Silent call pager

Abstract

A pager that produces a vibratory alerting signal when a paging signal is received. Vibrating motion is created by a motor, internal to the pager, rotating a weight. The rotating weight initially presents a small torque load to the motor, but 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.

Description

BACKGROUND OF THE INVENTION

In standard paging systems, a signal is transmitted to alert a person to the fact that the base station wishes to communicate with him. The transmitted signal is received by the pager and identified as being intended for a particular receiver. If the identification is positive, an alerting signal is generated which indicates to the user that he is being paged. The alert signal can either last for a specific time interval or until the call is acknowledged.

Paging receivers that use either audio or visual signals to alert the user are commonly available. An audio alerting signal is unsatisfactory in a high noise level environment, and a visual alerting signal must be constantly monitored in order to insure prompt reception of an alert signal by the user.

Pagers which create a vibrating alert signal have been developed, but such pagers do not economically use battery current while producing significant vibratory motion.

SUMMARY OF THE INVENTION

It is an object of this invention to illustrate a vibratory pager that operates with less battery current drain.

Another object of this invention is to provide a silent call pager which creates a large vibratory motion while conserving battery current.

Still another object of this invention is to use centrifugal force to displace the center of gravity of a weight to generate a large vibratory motion.

A motor, which is rigidly mechanically coupled to the frame of a pager, is activated when the pager receives a paging signal that is positively identified. The motor rotates a drive shaft about an axis of rotation and the drive shaft has a weight attached to it. The center of gravity of the weight is close to the axis of rotation when the motor is nonoperative and the pager is in an upright position. When the motor rotates, the weight moves due to centrifugal force so that the center of gravity of the weight is now substantially further away from the axis of rotation. Thus the weight presents a low initial starting torque to the motor, but also creates a large vibratory motion due to the rotational movement of the center of gravity of the weight about the axis of rotation at a greater distance.

DESCRIPTION OF THE DRAWINGS

Referring to the drawings:

FIG. 1 is a pictorial view of a silent call pager with part of the external casing removed to show a vibrator mechanism; and

FIG. 2 is an enlarged pictorial side view of the vibrator mechanism shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a portable paging receiver, generally referred to as pager 8, which generates a vibratory alerting signal when a correct radio frequency paging signal is received. The paging receiver includes a case 10 and a clip 11 attached to the case. The clip 11 is commonly used for attaching the receiver to a shirt pocket or a belt and serves to transmit the vibratory motion of the paging receiver to the body of the person being paged. A printed circuit board 13, which is rigidly attached to case 10, contains electronic components which perform the functions of receiving a paging radio signal, identifying the paging signal so that only intended signals will activate the pager, and generating an electrical signal to activate a motor. Since the electronic components on PC board 13 are not part of the invention herein disclosed and are adequately described by the prior art, they will not be described in any detail.

Referring to FIG. 1, a motor 15 is rigidly attached to PC board 13 by a bracket 14. Since PC board 13 is rigidly attached to case 10 of the pager, the motor is therefore mechanically coupled to the pager. The motor 15 is also electrically connected (not shown) to components on PC board 13 and is rendered operative by receiving voltage from PC board 13 when a properly identified paging signal is received by the electronic components on PC board 13. The motor 15 may be rendered operative by applying a constant DC voltage to the motor, by applying DC pulses to the motor, or by applying an AC signal to the motor. A battery 12 supplies the power to operate the electronic components on printed circuit board 13 and battery 12 also supplies the power to operate motor 15. A drive shaft 16 is attached to motor 15 and is rotated by motor 15 about an axis of rotation 19. In the specific embodiment shown in FIG. 1, axis of rotation 19 is coincident with the axis of drive shaft 16, however the invention disclosed is not limited to having the drive shaft rotated about its own axis. Drive shaft 16, for example, could have its axis horizontally displaced from axis of rotation 19 and still be rotated about axis of rotation 19 by motor 15.

A weight 17 is shown in FIGS. 1 and 2 and consists of two identical generally L-shaped solid sections which are oppositely outwardly facing and are rigidly jointed together at the top of their vertical legs by a horizontal crossbar. Each L-shaped section is symmetrically positioned with respect to a vertical line bisecting and perpendicular to the horizontal crossbar.

The separation between the L-shaped sections is greater than the width of drive shaft 16, to provide clearance for rotation of weight 17 about drive shaft 16. The bottom section of the horizontal leg of both identical solid sections has a radius of curvature extending from the outward vertical tip of the horizontal leg to the bottom of the vertical leg. A pivot pin 18 is attached to the vertical legs of the two solid L-shaped sections of weight 17, and pin 18 is parallel to and below the horizontal crossbar of weight 17. Weight 17 is capable of pivotal motion about pivot pin 18. Pivot pin 18 extends perpendicular through drive shaft 16 and positions weight 17 such that axis of the rotation 19 remains fixed midway between the two L-shaped sections of weight 17. A center of gravity 20 of weight 17 is shown coincident with the rotational axis 19 of drive shaft 16 and close to pivot pin 18, however the invention disclosed is not limited to the coincidence or proximity of center of gravity 20 to the rotational axis or pivot pin 18. Other embodiments wherein the pivot means consists of a hinge instead of pivot pin 18 and the center of gravity of weight 17 is not originally coincident with axis of rotation 19 are within the scope of the invention.

FIG. 2 is an enlarged sideview drawing of the vibrating mechanism shown in FIG. 1. When motor 15 is rendered operative by the pager receiving a proper paging signal, motor 15 starts to rotate drive shaft 16. Weight 17 then also begins to rotate since it is attached to drive shaft 16 by pivot pin 18. Weight 17 presents a small initial torque load to motor 15 since its center of gravity 20 is initially coincident with axis of rotation 19. As motor 15 continues to rotate, weight 17 will pivot on pivot pin 18 and move to a position generally referred to as 17' (shown dotted) in FIG. 2, because of the effect of centrifugal force. When weight 17 has moved to position 17', its center of gravity 20 is no longer coincident with axis of rotation 19 and is now in a position 20'. Pivot pin 18 and position 20' lie in a plane perpendicular to axis of rotation 19. Since the center of gravity of weight 17 is now displaced from axis of rotation 19, the rotation of motor 15 now creates substantial vibratory motion due to the rotation of a nonsymmetrical mass. If weight 17 was permanently mounted in position 17' to drive shaft 16, the initial starting torque of motor 15 would be substantially higher and therefore motor 15 would require a larger starting current.

The amount of centrifugal force necessary to cause weight 17 to pivot about pivot pin 18 is determined by the proximity of center of gravity 20 to pivot pin 18. While the particular embodiment shows a close proximity of center of gravity 20 to pivot pin 18, the invention is not limited to such proximity. A rotation of a weight which causes any shift in the position of the center of gravity of a weight with respect to the axis of rotation, such that a first original at rest position of the center of gravity is closer to the axis of rotation, than a second in motion position of the center of gravity, comes within the scope of the invention.

Thus a vibratory pager which has a low initial starting torque, but develops a substantial vibratory motion, has been disclosed. The low initial starting torque serves to substantially reduce the motor starting current and thus reduce the total current drain on the battery in a portable pager. Therefore the battery life is extended by the use of centrifugal force.

While this invention has been described with respect to a particular embodiment, the underlying inventive principles are not meant to be limited to such an embodiment. It is obvious that one skilled in the art may make additional modifications to the invention disclosed herein, but all such modifications which retain the basic inventive ideas disclosed and claimed herein are within the scope of this patent.

Claims

I claim:

1. A vibratory pager including:

a pager case;

a motor being responsive to receiving a paging signal and being mechanically coupled to said pager case;

drive shaft means attached to said motor and capable of being rotated about an axis of rotation by said motor;

weight means;

connection means for attaching said weight means to said drive shaft means, such that said weight means has a center of gravity with a first distance from the axis of rotation when said drive shaft is not being rotated, and said weight means moves, when said drive shaft means is being rotated, such that the center of gravity of said weight means is a second distance from the axis of rotation, said second distance being larger than said first distance.

2. The pager as claimed in claim 1 wherein the axis of said drive shaft means is coincident with the axis of rotation.

3. The pager as claimed in claim 2 wherein said connection means includes a pivot pin attached to said drive shaft means.

4. The pager as claimed in claim 3 wherein said pivot pin is attached substantially perpendicular to said drive shaft means.

5. The pager as claimed in claim 4 wherein the said first distance, between the center of gravity of said weight means and said axis of rotation, is approximately zero.

6. The pager as claimed in claim 5 wherein said pager case includes attachment means for mechanically coupling said pager case to a person's body.

7. A vibratory pager including:

a case;

a motor mechanically coupled to said case;

a drive shaft attached to said motor and rotatable by said motor about an axis of rotation;

a weight attached to said drive shaft;

said motor being operative in response to receipt of a paging signal;

said drive shaft means being coincident with the axis of rotation; and

connection means for attaching said weight to said drive shaft such that said weight has a center of gravity approximately coincident with the axis of rotation of said weight, when said drive shaft is not rotated and said pager is upright, and noncoincident when said drive shaft is rotated and said pager is upright.

8. A pager as claimed in claim 7 wherein the connection means includes a pivot pin.