JP4789856B2 - Manufacturing method of diaphragm for condenser microphone unit - Google Patents

Description

The present invention relates to the production how the vibration plate used in a condenser microphone unit and, more particularly, in conferring fine irregularities by heating the diaphragm material, so as not to cause wrinkles in the diaphragm material It is about technology.

  In particular, in a condenser microphone unit having a small diameter, a diaphragm provided with fine irregularities is used in order to improve sound collection characteristics in a low range (see, for example, Patent Document 1).

  As the diaphragm material, a gold vapor deposition film in which a gold thin film is vapor-deposited on one side of a thermoplastic resin film (for example, polyphenylene sulfide having a thickness of about 2 μm; PPS) is used. Patent Document 2 discloses a method for manufacturing a diaphragm that imparts fine irregularities to a diaphragm material.

  According to this manufacturing method, for example, a metal mold having a fine unevenness forming member made of a net having a mesh degree of about # 300 on the surface, a heating means for heating the mold, and a cooling means for cooling the mold, A pressurizing unit that blows pressurized air from above on the unevenness imparting member on the mold surface is used, and fine unevenness is imparted to the diaphragm material as follows.

  After placing the diaphragm material on the unevenness imparting member and heating the mold to a predetermined temperature with the heating means to soften the diaphragm material, the compressed air is blown by the pressure means to make the diaphragm material uneven The pressing member is pressed to give fine irregularities to the diaphragm material, and then the heating by the heating means is stopped, and the mold and the diaphragm material are cooled by the cooling means.

  According to this, the unevenness imparting member is a breathable net, and when the diaphragm material is pressed against the unevenness imparting member by blowing pressurized air, the air existing between the diaphragm material and the molding die is lateral. In order to escape in the direction, the diaphragm material can be brought into close contact with the unevenness imparting member.

  However, when the mold including the unevenness-imparting member is heated by the heating means, the diaphragm material has a very small heat capacity, so the temperature rises instantaneously due to the radiant heat from the mold and the unevenness-imparting member. End up.

  Normally, a uniaxially stretched film is used as the diaphragm material, and the thermal expansion coefficients in the longitudinal direction and the transverse direction are different. Therefore, wrinkles that are biased in one direction may occur in the diaphragm material due to the radiant heat described above.

  Even if the diaphragm material is disposed on the unevenness imparting member immediately before pressurization, as described above, the diaphragm material has an extremely small heat capacity, so that wrinkles are instantly generated.

JP-A-2-202800 JP-A-2-237300

  Accordingly, an object of the present invention is to prevent wrinkles from being generated in the diaphragm material when the diaphragm material is heated to give fine irregularities in order to improve the low-frequency sound collection characteristics.

In order to solve the above-mentioned problems, the invention according to claim 1 is a metal mold having an unevenness imparting member made of a net on the surface, a heating means for heating the mold, and cooling for cooling the mold. Uniaxial stretching of a thin film made of a thermoplastic resin and having different thermal expansion coefficients in the longitudinal and lateral directions , and a pressurizing means for blowing pressurized air from above to the unevenness imparting member on the mold surface A vibration plate material made of a film is placed on the unevenness imparting member, and a first step of heating the mold to a predetermined temperature by the heating means. The second step of pressing the plate material against the unevenness imparting member to give fine irregularities to the diaphragm material, the third step of stopping the heating by the heating means and cooling the mold by the cooling means, the capacitor micro In the method of manufacturing a diaphragm for a single unit, a negative pressure adsorption hole that is connected to a negative pressure source and exhibits a negative pressure adsorption action is opened on the surface of the mold, and at least in the first step, the diaphragm material the after placed on the pre-cooled by being the uneven application member on by the cooling means, the between at heating means to the heating the mold to a predetermined temperature, a negative pressure suction to the negative pressure suction hole It is characterized in that wrinkles due to heat are not generated in the diaphragm material by exerting an action to adsorb and fix the diaphragm material on the unevenness imparting member.

  In the first aspect of the present invention, as described in the second aspect, the negative pressure adsorption hole is caused to exert a negative pressure adsorption action in the second step subsequent to the first step when the unevenness is imparted in the second step, and the vibration. It is preferable to adsorb and fix the plate material on the unevenness imparting member.

  According to the present invention, a negative pressure that exerts a negative pressure adsorbing action with one end connected to a negative pressure source and the other end opened to the surface of the molding die, having a concavo-convex imparting member made of a net on the surface. Between the time when the diaphragm material is placed on the unevenness imparting member after the suction hole is provided and the mold is heated to a predetermined temperature, the negative pressure adsorption hole exerts a negative pressure adsorption action to make the diaphragm material uneven. By adsorbing and fixing on the imparting member, fine irregularities can be imparted to the diaphragm material without causing wrinkles due to heat in the diaphragm material.

  Next, an embodiment of the present invention will be described with reference to FIG. 1, but the present invention is not limited to this. FIG. 1 is a schematic front view showing an example of a diaphragm manufacturing apparatus according to the present invention.

  As shown in FIG. 1, the diaphragm manufacturing apparatus 10 includes a lower base 11, side frames 12 and 12 erected on the left and right of the lower base 11, and a side frame 12 as a basic framework of the apparatus. , 12 is provided with an upper base 13 installed in parallel with the lower base 11.

  On the lower base 11, a cooling means 21 in which a cooling water pipe (not shown) is stretched is disposed. A support base 23 is provided on the cooling means 21 via a spring 22 so as to be movable up and down. The support table 23 is supported at its four corners by springs 22.

  An opening is provided in the central portion of the support base 23, and the mold 24 is supported in the opening. The mold 24 is made of metal and includes a heating means 25 made of, for example, an electric heater. When the mold 24 is lowered, the heating means 25 is turned off, and the bottom surface of the mold 24 contacts the cooling means 21.

  On the surface (upper surface) of the mold 24, an unevenness imparting member 26 that imparts fine unevenness to the diaphragm material 50 is disposed.

  The unevenness imparting member 26 is made of a synthetic resin such as nylon or metal having sufficient flexibility to be compatible with the surface of the mold 24, for example, a net material on which fine meshes of about # 300 are formed, nickel, titanium, copper Metal fiber sintered bodies such as brass, monel metal, and stainless steel, or woven fabrics may be used.

  As the diaphragm material 50, a gold vapor deposition film in which a gold thin film is vapor-deposited on one surface of a thermoplastic resin film (for example, polyphenylene sulfide having a thickness of about 2 μm; PPS) is used. In order to prevent wrinkles from occurring at times, the mold 24 is provided with fixing means for temporarily fixing the diaphragm material 50.

  In the present invention, the fixing means for the diaphragm material 50 is constituted by a negative pressure suction hole 27 formed in the mold 24. The negative pressure suction holes 27 are preferably arranged at equal intervals throughout the mold 24, one end thereof is opened on the surface of the mold 24, and the other end is connected to a vacuum pump P 1 which is a negative pressure source.

  The negative pressure suction operation of the negative pressure suction hole 27 is controlled by turning on / off the vacuum pump P1 or turning on / off a solenoid valve (not shown) interposed in a connection pipe between the negative pressure suction hole 27 and the vacuum pump P1. The vacuum pump P1 is turned on / off or the electromagnetic valve is turned on / off based on an instruction signal from a control unit (not shown).

  An air cylinder 30 is mounted almost at the center on the upper base 13. The cylinder rod 31 of the air cylinder 30 penetrates the upper base 13 and extends downward (lower base 11 side), and a pressurizing pot 40 as a pressurizing means is attached to the lower end thereof. Yes.

  The pressurizing pot 40 has a pressurizing chamber 41 whose bottom surface is open, and an airtight O-ring 43 is provided on the open end side. The pressurizing pot 40 includes a pressurized air supply port 42 connected to the pressurizing pump P2. The supply timing of pressurized air from the pressure pump P2 is also controlled by the control unit.

  In order to manufacture the diaphragm, the diaphragm material 50 is disposed on the unevenness imparting member 26 placed on the surface of the mold 24 that has been cooled by the cooling means 21, and then the vacuum pump P1 is turned on and the negative pressure is applied. The diaphragm material 50 is adsorbed by negative pressure on the unevenness imparting member 26 through the adsorption holes 27 (at this time, the pressure pump P2 is in an off state).

  Next, the heating means 25 is turned on and heating of the mold 24 is started. When the temperature reaches a predetermined temperature, the heating means 25 is turned off. During this heating process, the diaphragm material 50 is fixed by the negative pressure adsorption action of the negative pressure adsorption hole 27, so that no wrinkles are generated by heating.

  Thereafter, the pressure pot 40 is lowered by the air cylinder 30, and the diaphragm material 50 is sandwiched and fixed between the O-ring 43 of the pressure pot 40 and the unevenness imparting member 26.

  Then, the pressure pump P <b> 2 is turned on, the pressurized air is blown out from the pressure chamber 41 toward the diaphragm material 50, and the diaphragm material 50 is pressed against the unevenness imparting member 26. Due to the heat from the mold 24 and the pressurized air supplied from the pressure pot 40, the fine unevenness of the unevenness imparting member 26 is reliably imparted to the diaphragm material 50.

  Thereafter, the mold 24 is brought into contact with the cooling means 21 to cool the mold 24, release the negative pressure adsorption of the negative pressure suction hole 27, and turn off the pressure pump P2, and then turn the air cylinder 30 is raised, and the diaphragm material 50 is peeled off from the unevenness imparting member 26.

  Thus, according to the present invention, fine unevenness can be imparted to the diaphragm material 50 by the unevenness imparting member 26 without causing wrinkles due to heat in the diaphragm material 50.

  In the above embodiment, the diaphragm material 50 is adsorbed under negative pressure until the step of cooling the molding die 24. However, the pressurizing pot 40 is lowered to provide unevenness with the O-ring 43 of the pressurizing pot 40. The negative pressure adsorption on the diaphragm material 50 may be released when the diaphragm material 50 is fixed between the member 26 and the member 26.

  Further, the air existing between the diaphragm material 50 and the unevenness imparting member 26 is naturally discharged to the side of the unevenness imparting member 26 because the unevenness imparting member 26 is a net body and has air permeability. According to the present invention, the air existing between the diaphragm material 50 and the unevenness imparting member 26 is forcibly sucked into the vacuum pump P1 from the negative pressure suction hole 27. It is unlikely that there will be air accumulation between them.

The typical front view which shows an example of the diaphragm manufacturing apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Diaphragm manufacturing apparatus 11 Lower base 12 Side frame 13 Upper base 21 Cooling means 22 Spring 23 Support base 24 Mold 25 Heating means 26 Concavity and convexity imparting member 27 Negative pressure adsorption hole 30 Air cylinder 40 Pressure pot 50 Vibration plate material P1 Vacuum pump P2 Pressure pump

Claims (2)

A metal mold having an unevenness-imparting member made of a net on the surface, a heating means for heating the mold, a cooling means for cooling the mold, and the unevenness-imparting member on the surface of the mold Pressure means for blowing pressurized air from above,
A diaphragm material made of a thin film uniaxially stretched film made of a thermoplastic resin and having different thermal expansion coefficients in the vertical and horizontal directions is placed on the unevenness imparting member, and the mold is brought to a predetermined temperature by the heating means. A first step of heating up to a second step of spraying pressurized air by the pressurizing means to press the diaphragm material against the irregularity imparting member and imparting fine irregularities to the diaphragm material, heating by the heating means In a method for producing a diaphragm for a condenser microphone unit through a third step of stopping and cooling the mold by the cooling means,
Opening a negative pressure adsorption hole that is connected to a negative pressure source and exerts a negative pressure adsorption action on the surface of the mold, and the unevenness that has been cooled in advance by the cooling means at least in the first step. After placing on the imparting member, the negative pressure adsorption hole exerts a negative pressure adsorption action until the mold is heated to a predetermined temperature by the heating means, and the diaphragm material is made uneven. A method of manufacturing a diaphragm for a condenser microphone unit, wherein the diaphragm material is prevented from being wrinkled by heat by adsorbing and fixing on an application member.   The diaphragm material is adsorbed and fixed on the irregularity-imparting member by causing the negative-pressure adsorption hole to exert a negative-pressure adsorption action during the irregularity imparting in the second step following the first step. Item 2. A method for manufacturing a diaphragm for a condenser microphone unit according to Item 1.

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