JPS6157132A - Reception display circuit of multi-broadcast receiver - Google Patents

Abstract

PURPOSE:To prevent malfunction at weak electric field input at a reception display by constituting an electronic switching circuit among a reception tuning display, a TV multiplex mode reception display and an FM stereo reception display. CONSTITUTION:A point A is connected to a reception level meter driving output terminal of an intermediate frequency amplifier IC, a point B is connected to a TV sound multiplex driving output terminal and a point C is connected to an FM multiplex driving output terminal respectively. When the reception state is in non-tuning or weak electric field state, since the point A is at a low level, transistors (TRs)Q1-Q3 of the electronic switching circuit are turned off and light emitting diodes LEDI-LED3 are not lighted. When a sufficient reception input exists, a driving power is fed to the point A, the TRQ1, Q2 are turned on and the reception tuning display device LED1 is lighted. In this state, in case of the TV stereo broadcast, the point B is in L level, and in case of the FM stereo broadcast, the points C, B are in L level and the TV and FM stereo display LED2 is lighted. In case of the multiplex broadcast, the point B is at H level, the TRQ3 is turned on and the LED3 is lighted.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to the reception tuning state, double broadcasting, The present invention relates to a reception display circuit that displays TV stereo broadcasts, FM stereo broadcasts, etc.

(Conventional configuration and problems thereof) Conventionally, for example, a portable receiver that receives only the audio of TV broadcasting does not normally use a regular antenna, so the input to the receiver is weak. Therefore, sufficient reception input cannot be obtained, so when receiving multiplex broadcasts in a weak electric field, the dual broadcast and T'V
Misjudging stereo broadcasts.

(Object of the Invention) The present invention prevents malfunctions in the conventional receiver, particularly in its reception indicator, when a weak electric field is input.

Only when there is sufficient input electric field during TV reception,
It is an object of the present invention to provide a reception display circuit capable of displaying multiple modes of demodulation in multiple modes.

(Structure of the Invention) In order to achieve the above object, the present invention provides a reception tuning display circuit drive output from a reception level display meter drive output curve of an intermediate frequency amplification stage (usually an IC is used) of a receiver. A transistor switching circuit is installed between the TV audio multiplex demodulation circuit and the FM multiplex drive circuit, so that if the reception tuning display circuit does not perform tuning display, it will display another multiplex or TV-FM stereo. By configuring this to be disabled, if complete reception tuning is achieved and the tuning indication is obtained, other mode indications can be made simultaneously.

(Explanation of Examples) An example will be described below with reference to the drawings.

In the figure, point A is the output terminal for driving the reception level meter of the intermediate frequency (IF) amplification IC, point B is the output terminal for driving the TV audio multiplex, and point 0 is the output terminal for driving the FM stereo multiplex (MPX). output) 1 These are the points connected to the respective terminals. These A.

A light emitting diode LE is installed between points B and C as a reception tuning indicator.
For DI, TV and FM stereo display, light emitting diode LED3 for display, and transistor Rokuri Q construction,
Q2. An electronic switching circuit constituted by Q is provided. Note that the transistor Qs t02, Q,
For example, 2SC945L is used for Q engineering, Q, and 2S is used for Q2.
A564 is used.

The circuit of the above embodiment is as follows. First, when the receiving state is out of tune or the receiving electric field is extremely weak, the voltage level at point A in the figure is low, so Q+ D=x+ 21
Each transistor of the electronic switching circuit according to 3) is in an off state, and the light emitting diodes LEDI to LED3 do not emit light, that is, there is no display. Next, if there is sufficient receive input and proper tuning operation, sufficient drive voltage is applied to point A from the IC of the IF amplifier stage, transistors Q1 and Q2 are turned on, and therefore the light emitting diode LEDI
When the light emitting diode LEDI does not display light, no high level voltage is applied to the collector of the transistor Q2, regardless of whether the B and 0 points are at high or low level. Therefore, the light emitting diode LED2 for TV and FM stereo display and the light emitting diode LED3 for multi-ff1 (duplex) broadcast display do not emit light.

When the light emitting diode LEDI is emitting light, in the case of TV stereo broadcasting, point B becomes low level and the light emitting diode LED2 emits light to indicate that it is TV stereo broadcasting, and in the case of FM stereo broadcasting, the 0 point is low level. Therefore, point B also becomes low level, and the light emitting diode LED2 emits light to indicate that it is an FM stereo broadcast. Further, in the case of multiplex (duplex) broadcasting, the point B becomes high level and transistors 1 to Q are turned on, so that the light emitting diode LED 3 emits light to indicate that it is multiplex (duplex) broadcasting.

(Effects of the Invention) As is clear from the detailed explanation using one embodiment, the present invention can avoid unstable reception conditions when a weak electric field is input in the correct reception tuning state, and the reception tuning indicator (main In the embodiment, the light emitting diode LED2 or LED3 for the other broadcast display is made to emit light at the same time as the LED I) is emitted, and when the reception tuning display LED1 does not emit light, the light emitting diode LED2 or LED3 for the other broadcast display is made to emit light. It does not require any luminous display, and has the advantage of eliminating the unpleasant display operation that occurs before tuning, which is the case in the prior art, and is advantageous when used in small TV audio receivers and the like.

[Brief explanation of the drawing]

The figure is a circuit diagram of an embodiment of the present invention. Q,',Q,,Q,... 1 helangister, LED
I. LED2. LED3...Light emitting diode.

Claims (2)

[Claims] (1) In the reception display circuit of a multi-broadcasting receiver having a reception tuning indicator, a TV multiple mode reception indicator, and an FM stereo reception indicator, the reception tuning indicator and the TV
By configuring an electronic switching circuit between the multimode reception indicator and the FM stereo reception indicator, any of the other indicators can be operated simultaneously with the display operation of the reception tuning indicator. Receiving display circuit for multi-broadcast receiver. (2) A reception display circuit for a multi-broadcast receiver according to claim (1), wherein each display circuit is constructed of a light emitting diode.