U.S. patent application number 09/169642 was filed with the patent office on 2002-01-31 for a small sized optical transmission unit suitable for non-simultaneous transmission and reception.
Invention is credited to KAIKURANTA, TERHO.
Application Number | 20020011555 09/169642 |
Document ID | / |
Family ID | 8549717 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011555 |
Kind Code |
A1 |
KAIKURANTA, TERHO |
January 31, 2002 |
A SMALL SIZED OPTICAL TRANSMISSION UNIT SUITABLE FOR
NON-SIMULTANEOUS TRANSMISSION AND RECEPTION
Abstract
The invention relates to optical communication, particularly to
small-sized transmitter/receiver units. An optical transmission
module according to the invention is advantageously applied for
data transmission according to the IrDA standard.
Inventors: |
KAIKURANTA, TERHO;
(PIISPANRISTI, FI) |
Correspondence
Address: |
CLARENCE A GREEN
PERMAN & GREEN
425 POST ROAD
FAIRFIELD
CT
06430
|
Family ID: |
8549717 |
Appl. No.: |
09/169642 |
Filed: |
October 9, 1998 |
Current U.S.
Class: |
250/214.1 |
Current CPC
Class: |
H04B 10/116 20130101;
H04B 10/1143 20130101; G02B 6/4246 20130101 |
Class at
Publication: |
250/214.1 |
International
Class: |
H01L 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 13, 1997 |
FI |
973943 |
Claims
1. An optical transmission unit comprising a transmitter and a
receiver operating in the optical wavelength range, characterised
in that it further comprises an optical element, and that both said
transmitter and said receiver are arranged to utilise the same said
optical element and in that the transmitter is between the receiver
and the optical element.
2. An optical transmission unit according to claim 1, characterised
in that said optical element has a certain focus, and that said
transmitter is located in said focus of the optical element.
3. An optical transmission unit according to claim 1, characterised
in that said receiver is a PIN diode.
4. An optical transmission unit according to claim 1, characterised
in that said transmitter is a light emitting diode.
5. An optical transmission unit according to claim 1, characterised
in that said transmitter is a semiconductor laser.
6. An optical transmission unit according to claim 1, characterised
in that said optical element comprises at least one lens.
7. An optical transmission unit according to claim 1, characterised
in that said optical element comprises at least one diffractive
optical element.
8. An optical transmission unit according to claim 1, characterised
in that it further comprises a signal processing circuit, whereby
the receiver is located between said signal processing circuit and
the transmitter.
9. An optical transmission unit according to claim 1, characterised
in that the transmitter and the receiver are separated by a certain
distance for reducing the effect of shadowing of the receiver by
the transmitter.
10. A mobile station, characterised in that it comprises an optical
transmission unit, which optical transmission unit comprises: a
signal processing circuit; a transmitter and a receiver operating
in the optical wavelength range; and an optical element; whereby
the transmitter is between the receiver and the optical element,
and whereby both said transmitter and said receiver are arranged to
utilise the same said optical element.
11. An optical transmission unit comprising an optical element for
collecting optical signals, a receiver for receiving said optical
signals, said receiver being a PIN diode, a transmitter between
said receiver and said optical element for transmission of optical
signals through said optical element.
Description
[0001] The invention relates to optical transmission, particularly
to small-sized transmitter/receiver units.
[0002] In many communication applications an optical transmission
link, particularly an infrared link, is an advantageous way to
realise a transmission link. In most cases the optical transmission
link is realised with an optical transmission, unit comprising a
transmitter operating in the optical wavelength range and a
receiver operating in the corresponding range. In this application
the optical wavelength range means that range of the
electromagnetic spectrum, which ranges from and comprising the
ultra-violet region (UV) up to and comprising the infrared region
(IR), whereby it also comprises the range of visible light.
[0003] A generally used standard in optical transmission is the so
called IrDA standard, and infrared links according to his standard
are used i.a. in different infrared remote control devices, in data
communication between computers and printers, and generally in the
data communication of small-sized portable equipment. The IrDA
Standard is so widely used that currently there are available very
small modules realised in hybrid techniques and containing a
transmitter and receiver as well as a preamplifier circuit, which
are required for the infrared link. Typically a light emitting
diode (LED) acts as the transmitter, and a PIN diode acts as the
receiver.
[0004] The smallest prior art IrDA modules have a structure like
that in the example shown in FIG. 1. In the prior art solutions the
PIN diode 2, the LED 1 and the preamplifier circuit 3 are placed
side by side in a row on a substrate 7, whereby the width of the
module 5 will be essentially the width of this row. In prior art
arrangements it is also common that the transmitter 1 or LED uses a
separate lens 4 and that the receiver 2 or the PIN diode uses
another separate lens 6. Further the module 5 comprises a casing 9.
The transmitter 1, the receiver and the preamplifier 3 are
connected with bonding wires to the conductor pattern on the
substrate, whereby conductor patterns on the substrate 7 form the
required electrical connections between the pins and the
preamplifier circuit 3, the receiver 3 and the transmitter 1. The
module pins 11 can also be a part of the substrate, or they can
also form the whole substrate, whereby the signal processing
circuit 3, the receiver 2 and the transmitter 1 are directly
mounted on the pins 11.
[0005] There are substantial disadvantages related to the prior art
optical transmission modules. Even the smallest prior art optical
transmission modules are often too wide and large to be used for
instance in mobile communication means. Further, it is very
cumbersome and expensive to acquire and install two different
lenses separately for the receiver and the transmitter.
[0006] The object of the invention is to realise an optical
transmission module, which is smaller than known prior art
solutions.
[0007] These objects are attained by mounting the preamplifier
circuit 3, the receiver 2 and the transmitter 1 at least partially
on top of each other, whereby the structure occupies substantially
less space in the sidewards direction than prior art solutions. In
such a solution the transmitter 1 shadows the receiver, whereby the
reception sensitivity decreases. However, typical LEDs are small
compared to the sensitive PIN diode, so that the savings in the
mounting area of the module attained by the solution according to
the invention will be a greater advantage than the disadvantage due
to the decreased reception sensitivity.
[0008] The optical transmission unit according to the invention is
characterized by that, which is stated in the characterizing part
of the independent claim directed to an optical transmission unit.
The mobile station according to the invention is characterised by
that, which is stated in the characterizing part of the independent
claim directed to a mobile station. The dependent claims describe
further advantageous embodiments of the invention.
[0009] The invention is described in more detail below with
reference to preferred embodiments presented as examples and to the
enclosed drawings, in which:
[0010] FIG. 1, which was described above in connection with the
prior art description, shows an optical transmission module
according to prior art;
[0011] FIG. 2 shows a preferred embodiment according to the
invention;
[0012] FIG. 3 shows a possible module design according to the
embodiment of FIG. 2;
[0013] FIG. 4a shows a possible modification of the embodiment in
FIG. 2;
[0014] FIG. 4b shows another possible modification of the
embodiment in FIG. 2;
[0015] FIG. 5 shows an embodiment of the invention where the
transmitter is mounted in a recess in the receiver;
[0016] FIG. 6 shows an embodiment of the invention where there is
no conductor pattern on the substrate 7;
[0017] FIG. 7a shows a possible design of the optical unit 13
according to the invention;
[0018] FIG. 7b shows another possible design of the optical unit 13
according to the invention;
[0019] FIG. 8 shows a module according to the invention applied in
a mobile station; and
[0020] FIG. 9 shows the block diagram of a preferred embodiment of
the invention.
[0021] The same reference numerals and markings are used for
corresponding components in the figures.
[0022] FIG. 2 shows a preferred embodiment of the invention as seen
from one side. In this embodiment the transmitter 1 is located on
top of the receiver 2, which in turn is placed on top of the signal
processing circuit 3. The transmitter 1 is preferably in the focus
13' of the optical element 13, or in this embodiment of the lens
13. The transmitter 1 sends optical signals through the optical
element 13. The optical element collects optical signals for the
receiver 2. The dotted lines in FIG. 2 illustrate the path of the
light rays. In this embodiment conductors are formed on the
substrate 7, to which conductors the transmitter, the receiver and
the signal processing circuit 3 are connected by bonding wires 12.
The module pins 11 are also fixed to the substrate so that they are
connected to the substrate conductor pattern by bonding wires or by
some other prior art method. The pins 11 of the module can also in
a prior art manner form a part of the substrate or the whole
substrate, whereby the signal processing circuit 3, the receiver 2
and the transmitter 1 are fixed directly on the pins 11.
[0023] The transmitter 1 can preferably be a light emitting diode
(LED). For instance a semiconductor laser or another means for
sending optical signals can also be used as the transmitter.
[0024] FIG. 3 shows a possible design used in the embodiment
according to FIG. 2. For the sake of clarity FIG. 3 does not show
the module's substrate, casing, pins and lens. The transmitter 1
can be attached on Top of the receiver 2, for instance by gluing or
any other of the methods well known to a person skilled in the art
in order to attach two microcircuits on top of each other.
Advantageously conductor patterns 16 can be formed on the surface
of the receiver 2, whereby the receiver can be connected by bonding
wires to these conductor patterns. In such a solution the bonding
wires required for the connection of the transmitter do not have to
be long. The conductor patterns 16 can be connected by bonding
wires either to the connection points 15 of the signal processing
circuit 3, or directly to the connection points (not drawn in the
figure) of the substrate. The receiver can be fixed on the surface
of the signal processing circuit 3 by gluing or by any of the
methods well known to a person skilled in the art in order to
attach two microcircuits on top of each other.
[0025] Above we noted in connection with the description of FIG. 2
that the transmitter 1 can preferably be located in the focus 13'
of the optical element 13. However, the invention is nor limited to
this, but other locations are also conceivable, according to the
design of the optical element. The location of the transmitter 1
and the receiver 2 regarding the focus 13' or focal points of the
optical element 13 can be solved according to the requirements of
the application, so that the entity formed by the optical element
13 and the transmitter 1 and the receiver 2 meets the application's
requirements in an optimal way.
[0026] FIG. 4a shows an advantageous embodiment of the invention
where the transmitter 1 is in front of the receiver 2, in the same
way as in the embodiment of FIG. 3, but at a certain distance from
it. In an embodiment of this kind the shadow area caused by the
transmitter 1 on the surface of the receiver 2 is smaller Than the
transmitter's 1 bottom area, because the received light can be
scattered, refracted or reflected from the different parts of the
optical element 13 to the area under the transmitter's bottom. The
larger the distance between the transmitter and the receiver, the
more optical radiation is received by the receiver 2, because a
hither ratio of the rays from the edges of the optical unit 13 can
reach also the receiver area which is directly behind the
transmitter.
[0027] In the embodiment of FIG. 4a the transmitter is mounted on a
platform 25, which is made of a material which is transparent at
the applied wavelength range.
[0028] FIG. 4b shows another way to mount the transmitter 1 at a
certain distance from the receiver 2. In this embodiment the
transmitter 1 is mounted on a particular bracket 26. The bracket 26
is preferably so narrow, that it does not substantially shadow the
receiver 2. Advantageously the bracket 26 can also be made of
optically transparent material, so that it does not shadow the
receiver 2.
[0029] FIG. 5 shows a preferred embodiment of the invention. For
the sake of clarity FIG. 5 does not show the module's substrate,
casing, pins and lens. In this embodiment the transmitter 1 is
mounted in a recess or opening 19 made in the receiver 2.
[0030] Depending on the thickness of the receiver 2 and the
transmitter 1 the recess 19 can extend through the receiver 2, or
it can extend only to a certain depth within the receiver 2. A
module according to this embodiment can be made thinner than the
module according to the embodiment of FIG. 3. In FIG. 5 the opening
or recess 19 has a quadratic form, but that is no limitation for
different embodiments of the invention. The opening or recess 19
can for instance also be circular, according to the manufacturing
method.
[0031] FIG. 6 shows an advantageous embodiment of the invention. In
this embodiment there are no electrically conducting connections on
the substrate 7, but the substrate is only a mechanical support
means. In this embodiment the transmitter and the receiver are
connected to the signal processing circuit 3, which by bonding
wires 12 is connected directly to the pins 11.
[0032] FIG. 7a shows an advantageous embodiment of the invention.
In this embodiment the optical element 13 is a lens system
comprising more than one lens. The lens system can contain both
convex and concave lenses, depending on the requirements. An
embodiment of this kind is particularly advantageous in such cases
where particular requirements, such as accurate directivity, are
placed on the optical element. Instead of, or in addition to the
conventional lenses in the optical element 13 it is also possible
to use any known prior art optical elements, such as different
diffractive optical elements (DOE), for instance lenses, grids and
mirrors realised by diffractive structures.
[0033] FIG. 7b shows an advantageous embodiment of the invention,
where the optical element 13 is substantially an optical fibre
connector. An optical fibre 21 can be connected to the optical
fibre connector 13 by an optical fibre plug 22. With the aid of an
embodiment this type the module according to the invention can
easily be connected to transmission systems which utlise optical
fibres.
[0034] Advantageously the module according to the invention can be
used in portable mobile stations, as in cellular telephones. In
mobile stations the module according to the invention can be used
to establish a link for instance between the mobile station and a
portable computer, or between the mobile station and a printer. In
embodiments of this type the module according to the invention can
eliminate the need for separate connecting cables. The module
according to the invention can be used for all kinds of data
communication between the mobile station and external equipment,
such as vehicular holders, whereby the mobile station does not
require a separate connector for the data communication. This
enhances the operation reliability and the total reliability of the
mobile station, because connectors are sensitive components which
get dirty and break easily. With the aid of optical data
communication the need for mechanical contacts is avoided and a
more reliable operation of the system formed by the mobile station
and peripherals is obtained.
[0035] FIG. 8 shows some possible locations in a mobile station 300
where a module 320 according to the invention can be mounted. In
the embodiment of FIG. 8 a module is mounted in the bottom part of
the mobile station, so that the module will detect light coming in
a direction from the bottom of the mobile station. The module 320
can for instance be installed in a particular recess 321 so that it
does not form a protrusion at the edge of the mobile station,
whereby the mobile station's casing will protect the module 320
against blows. Of course the module can also be located in other
ways. In addition to the location at the bottom of the mobile
station the module can be located at the sides or at the top of the
mobile station, for instance in some of the ways shown in FIG. 8.
Advantageously also more than one module, for instance two modules
320, can be located in the mobile station, whereby at least one of
the modules is not covered by a hand or some part of the mobile
station' desktop holder when the mobile station is in its
conventional position in the user's hand or for instance in the
desktop holder.
[0036] FIG. 9 shows in a block diagram a mobile station according
to an exemplary embodiment of the invention. The mobile station
comprises parts which are typical to a device, such as a microphone
301, a keyboard 307, a display 306, an earphone 314, a
transmit/receive switch 308, an antenna 309, and a control unit
305. Further the figure shows the transmitter and receiver blocks
304, 311. The transmitter block 304 comprises the functions
required for speech encoding, channel encoding, encryption and
modulation as well as the RF functions. The receiver block 311
comprises the corresponding RF functions as well as the functions
required for demodulation, decryption, channel decoding and speech
decoding. A signal from the microphone 301, amplified in the
amplifier stage 302 and converted into a digital form in the A/D
converter, is supplied to the transmitter block, typically a speech
encoding means in the transmitter block. The emission signal,
prepared and modulated and amplified in the transmitter block, is
supplied via the transmit/receive switch 308 to the antenna 309.
The received signal is supplied from the antenna via the
transmit/receive switch 308 to the receiver block 311, which
demodulates the received signal and performs the decryption and
channel decoding. The speech signal obtained as the result is then
supplied via the D/A converter 312 to the amplifier 313 and further
to the earphone 314. The control unit 305 controls the functions of
the mobile station, reads the instructions given by the user
through the keyboard 307, and presents messages to the user via the
display 306. The optical transmission module 320 according to the
invention is functionally connected to the control unit 305, which
receives the signals detected by the module and supplies the
signals transmitted to the module. Via the module 320 the control
unit 305 can for instance transmit text to be printed on a printer,
or receive data from a portable computer via the module 320.
[0037] With the solution according to the invention it is possible
to realise an optical transmission module which is substantially
smaller and handier to use than an optical transmission module
according to prior art. Only one lens is required to realise the
optical transmission module according to the invention. Further the
assembly of the solution according to the invention is simpler and
more economic than the assembly of a solution according to prior
art.
[0038] Instead or the bonding wires 12 it also possible to use
other connecting methods known by a person skilled in the art, for
instance methods used to realise hybrid circuits.
[0039] The module according to the invention can be used for all
kinds of optical transmission, but particularly advantageously it
can be used for audio signal transmission or data transmission
according to the IrDA standard by infrared radiation.
[0040] The transmitter 1 can advantageously be a LED. The receiver
2 can advantageously be a PIN diode, but it can also be any other
common light sensitive means. The signal processing circuit 3
comprises advantageously at least a preamplifier. However, the
signal processing circuit 3 can also contain other functions, such
as the protocol control functions required by the IrDA
standard.
[0041] Even though the invention has been described with reference
to the enclosed embodiments, it is obvious that the invention is
not limited to these, but that it covers all possible embodiments
which can be realised within the inventive idea and the scope of
the enclosed claims.
* * * * *