JP3143387B2 - Electronic equipment unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna switching circuit provided with an RF modulator circuit, and a PLL tuning circuit.
A tuner circuit unit including a PLL tuning circuit having C;
The present invention relates to an electronic device unit in which an IF circuit unit and an audio multiplex circuit unit are provided integrally.

[0002]

2. Description of the Related Art A conventional electronic device unit is divided into an RF modulator including an antenna switching circuit, a tuner unit including a PLL tuning circuit, an IF unit, and an audio multiplex demodulation unit. However, with the downsizing of the VTR, a 2IN1 tuner integrated with an RF modulator unit and a tuner unit, a 3IN1 tuner integrated with an IF unit, and a 4IN1 tuner integrated with an audio multiplex demodulation unit have been developed.

The PLL tuning circuit of the tuner circuit is a circuit that outputs reception frequency data and band data input from the tuning microcomputer for each reception channel as tuning voltages and band switching signals required for the tuning operation.

At present, the PLL tuning IC of the tuner circuit is:
The main focus is on the 3-wire control system. However, in order to reduce the number of control ports for channel selection microcomputers in multifunctional VTRs and the like, two lines (SCL, SDA)
It is considered that the number of I2C bus control systems that can control many ICs only by using the IC alone increases.

However, RF modulator IC, IFIC,
The voice multiplex IC has no input / output data and the PLL tuning I
Because the switching function is very small compared to C,
Does not have 2C bus control. Therefore, control of the switching function is executed by occupying a single channel-selecting microcomputer port individually.

[0006] In addition, the channel selection microcomputer is required to process at a high speed as the VTR becomes multifunctional, and the clock frequency is improved by improving the clock frequency. However, since the clock frequency has been increased, harmonics of the clock oscillation have come to have an adverse effect such as a beat on a TV broadcast screen or audio via the electronic device unit.

[0007] As a countermeasure for this, first, in order to improve the influence of radiation, it is necessary to take a countermeasure such as increasing the distance from the channel selection microcomputer or blocking with a shield plate.
Further, in order to reduce the leakage of harmonics on the signal line, a low-pass filter has to be added on the signal line between the tuning microcomputer and the electronic device unit. For this reason,
Circuit wiring is very complicated on a printed circuit board with a narrow VTR that is being miniaturized. By arranging a large number of circuit wirings for a long time, it has become susceptible to noise of other circuits and external noise.

FIG. 4 shows a configuration diagram of a conventional electronic device unit.

[0009] The broadcast signal is output from the antenna 1 through the antenna switching circuit 3, the tuner circuit 5 and the IF circuit 7, and the audio is output through the audio multiplex demodulation circuit 8. Conversely, the output from the VTR side is transmitted from the RF modulator circuit 4 through the antenna switching circuit 3 to the TV
2 is output.

In the electronic equipment unit 9, in the circuits other than the PLL channel selection circuit 6, there are the following switching signals as connection signals with the channel selection microcomputer 10.

That is, the antenna switching circuit 3 has a TV / VTR switching signal 11b for switching between a broadcast signal from an antenna and an RF modulator output from a VTR, and an RF modulator output channel (normally a Japanese modulator). In this case, there is an RF channel switching signal 12b for switching between 1ch and 2ch).

The IF circuit 7 has a video mute signal 15b for muting the video signal when the receiving channel is switched or when the electric field is weak.

The audio multiplex demodulation circuit 8 includes an audio mute signal 1 for muting an audio signal during a tuning operation or a weak electric field.
6b and an audio multiplex mode switching signal 17b for switching the mode (MAIN / BOTH / SUB) of the output matrix in the audio multiplex demodulation IC.

Conversely, as signals output to the channel selection microcomputer, there are a stereo broadcast discrimination signal 18b and a double broadcast discrimination signal 19b which are discrimination signals of the audio multiplex demodulation IC.

[0015]

As described above, conventionally, the switching function is performed by occupying many ports of the channel selection microcomputer for the electronic equipment unit.

Further, through the wiring between the electronic equipment units of the tuning microcomputer, the harmonics of the clock of the tuning microcomputer become
This had adverse effects such as broadcast video beats and audio buzz.
As a countermeasure, a low-pass filter had to be added to all signal lines between the tuning microcomputer and the electronic device unit.

[0017] For this reason, circuit wiring has become very complicated on a printed circuit board having a narrow VTR to be miniaturized. Furthermore, by laying a large number of circuit wirings long. It was also susceptible to noise from other circuits and external noise.

Accordingly, an object of the present invention is to solve such a problem.

[0019]

SUMMARY OF THE INVENTION The present invention provides an antenna switching circuit having an RF modulator circuit, a tuner circuit having a PLL tuning circuit having a PLL tuning IC, an IF circuit, and a voice multiplexing circuit. Is an electronic device unit integrally provided, wherein the IC is connected to a tuning microcomputer provided outside the unit by a bus line, and the respective circuit units are provided in the IC. And a plurality of input / output terminals.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an electronic equipment unit according to an embodiment of the present invention, and FIG. 2 is a block diagram of a PLL-IC in a PLL tuning circuit 6 used for the electronic equipment unit.

In FIG. 1, 1 is an antenna, 2 is a TV,
3 is an antenna switching circuit, 4 is an RF modulator circuit, 5 is a tuner, 6 is a PLL tuning circuit, 7 is an IF circuit, 8 is an audio multiplex demodulation circuit, 9 is an electronic equipment unit,
0 is a channel selection microcomputer, 11a is a TV / VTR switching signal, 12a is an RF modulator output channel switching signal, 13 is SDA (serial data), 14 is SCL
(Serial clock), 15a is a video mute signal, 1
6a is an audio mute signal, 17a is a sound multi-mode switching signal, 18a is a stereo broadcast discrimination signal, 19a is a double broadcast discrimination signal, 20 is tuning band data, 21 is tuning frequency data, and 22 is L.L. P. F. It is.

In FIG. 2, 13 is an SDA, 14
Is an SCL, 23 is an RF input, 24 is a preamplifier, 25 is a prescaler, 26 is a programmable frequency divider, 27 is a crystal, 28 is an oscillator, 29 is a frequency divider, 30 is a phase shift detector, 31 is a tuning voltage, 32 Is a bus receiver, 33 is a port switch driver, 34 is P0, 35 is
P1, 36 are P2, 37 is P3, 38 is P4, 39 is P5, 40 is
P6 and 41 are P7 and 42 are PLL tuning ICs.

As the PLL-IC, GEC PLE is used.
A PLL-IC (part number SP5610) manufactured by SSEY is used. The input / output port of this PLL IC is P0
There are eight terminals 34 to P741. Of these, P034-P2
The three terminals 36 are output-only terminals. P337 is an output function + address setting terminal. P438 to P741 are input / output terminals capable of bidirectional communication. The output of each terminal is determined by SDA13. WRITE DA of SDA13
TA FORMAT is shown in FIG. The output of each terminal is determined by the port DATA of BYTE5. FIG. 8 shows the address setting.

The information of the input terminal is switched from the WRITE mode to the READ mode (the 8th bit of the address is set to 0).
→ Change to 1) and read it. SDA1
The READ DATA FORMAT of No. 3 is shown in FIG.
BYTE2 3-bit I2, 4-bit I1, 5-bit I
0: Information of P7, P5, P4 terminals (HIGH / LOW)
Read. P6 terminal only, 6 bits A2 to 8 bits A
Five levels of voltages can be read with three bits up to zero. FIG. 7 shows data at the P6 DC level.

However, in the case of a general tuner, three frequency bands VL, VH, and U are required at the time of tuning. Even if this is connected to P0 to P2, the remaining five terminals are unused terminals.

Therefore, according to the present invention, an unused terminal of the PLL-IC which is not used for band switching is connected to a switching signal other than the tuner circuit (TV / VTR switching signal, RF channel switching signal, video mute signal, audio mute signal, sound mut). Mode switching signal, stereo broadcast discrimination signal,
Utilizing for dual broadcast discrimination signal), the signal line between the channel selection microcomputer and the electronic equipment unit and the control port of the channel selection microcomputer are reduced, and on a narrow printed circuit board of a VTR,
Circuit wiring can be facilitated. In addition, since the number of signal lines is reduced, the influence of noise in other circuits can be improved, countermeasure circuits (such as low-pass filters) can be reduced, and a circuit can be formed at low cost.

FIG. 3 shows a second embodiment of the present invention. The difference from the previous embodiment is that the audio multiplex demodulation circuit 8
Output Q signal output terminal (for stereo broadcasting, HIGH
Voltage, LOW voltage for dual broadcasting, MI for monaural broadcasting
D voltage) 43a and the voltage discrimination terminal P of the PLL-IC 42
By connecting to the 640, the broadcast mode can be determined based on the voltage, so that the conventionally used stereo determination signal 18 and dual broadcast determination signal become unnecessary.

This further simplifies the circuit configuration,
The number of signal lines between the channel selection microcomputer and the electronic device unit and the control port of the channel selection microcomputer can be reduced, and circuit wiring can be simplified.

[0030]

As described above, according to the present invention, the number of selected microcomputer ports used is reduced, and the number of connections between the electronic device unit and the selected microcomputer is reduced. The effects of noise from other circuits and external noise can be reduced, circuit wiring becomes very easy, and a circuit configuration can be improved to a low-cost and simple circuit by reducing countermeasures against interference on the circuit.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of an electronic apparatus of the present invention.

FIG. 2 is a diagram showing a PLL circuit used in the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram for explaining a conventional example.

FIG. 5 is a diagram showing a write data format.

FIG. 6 is a diagram showing a read data format.

FIG. 7 is a diagram showing ADC levels.

FIG. 8 is a diagram illustrating an address setting.

[Explanation of symbols]

Reference Signs List 1 antenna 2 TV 3 antenna switching circuit 4 RF modulator circuit 5 tuner 6 PLL tuning circuit 7 IF circuit 8 audio multiplex demodulation circuit 9 electronic equipment unit 10 tuning microcomputer 11a, b TV / VTR switching signal 12a, b RF modulator output channel Switching signal 13 SDA 14 SCL 15a, b Video mute signal 16a, b Audio mute signal 17a, b Multi-mode switching signal 18a, b Stereo broadcast discrimination signal 19a, b Dual broadcast discrimination signal 20 Tuning band data 21 Tuning frequency Data 22 L.R. P. F.

Claims (3)

(57) [Claims] 1. An antenna switching circuit unit having an RF modulator circuit, a tuner circuit unit having a PLL tuning circuit having a PLL tuning IC, an IF circuit unit, and an audio multiplexing circuit unit are integrally provided. An electronic device unit, wherein the IC is connected to a tuning microcomputer provided outside the unit by a bus line, and each of the circuit units includes a plurality of input / output terminals provided in the IC. An electronic device unit to be connected. 2. The electronic device unit according to claim 1, wherein said bus line is an I2C bus. 3. An antenna switching circuit having an RF modulator circuit, a tuner circuit having a PLL tuning circuit having a PLL tuning IC, an IF circuit, and an audio multiplexing circuit are provided integrally. The IC is connected to a tuning microcomputer provided outside the unit by a bus line, and the respective circuit units are connected to a plurality of input / output terminals provided in the IC. Video tape recorder equipped with an equipment unit.