WO1991006932A1

WO1991006932A1 - Selective call receiver

Info

Publication number: WO1991006932A1
Application number: PCT/US1990/006040
Authority: WO
Inventors: Tuan Kien Nguyen; Edward Lee Ehmke
Original assignee: Motorola, Inc.
Priority date: 1989-11-06
Filing date: 1990-10-22
Publication date: 1991-05-16
Also published as: AU6718190A

Abstract

A method for operating a vibrating motor (15) in a selective call receiver (10) comprises the step of driving the vibrating motor (15) with a variable duty cycle signal (Figure 3) for slowly increasing the intensity of the vibration.

Description

SELECTIVE CALL RECEIVER

Field of the Invention

This invention relates in general to selective call receivers and more particularly to a selective call receiver having a vibrating alert that varies in amplitude during the alert in response to a signal having a variable duty cycle.

Background of the Invention

Selective call radio receivers such as pagers alert a user of a received message. Such devices generally incorporate a radio receiver capable of producing either an audible alert which may be heard by the user or a tactile alert such as a vibrating sensation which may be felt by the user. Some pagers provide the additional features of a voice message following the alert or a message visually displayed on a screen.

Each selective call receiver is identified by a specific address that typically precedes each message. When a selective call receiver receives a message including the selective call receiver address, the message is stored within a memory.

If the user has selected the silent (vibrating) mode for the pager, the user typically must be wearing the pager to receive proper tactile feedback during the vibrate alert of a new incoming message. The amplitude of the vibrations reaches maximum very quickly, and typically will surprise or startle the user, thereby causing the user to "jump".

One known vibrating pager comprises varying the amplitude of the vibration. The vibration is created by a motor, internal to the pager, rotating a weight. The rotating weight initially presents a small torque load to the motor; however, subsequently a large vibrating motion is created because the center of gravity of the rotating weight moves further away from the axis of rotation due to centrifugal force. Another known technique comprises a vibrating motor activated by a series of regularly spaced electrical pulses. The motor periodically accelerates a cyclically mounted mass to produce tactually sensible vibrations. However, these two methods provide only a small "ramp up" which, while beneficial to the motor, is relatively fast in obtaining maximum vibrations and tend to startle the user.

Thus, what is needed is a selective call radio receiver having a vibrating alert that slowly increases the amplitude of the vibration during the alert in response to a signal having a variable duty cycle.

Summary of the Invention

In carrying out the invention in one form, there is provided a method for operating a vibrating motor comprising the step of driving the vibrating motor with a variable duty cycle signal.

Brief Description of the Drawing

FIGURE 1 is a block diagram of the present invention.

FIGURE 2 is a partial block diagram of a drive circuit as used in the present invention.

FIGURE 3 illustrates a variable duty cycle signal suitable for use by the present invention.

Detailed Description of the Invention

Referring to FIG. 1, an electronic device such as a selective call receiver including a pager comprises an antenna 11 for receiving signals coupled to a receiver circuit 12 which demodulates the signals received. A memory 14 is coupled to the microprocessor 13 for storing those messages containing the address of the selective call receiver as determined by the microprocessor 13. The microprocessor 13 also controls the storing and recalling of those messages. An alert device 15 provides a vibrating alert to the user that a message has been received and is ready to be presented. An output device 16 may be a visual display or a speaker controlled by the microprocessor 13. The controls 17 allow the user to command the microprocessor 13 to perform the selective call receiver operations well known to those skilled in the art and typically include control switches such as an on /off control button, a function control, etc. The output device 16 is optional, as the invention described herein functions equally well for an alert only pager. For a more detailed description of the structure and operation of a selective call radio paging receiver of the type shown in FIG. 1, reference is made to U.S. Patent Number 4,749,392, U.S. Patent Number 4,518,961, U.S. Patent Number 4,649,538, and U.S. Patent Number 4,755,816, all commonly assigned to the assignee of the present invention, and the teachings of which are hereby incorporated by reference.

In accordance with the present invention, a variable duty cycle drive circuit 18 provides pulses having a selectable duty cycle to the vibrating alert 15 in response to the microprocessor 13. Referring to FIGURE 2, the drive circuit 18 comprises a voltage generator 21 that provides a linear control voltage Vc to a differential amplifier 22 in response to a digital signal 19 from the microprocessor 13. The differential amplifier 22 compares this control voltage Vc with a signal voltage Vs having a frequency f and a period T = 1/f from a signal generator 23 for providing a drive voltage VD through a resistor 24 for driving a PNP transistor 25. The transistor 25 provides a current 20 to the vibrating alert 15. Diode 26 protects the transistor 25 from transient surges. The voltage Vs may comprise a signal having a constant frequency, such as a sawtooth waveform. The drive voltage VD has an output in either a high or low state. The threshold voltage Vj (Vc/Vs) may be any time function and the duty cycle is either 100(Vc/Vs) or 100(1 - Vc/Vs) depending upon the polarity of the differential amplifier 22 inputs Vc and Vs. For example, the time function may be time varying resulting in a vibration that increases in amplitude over time, or cyclic resulting in a vibration that increases in time in repeating increments. The time function or duty cycle is controlled by the control voltage Vc from the voltage generator 21. Data programmed into the microprocessor 13, such as by code plug or controls 17, determine the operation of voltage generator 21. Referring to FIGURE 3, the signal voltage Vs represented by a sawtooth waveform, for example, is added to each of control voltages Vci_/ Vc2, c3, Vc4 and Vcs, for example, to produce the drive voltages VDI VD2 VD3 VD4 and VD5 respectively. As the control voltage Vc increases in amplitude and is compared to the signal voltage Vs by the amplifier 22, the drive voltage VD goes high when the threshold voltage VT is reached. In the example for drive voltage VDI, the user is alerted by a vibration that initially is small in amplitude (intensity) and that progressively increases in amplitude until the user acknowledges the alert by activating one of the controls 17 or a predetermined time has passed. For the drive voltage VD2 the user is alerted by a vibration that initially is small in amplitude (intensity) and that progressively increases in amplitude in a series of pulses. For the drive voltage VD3_/ the user is alerted by a vibration that initially is small in amplitude (intensity) and that progressively increases and decreases in amplitude in a series of pulses. For the drive voltages VD4 and VD5_/ the vibration is at maximum or at zero, respectively. For example, the drive voltage VD4 will be maximum when the control voltage Vc is above the threshold voltage VT and is the inverting input to the differential amplifier 22, and the signal voltage Vs is the noninverting input to the differential amplifier 22. Further, the drive voltage VD4 will be zero when the control voltage Vc is below the threshold voltage VT and is the inverting input to the differential amplifier 22, and the signal voltage Vs is the noninverting input to the differential amplifier 22. The vibrations for each example would continue until the user acknowledges the alert by activating one of the controls 17 or a predetermined time has passed.

Claims

1. A method for operating a vibrating motor comprising the steps of: varying the duty cycle of a drive signal having a plurality of pulses; and driving the vibrating motor with the drive signal, the amplitude of the vibrating motor automatically changing at a noticeably increasing rate.

2. The method according to claim 1 wherein the varying step comprises the step of selecting the duty cycle of the drive signal.

3. An apparatus comprising: a vibrating motor; and circuit means for driving the vibrating motor with a drive signal including a plurality of pulses and having a variable duty cycle, the amplitude of the vibrating motor automatically increasing at a noticeable rate.

4. The apparatus according to claim 3 wherein the circuit comprises control means for selecting the duty cycle.

5. A method of alerting the user of a selective call receiver to the receipt of a message, comprising the steps of: varying the duty cycle of a drive signal having a plurality of pulses; and driving the vibrating motor with the drive signal, the amplitude of the vibrating motor automatically increasing at a noticeable rate.

6. The method according to claim 5 wherein the varying step comprises the step of selecting the duty cycle.

7. A selective call receiver comprising: receiver means for receiving an RF signal; vibrator means for vibrating the selective call receiver in response to the RF signal; and circuit means for varying the amplitude of the vibrations by driving the vibrator means with a drive signal including a plurality of pulses and having a variable duty cycle, for causing the vibrator means to alert a user of the selective call receiver by vibrating at a noticeably increasing rate.

8. The selective call receiver according to claim 7 wherein the circuit means comprises control means for selecting the duty cycle.

9. The method according to claim 1 wherein the varying step comprises the step of summing a reference signal with a control signal for producing the drive signal.

10. The apparatus according to claim 4 further comprising reference means for generating a reference signal, the control means generating a control signal that is summed with the reference signal for producing the drive signal.

11. The method according to claim 6 wherein the varying step comprises the step of summing a reference signal with a control signal for producing the drive signal.

12. The selective call receiver according to claim 7 wherein the circuit means comprises: reference means for generating a reference signal; and control means for summing a control signal with the reference signal for producing the drive signal.