KR0134815Y1 - Free amp circuit in remocon - Google Patents

Abstract

The present invention relates to a pre-amp circuit for the remote control, in particular a strong fluorescent light in the room and a light source of the outside of the remote control (Remocon) of household appliances such as TVs and VTRs using the preamp circuit is applied The present invention relates to a preamplifier circuit for a remote controller that enables amplification of the remote controller to operate normally even if infrared rays are detected.

In the preamplifier circuit for a remote control according to the prior art, strong light is sensed by a photodiode by an infrared ray such as an external fluorescent lamp and solar energy, and an excessive current flows in the photodiode so that a DC voltage is constant at the input of the differential amplifier. There is a problem that the operation as a differential amplifier becomes impossible by lowering below.

Therefore, the present invention is to solve the above-mentioned general problems, the differential amplifier for amplifying and outputting by the two input signal difference of the transistor; A negative feedback unit for negatively feedbacking and amplifying the output signal of the differential amplifier; An open gain determining unit configured to determine an open loop gain of the amplified signal output from the differential amplifier; A preamplifier circuit for a remote controller including a feedback conditioner for determining the amount fed back from the negative feedback unit, the attenuator for raising the voltage lowered by the light source applied from the outside of the differential amplifier part by a predetermined level. Even if strong light is inputted by the infrared and external light sources of the remote controller applied to home appliances and the reference input voltage of the amplifier is lowered, the predetermined reference voltage of the reduced amplifier is compensated above a certain reference voltage for normal amplification. The remote control output can be effectively obtained.

Description

Preamplifier Circuit for Remote Control

1 is a configuration diagram of a preamplifier for a remote control according to the prior art.

2 is a schematic diagram of a preamplifier circuit for a remote controller according to the present invention.

* Explanation of symbols for main parts of the drawings

10: voltage source 20: active load unit

30: feedback condition determination unit 40: negative feedback unit

50: current source 60: differential amplifier

70: open gain judgment 80: reduction

Q _{1 to} Q ₁₃ : transistors D ₁ and D ₂ : photodiodes

The present invention relates to a pre-amp circuit for a remote controller, and in particular, a strong fluorescent lamp and an external light source in a room for a remote controller (Remocon) of home appliances such as TVs and VTRs using the preamp circuit, and the The present invention relates to a preamplifier circuit for a remote controller that enables the amplification of the remote controller to operate normally even when infrared rays generated from home appliances are detected.

1 is a configuration diagram of a preamplifier for a remote controller according to the prior art.

In general, a remote control preamplifier circuit according to the prior art includes a voltage source 10 for supplying a power supply voltage by connecting transistors Q _{1 to} Q _{4 in} series with each other, as shown in FIG. A current source 50 composed of a transistor Q ₇ and a resistor R ₃ supplied with a current; A differential amplification part connected to the voltage source 10 and the current source 50 and having transistors Q ₅ and Q ₆ connected symmetrically to each other and amplified and outputted by a signal difference between the inputs of the transistors Q ₈ and Q ₉ ; 60); Negative feedback unit for negative feedback amplification through the transistors Q ₁₀ and Q ₁₁ configured as emitter followers and resistors R ₅ to R ₇ through the output of the differential amplifier 60. 40; An open gain determination unit 70 for determining the open gain of the signal output from the differential amplifier 60 by connecting the resistor R ₄ and the capacitor C _{1 in} series; An active load unit 20 configured to be connected to transistors Q ₈ and Q ₉ and resistors R ₁ and R ₂ as an active load of the differential amplifier 60; The feedback conditioner 30 is configured to determine an amount fed back from the negative feedback unit 40 through the resistor R ₈ and the capacitor C ₂ .

Here, the preamplifier circuit for a remote controller according to the related art configured as described above detects an infrared signal transmitted from an infrared transmitter of a home appliance, such as a TV and a VTR, by the photodiode D _{1 as} shown in FIG. The signal is amplified by the differential amplifier 60 and the negative feedback unit 40 with the following amplification.

First, in the negative feedback unit 40, as in the principle of negative feedback amplification below.

ν _i '= ν _i -βν _o .

Where β is the negative feedback rate and Ao is the amplification degree.

At this time, the output νo is

Since ν _o '= ν _i ' A _o = (νi'-βν _o ) A _o , the amplification degree A _f in the negative feedback unit 40 is

Therefore, it can be seen that the original amplification is lowered to 1 / (1 + βA _o ) than A _o .

If βA _o is an open gain and the ratio of A _o and A _f is the feedback amount F, the feedback amount F in the feedback condition determining unit 30 is

In addition, the (Ⅰ) expression A _o A _f as a variable, so that when a function of a differential Ao _o A

Substituting the above formula (II) into this equation

Thus the rate of change of _f dA A _f / A _f can be seen that the ratio dA _o / A _o than 1/1 + βA _o decrease in the change of A _o.

That is, stability is improving by that much.

Increasing the open gain βA _o can be set to βA _o ≫ 1 in the above formula (I) The amplification degree Af thus becomes equal to the inverse of the feedback amount β.

At this time,

Af ≒ 50dB, which amplifies the input signal by about 50dB.

As described above, when negative feedback amplification is performed in the negative feedback unit 40, stability of the amplification degree is improved, and noise or distortion occurring at the output generated inside the amplifier is reduced to 1/1 + βA _o .

In addition, the frequency bandwidth can be flattened and widened, and the input / output impedance can be changed.

At this time, a problem in the preamplifier circuit for the remote control according to the prior art is that strong light by infrared rays such as external fluorescent lamps and solar energy is sensed in the photodiode so that excessive current flows in the photodiode so that the DC voltage is input to the differential amplifier. As a result of lowering below a predetermined reference voltage, there is a problem in that the operation as a differential amplifier becomes impossible.

Therefore, the preamplifier circuit for remote control according to the present invention was devised to solve the above problems according to the prior art. The object of the present invention is to operate the remote control of home appliances such as TV and VTR using the preamplifier circuit. The present invention provides a preamplifier circuit for a remote controller to prevent external fluorescent light and infrared rays from being detected so that excessive current flows to the photodiode of the remote controller so that differential amplification does not operate normally.

A preamplifier circuit for a remote control according to the present invention for achieving the above object includes a differential amplifier for amplifying and outputting by two input signal difference of the transistor; A negative feedback unit for negatively feedbacking and amplifying the output signal of the differential amplifier unit; An open gain determining unit configured to determine an open loop gain of the amplified signal output from the differential amplifier; A preamplifier circuit for a remote controller including a feedback conditioner for determining the amount fed back from the negative feedback unit, the attenuator for raising the voltage lowered by the light source applied from the outside of the differential amplifier part by a predetermined level. Characterized by including a part.

Hereinafter, a preamplifier circuit for a remote controller according to the present invention will be described with reference to the accompanying drawings.

2 is a configuration diagram of a preamplifier circuit for a remote controller according to the present invention.

First, as shown in FIG. 2, a remote control preamplifier circuit according to the present invention includes: a voltage source 10 in which transistors Q _{1 to} Q ₄ are connected in series to supply a power supply voltage; A current source 50 composed of a transistor Q ₇ and a resistor R ₃ supplied with a current; The differential amplifier 60 is connected to the voltage source 10 and the current source 50, and the transistors Q ₅ and Q ₆ are symmetrically connected to each other and amplified by the input signal difference of the transistors Q ₈ and Q ₉ . )Wow; Negative feedback unit for amplifying the output of the differential amplifier 60 through the transistors Q _{10 to} Q ₁₁ composed of emitter followers and resistors R _{5 to} R ₇ . 40); An open gain determination unit 70 for determining the open gain of the signal output from the differential amplifier 60 by connecting the resistor R ₄ and the capacitor C _{1 in} series; An active load unit 20 configured to be connected to transistors Q ₈ and Q ₉ and resistors R ₁ and R ₂ as an active load of the differential amplifier 60; A feedback condition determining unit 30 determining an amount fed back from the negative feedback unit 40 through a resistor R ₈ and a capacitor C ₂ ; Attenuator 80 connected to the differential amplifier 60 so as to increase a predetermined level of a voltage at which the input voltage of the differential amplifier 60 is lowered by a light source applied through the photodiode D ₁ from the outside. It is composed.

The attenuator 80 has a photodiode D ₂ and transistors Q ₁₂ and Q ₁₃ connected in series, and both terminals Q ₁₂ and Q ₁₃ have a transistor Q of the differential amplifier 60. ₅ ) It is configured to be connected to the base input terminal.

Referring to the operation of the preamplifier circuit for a remote control according to the present invention configured as described above are as follows.

First, as shown in FIG. 2, when the infrared ray transmitted by the remote control transmitter of a general household appliance is _first received through the photodiode D ₁ , the base input of the transistor Q ₅ of the differential amplifier 60 is received. Since the transistor Q ₁₃ of the attenuator 80 is turned on and the transistor Q ₁₂ is turned off because the voltage exceeds the predetermined reference voltage, the power supply voltage Vcc supplied from the photodiode D ₂ is cut off and normally The differential amplifier 60 is operated.

And the signal output by the normal operation of the differential amplifier 60 is the negative feedback unit 40

Become,

At this time, the mask by increasing the βA _o can be placed into βA _o »1, therefore, the expression Becomes

Here, the negative feedback unit 40 shown in FIG. 2 is amplified by A _f ≒ 50 dB.

However, when strong light such as an infrared ray, an external fluorescent lamp, and solar energy is input from the photodiode D ₁ , the transistor Q ₅ base input voltage of the differential amplifier 60 decreases below a predetermined reference voltage.

At this time, the transistor Q ₁₃ of the attenuator 80 is turned off, and the transistor Q ₁₂ is turned on by the power supply voltage Vcc applied through the photodiode D ₂ , so that the transistor of the differential amplifier 60 is turned on. (Q ₅ ) The differential amplifier 60 operates normally by raising the base input voltage above a predetermined reference voltage.

Therefore, the output normally amplified by the differential amplifier 60 has the amplification factor according to the above equation in the negative feedback unit 40 to obtain a normal remote controller output.

As described above, the preamplifier circuit for the remote control according to the present invention has a constant reference voltage of the reduced amplifier even if a strong light is input by the infrared light source and an external light source of the remote control applied to the home appliance and the reference input voltage of the amplifier is lowered. By compensating above a certain reference voltage, the remote control output can be effectively obtained by normal amplification.

Claims (2)

A differential amplifier for amplifying and outputting the two input signal differences of the transistors; A negative feedback unit for negatively feedbacking and amplifying the output signal of the differential amplifier unit; An open gain determining unit configured to determine an open loop gain of the amplified signal output from the differential amplifier; A preamplifier circuit for a remote controller, comprising a feedback conditioner for determining an amount fed back from the negative feedback unit; And attenuating part for raising the voltage lowered by the light source applied from the outside of the differential amplifier part by a predetermined level. The preamplifier circuit of claim 1, wherein the attenuation unit is configured such that a photodiode and a transistor are connected in series with each other and are connected to both terminals of the transistor and a transistor base input terminal of the differential amplifier.