HK1020130B - A radiotelephone including an acoustic horn - Google Patents

Description

Wireless telephone with microphone

Technical Field

The present invention relates generally to coupling acoustic energy into and out of electronic equipment, and more particularly to specially constructed articulating passive microphone components that facilitate coupling to an active acoustic transducer, providing good electro-acoustic operation and mechanical protection to a radiotelephone in which the microphone component is mounted.

Background

There is a long development of all types of acoustic transducers used in audio communication systems. To a large extent, the improvement in transducer performance and the adoption of a race between electronic circuits that optimize the interface with any given transducer have proven to be a hypothetical marathon race. Early microphones and speakers, which were primarily based on mechanical principles, were replaced by variable resistance/variable electromagnetic types, which more helped to improve their own amplification and frequency response performance. Often, the transducer type and characteristics are adapted to perform the latest available functions of electronic devices — low noise FETs (high impedance), feedback networks (passband processing), and current mirror amplifiers (low impedance). With the advent of advanced cellular radiotelephone systems that significantly improve signal-to-noise ratios, the sound transmission quality of their audio input devices and audio output devices has received significant attention. As are their costs. As indicated by the present invention, such a combination of directly coupling an inexpensive passive acoustic transmission device to an input microphone (or output speaker) carried by a high quality radiotelephone device significantly improves the technical and operational performance of its associated radio communication system.

A description of the existing typical methods of acoustic coupling techniques for electronic devices can be found in many US patents. All concepts of combining microphone into an output device for a portable radiotelephone are found in US patent 3,748,583 to Anderson et al. In particular, it is pointed out that a folded double-curved microphone is used for directing sound towards the user.

One such technique is disclosed in european patent 0275966 to Schon et al, which places a sound-carrying conduit (sound-carrying conduit) within a flap member that covers the control pad of the handset. The conduit is tapered to feed the incoming voice through an input opening (admitting opening) to a microphone in the handset, the inlet opening being aligned with the microphone input only when the flap is fully open. No description is given of the structure of the sound-carrying conduit.

One such technique is disclosed in Steuart, US patent 1,818,654, which uses a funnel shaped mouthpiece coupled to the early (1931) telephone microphone via two rotational joints. The two articulations allow for vertical and horizontal adjustment of a circular input port by means of several tapered cylindrical tubes.

Other US patents that show interest in microphone structures or wireless telephone input sound I/O techniques are: US 5,384,844 to Rydbeck, US4,171,734 to Peveto et al and US 3,249,873 to Whitemore, jr.

In addition to the patent literature, published scientific literature also provides useful descriptions of ideal characteristics of exponentially curved microphones with respect to sound propagation. Specifically, the paper published by c.r.hanna et al in 1924 a.i.e.e. mentions theoretical basis for microphone design for optimal sound propagation.

Disclosure of Invention

It is therefore a primary object of the present invention to provide improved methods and apparatus for coupling acoustic energy into or out of electronic devices.

It is another object of the present invention to provide a method and apparatus for improving the acoustic coupling capability based on a dual-purpose pivotable microphone member.

It is a further object of the present invention to provide a microphone formed as an internal cavity within a pivotable flip member configured to act as an input or output microphone coupling member for a radiotelephone device.

In a preferred embodiment, the exponential horn microphone is formed as an internal cavity within a planar flip member of a cellular radiotelephone device. The flip member has two purposes: implementing its conventional functions in the first, closed position, protecting and covering the user operated dial/function keys of the radiotelephone; in addition, a sound-transmitting pivot joint forms a high-efficiency sound input coupling device. These two aspects combine to provide a new mode of operation that combines practical protection with low cost, efficient input sound coupling, resulting in an improved radiotelephone apparatus.

Brief description of the drawings

Other objects and advantages of the present invention will become apparent to those skilled in the art from the following description taken in conjunction with the accompanying drawings, in which:

fig. 1 is a perspective view of a hand-held cellular radiotelephone apparatus in which the acoustic input coupling element is implemented as a horn microphone in accordance with the present invention;

fig. 2 shows, schematically and in highly simplified form, a plan view substantially of a microphone adapted to be made in a flip of a radio telephone apparatus;

fig. 2A is a partial plan view of another microphone structure for use in the present invention;

fig. 3 is a perspective view of a flip cover (partially in phantom) showing additional mechanical and acoustic components of an alternative microphone construction;

fig. 4 shows a further embodiment of the microphone structure in longitudinal section through the basic microphone opening.

Description of the preferred embodiments

Referring to fig. 1, there is shown a perspective view of a hand-held cellular telephone device embodying an input acoustic coupling element as a microphone in accordance with the present invention. The entire telephone unit 10 is enclosed within a housing 12, the housing 12 having an aperture 14 for emitting sound from a built-in speaker (not shown). A dual-purpose flip 16 is mounted on the housing 12, the flip 16 being hingedly mounted at the lower end of the housing 12, the flip 16 being formed to include a flared microphone which serves as an input energy coupling element for a microphone for use with a transceiver mounted within the housing 12. The telephone apparatus 10 further includes: a display unit 18; control keyA unit 20 with a user operation key surface on the key surface; and an antenna 22, all of which are well known and conventional in construction. Cellular telephone devices that are easy to implement the unique features provided by the present invention are described in Ericsson Inc (of Research Triangle Park, North Carolina) Product challenge CEL4000 *, 1995 and CEL4000 * 1995. The flip 16 is shown via a pair of hinges 16H and 16^@Mounted around the position occupied by it and having an inlet mouth 24. When the telephone device is not in use, the flip 16 can be pivoted to its closed position to tightly cover and protect the control keys 20.

Fig. 2 is a plan view of an illustrative basic microphone in highly generalized form, particularly configured to be formed within flip 16. The sound collecting and transmitting microphone itself is formed as a flared cavity 26 in the flip 16 having a mouth or open end 24 and a throat end 28. At any point along the central axis 30 of the microphone curve, between the mouth 24 and the throat 28, the incoming acoustic pressure is at some intermediate value between its maximum pressure at the throat and its minimum pressure at the mouth. The actual way in which the sound pressure varies depends on the rate of increase of its cross-sectional area. This increase in cross-sectional area is determined by the law of microphone expansion. In a preferred embodiment herein, extensions to the exponent type will be considered. As an exponential type device, the microphone 26 acts as a very efficient impedance matching device between the source of the incoming acoustic energy (or sound) from its mouth opening and its throat. When the throat 28 passes through a suitable rotary acoustic joint 16^@The telephone apparatus 10 of fig. 1 is well suited to provide its unique advantages to cellular telephone users when properly routed to the microphone 32.

In operation, the basic exponential microphone 26 may be configured to exhibit a high frequency cutoff in the 3-5KHz range, and a smooth response curve may be obtained with both rising. The actual operating characteristics of the microphone 26 can be made very close to the theoretically desired values by means of appropriately arranged attenuating elements, such as thin layers or discrete parts (not shown) of foam/resilient material.

Other microphone types are also contemplated for implementing the present invention. These types may include cone microphones, parabolic microphones, hyperbolic microphones, and other shapes and types.

Fig. 2A shows another embodiment of a microphone and sound input structure that facilitates utilization of the present invention. A modified microphone 26 is fabricated into a flip 16 'as previously described, but the sound entrance to the mouth or open end of the flip 16' is in the form of a plurality of appropriately sized and shaped openings 24 'in the upper surface of the flip 16'. Thus, the length of the microphone 26 ' terminates a short distance from the end of the flip 16 ', and the incoming acoustic energy is coupled into the microphone through the top opening 24 ', instead of the side opening 24 shown in fig. 2. There may be a number of small baffle-like structures between the upper and lower flip surfaces to reinforce the microphone adjacent opening 24 ', all openings 24' providing an enhanced sound input structure for this embodiment. Additional description of the separator plate like structure is described below in conjunction with the description of fig. 4.

Referring briefly to fig. 3, additional mechanical and acoustic construction details of another embodiment of the flip cover 20 and its modified internal microphone are shown. The flip 16 is generally planar and is formed as a thin, flat member with a pair of hinged members at one end. A pair of pivot pins 34 and 36 guide the rotation of flip cover 16. pin 36 carries an internal coaxial opening or channel 38 for directing throat-end acoustic pressure into a microphone (not shown) secured within the body of phone 10. In a particularly preferred embodiment, the horn microphone 26 (e.g., horn microphone 26' of fig. 2A) is rectangular in cross-section and has a length L from the throat end to the mouth opening of up to 60mm (about 2.3 inches), which does not include a short transition passage connecting the throat end 28 to the channel 38. Its hole or nozzle width W may be 40mm (about 1.6 inches) and its hole or nozzle height H may be 1-2 mm. The actual size and shape of microphone 26 is substantially the same as 26' in fig. 2A; for clarity of illustration, many of the labels have been omitted. The dashed lines depict the general outline of the microphone 26 and the thin rectangular cover member 29. One or more input ports 24 (two openings 24 are shown schematically) are used to couple incoming acoustic energy into the mouth of the microphone 26. An opening 24 is made in the top surface of the flip 16 so as to protrude slightly beyond the edge of the cover 29.

For positive mechanical action, the hinge pivot pin area may include suitable stop means that act in conjunction with cooperating structure formed in the housing 12. Suitable sealing means are required in order to couple the sound pressure from the microphone 26, 26' or 26 to the microphone 32 without losses. For simplicity of illustration, the stop and seal means are not shown and are of well known design and construction.

The flap 16, 16' or 16 may be made of any of a number of highly elastic plastic materials. One particularly desirable feature of these plastics is that they can be produced accurately using existing low cost production techniques. Thus, the internal cavity forming the outer perimeter of various microphone 26 embodiments can be precisely and very smoothly fabricated, thereby achieving an efficient acoustic coupling structure.

Additional operating efficiency may be achieved in certain operating environments using the auxiliary microphone structure of fig. 4. A plurality of thin partitions 42 inserted into the microphone mouth opening 24 and extending along a substantial portion of the microphone length divide the input area of the microphone into a plurality of smaller base units. The length of these exemplary baffles is indicated by the length of dashed line 30P in fig. 2. The partition 42 serves two functions: one to define the directivity of the microphone 26 by reducing their sensitivity to sound energy arriving at large oblique angles and the other to actually stiffen the flip 16. When used primarily for reinforcement, the actual length may be shorter as shown in the embodiment of fig. 3.

While the invention has been described in terms of selected preferred embodiments, it is not to be considered limited thereto since other embodiments and modifications will readily occur to those skilled in the art. For example, described herein is the use of a microphone to couple incoming sound into a microphone secured to the housing of a radiotelephone device via a pivoting microphone hinge. It is clear that the reciprocity of the sound transmission means that the method and device according to the invention are equally applicable to the transmission of sound from a built-in electromagnetic transducer via a pivoting sound transmission joint to an output microphone. Thus, the transducer together with the microphone may constitute a sound generating and directing loudspeaker by pivoting the joint. Also, although the microphone 32 of fig. 2 is shown as being fixed near the throat end of the microphone 26, this need not be the case. The microphone 32 may be secured at any suitable location within the radiotelephone device simply by resetting and/or extending the interconnecting sound transmission path; the size, shape and location of the input opening on the top side of the flip cover may also be varied to achieve optimal performance, appearance and user acceptance. It is, therefore, to be understood that the appended claims are intended to cover all such modifications as fall within the true spirit and scope of the invention.

Claims (9)

1. A radiotelephone (10) comprising:

a wireless telephone having: a body portion (12); a microphone (32) provided in the main body portion (12); and a flip (16) pivotally connected to the main body portion (12); and

a microphone (26) forming a cavity inside the flip (16), the microphone having a mouth opening (24) and a throat (28);

the wireless telephone is characterized in that:

a sound coupling hole pivotally coupling the flip cover to a main body portion (12) of the radiotelephone and transmitting sound energy from the throat of the microphone into the main body (12) of the radiotelephone, where sound is transmitted to a microphone disposed therein; and

the acoustic coupling aperture includes a hinge pin (34, 36) for effecting articulation of a portion of the flip cover to a portion of the radiotelephone body (12), wherein the hinge pin includes an axial acoustic passage (38), the passage (38) communicating with the throat end of the microphone for transmitting sound from the microphone into the radiotelephone body (12) so that sound emanating from the throat end of the microphone passes axially through the hinge pin.

2. A radio telephone according to claim 1, further comprising user operated keys (20) located in a key plane, wherein said flip is pivotable to lie parallel adjacent said key plane to cover and protect said keys.

3. The radiotelephone according to claim 1, wherein the pivot angle of the flip is less than 180 degrees, and the acoustic coupling hole is operable to direct sound from the microphone into the radiotelephone body (12) throughout the range of the pivot angle of the flip.

4. A radiotelephone according to claim 1 wherein the cross-section of the microphone extends exponentially from the throat to the mouth along a curved central microphone axis (30).

5. A radiotelephone according to claim 4 wherein said flip cover includes one or more apertures (24), the apertures (24) being formed in an upper surface thereof for coupling incoming acoustic energy into said microphone.

6. The radiotelephone according to claim 4 wherein the mouthpiece of the microphone further comprises means for adjusting the directionality of the microphone input.

7. A radiotelephone according to claim 6 wherein the means for adjusting comprises a spacer member (42) extending into the mouth of the microphone along a line aligned with the axis of the curved central microphone.

8. A method of axially transmitting sound through a hinge pin (34, 36), the hinge pin (34, 36) pivotally connecting a portion of a main body (12) of a radiotelephone (10) to a portion of a flip (16), characterized by the steps of:

pivotally connecting a portion of the radiotelephone body to a portion of the flip cover via a hinge pin such that the flip cover can be flipped back and forth about the hinge pin axis;

directing sound from a mouth opening (24) of a microphone (26) formed in the flip toward a throat end (28) of the microphone;

introducing sound from the throat end of the microphone and axially through a sound passage (38) formed in the hinge pin into the radiotelephone where it can be transmitted to a microphone (32) disposed within the radiotelephone; and

wherein the transmitted sound is transmitted by the hinge pin and an axial sound passage formed in the pin in a movable range in which the flip is pivotable about the axis with respect to the radiotelephone main body.

9. The method of claim 8, wherein the axial sound passage is formed inside the hinge pin and extends completely through the hinge pin.