JPS58215809A - Crystal oscillator - Google Patents

Abstract

PURPOSE:To provide a function of voltage controlled oscillation and reference oscillation for a crystal oscillator, by providing a changeover switch for an oscillating circuit used for a signal processing circuit of a VTR for attaining switching for cases of applying a voltage to a filter through a voltage controlled phase shifter and applying it directly from an amplifier. CONSTITUTION:The crystal oscillator used for the signal processing circuit of the VTR is provided with a filter comprising a crystal oscillating element 24, capacitors 25, 27, resistors R1, R3 and a transistor (TR) 28. One end of this filter is connected to the input of the amplifier 21 and the voltage controlled phase shifter 22 is connected to the output of the amplifier 21. Further, the changeover switch 23 switching the outputs of the phase shifter 22 and the amplifier 21 is provided, the outputs of the amplifier 21 and the phase shifter 22 are changed over with the switch 23 and its output voltage is applied to the crystal oscillating element 24 of the filter. Moreover, the impedance of the filter is made high or low in response to the changeover of the switch 23 and one crystal oscillating element 24 is used as the reference oscillator and the voltage controlled oscillator, allowing to simplify the circuit constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to, for example, a color signal processing port of a video tape recorder w! 9. Regarding the crystal shaker used in rVC. In particular, it relates to a crystal oscillator having two functions: a reference oscillator and a voltage-controlled oscillator.

FIG. 1(a) is a block diagram of a color signal processing circuit of a video tape recorder (hereinafter referred to as VTR) using a conventional crystal oscillator during reproduction. In the figure, the color signal input terminal +11 is connected to one input of the frequency converter (2) of 41, and the output of this is connected to the output terminal (3) and one of the phase comparators (4). ing. The output of a reference frequency oscillator C5) is connected to the other input of this phase comparator (4), and the output of this phase comparator f4+ is connected to the input of a voltage-controlled oscillator (6).
The output of the oscillator (5) is connected to one input of a second frequency converter (7), and the output of the other human power oscillator (5) of this second frequency converter (7) is connected. The output of this 742 frequency converter (71 is the first frequency converter (
2), and constitutes a 7-A lock droop (hereinafter referred to as PLL) during playback. The voltage controlled oscillator (61) also forms a closed loop with the mislock detector (8J).

Next, the operation during reproduction will be explained, focusing on the oscillator (5) using a crystal resonator.

'When the low frequency converted color signal taken out from the head of the VTR is input to the input terminal Full VC, the output converted to a predetermined frequency by the first frequency converter (2) is output from the output terminal (3). taken out. Since the color signal taken out from the head at this time includes jitter, it is finally output to one input of the phase comparator (4), that is, the output terminal (
, 3) are locked to the frequency and phase of the reference oscillator (5), and time axis fluctuations are removed. At this time, the mislock detector (8) prevents the PLL from malfunctioning. Since the reference oscillation a (5J) in this frequency conversion operation requires high frequency stability, a Q value quotient oscillator using a crystal resonator is used.

Figure #11 (b) is a block diagram of the color signal processing circuit of the VTR during recording. In the figure, the color signal input terminal (1
) is connected to one input of the first frequency converter (2), the output of which is connected to the output terminal (3). The input terminal (11) is also connected to one input of a phase comparator (9), the output of which is connected to a voltage controlled oscillator u (j Vc) using a crystal oscillator; connected to one input of the frequency converter t73 of 2,
Its output is connected to the other input of the first frequency converter (2). The output of voltage controlled oscillator 4 is also connected to the other input of phase comparator (9) to form a PLL. Roughly, the horizontal synchronization signal input terminal (11) is connected to the input of the PL multiplier circuit 0, and the output of this is connected to the other input of the second frequency converter +73 to convert the color signal low frequency conversion circuit. It is configured.

The operation of the circuit configured as above during recording will be explained with a focus on the oscillator using a crystal resonator.

When a color signal is input to the input terminal [11VC], it is converted into a low frequency converted color signal by the first frequency converter (2), and is taken out from the output terminal (3) and magnetically recorded on a magnetic tape. A PLL consisting of a phase comparator (9) and a voltage controlled oscillator 11 is configured so that the output frequency of the voltage controlled oscillator 1 is locked to the frequency and phase of one of the phase comparators (9), that is, the frequency and phase of the color signal. Operate.

In this case, in order to ensure the voltage control A1 oscillator interval, necessary lock range, etc., a crystal oscillator is used, although the Q value is lower than that of the reference oscillator (5) during playback, but high frequency stability is required. A Taki suppression # oscillator is used.

As mentioned above, the conventional VTR color signal processing circuit li! requires an oscillator that uses two crystal oscillators: a reference oscillator (5) that uses a crystal oscillator exclusively for playback, and a voltage-controlled oscillator (4) that uses a crystal oscillator exclusively for recording, which reduces the cost of the oscillator. The disadvantage was that it was expensive.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and includes a filter consisting of a crystal resonator and an impedance means containing an actance component, and one end of this filter is connected to an input end. a voltage-controlled phase shifter in which the output end of the amplifier is connected to the input end, and the other end of the filter is switchably connected to the output end of the amplifier or the output end of the phase shifter. The purpose of this invention is to obtain a crystal oscillator having two functions as a reference oscillator and a voltage controlled oscillator using one crystal resonator.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. Figure 2 is a circuit diagram of a crystal oscillator used in the color signal processing circuit of a VTR. One terminal of switch 4 (23
a), and the output of switch 14 (4) is connected to the other terminal (23b) of switch 4 (VC). The common terminal (230) of the switch is connected to one terminal of a crystal oscillator, the other terminal of this is connected to one terminal of a capacitor with capacitance C1), and the other terminal of this is connected to one terminal of an amplifier ( It is connected to the input of (b) and grounded via a resistor 4 having a resistance value R1.

The other terminal of capacitor 4 is also connected to one terminal of capacitor ■, which waits for the capacitance to+, and the other terminal of this is connected to the collector of an NPN) transistor (c), that is, a switch that switches the impedance between two states. and is connected to a bias terminal (7) via a resistor having a resistance value R3, and the emitter of this bias terminal is grounded by the power supply. The base of this is the control terminal e
J). By applying a predetermined voltage to this control terminal 6υ, the transistor is turned on,
It can be turned off. Here, to the capacitor),
The circuit consisting of @ and the resistor is an impedance means including a reactance component, and constitutes the load of the crystal resonator (c). In other words, turn on the transistor,
By turning it off, the Q value of the oscillator can be changed. The resistance value (R1<<Rs) is designed to be sufficiently larger than the resistance value of the load resistance (R1<<Rs).

Also, when the transistor ) is ON, that is, when the VTR
When regenerating, one terminal (23a) of the switch block becomes conductive with the common terminal (2k), and the transistor (to)
When the power is off (that is, when the VTR is recording), the other terminal (23b) of the switch terminal is switched to be in a conductive state with the common terminal (23a), and the single oscillation loop is changed. There is.

In the crystal oscillator configured as above, during playback, a predetermined pressure is applied to the control terminal (b) and the transistor (
When switch c) is turned on, one terminal of switch 4 (23a
) is in conduction with the common terminal (23a), thereby constructing an oscillator that does not pass through the phase shift gap. At this time, the load on crystal oscillator 4, ignoring the input/output impedance of amplifier (2), is OX and z -R1/(1+a% 0,2R,")
It is a series of +VCjω((1+ω size, 2H, B)/ω2C♂R□勺)].Here, ω-2πf is the value, and f is the frequency. For example, Ox -02-27pF, R1-
f −4,43M in Ω to 2) When IZ, the isometric VC
As shown in Figure 3(a), the resistance component is o, 6Kn, and the capacitance component is 16p since 39pF and Ol are in series.
It becomes F. The transfer characteristic of the crystal oscillator (c) at this time is the fourth
It is possible to operate the crystal oscillator as a reference oscillator a (5) shown in Figure 1 (a) by using the crystal oscillator operated in this way. For example, it is possible to process color signals during KVTH reproduction as in the past.

Next, during recording, when the +11JIlil terminal Qυ is grounded and the transistor is turned off (VC), the other terminal (sb) of the switch - switches to the state of communication with the common terminal (23c), and the phase shifter (4) is turned off. A suppressed groan-shaped oscillator is constructed. At this time, the load on the crystal vibrating dried sardine is R1<< R3
Therefore, as shown in Figure 3(b), C1-2'lp
F and Rx become -2KO, and VcQ as shown in Figure 4 (to)
The value is lower than that expected for the reference oscillator, and its phase characteristics change over a wide range of frequencies compared to the characteristics when the Q value is high, as shown in Figure 5 (to). .

This voltage-controlled oscillator is shown in Figure 1(b).
If used as a shaker or shaker, it has the lock range necessary as a PLL, so it can also process color signals during VCVTR recording as in the past. Here the amplifier eυ
, capacitor 4, resistor) and transistor (2) are shared during playback and recording, making it suitable for integration.

Note that a resistor may be used instead of the capacitor used in the above embodiment. In this case, by damping, the frequency showing the peak value of the response characteristic in Figure 4 does not deviate much compared to the case without damping, but
When using a capacitor, damping causes the peak frequency to shift slightly and the overall phase characteristics to shift as well.

Further, in the above embodiment, a switch KNPNI-gingister □□□ for changing the impedance between two states is used, but this is not limited to VC, and other switches may also be used. I had linked the on/off 9 switching and the switching between passing the phase shifter and not passing it through the phase shifter.
Furthermore, the method of coupling impedances is not limited to the above embodiment, and there may be no switch for switching the master impedance between two states, and the intended purpose can be achieved in the same way.

Incidentally, in the above description, the present invention was applied to a color signal processing circuit of a VTR, but it goes without saying that it can also be applied to other signal processing circuits.

As described in detail above, according to the present invention, there is provided a filter composed of a crystal resonator and an impedance means including an actance component, an amplifier, and a voltage-controlled phase shifter. Since the crystal oscillator is configured so that it can be switched between when it does not pass through the instrument and when it passes through it, one crystal oscillator is used to have two functions as a reference oscillator and a pressure-controlled oscillator. This has the effect of reducing the cost of circuits to which this crystal oscillator can be applied.

[Brief explanation of the drawing]

Figure 41 (a) is a block diagram of a VTR color signal processing circuit using a conventional reference oscillator during playback, Figure 1 (1)) is a block diagram of it during recording, and Figure 2 is a block diagram of this Seimei color signal processing circuit. A circuit diagram showing an embodiment, Fig. 3 (equivalent circuit diagram of impedance when the impedance is in one state, Fig. 3)
FIG. 4 is a diagram showing the response characteristics of a persimmon example of the present invention, and FIG. 5 is a diagram showing its phase characteristics. In the figure, e]) is an amplifier, and (4) is a four-pressure controlled transfer (
1 device, the threat is a changeover switch, (c) is a crystal oscillator, W, g
I) is a capacitor, (4), @ is a resistor, and ) is a transistor. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1 Figure 2 Figure 3 - (0) (b) Figure 4 Shu Te & Fu (M/-/Z) Doujo (MH2 Procedural Amendment - (Spontaneous) Patent Office , Director-General 1. Indication of the case h' Application No. 57-100251 2. Name of the invention: Crystal oscillator 3. Relationship with the case by the person making the amendment Patent applicant address: 2-2-3 Marunouchi, Chiyoda-ku, Tokyo. Name (601,) Mitsubishi Electric Corporation Representative Hitoshi Katayama 4, Agent address 2-2 Marunouchi, Chiyo, Tokyo 1:I]
No. 3 No. 5, Detailed explanation of the invention column 6 of the specification to be amended, Contents of the amendment (1) "In Figure 4" on page 9, line 7 of the specification [Figure 4 C11) J I am corrected. (2) "Rock range" on page 9, lines 12-18 of the same book is corrected to "rock range, etc." (3) In the same book, page 9, lines 14 to 17, it says, “Here, the amplifier Qp
...It has become a thing. ” will be deleted. (4) In lines 8 to 11 of page 10 of the same book, delete the statement ``Also, it is not necessary to link the switches...''. (5) In the same book, page 10, line 12, ``1, without limitation'' is corrected to ``without limitation.'' (6) The entire statement on page 10, lines 18-15 of the same book will be deleted. that's all

Claims (1)

[Claims] (11) A filter consisting of a crystal oscillator and an impedance means including an actance component, one end of this filter is connected to an input end and an amplifier, and an output end of this amplifier is connected to an input end. A crystal oscillator comprising a voltage-controlled phase shifter, the other end of the filter being switchably connectable to the output end of the amplifier or the output end of the phase shifter. (2) The crystal oscillator according to claim 1, wherein the impedance means is configured to be able to switch its impedance between two values in response to the switching connection of the other end of the filter. 3. The crystal oscillator according to claim 2, wherein the crystal oscillator has a high impedance when the other end is connected to a phase shifter and a low impedance when the other end is connected to an amplifier.