JPH0227638Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a structure in which the high-frequency coils and variable capacitance diodes of the input tuner part of a receiver, including other elements, are combined into one block.

Traditionally, various types of receivers use a tuning coil, a local oscillation coil, and a variable capacitance element for tuning on the antenna input side to cover the specified minimum and maximum receiving frequency, and to cover all points within that band. Tracking adjustment is made to keep the sensitivity within a certain deviation, and the inductance of each coil element is adjusted, as well as the trimmer capacitor that is always added. However, since the distributed capacitance of a typical small coil has a large variation of about 3 to 6 PF, it is necessary to perform troublesome tracking adjustment using a trimmer capacitor after the set is assembled.

The present invention improves this drawback, reduces the distributed capacitance of the coil, reduces its variation, eliminates the trimmer capacitor, and integrates the circuit part using coils, electronic tuning diodes, and some elements into one block. After assembling and incorporating it into a set, it provides a structure that requires no adjustment and reduces costs.

The present invention will be explained below with reference to the drawings.

FIG. 1 is an elevational sectional view showing the structure of a high frequency coil used in the coil block of the present invention, and FIG. 2 is a diagram of the present invention. In the figure, 1 is a drum core, 2 is a winding portion, 3 is a cap core, 4 is a base, 5 is an internal capacitor, 6 is a shield case, and 7 is a terminal pin. One of the features of the present invention lies in the structure of the drum core used in these coils. That is, the winding width B of the winding portion 2 is larger than the flange thickness A of the drum core 1.
have a structure that is approximately equal or smaller. Therefore, the distributed capacitance of a coil wound with this winding width B is smaller than that of a coil with a large winding width like a normal drum, and the distributed capacitance is 2 to 3 PF, and its variation is also small. The reason for this is that normally, the distributed capacitance of a multilayer coil is such that the smaller the difference in the number of turns between the beginning of a certain layer and the end of the second layer after folding the first layer, the smaller the distributed capacitance between the lines. That is, the smaller the winding width, the smaller the winding width. In addition, with the drum core-like shape of a normal small coil, it is impossible to wind in perfect alignment, and overlapping windings occur along the way, resulting in variations that are not necessarily constant. Therefore, the size of the winding width greatly affects the distributed capacitance. Regarding the winding width B and collar thickness A of the present invention, B≦
Condition A is determined within a range that is sufficient for practical use.The smallest variable capacitance diode has a minimum capacity of around 25P, and the distributed capacitance of the coil is 2 to 3PF, and its variation is even. It has become something that can be ignored. The actual data is shown in FIG. All drum cores have a height of 4.5mm, the number of turns is 100T, and curve 1 is the most commonly used of this invention, with the thickness A of the upper and lower brim being 1.6mm, and the winding width B
is 1.3mm and its distributed capacity is MAX2.53PF,
MIN2.20PF, average is 2.324PF, curve 2 shows the case where A=B=1.5mm,
MAX3.37PF, MIN3.0PF, is 3.219PF.
On the other hand, the drum core normally used for IFT has a top and bottom brim thickness B of 1.1mm, a winding width B of 2.3mm, and a distributed capacity of MAX5.97PF and MIN5.07PF, with an average of
5.516PF is shown by curve 3, and curve 4 has a thin upper brim of 0.6 mm, a lower brim of 1.1 mm, and a winding width B of 2.9 mm, which is MAX7.9PF, MIN6.3PF,
The average is 7.254PF. In this way, if the winding width B and the flange thickness A are equal or B<A, the minimum capacitance of the variable capacitance diode, which is around 25PF, can be ignored. Note that 5 is a fixed capacitor that supplements the capacitance of the variable capacitance diode so as to cover the reception band, and is installed inside the terminal board of the coil to save space.

Next, in Fig. 2, 11 is a high frequency tuning coil;
12 is a local oscillation coil, 13 is a variable capacitance diode, 14 is a resistor, 15 is a board of the block, and 16 is a terminal pin for attachment thereof. The circuit configuration of this block is shown in FIG. As will be clear from this, there is no need for a trimmer capacitor, and all adjustments can be made while assembled on the coil block.Set manufacturers only need to assemble this on the board, and then no adjustments are required, eliminating the tedious adjustment process of the past. It can be omitted.

As described above, according to the present invention, the number of components in the tuner part of the receiver is reduced, variations in the distributed capacitance of the coil are reduced, and some of the capacitors are also housed within the coil, making it compact as a single coil block. This eliminates the need for troublesome adjustments by the set manufacturer and reduces overall costs, which has great practical effects.

[Brief explanation of the drawing]

Figure 1 is an elevational sectional view showing the structure of the high frequency coil used in the coil block of the present invention, Figure 2 is an elevational view of the coil block of the invention, Figure 3 is its circuit diagram, and Figure 4 is the core. It is a characteristic diagram of the distributed capacitance of each shape. 1... Drum core, 2... Winding part, 3... Cap core, 4... Base, 5... Capacitor,
6... Shield case, 7... Terminal pin, 11...
...Tuned coil, 12...Local oscillation coil, 13...
...Variable capacitance diode, 14...Resistor, 15...
substrate.

Claims (1)

[Scope of utility model registration request] In the input electronic tuning tuner circuit of a receiver, the parts of the circuit that require adjustment, including the high frequency tuning coil, local oscillation coil, and variable capacitance diode for electronic tuning, are configured into one circuit block, and used for these coils. A coil block for electronic tuning, characterized in that the drum core has a winding width B of the winding portion that is approximately equal to or smaller than the thickness A of the collar, thereby reducing the stray capacity of the coil.