JPS626787Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to an improvement of a divided network circuit for a multi-way speaker system using piezoelectric ceramic type speakers using piezoelectric ceramic as a driving source. In recent years, piezoelectric ceramic speakers have been widely used as inexpensive speakers because their drive configuration is extremely simple compared to conventional electrodynamic drive configurations. On the other hand, the impedance of the piezoelectric ceramic type speaker is significantly different from that of the electrodynamic type speaker (for example, the impedance of the electrodynamic type is 6Ω and 8Ω, and the impedance of the piezoelectric type is about 200Ω).
Therefore, when used as a speaker unit in a multi-way speaker system such as a 2-way or 3-way speaker system, the signal divided by the division network must be input through a matching transformer. This idea attempts to measure impedance matching without using a special matching transformer by devising the chain coil that constitutes the divided network of multi-way speakers, and the embodiment shown in Figs. 1 and 2 will be explained in more detail. Figure 1 shows the present invention applied to a bass speaker 2, a midrange speaker 3, and a 12 dB/octave two-way split network circuit.
1b is an input terminal, L ₁ and C ₁ are a chiyoke coil and a capacitor connected in series between the input terminals, and bass speakers 2 are connected to both ends of the capacitor C ₁ to form a low-pass filter. _L2 is a chiyoke coil, and a piezoelectric ceramic speaker 4 for high-pitched sound is connected to both ends of the coil. A medium sound speaker 3 is connected between the intermediate tap TP and one winding end of the choke coil _L2 , an input terminal is connected to the intermediate tap via the capacitor _C2 , and the one winding end is connected to the other input terminal 1b. has been done. That is, a high pass filter is formed by _C2 connected in series between the input terminals 1a and 1b, and the coil between tap TP and one end of the chain coil _L2 . Next, as an example, each constant will be explained when the cut-off frequency of the low-pass filter and the high-pass filter is selected to be 1000 Hz. If the inductance of the partial coil between _the tap TP and one terminal of the chain yoke coil L2 is _L2a ,

From [formula] C ₁ = C ₂ = 14μF

From [Formula], L ₁ =L _2a =1.8mH. However, c: Cutoff frequency (Hz) Ro: Speaker impedance (8
Ω) A coil L _2a having an inductance of 1.8 mH can be obtained, for example, by winding a 1.0 mm conductor wire approximately 270 times around a bobbin having a width of 22.5 mm and a diameter of 24 mm. Therefore, the total number of turns N of Chi York coil L ₂ is γ = (N/n) ² R, so N = approximately 1900 times. However, γ: Input impedance (8Ω) R: Output impedance (200Ω) n: Coil L _2a As is clear from the above, a piezoelectric ceramic speaker 4 with an impedance of about 200 Ω is placed at both ends of the York coil L ₂ which has been wound approximately 1900 times.
By connecting the midrange speaker 3 to the intermediate tap TP of the 270, the chain coil _L2 functions as an inductance element of a high-pass filter and a matching transformer element of the piezoelectric ceramic speaker 4. Note that in the above embodiment, the signal component input to the piezoelectric ceramic speaker is slightly wider than the band of the signal input to the midrange speaker, but the piezoelectric ceramic speaker has extremely steep low frequency cutoff characteristics. Therefore, there is no risk of mutual interference with midrange speakers. FIG. 3 shows a low-pass filter in which the choke coil is also used as a matching transformer, and has the same effect as the previous embodiment. As explained above, this invention provides a multi-way speaker system using at least one piezoelectric ceramic speaker and an electrodynamic speaker, in which an intermediate tap is formed on at least one of the choke coils constituting the dividing filter. It is characterized in that an electrodynamic speaker is connected to the intermediate tap and a piezoelectric ceramic speaker is connected to the end of the winding, and the choke coil is made to function as both the inductance of the divided network circuit and the matching transformer. As a result, piezoelectric ceramic speakers can be operated at the optimum point of efficiency without the need for a special matching transformer, as is the case with conventional speakers. Further, by changing the number of turns N of the chiyoke coil as appropriate, the sound pressure of the piezoelectric ceramic speaker can be controlled, thereby providing a multi-way speaker system that has a well-balanced sound pressure with other electrodynamic speakers. .

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of this invention, and FIG. 2 is a circuit diagram of another embodiment.

Claims (1)

[Scope of utility model registration request] In a multi-way speaker system using at least one piezoelectric ceramic speaker and an electrodynamic speaker, an intermediate tap is provided on at least one of the chain coils constituting the divided network, and the electrodynamic speaker is attached to the intermediate tap of the chain coil. A speaker system characterized by piezoelectric ceramic speakers connected to each end of the winding.