JPS5952597B2 - condenser microphone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitor microphone, and particularly to an improvement in its output terminal arrangement structure.

As is well known, condenser microphones are used as built-in microphones in tape recorders (including those with radios), and their structures are shown in Figures 1a and 1.
).

That is, a fixed disc-shaped electrode using an electret or the like and a movable electrode (diaphragm) are arranged in a front end opening (not shown) of a metal cylindrical case 11 with a predetermined gap therebetween via a ring-shaped insulating spacer. An integrated circuit including a field-effect transistor for impedance conversion (or preamplifier), etc., whose input terminal 121 is electrically connected to a fixed electrode of an electrostatic unit l- (not shown) which is arranged oppositely in the state. The converted circuit device 12 is housed in the case 11 in a substantially central position.

Output terminals 122 and 123 of this circuit device 12 are inserted through lead insertion holes 131 and 132 of a disk-shaped printed wiring board 13 that closes the rear end opening of the case 11 and protruded to the outside.

In this case, the printed wiring board 13 has lead insertion holes 131 and 13 that are axially symmetrical and spaced apart from the center by a predetermined distance.
Conductor patterns 13 for positive electrode (hot) and negative electrode (cold or ground) are provided on the back side of each of the two parts.
3,134 are formed, and the pattern 13 is
3,134 parts of the output terminals 122,1 of the circuit arrangement 12;
By soldering the protruding base portion 23, the condenser microphone 10 is completed.

The positive electrode conductor pattern 133 has a simple small circular shape, and the negative electrode conductor pattern 134 is connected to a ring-shaped portion along the inner circumference of the case 11.

FIG. 2 shows an example of mounting the conventional condenser microphone 10 configured as described above, in which a rubber ring or the like is held inside the sound collection hole 141 formed in the front cabinet (panel) 14 of a tape recorder. A condenser type microphone 10 is disposed via a member 15, and its output terminals 122 and 123 are connected and fixed to a printed wiring board 16.

FIG. 3 is a wiring diagram showing the internal and external connections of the capacitor-type microphone, in which M is an electrostatic unit omitted in FIG.
Impedance transformation (or preamplifier) included in 2
It consists of a field-effect transistor and its bias diode.

Note that the field effect transistor F included in the circuit device 12
ET has its gate) G and source S electrodes directly connected to the fixed electrode M1 of the electrostatic unit 1-M and via the metal case 11 as an input terminal 121 and an output terminal 123 on the negative (cold or ground) side, respectively. The movable electrode (diaphragm) M2 is connected correspondingly to the movable electrode (diaphragm) M2, and a diode D1 is connected between both electrodes G-5, and its drain electrode is further connected to the positive (hot) side output terminal 122. There is.

The negative output terminal 123 from the circuit device 12 is grounded on the mounting printed wiring board 16 side, and the positive output terminal 122 is also connected to a bias power supply (10B) via a resistor R and a capacitor C. It is configured such that it is selectively connected to an external microphone output or the like to a recording system circuit (not shown) via a recording circuit (not shown).

4a and 4l) show modified examples of the output terminals 122, 123 of the circuit device 12 and the conductor patterns 133, 134 of the printed wiring board 13 in the above.
In both cases, including the case shown in the figure, the arrangement structure of the output terminals 122 and 123 of the circuit device 12 is still axially symmetrical or line symmetrical.

By the way, the above 10 condenser microphones
After assembly is completed, the device is subjected to an inspection process as soon as it can demonstrate the desired performance before being mounted on a tape recorder or the like.

FIG. 5 schematically shows the inspection process for such conventional condenser microphones. After each group of 10 condenser microphones to be inspected is assembled as a single unit, they are placed on a straight feeder 17 and placed on a measuring device 18.
The pair of testers 181 will be sequentially transferred to a certain position, but during this time each output terminal 122, 12
Due to the presence of the alignment guide 19, the three groups are aligned so that they are correctly aligned.

That is, this is necessary for automating the inspection process, and when the 10 groups of condenser microphones are sequentially transferred to a predetermined position, a pair of test elements 181 are lowered each time to connect their respective output terminals 122, 123. The group is sequentially contacted to provide measurement input to the measuring device 18.

Note that SP in the figure is a speaker that provides acoustic output for testing.

However, in such a conventional inspection process, although the output terminal groups are aligned, they are not aligned in consideration of their polarities.
If the output terminals 81 are in contact with each other and the polarities of the output terminals are opposite, it is necessary to rotate the pair of test elements 181 by 180°.

That is, the supporting structure of the tester 181 becomes more complicated, and the testing process itself inevitably becomes complicated and inefficient.

In addition, in this case, the support structure for the pair of testers 181 needs to be structured so that it can contact them as well as possible considering the mechanical strength of the output terminal part since they are a pair. , which tended to be more complex and expensive.

Furthermore, when connecting to a device such as a tape recorder, the polarity of each output terminal must be determined by some means before making the connection, which makes the connection work complicated and often leads to incorrect connections. It has the disadvantage that it tends to cause

Therefore, this invention has been made in view of the above points, and by improving the output terminal arrangement structure, the inspection process can be simplified and performed efficiently, and the support structure of the tester can be simplified and the cost can be reduced. It is an object of the present invention to provide an extremely good condenser type microphone which can be easily used without the need for polarity discrimination during connection work, and which can reliably prevent erroneous connections.

That is, in the capacitor type microphone according to the present invention, either one of the positive (hot) terminal and the negative (cold) terminal among the output terminals is connected to a cylindrical case, that is, a printed wiring board provided at the rear end of the case. By arranging the test element at the center, it is possible to simplify the structure of the test element by eliminating the need for alignment work and polarity determination work during the inspection process.

An embodiment of the present invention will be described in detail below with reference to the drawings.

That is, in FIGS. 6a and 6l), 21 is a metal cylindrical case, and the front end opening (not shown) of this case 21 has a ring-shaped fixed electrode made of an electret or the like and a movable electrode. Electrostatic units (not shown) are disposed opposite to each other with a predetermined gap therebetween via an insulating spacer.

Also, inside the case 21 is a circuit device 22 which is an integrated circuit including a field effect transistor for impedance conversion (or preamplifier) whose input terminal is electrically connected to the fixed electrode of the electrostatic unit. It is stored.

Output terminals 222 and 223 of this circuit device 22 are connected to lead insertion holes 231 and 23, which will be described later, formed in a disk-shaped printed wiring board 23 that closes the rear end opening of the case 21.
2 and protrudes to the outside.

In this case, one lead insertion hole 231 is formed at the center of the printed wiring board 23, and the other lead insertion hole 232 is formed at a predetermined distance from the lead insertion hole 231. There is.

Here, the printed wiring board 23 has a small circular positive electrode (hot) conductor pattern 233 surrounding one lead insertion hole 231 on the back side thereof, and also surrounds the positive electrode conductor pattern 233. For a negative electrode (cold or ground), it has a double ring shape, and the inner ring part includes the other lead insertion hole 232, and the inner ring part and the outer ring part are connected near the lead insertion hole 232 part. A conductor pattern 234 is formed.

Thereafter, the bases of the output terminals 222, 223 of the circuit device 22 protruding from the respective lead holes 231, 232 are soldered to these conductor patterns 233, 234, and the outer ring-shaped portion of the conductor pattern 234 is soldered. case 21
The capacitor type microphone 20 is completed by electrically connecting it to the corresponding part of the capacitor by soldering or using another conductive material.

The condenser microphone 20 configured as described above is mounted as a built-in microphone in a tape recorder, for example, with the configuration shown in FIG. The configuration itself as shown in is the same as the conventional case.

Thus, after the above-mentioned condenser type microphone 20 is assembled, it is subjected to an inspection process as soon as it can exhibit the expected performance before being used for mounting.

FIG. 7 shows such an inspection process. After each of the 20 groups of condenser microphones to be inspected is assembled as a single unit, it is placed on a metal linear feeder 27 and brought to the position where the probe 281 of the measuring device 28 is located. Transferred sequentially.

As a result, when the capacitor microphones 20 are sequentially transferred to predetermined positions, the tester 181 is lowered each time to connect the output terminal group 222 for each positive electrode (hot).
The measuring device 28 is provided with a measuring input by sequentially contacting the measuring device 28.

Note that SP in the figure is a speaker that provides acoustic output for testing.

By the way, in such an inspection process, the negative electrode (cold or ground) side connection to the measuring device 28 is made through the metal linear feeder 27.

This means that each metal case 21 of 20 groups of condenser microphones has an output terminal 2 for each negative pole (cold or ground).
It utilizes the fact that it is electrically connected to 23.
It is sufficient to connect the negative (cold or ground) input terminals of the metal linear feeder 27 and the measuring device 28 to the ground point in advance.

As a result, the tester 281 of the measuring instrument 28 may be a single member rather than a pair as in the conventional case, and the tester 281
Since each positive electrode (hot or ground) output terminal 222 of the 20 groups of capacitor microphones 81 to be contacted is arranged at the center of the disk-shaped printed wiring board 23, that is, the cylindrical case 21, the probe 281 Since the polarity of the output terminal will not be reversed when the tester is in contact with it, there is no need to rotate the tester 180 degrees as in the conventional case, and the structure of the tester 281 can be changed accordingly. Not only can the process be made simpler and cheaper, but the inspection process itself can be simplified and made more efficient.

Additionally, this means that there is no need to perform any alignment work on each output terminal 222, 223 of the 20 groups of condenser microphones, so there is no need for alignment using a conventional alignment guide. By being able to do this, the above-mentioned effects can be further promoted.

Furthermore, since only a single probe 281 is required to make contact, the mechanical strength of the output terminal part is not much of a problem, and the structure allows good contact to be easily achieved, which further promotes the above-mentioned effects. It is possible.

FIG. 8 shows another embodiment, in which a conductor pattern 234' for the negative electrode (cold or ground) formed on the printed wiring board 23' is connected to the lead insertion hole 232 and the conductor pattern for the positive electrode (hot). The condenser type microphone 20' is constructed in the same manner as in the case of FIG. 6, except that the patterns 233 are formed almost entirely over the entire surface, leaving each pattern 233 in the form of an island (however, the former is in the form of a continuous land).

In other words, in both the capacitor microphones 20 and 20' shown in FIGS. 6 and 8, the negative electrode (cold or ground) conductor patterns 234, 234' have as large an area as possible, and the positive electrode (hot) conductor pattern 233
Since it surrounds the positive electrode (hot), the shielding effect can be improved accordingly, and the positive electrode (hot)
Since the output terminal 221 is arranged in the center, it has the advantage that it is possible to remove the wiring during mounting and to eliminate mistakes in connection polarity.

In addition, in the above, the positive electrode (Hora 1~) and negative electrode (cold or earth) relationship may be interchanged, and the present invention is also limited to the above-described and illustrated embodiments. It goes without saying that various modifications and applications can be made without departing from the gist of the invention.

Therefore, as detailed above, according to the present invention, by improving the output terminal arrangement structure, the inspection process can be simplified and performed efficiently, and the supporting structure of the tester can be simplified and made inexpensive. At the same time, it is possible to provide an extremely good capacitor type microphone which can be easily performed by eliminating the need for polarity discrimination during connection work, and which can reliably prevent erroneous connections.

[Brief explanation of the drawing]

Figures 1a and 1) are exploded perspective views and rear perspective views of the main parts of a conventional condenser microphone, and Figures 2 and 3 are cross-sections of the main parts showing an example of mounting the condenser microphone of Fig. 1. Connection diagram showing a side view and an example of internal and external connections, No. 4
Figures a and b are rear views showing modified examples of the output terminal of the circuit device and the conductor pattern of the printed wiring board in Figure 1;
The figure is a diagram simulating the inspection process of a conventional condenser type microphone, Figures 6a and l) are exploded perspective views and rear perspective views of essential parts showing an embodiment of the condenser type microphone according to the present invention, FIG. 7 is a diagram schematically showing the inspection process of the condenser type microphone shown in FIG. 6, and FIG. 8 is a rear view showing another embodiment. 20... Condenser microphone, 21...
...Case, 22...Circuit device, 221.
...Input terminal, 222,223...Output terminal, 23...Printed wiring board, 231,232...
...Lead insertion hole, 233.234...
conductor pattern.

Claims (1)

[Claims] ] An electrostatic unit disposed in the opening at one end of the cylindrical metal case, a gate connected to one electrode of the electrostatic unit as an input terminal, and a source connected to the other electrode of the electrostatic unit cold. a circuit device housed inside the case, comprising at least a field effect transistor whose drain electrode is led out as an output terminal for hot use and whose drain electrode is led out as an output terminal for hot use; and an opening at the other end of the case. , and is connected to each of the hollow I and cold output terminals derived from the circuit device with one of them located in the center and the other offset from the center. What is claimed is: 1. A condenser type microphone comprising: a printed wiring board;