JPS6228098Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in receiving frequency preset receivers.

A reception frequency preset receiver (hereinafter referred to as a reception frequency preset receiver) that presets the conventional reception frequency, selects the preset reception frequency, and receives broadcasts on the reception frequency.
The desired reception frequency is preset by, for example, tuning the preset receiver to a desired reception frequency and pressing a memory switch and a preset switch. The number of preset reception frequencies can be 4 to 5 or more. On the other hand, even if a preset receiving frequency is selected, broadcasts of the receiving frequency may not be received, especially in locations far away from areas where the electric field strength of the receiving frequency is weak in the vehicle-mounted preset receiver. In such a case, you must select another preset reception frequency to receive another broadcast, or search for receivable stations by scanning or searching the reception frequency key to find the reception frequencies of receivable stations. There were some unavoidable flaws.

The present invention has been made in view of the above, and it is an object of the present invention to provide a preset receiver that eliminates the above-mentioned drawbacks. , by automatically performing a scanning or investigation operation when there is no broadcast.

The present invention will be explained below with reference to examples.

The figure is a block diagram of one embodiment of the present invention.

In the figure, 1 is the first switch that is turned on and off in conjunction with the memory switch for recalling the memory circuit, and 2 is the first switch that is turned on and off in conjunction with the preset switch that is pressed together with the memory switch to preset the reception frequency. 3 is a push-button switch for scanning or investigating the received frequency (hereinafter simply referred to as "scanning"); by pressing the push-button switch 3, an up/down counter 4 is driven. do. For example, if a variable capacitance diode is used as a variable reactance in the tuning tank circuit of a preset receiver, the output of the up/down counter 4 is input and the voltage applied to the variable capacitance diode is controlled by the up/down counter 4. The tuning frequency is changed step by step according to the output to match the frequency interval of FM radio waves.
It is configured to change every 100KHz. Furthermore, in the case of a preset receiver constructed from a synthesizer tuner constructed using a PLL circuit,
The output of up/down counter 4 changes the frequency division ratio of the programmable divider of the PLL circuit.
It is configured to change the tuning frequency every 100KHz.

On the other hand, a NAND gate 5 inputs the detection output A of the preset receiver and a carrier signal output B of the receiving frequency; an AND gate 6 inputs the output of the NAND gate 5 and the output when the first switch is turned on; A reception detection circuit for detecting the presence or absence of a preset reception frequency is constituted by a transistor 7 connected between the contacts of the pushbutton switch 3 and driven by the output of the AND gate 5. Also, the first switch 1
A scanning circuit consisting of an AND gate 8 whose inputs are the output when the switch is on and the output of the second switch 2, and a transistor 9 which is driven by the output of the AND gate 8 and connected so as to lead the output of the AND gate 6 to ground. Configure a prohibited circuit.

Now press the memory switch to call up the desired preset reception frequency. By pressing this memory switch, the first switch 1 is turned on.
At this time, when the broadcast of the preset reception frequency is received, the detection output A and the carrier signal B of the preset receiver are present. Therefore, the output of the NAND gate 5 becomes a low potential output, the output of the AND gate 6 also becomes a low potential output, the transistor 7 is turned off, the up/down counter 4 is not driven, no scanning is performed, and the broadcast of the preset reception frequency is received. do. However, because the electric field strength of the reception frequency is weak due to reasons such as moving to a remote location from the broadcasting station of the preset reception frequency, when the memory switch is pressed to call up the preset reception frequency, the reception frequency of the preset reception frequency is Unable to receive. Therefore, carrier signal B and detection output A do not exist, and the output of NAND gate 5 becomes a high potential. At this time, since the first switch 1 is also on, the output of the AND gate 6 is a high potential output, and the transistor 7 is on.
The down counter 4 is driven to scan the reception frequency. The same applies when either the carrier signal B or the detection output A is absent.

However, when the preset switch is pressed for presetting, the second switch 2 is also turned on, and the output of the AND gate 8 becomes a high potential output.
Therefore, the transistor 9 is turned on and the output of the AND gate 9 is grounded, so the transistor 7 is turned off and the up/down counter 4
is not driven and does not shift to the receiving frequency scanning mode.

As explained above, according to the present invention, if reception is not possible when calling the preset reception frequency,
The scanning mode is automatically entered and a receivable frequency is automatically searched for, and there is no need to repeatedly press a button to search for a receivable reception frequency as in the past.

Further, when receiving a broadcast at the selected preset reception frequency or when presetting the reception frequency, there is no transition to the scanning mode.

Furthermore, since the preset detection output is also detected, the scanning mode is automatically set even when only the carrier signal is present.

[Brief explanation of drawings]

The figure is a block diagram of one embodiment of the present invention. 1 and 2...first and second switches,
3...Push button switch, 4...Up/down counter, 5...Nand gate, 6 and 8...
And gate.

Claims (1)

[Scope of utility model registration request] A memory switch for recalling a memory circuit that stores preset reception frequencies, a preset switch that is pressed while the memory switch is pressed to preset a desired reception frequency, and a push button for scanning or searching within the reception frequency band. In a reception frequency preset receiver equipped with a button switch, a switching element is connected in parallel to the pushbutton switch, detects the presence or absence of broadcasting at the preset reception frequency, and compares the output when there is no broadcasting with the memory switch. The switching element is driven by the AND output of the first switch that operates in conjunction with the output of the first switch and the output of the second switch that operates in conjunction with the preset switch. A reception frequency preset receiver, characterized in that the switching element is deactivated by an AND output, and automatically shifts to a scanning or investigation state when broadcasting at the preset reception frequency cannot be received.