JPH03218127A - Selective call radio receiver - Google Patents

Abstract

PURPOSE:To prevent reduction in the sensitivity of a receiver by weakening a reception ringer tone when a power voltage is decreased down close to a reference voltage or weakening the reception vibration so as to suppress current consumption due to ringer tone or vibration. CONSTITUTION:A 1st voltage comparison means 8 comparing a 1st reference voltage (a) set to a voltage slightly higher than a substantial reference voltage and a battery voltage Vcc and outputting a 1st low voltage signal S3 and a 2nd voltage comparison means 9 comparing a 2nd reference voltage (b) set to a substantial reference voltage and a battery voltage Vcc and outputting a 2nd low voltage signal S4 are provided to the receiver. Then a means 4 is provided, which outputs a drive control signal S5 based on the low voltage signals S3, S4 to thereby controlling the strength of a ringer tone of a speaker 13 or the strength of the vibration of a vibrator 14. When the battery voltage Vcc is decreased down close to the reference voltage, the ringer tone or vibration is weakened and the drive current is reduced to suppress production of noise thereby preventing the deterioration in the sensitivity of the receiver depending on a limiting amplifier.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radio selective call receiver, and more particularly to a receiver equipped with an alarm means for when battery voltage drops.

[Conventional technology]

With the development of integrated circuit technology in recent years, wireless selective calling receivers (hereinafter simply referred to as receivers) have been miniaturized. One of the methods for downsizing this receiver is a direct conversion reception method.

The direct conversion reception method is a method of converting an input signal into two systems of Haeshand frequencies with a phase difference of 90 degrees. This method is considered suitable for the configuration of small receivers because it does not require an image filter because there is no image response, and it does not require an IF filter because the channel filter can be configured at the baseband frequency. .

[Problems to be Solved by the Invention] By the way, in the conventional receiver as described above, when the voltage of the battery as a power source drops below a preset reference voltage, a low voltage alarm is generated and the battery is required to be replaced. At the same time, it alerts the wearer that the reliability of the receiver may be compromised.

In this case, the receiver operates normally even when the power supply voltage drops and approaches the reference voltage, and when it receives a selective call signal, it notifies the receiver by making a sound, flashing an LED, or vibrating the receiver itself. It is carried out.

However, in a receiver that uses a limiting amplifier in Heath Hunt, such as the direct conversion reception method described above, when the battery voltage approaches the reference voltage, the constant voltage circuit becomes saturated, causing the reception alarm to sound or vibrate. The large current flowing through the speaker or hibrator will generate noise in the constant voltage circuit. Therefore, noise contained in the output of the constant voltage circuit causes the limit noting amplifier to operate and suppress the signal, resulting in a problem in that the sensitivity of the receiver deteriorates.

An object of the present invention is to provide a receiver that prevents a decrease in reception sensitivity due to a decrease in battery voltage.

[Means for Solving the Problems] The receiver of the present invention includes a first reference voltage that is set to a voltage slightly higher than the original reference voltage and a battery voltage, and outputs a first low voltage signal. a second voltage comparison means that outputs a second low voltage signal by comparing the battery voltage with a second reference voltage set to the original reference voltage; The apparatus includes means for outputting a drive control signal based on the low voltage signal and controlling the strength of the sound of the speaker or the vibration of the vibrator using the drive control signal.

In this case, the battery voltage drops below the first reference voltage, and the second
When the reference voltage is higher than the reference voltage, the drive control signal is used to mute the speaker or to control the high frequency to a weak vibration.

[Effect]

According to the present invention, when the battery voltage drops close to the reference voltage, the drive control signal weakens the sound or vibration, reduces the drive current, and suppresses the generation of noise.
Prevents deterioration of receiver sensitivity due to liminoting amplifier.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a bronch diagram of one embodiment of the present invention.

In the figure, a received signal S1 received by receiving antenna 1
is input to the line concentrator 2, where it is amplified and demodulated, and then passed through the waveform shaping circuit 3 to become received data S2 and sent to the decoder 4. In the decoder 4, if the individual selective call number registered in the ROM 5 and the received data S2 match,
A speaker drive signal S6 for notification of reception is sent to the speaker drive circuit 10 to cause the speaker 13 to sound, or a hibrator drive signal S7 is sent to the hibrator drive circuit 11 to drive the hibrator 14 and vibrate the receiver body.

On the other hand, the voltage of battery 12 is ■. 0 is compared with the first reference voltage a generated by the first reference voltage generation circuit 6 in the first comparison circuit 8, and outputs the first low voltage signal S3 to the decoder 4 based on the comparison result. Similarly, the voltage of battery 12 ■. , is compared with the second reference voltage b generated by the second reference voltage generation circuit 7 in the second comparison circuit 9, and outputs a second low voltage signal S4 to the decoder 4 based on the comparison result. The decoder 4 outputs a drive control signal S5, which will be described later, based on these first and second low voltage signals S3 and S4.

Here, the second reference voltage b is set to a conventionally used low voltage alarm voltage, and the first reference voltage a is set to a voltage slightly higher than this.

As shown in FIG. 2, in the first comparison circuit 8, when the battery voltage VCC is higher than the first reference voltage a,
''', and outputs 'H' when it is low, and the second comparison circuit 9 outputs 'L' when the battery voltage VCC is higher than the second reference voltage b, and outputs 'H' when it is low. It is configured to output "H".

The operation of the receiver in this configuration will be explained using the following table.

First, when the voltage VCC of the battery I2 is higher than the first reference voltage a, the first and second low voltage signals S3 and S4 are "L".
', and the drive control signal S5 output from the decoder 4 is "L". Thereby, the speaker 13 and the vibrator 14 perform a normal notification operation.

Battery voltage■. , is lowered than the first reference voltage a, then
The first low voltage signal S3 sent from the first comparator circuit 8 to the decoder 4 becomes "l H l', but since the reference voltage ■,c is larger than the second reference voltage b, the first low voltage signal S3 sent from the second comparator circuit 9 to the decoder 4 becomes The second low voltage signal S4 sent to the second low voltage signal S4 remains at "L". As a result, the drive control signal S5 from the decoder 4 becomes "'H" and is sent to the speaker power drive circuit 10 or the hibrator drive circuit 11. When the reception notification is performed at this time, the drive control signal S5 controls the speaker drive circuit 10 to reduce the drive current so that the speaker 13 sounds at a low volume, or controls the hibrator drive circuit 11 to control the hibrator The drive current is reduced to weaken the vibration of 14.

This suppresses the occurrence of noise in the reception notification when the battery voltage approaches the reference voltage b, suppresses the signal suppression operation in the limiting amplifier, and prevents a decrease in receiver sensitivity.

When the battery voltage VCC is further reduced and becomes lower than the second reference voltage b which is the original reference voltage, the second low voltage signal S4 of the second comparator circuit 9 becomes "H" and is output to the decoder 4. As a result, the drive control signal S5 from the lever 4 becomes "L", and the suppression of the drive current in the sputter drive circuit 10 and the vibrator drive circuit 11 is released. Therefore, the speaker drive signal S6 from the decoder 4
The speaker drive circuit 10 or the hibrator drive circuit 11 is operated by the hiflator drive signal S7, and the low voltage alarm is generated by the speaker 13 or the vibrator l4 with a loud sound or strong vibration as in the conventional case.

〔Effect of the invention〕

As explained above, when the power supply voltage drops to near the conventional reference voltage, the present invention makes the received sound at that time weak or the received vibration weak, so that the current caused by these sounds and vibrations is reduced. This has the effect of suppressing consumption and preventing a decrease in receiver sensitivity.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram of an embodiment of the receiver of the present invention, and FIG.
The figure is a diagram showing the relationship between the battery voltage, the first reference voltage a, and the second reference voltage b. DESCRIPTION OF SYMBOLS 1... Antenna, 2... Radio part, 3... Waveform shaping circuit, 4... Decoder, 5... ROM, 6... First reference voltage generation circuit, 7... Second Reference voltage generation circuit,
8... first comparison circuit, 9... second comparison circuit, 10.
...Speaker drive circuit, ■■...High break drive circuit, 1 2...Battery, 1 3...Speaker, ■4...High break.

Claims (1)

[Scope of Claims] 1. In a wireless selective calling receiver that notifies reception by sound from a speaker or vibration from a vibrator, a first reference voltage set to a voltage slightly higher than the original reference voltage and a battery voltage are used. a first for comparing and outputting a first low voltage signal;
a second voltage comparison means that compares a second reference voltage set to the original reference voltage with the battery voltage and outputs a second low voltage signal; A radio selective calling receiver comprising means for outputting a drive control signal based on a voltage signal, and controlling the strength of the sound of the speaker or the vibration of the vibrator using the drive control signal. 2. Claim 1, wherein when the battery voltage is lower than the first reference voltage and higher than the second reference voltage, the drive control signal is used to make the speaker weak or to control the vibrator to weak vibration. Wireless selective calling receiver. 3. The radio selective calling receiver according to claim 1 or 2, wherein the reception method is a direct conversion method.