JPH0355102Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a frequency generator FG for detecting the speed of rotating bodies such as head drum motors and capstans used in VTRs. This is related to the configuration of the called FG.

Conventional configuration and problems The design problems of capacitive FG include how to insulate the external gear from the ground plane and how to extract signals from the insulated external gear. However, in the past, the member used for insulation and the member for extracting signals from the external gear were separate, requiring a relatively large space.
Also, you can solder the signal line directly to the external gear,
Alternatively, the signal line is directly fastened to the external gear using screws, which results in very poor workability and poor reliability, making this method difficult to use, especially when design space is limited. It was hot.

Purpose of the invention This invention uses a printed wiring board to facilitate signal extraction from external gears, and also uses the printed wiring board as an insulator to solve the problems with the conventional configuration described above. This is what I am trying to do.

Structure of the invention The present invention fixes an external gear to a fixing part via a printed wiring board having a conductive layer on at least one surface such that the conductive layer and the external gear are in contact with each other. As a result, signals are obtained through the printed wiring board, and the printed wiring board is used for insulating the fixed part and the external gear.

DESCRIPTION OF THE EMBODIMENTS The drawing shows an embodiment in which the FG according to the present invention is incorporated into a direct drive type head drum motor.

In the drawings, 1 is a housing, and 3 is a rotating shaft rotatably held in the housing 1 by a bearing 2. 4 is an insect screw 5 which connects the rotating shaft 3
A cylindrical rotor 6, which is a boss fastened to the rotor 6 and has an opening at the bottom, is fastened to the boss 4 by a screw 7, and rotates together with the rotating shaft 3.

Reference numeral 8 denotes a magnetized annular permanent magnet, which is fixed inside the rotor 6 . Reference numeral 9 denotes a stator wound with a coil, which is fixed to the housing 1 so as to face the permanent magnet 8 from the inside, and is configured so that rotational force is generated in the rotor 6 by passing a current through the coil 9. There is.

Reference numeral 10 denotes an internal gear fixed to the rotor 6 with a screw 12 so as to be concentric with the rotating shaft 3, and is grounded through the rotating shaft 3.

11 is an external gear having an outer diameter slightly smaller than the inner diameter of the internal gear 10, and has the same number of teeth as the internal gear 10. 13 is a printed board which is a feature of the present invention, and at least a conductive foil is provided on the side in contact with the external gear 11. The external gear 11 is fixed to the pedestal 14 via the printed board 13 with screws 19.

Reference numeral 15 denotes a shielded wire for extracting signals, and its ground terminal 17 is fixed to the base 14 with a screw 18 and is also grounded. This shield wire 15
The true wire 16 passes through a minute hole 13' provided in the printed board 13 and is soldered to the conductive foil of the printed board 13. The external gear 11 includes:
An escape hole 11' is provided so that the true wire 16 soldered to the printed board 13 does not interfere with the close contact between the printed board 13 and the external gear 11.

With the above configuration, the external gear 11 satisfies the requirements of completely insulating it from the pedestal 14 and taking out the capacitance change of the external gear 11 with the ring-shaped printed board 13 having foil on one side. The space is only the thickness of the printed board 13,
In the example, it is 0.5 m/m.

Effects of the invention According to the invention, the printed board plays the role of insulation and conduction of the external gear to the signal line, so it requires very little space.

Furthermore, if the signal wires are soldered to the printed board in advance, all one has to do is stack them and tighten them with screws, which eliminates the need for the difficult task of soldering the signal wires to the external gears, resulting in very high workability.

Furthermore, since the printed board and the external gear can be in contact over the entire circumference, very stable capacitance detection is possible.

[Brief explanation of drawings]

The drawing is a sectional view of an embodiment of the capacitive FG of the present invention. 1... Housing, 3... Rotating shaft, 6... Rotor (rotating body), 7... Screw, 10... Internal gear,
11... External gear, 13... Printed board, 15...
…Shielded wire.

Claims (1)

[Scope of utility model registration request] An internal gear that is electrically grounded and arranged on the rotating body concentrically with respect to the rotation center of the rotating body, and is insulated from the ground plane and has an outer diameter slightly smaller than the inner diameter of the internal gear. An external gear is fixed to a fixed part concentrically with respect to a rotation center, and a change in capacitance that occurs between the external gear and the internal gear due to rotation of the internal gear is used as a speed signal of the rotating body. The capacitive frequency generator is a capacitive frequency generator, in which a ring-shaped printed board is placed between the boards for fixing the external gear, with the conductive foil side of the board being placed in close contact with the external gear. .