the contradiction between lever torque and contact pressure, which has traditionally been difficult to resolve, especially in paper detection switches for office automation equipment, etc. Not only does it provide low torque and high detection accuracy, but its self-cleaning action also reliably prevents poor contact between contacts due to the formation of oxide films and the presence of foreign matter such as dust and paper dust. , there are no operational errors, and the reliability of the switch is further increased.

In addition, this proposed switch can be applied not only to paper detection and detection of moving parts in OA equipment, but also as a detection switch for various devices that require low operating torque for other lightweight and thin objects to be detected. It has an extremely simple structure, is compact, and can be manufactured at low cost, and has excellent practical advantages that are difficult to expect from conventional paper detection switches.

[Brief explanation of the drawing]

Fig. 1a is a front view of the proposed low torque contact type switch, Fig. 1b is a right side view thereof, and Figs. be. In the figure, 1... rotor cam, 2... shaft, 3...
...Lever, 4, 4'... Contact plate, 5, 5'... Contact, 6, 6'... Semicircular part.

Claims (1)

[Scope of utility model registration request] An actuator lever 3 that is sufficiently long compared to the radius of the rotor cam is fixed to the non-conductive rotor cam 1, and contact plates 4 and 4' are provided opposite each other with the rotor cam 1 in between. A low torque contact type switch characterized in that semicircular parts 6, 6' having contacts 5, 5' which can be freely brought into contact and separated by the rotor cam 1 are formed in the middle of the contact plates 4, 4'.