JPH03261203A - Oscillation circuit - Google Patents

Abstract

PURPOSE:To suppress production of the microphonic noise due mechanical shock and vibration and to prevent production of microphonic noise due to load fluctuation by inserting a conductive gel between an oscillator case and a panel case. CONSTITUTION:A conductive gel is inserted between a case 1 of an oscillator and a case 2 of a panel containing the oscillator. Thus, the conductive gel 3 absorbs the energy of mechanical shock and vibration of the oscillator case 1 to attenuate it and since the oscillator case 1 connects to ground of the panel case 2 via the conductive gel 3, the capacitance between the oscillator case 1 and the panel case 2 being a cause to load fluctuation is eliminated thereby avoiding load fluctuation. Thus, the generation of microphonic noise caused by the mechanical shock and vibration and the generation of microphonic noise caused by load fluctuation are prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an oscillation circuit, and in particular to an oscillation circuit that suppresses the generation of noise (micronic noise) in the oscillation circuit output caused by mechanical shock or vibration. Regarding.

[Conventional technology]

FIG. 2 is a schematic cross-sectional view showing an example of a conventional oscillation circuit, and FIG. 3 is an equivalent circuit diagram of FIG. 2.

As shown in FIG. 2, in the conventional oscillation circuit, a sponge 4 is placed between the oscillator case 1 and the panel case 2 as a cushioning material to absorb mechanical shocks and vibrations applied from the outside.

[Problem to be solved by the invention]

The conventional oscillation circuit described above uses an insulating sponge as a cushioning material to absorb this vibration in order to reduce the noise (micronic noise) in the oscillation circuit output caused by mechanical shock or vibration to the oscillator. I was using it.

However, this sponge separates the ground plane of the oscillation circuit and the ground plane of the panel housing the oscillator at high frequencies.
As shown in FIG. 3, the capacitance 11 between the oscillator case surface 6 and the panel case surface 7 is connected in series to the load 10. When the oscillator case surface 6 vibrates due to mechanical shock or the like, this capacitance 11 changes in accordance with a change in the distance between the cases. When viewed from the perspective of the oscillator 5, changes in the capacitance 11 result in changes in the load on the oscillator 5, generating noise that changes the oscillation frequency, ie, microphonic noise.

In other words, although conventional oscillation circuits reduce microphonic noise caused by fluctuations in the oscillation element itself due to mechanical shock or vibration, they have the disadvantage of generating microphonic noise due to load fluctuations.

For reference, the maximum value ΔF of the frequency fluctuation of the oscillator due to load fluctuation is expressed by the following equation.

ΔF=fo (ρ-(1/ρ)) (QOQL>/4QOQL where f.: Oscillation frequency Qo: No-load Q of the oscillator QL; Load Q of the oscillator ρ: Reflection coefficient of the load and ρ=l (ZL 20 ) / (ZL 10 Z.) ZL ;Load impedance [Means for solving the problem] The oscillation circuit of the present invention includes a conductive cushion material between the oscillator case and the panel case that houses the oscillator. The conductive cushion material is a conductive gel.

〔Example〕

Next, the present invention will be explained with reference to FIG.

FIG. 1 is a schematic cross-sectional view showing an embodiment of the oscillation circuit of the present invention.

In the oscillation circuit of this embodiment, a conductive gel 3, which is a conductive cushioning material, is inserted between an oscillator case 1 and a panel case 2 that houses the oscillator. In this way, the conductive gel 3 absorbs and attenuates the mechanical shock and vibration energy of the oscillator case 1, and the oscillator case 1 is connected to the earth at the same potential as the panel case 2 via the conductive gel 3. Since they are connected, the capacitance between the oscillator case 1 and the panel case 2, which causes load fluctuations, is eliminated, so that load fluctuations do not occur, and no microphonic noise is generated thereby.

Note that the same effect can be obtained even if the conductive cushion material is a conductive sponge, a conductive paint coated material, or a notion material.

〔Effect of the invention〕

As explained above, the present invention inserts a cushioning material, particularly a conductive gel, between the oscillator case and the panel case to absorb the energy of mechanical shock and vibration, and to absorb the energy caused by fluctuations in the oscillation circuit element itself. In addition to suppressing the occurrence of microphonic noise, the capacitance between the cases can be removed by ensuring conductivity between the two cases, which has the effect of preventing the occurrence of microphonic noise due to load fluctuations.

7... Panel case surface, 8... Signal line, 9... Earth wire, 10... Load, 11... Capacity.

Claims (2)

[Claims] 1. An oscillation circuit characterized in that a conductive cushion material is inserted between an oscillator case and a panel case that houses the oscillator. 2. 2. The oscillation circuit according to claim 1, wherein the conductive cushion material is a conductive gel.