JPH0434576Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention provides a method for easily setting an initial tuning voltage for an electronic tuning device such as a radio receiver and storing it in the electronic tuning device. The present invention relates to a device for detecting an optimum tuning voltage.

(Prior art) In a conventional PLL type receiver using a variable capacitance diode (hereinafter also referred to as a varactor), as disclosed in Japanese Patent Publication No. 58-34051, the OSC
The voltage applied to the varactor of the ANT tuning circuit (local oscillation circuit) was also applied to the varactor of the RF tuning circuit.

In addition, in this type of electronic tuning device, the OSC
The oscillation frequency 0 is the receiving frequency r, the intermediate frequency i
There is the following relationship.

0=r±i For this reason, capacitors are installed in each of the OSC, ANT tuning circuit, and RF tuning circuit, and for example,
Taking an AM receiver as an example, 600kHz, 100kHz,
The capacitance of the capacitor was adjusted so that tracking could be achieved at three points at 1400kHz.

According to the above-mentioned conventional electronic tuning device, the above-mentioned
The varactors used in the OSC, ANT tuning circuit, and RF tuning circuit must be selected so that they all have the same applied voltage vs. capacitance, and selecting such components is complicated.

Furthermore, as mentioned above, when tracking adjustment is made at three locations, for example, as shown in Figure 8, other than the tracking adjustment,
The ANT and RF tuning circuits had a tuning shift with respect to the receiving frequency, and the sensitivity could not be said to be good.

By the way, as an improvement to the channel selection device of a television tuner, a proposal has been made to completely adjust the tracking (Japanese Patent Application Laid-Open No. 150323/1983).

This proposal involves storing pre-selection tuning voltages and inter-stage selection tuning voltages for multiple reception channels in a non-volatile memory, and directly outputting the contents of this non-volatile memory, or directly outputting the contents of the memory. Each tuning voltage corresponding to the reception channel is obtained by executing a predetermined calculation formula based on the received signal and outputting the calculation result.

The present applicant also registered a utility model on the same date as the present application for an electronic tuning device suitable for radio receivers that calculates and applies a tuning voltage by linear interpolation based on the characteristic of frequency versus applied voltage stored in advance. It is proposed in the application.

(Problem that the invention aims to solve) In the conventional tracking adjustment using three frequency points, the capacitance of the trimmer capacitor is adjusted at each frequency using a screwdriver. The rotation angle is roughly adjusted, and finally the SG (signal generator) oscillates three different frequencies, and the final adjustment of the capacity is made so that the signal meter when receiving this is at its maximum. .

However, this method imposes a heavy burden on the worker;
Productivity was also not good.

On the other hand, the method of storing the tuning voltage for a predetermined reception frequency in memory has the advantage that no adjustment is required once it is written to the memory, but it is necessary to increase the tuning voltage one by one to detect the optimum tuning voltage. If the meter detects the maximum voltage, it takes a long time to detect it, and productivity cannot be improved. Another option is to rely on experience and intuition to set the expected tuning voltage for each reception frequency to an appropriate value, but this also depends on the ability of the worker, so although it may improve productivity across the board. Nakatsuta.

Therefore, the purpose of the present invention is to eliminate the above-mentioned conventional drawbacks and to allow anyone to extremely easily detect the optimal tuning voltage to be stored in the electronic tuning device, regardless of the ability of the operator. The object of the present invention is to provide a tuning voltage detection device for an electronic tuning device that can perform the following steps, thereby significantly improving productivity.

[Structure of the invention] (Means for solving the problems) The present invention provides an electronic tuning device that has a tuning circuit equipped with a variable capacitance diode and stores in advance a tuning voltage of the variable capacitance diode for a predetermined receiving frequency. A device for detecting the tuning voltage of
The apparatus is configured to include a control means for automatically applying an initial tuning voltage close to an optimum tuning voltage corresponding to the predetermined receiving frequency to the variable capacitance diode.

(Function) In order to detect the tuning voltage early, it is effective to set the initial tuning voltage to be first applied to the variable capacitance diode of the tuning circuit to a value close to the final tuning voltage.

In this invention, the initial tuning voltage is automatically set according to the reception frequency at which the optimal tuning voltage is to be detected, so it is easier to set the voltage than the conventional method of setting by trial and error or the voltage setting that relies on experience and intuition. For example, it is possible to reliably and quickly detect the tuning voltage that allows optimal tuning.

(Example) Hereinafter, the present invention will be specifically described with reference to the illustrated example.

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

First, electronic tuning device A will be explained. The electronic tuning device A shown in the figure is a tuning device for a multi-band radio receiver that can receive AM, FM, etc., but the configuration of the tuning section for each band is almost the same, so here we will explain how to tune FM. Let me explain about the section.

In the figure, 1 is an antenna, 2 is an ANT tuning circuit, 3 is an RF amplifier, 4 is an RF tuning circuit, 5 is a mixer, 6 is an IF amplifier, 9 is a signal detection circuit,
The ANT tuning circuit 2 includes a first varactor 2A,
Each of the RF tuning circuits 4 has a built-in second varactor 4A. Optimum tuning is achieved by independently controlling the voltages applied to the first and second varactors 2A and 4A, as will be described later.

Voltage controlled oscillator (hereinafter also referred to as OSC) 7
is for controlling the local oscillation frequency mixed by the mixer 5, and is provided with a PLL circuit 8 for locking the oscillation frequency of the voltage controlled oscillator 7 to, for example, the sum of the receiving frequency and the intermediate frequency. . As shown in the figure, this PLL circuit 8 is composed of a reference frequency oscillator 8A, a programmable counter 8B, a phase comparator 8C, and a low-pass filter 8D. The voltage is applied to the No. 3 varactor 7A. Incidentally, the output of this low-pass filter output 8D is used for setting the initial tuning voltage as described later.

Next, the configuration for setting and controlling the voltages applied to the first and second varactors 2A and 4A will be explained. As shown in the figure, it is composed of a microcomputer 10 which is a calculation means and a non-volatile memory 11. There is.

The nonvolatile memory 11 stores in advance the reception frequency vs. applied voltage characteristics for three or more reception frequencies for the variable capacitance diodes 2A and 4A of the tuning circuits 2 and 4, and in this embodiment, the reception frequency As shown in Figure 7, the characteristics of the applied voltage versus the applied voltage are the applied voltage Vmin for the lowest reception frequency min, and the applied voltage change a for each predetermined frequency within each band obtained by dividing the band up to the maximum reception frequency max by a predetermined number. I remember ~g.

Here, the contents stored in the nonvolatile memory 11 are generated by generating the frequencies min, 1, 2, ... max shown in FIG. 7 in advance by an SG (signal generator) at the manufacturing stage of the electronic tuning device. , the voltages applied to the first and second varactors 2A and 4A are determined by measuring the voltages applied to the first and second varactors 2A and 4A at which optimum tuning can be achieved by the tuning circuits 2 and 4 for each receiving frequency. Specifically, for example, the varactor applied voltage at which the signal meter output of the signal detection circuit 9 is maximum
Vmin, V1, V2, ... Vmax will be found. A tuning voltage detection device B is provided to detect this voltage applied to the varactor.
Note that this tuning voltage detection device B will be described later.

The applied voltage changes a to g for each predetermined frequency within each band are calculated by calculating the number of stations from a = V1 - Vmin/min to 1, and the applied voltages for b to g are determined in the same way. It can be determined by dividing the difference by the number of stations between them. In addition, taking FM as an example, the number of stations mentioned above means every 100KHz in Japan, every 200KHz in America, and 50KHz in Europe.
There are broadcasting stations at every frequency, and it can be determined by how many stations there are at each of these frequencies. Alternatively, the number of stations may be set at intervals smaller than the above frequency.

Incidentally, the applied voltage Vmin and the applied voltage changes a to g with respect to the minimum reception frequency min are determined for the first and second varactors 2A and 4A, respectively. Regarding the selection of receiving frequencies 1 to 6 for determining applied voltage changes a to g, the curve of the receiving frequency-applied voltage characteristic shown in Fig. 7 should narrow the frequency interval in the band where it is non-linear, and It is preferable to set a wider frequency interval for a band closer to , in order to improve accuracy during linear interpolation, which will be described later.

The microcomputer 10, as shown in FIG.
CPU10A, ROM (read only memory)
10B, RAM (Random Access Memory)
10C, and a D/A converter 10D. When a channel selection command is received by pressing a preset switch, Seek mode, etc., display data of the selected receiving frequency and a hex signal are sent to the PLL circuit 8. The value and the voltage applied to the first and second varactors 2A and 4A are respectively calculated.

For this purpose, the ROM 10B has the frequency
min, 1, ...max, the minimum receiving frequency
Hex value corresponding to min, unit frequency that should be added sequentially to calculate frequency display data (100KHz in Japan, 200KHz in America,
In Europe, 50KHz, etc.), the PLL circuit 8
A unit addition value for calculating a hex value for , etc. is stored. In addition, the frequency min, 1,...
...max can be fixed as long as the characteristics of the varactor shown in FIG. 7 do not change significantly, so in this example,
Although the data is written in the ROM 10B, if there are variations in the characteristics of the varactors, the data may be written in the nonvolatile memory 11 as set-specific data.

In addition, as shown in FIG. 6, the RAM 10C has an area A for rewriting frequency display data.
1, a hex value rewriting area A2, a first varactor applied voltage rewriting area A3, and a second varactor applied voltage rewriting area A4 are provided.

Next, the tuning voltage detection device B will be explained.

This tuning voltage detection device B detects the aforementioned varactor applied voltages Vmin, V1, ... Vmax, and includes a microcomputer 20 and a signal generator (SG) 21 as control means.
It is composed of.

As shown in FIG. 2, the microcomputer 20 includes a COU 20A, an A/D converter 20B,
Consisting of a D/A converter 20C and a RAM 20D, the low-pass filter output of the PLL circuit 8 is input to the CPU 20A via the D/A converter 20B, and the CPU 20A inputs a voltage having the same value as this input voltage to the initial tuning. The voltage is applied to the first and second varactors 2A and 4 via the D/A converter 20C.
It is designed to be applied to A. Further, after setting the initial tuning voltage, this microcomputer 20 inputs the output of the signal detection circuit 9 via the A/D converter 20B, stores this signal meter output in the RAM 20D, and then The voltage is raised or lowered from the initial tuning voltage, and the voltage at which the signal meter output is maximum is detected as the optimum tuning voltage. The microcomputer 20 controls the oscillation frequency of the SG 21 and repeatedly executes the above operation for each of the min, . . . , max reception frequencies to obtain the optimum tuning voltages Vmin, . . . , Vmax. It is designed to be detected sequentially.

The operation of the tuning voltage detection device B for the electronic tuning device A of the radio receiver configured as above will be explained.

First, the CPU 20 of the microcomputer 20
A controls the SG 21 to oscillate min, which is the lowest reception frequency, and causes the electronic tuning device A to receive the frequency through the antenna 1. This frequency tuning command is also input to the programmable counter 8B of the PLL circuit 8, and the PLL circuit 8
In order to lock the oscillation frequency of OSC7 to the frequency obtained by adding the intermediate frequency to the receiving frequency,
A DC voltage is output from the LPF 8D and applied to the third varactor 7A.

Here, in the device of this embodiment, the PLL circuit 8
The DC voltage of D is input to the microcomputer 20 of the tuning voltage detection device B. The microcomputer 20 inputs the DC voltage to the CPU 20A via the A/D converter 20B, and inputs the DC voltage to the CPU 20A.
The varactor applied voltage having the same voltage value as the voltage is used as the initial tuning voltage to the first,
The voltage is applied to the second varactors 2A and 4A.

The reason why the LPF output of the PLL circuit 8 is input to the microcomputer 20 and used for setting the initial tuning voltage is as follows. That is,
Optimum tuning can be achieved by applying the same voltage to the first to third varactors 2A, 4A, and 7A as long as the applied voltage vs. capacitance characteristics are the same. However, in this embodiment, it is assumed that there are variations in the characteristics. When, the LPF output is the first and second varactors 2A,
Since this value is close to the optimum tuning voltage of 4A, this LPF output is used as the initial tuning voltage to enable early detection of the optimum tuning voltage.

As a result, compared to the conventional method, the time required to search for a value close to the optimal tuning voltage can be significantly reduced, and the detection time can be uniformly shortened regardless of the ability of the operator. Therefore, it is possible to significantly improve productivity.

After setting the initial tuning voltage, the optimal tuning voltage can be detected by manually changing the voltage applied to the varactor while watching the signal meter, but in this embodiment, the subsequent detection operation is also automated.

An example of this detection operation will be explained with reference to the flowchart of FIG.

In step 1, the initial tuning voltage is set as described above. Then, the signal meter output, which is the output of the signal detection circuit 9 under this tuning voltage, is sent to the CPU 20A via the A/D converter 20B.
and store it in the RAM 20D (step 2).

Next, in order to detect the optimum tuning voltage of the first varactor 2A, the voltage applied to the second varactor is fixed to the initial tuning voltage, and the voltage applied to the first varactor 2A is increased by, for example, one step. Step 3). Similarly, the signal meter output at this time is stored (step 4).

Next, in step 5, it is determined whether there is a change in the output. If there is no output change, the case is as shown in Figure 4a (possible in the case of FM), and in this case, as shown in the figure, check multiple points where there is no output change, and tune the intermediate voltage V to the optimum. voltage (step 6).

If there is a change in the output in step 5, it is determined whether the change is in a positive direction (step 7). If the change is in a negative direction and the previous change was positive, it is determined (step 7) 8),
Since this is the case shown in FIG. 4b, in step 12, the previous voltage is set as the optimum tuning voltage and the process ends.

If it is determined in step 8 that the change is in the positive direction, and the previous change is also positive in step 9 (including cases where there was no previous measurement), the tuning voltage is increased by one step (step 10), and the process is repeated in step 4.
Return to and execute the detection operation. In this case, since it is the case of Figure 4c, the final steps are steps 8 and 12.
The optimum tuning voltage can be detected by the following route.

If it is determined in step 9 that the previous change was a negative change, this is the case in Figure 4 d, so step
At step 11, the tuning voltage is lowered by one step, and the process returns to step 4 to repeat the detection operation.

In this way, the first varactor antenna 2A
When the optimum tuning voltage for the reception frequency min is detected, the voltage detection operation for the second varactor 4A is performed in the same way while keeping this optimum tuning voltage fixed, and this is done for each frequency after reception frequency 1. Repeat the above tuning voltage
The detection of Vmin, ..., Vmax is completed.

Then, based on the tuning voltage detected as described above, the applied voltage changes a to g are calculated, and these and the minimum tuning voltage Vmin are written in the nonvolatile memory 11, thereby completing the electronic tuning device A. I will do it.

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

For example, for automatic setting of initial tuning voltage,
In addition to those that utilize the low-pass filter output of the PLL circuit 8, the initial tuning voltage corresponding to the frequency mentioned above is measured in advance and stored in the memory within the control means 20, and it is read out and applied according to the frequency. You can do it like this. At this time, each time the optimal tuning voltage is detected, the voltage value and its frequency value are stored in the memory, and the voltage value with the largest frequency value is applied as the initial tuning voltage, thereby further shortening the detection time of the optimal tuning voltage. be able to.

Note that the tuning section of an electronic tuning device to which the present invention is applied is not necessarily limited to those having two or more types of tuning sections, ANT and RF, but also those that adopt a double conversion method in the AM tuning section. Usually, only one tuning section is required, and in the case of such an AM tuning section, it is sufficient to detect one type of varactor applied voltage.

Furthermore, the present invention is not limited to being applied to AM and FM tuning units, but can be similarly applied to devices with other bands such as short waves and long waves, and even electronic tuning equipment for televisions. Detection of the tuning voltage can be similarly optimized.

[Effects of the invention] As explained above, according to the invention, the initial tuning voltage when detecting the optimum tuning voltage of the electronic tuning device is automatically set to a value close to the optimum tuning voltage, so that the optimum tuning voltage can be set automatically. The tuning voltage detection time is significantly shortened, which can greatly contribute to improving productivity.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an example of the configuration of the control means;
FIG. 3 is a flowchart showing an example of the optimal tuning voltage detection operation, FIGS. 4a to 4d are explanatory diagrams of the optimal tuning voltage detection operation, and FIG. 5 is a block diagram showing an example of the configuration of the microcomputer of the electronic tuning device. , Fig. 6 is a schematic explanatory diagram showing the storage area of the RAM of the electronic tuning device, Fig. 7 is a characteristic diagram showing frequency-applied voltage characteristics, and Fig. 8 is frequency tuning in the case of conventional three-point tracking adjustment. FIG. 2 is a schematic explanatory diagram showing misalignment. A... Electronic tuning device, B... Tuning voltage detection device, 2, 4... Tuning circuit, 2A, 4A... Variable capacitance diode, 20... Control means.

Claims (1)

[Claims for Utility Model Registration] (1) A tuning circuit including a variable capacitance diode, storage means for storing in advance a tuning voltage of the variable capacitance diode for a predetermined receiving frequency, Used in an electronic tuning device having a local oscillator that outputs an oscillation frequency to be mixed, a frequency mixer that mixes the received frequency and the oscillation frequency, and a PLL circuit that locks the oscillation frequency of the local oscillator. A tuning voltage detection device for detecting the tuning voltage to be stored in the storage means, comprising: a signal generator that outputs a signal of the predetermined receiving frequency to the tuning circuit; The above-mentioned device operates in accordance with a tuning command for a predetermined reception frequency.
Based on the low-pass filter output of the PLL circuit,
A tuning voltage detection device for an electronic tuning device, comprising: control means for setting an initial tuning voltage to be applied to the variable capacitance diode. (2) The tuning voltage detection device for an electronic tuning device according to claim 1, wherein the control means sets the initial tuning voltage to the same voltage as the output of the low-pass filter of the PLL circuit. (3) The control means is provided with a memory for storing the initial tuning voltage, and reads out the initial tuning voltage corresponding to a predetermined reception frequency from the memory and applies it. Tuning voltage detection device for electronic tuning equipment. (4) The control means stores the tuning voltage value and its frequency value in the memory every time the optimum tuning voltage to be stored in the storage means is detected, and stores the tuning voltage with the maximum frequency value in the memory. A tuning voltage detection device for an electronic tuning device according to claim 3, which is set as an initial tuning voltage. (5) After setting the initial tuning voltage, the control means stores the signal meter output when tuning with this tuning voltage, increases or decreases the voltage from the initial tuning voltage, and sets the voltage at which the signal meter output is maximum. A tuning voltage detection device for an electronic tuning device according to any one of claims 1 to 4, which detects the tuning voltage as the optimum tuning voltage. (6) The electronic tuning device according to claim 5, wherein the control means detects an intermediate voltage as the optimum tuning voltage when there are a plurality of tuning voltages at which the signal meter output becomes maximum. Tuned voltage detection device.