CA2091107C - Static optical storage device - Google Patents
Static optical storage device Download PDFInfo
- Publication number
- CA2091107C CA2091107C CA 2091107 CA2091107A CA2091107C CA 2091107 C CA2091107 C CA 2091107C CA 2091107 CA2091107 CA 2091107 CA 2091107 A CA2091107 A CA 2091107A CA 2091107 C CA2091107 C CA 2091107C
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- CA
- Canada
- Prior art keywords
- information
- medium
- array
- retrieval
- storage
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C13/00—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00
- G11C13/04—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using optical elements ; using other beam accessed elements, e.g. electron or ion beam
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C13/00—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00
- G11C13/04—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using optical elements ; using other beam accessed elements, e.g. electron or ion beam
- G11C13/06—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using optical elements ; using other beam accessed elements, e.g. electron or ion beam using magneto-optical elements
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Abstract
Devices for optical storage of information consist of an optical storage medium and an optical device, generally known as a head to read information from or write information onto the medium. In order to read from or write information onto the various points on the surface of the medium there usually is relative motion between the head and the surface of the storage medium. This is usually accomplished by moving the head, the surface or both in such a manner as to bring the desired points of the surface to the immediate neighbourhood of the head so that the head may read information from or write information to these points. It is most common to have the storage medium in the form of a circular platter which spins while the head traverses the surface of the disc following a path which is approximately radial relative to the platter.
In this invention, the need for relative motion between the optical storage medium and the head is eliminated by the use of a two dimensional array of optical elements which cover the surface of the corresponding two dimensional optical storage medium. Each element consists of optical reading and writing devices which are used to read information from or write information onto a location on the surface of the optical storage medium which is directly opposite to the optical element. The optical elements may be packed together as closely as is permitted by the currently available technology and the shape of this two dimensional array of optical elements and the two dimensional optical storage medium may be made to correspond to each other so as to maximise the amount of information stored on the surface of the optical storage medium.
The array of optical elements can be controlled so as to concurrently write to or read from multiple locations on the storage medium or to write to or read from only one point at any given instant of time.
Furthermore, by using two arrays of optical elements, one on each side of a two dimensional optical storage medium capable of storing information on both sides, information may be written to or read from both surfaces of the storage medium.
In this invention, the need for relative motion between the optical storage medium and the head is eliminated by the use of a two dimensional array of optical elements which cover the surface of the corresponding two dimensional optical storage medium. Each element consists of optical reading and writing devices which are used to read information from or write information onto a location on the surface of the optical storage medium which is directly opposite to the optical element. The optical elements may be packed together as closely as is permitted by the currently available technology and the shape of this two dimensional array of optical elements and the two dimensional optical storage medium may be made to correspond to each other so as to maximise the amount of information stored on the surface of the optical storage medium.
The array of optical elements can be controlled so as to concurrently write to or read from multiple locations on the storage medium or to write to or read from only one point at any given instant of time.
Furthermore, by using two arrays of optical elements, one on each side of a two dimensional optical storage medium capable of storing information on both sides, information may be written to or read from both surfaces of the storage medium.
Description
200 pan 23 STATIC OPTICAL STORAGE DEVICE
SPECIFICATION
_ This invention relates to a device for the optical storage and retrieval of information.
Devices for optically storing and retrieving information normally consist of a medium on which the information is stored and a head to read information from or write information onto the storage medium. In most optical storage devices the storage medium is in the form of circular disks which rotate about a central axis. The head moves radially across the disk surface. The combination of the two motions permits inform<~tion to be read from or written to various points on the surface of the disk. In certain other types of devices, there is no rotational motion but instead the head and/or the medium move linearly, thus enabling information to be transferred between the head and the medium from various points on the surface of the storage medium. In such devices the storage medium is in the form of rectangular cards, strips, or tapes.
All the devices described above use relative motion between the head and the optical storage medium in order to read from or write to various points on the medium. Consequently such devices have several disadvantages. Since the relative motion has to be provided by mechanical or electromechanical components contained in t'he device, wear and tear of the mechanisms may result in misalignment. Shock or vibration may cause errors or damage to the mechanisms. These can result in erroneous operation or failure of the device.
Also, since information has to be transferred while there is relative motion between the head and thE~ storage medium, this limits the speed at which information can be read from or written onto the optical storage medium.
These disadvantages can be removed by the elimination of relative motion between the head and the storage medium. In order to eliminate relative motion, the single head is replaced by an array of optical elements which covers the surface of the optical storage medium. Each optical element is capable of performing read and write functions similar to the single head, except that the optical element is stationery with respect to the optical storage medium. The shape of this array corresponds to the shape of the storage medium. The array and the medium are stationary with respect to each other. Each optical element reads from or writes to a single point on the surFace of the storage medium.
The amount of information stored on the medium is directly proportional to the number or optical elements associated with the surface of the storage medium.
Kabeer A. Sayeed page 2 of pages 9 200 pan 23 STATIC OPTICAL STORAGE DEVICE
Since there is no relative motion between the optical elements and the storage medium, there is no need for any mechanical or electromechanical components in this type of storage devicE~ thus eliminating all the problems described above.
Due to the absence of relative motion, the rate of information transfer between the optical elements and the storage medium is limited only by their respective response times and not by the response times of mechanical components. Since no relative motion is involved this device is hereinafter referred to as Static Optical Storage Device.
Figures 1, 2, 3, 4, and 5 illustrate the construction of the Static Optical Storage Device. Figure 6 illustrates one possible application of the device.
Figure 1 shows a single sided implementation of the Static Optical Storage Device, which hereinafter will be referred to by its abbreviation, namely, SOSD.
In this implementation, the device consists of a two dimensional array of optical elements of square or rectangular shape which is positioned over an optical storage medium having a sirnilar shape.
The optical storage medium may consist of media such as read only media, write-once/read-many, or erasable media. The optical storage medium may use magneto-optic technology, phase change technology, dye polymer technology, or any other technology which may be used for optical or magneto-optical storage and retrieval of information. The optical storage medium is usually in the form of square or rectangular sheets which may be either permanently installed in the SOSD or may be removable.
Each optical element in the array of optical elements consists of one or more sources of electromagnetic radiation of suitable wavelength such as a laser, and one or more detector of Electromagnetic radiation. Alternatively, the optical element may consist of one or more optical waveguides and one or more detectors and may be supplied with electromagnetic radiation having the required frequency from sources internal or external to the optical element which may be contained within the SOSD. The laser sources in conjunction with the detectors are used to read information from or write information onto the optical storage media.
In the case of a SOSD using magneto-optic storage media, the array of optical elements will also contains electromagnets associated with the optical element to magnetise the medium a~t the required point with magnetism of the required polarity.
Kabeer A. Sayeed page 3 of pages 9 200 pan 23 STATIC OPTICAL STORAGE DEVICE
The actual details of the methods of transferring information to and from the optical storage medium are extremely complex and have been documented extensively. Hence, it will b~e sufficient for the purposes of this specification to say that the SOSD will use the currently available methods for the optical storage and retrieval of information, such as those listed above, and any other suitable methods which may be developed in the future. Consequently, there may be as many implementations of the SOSD, as there are optical storage media. However, all these irnplementations will embody the main features which distinguish the SOSD from other optical storage devices, namely, the absence of relative motion between they medium and the reading/writing elements, and the use of arrays of reading/writing elements.
The optical elements in the two dimensional array may be as closely spaced as is possible with the currently available technologies for optical and optoelectronic devices and their integration. Currently available technologies may permit the spacing between each optical element to be 100 micrometers or less. Future advancements in these technologies may permit higher densities to be achieved.
The fabrication of the array of optical elements may be done using a combination of integrated circuit technology, integrated optics technology, and related technologies.
Figure 2 shows a double sided implementation of the SOSD. The double sided implementation is similar to the single sided one except that the optical storage medium used is capable of being written on both sides using two dimensional arrays of optical elements positioned on each side of the medium. This increases the amount of information which may be stored per unit volume of the device.
Figure 3 shows several SOSDs stacked together to increase the information storage capacity. Several stacks of these devices may be used together to provide even greater information storage capacity.
Figure 4 shows the external block diagram of the SOSD. This diagram shows the power inputs, signals for control and communication with the SOSD, signals for selection of the required optical element or elements, and data (information) signals associated with the SOSD. These signals enable the SOSD to be used in conjunction with other devices which require the storage and retrieval of information.
Kabeer A. Sayeed page 4 of pages 9 200 pan 2s STATIC OPTICAL STORAGE DEVICE
Figure 5 shows the internal block diagram of the SOSD. This diagram shows the various internal circuits which may be used in the operation of the SOSD. The power distribution circuit supplies power to the optical elements and other devices within the SOSD. The optical element selection circuit selects one or more optical devices which will be used to transfer information to or from the optical storage medium. The signals for control of and communication with the optical storage device are used to determine the nature of the data transfer, that is, whether information is to be stored on the optical storage medium or retrieved from it. The data control circuit controls the transfer of information to and from external devices which make use of the SOSD for information storage and retrieval.
Figure 6 shows a block diagram of one possible application of the SOSD. In this example, the SOSD is used for information storage and retrieval in a computer system. Control signals (Chip Select, ReadMlrite) from the CPU (Central Processing Unit} of the cornputer system are supplied to the optical element control circuit of the SOSD. From these signals the optical element control circuit determines whether information is to be written on the optical storage medium or retrieved from it. Address signals from the address bus of the CPU are supplied to the optical element selection circuit which may use these signals to select one or more optical elements. Depending on whether a read or write operation has been requested by the CPU (determined as above by the Optical Element Control Circuit), the selected optical elements either read the information from the Optical Storage Medium and supply them to the CPU via the Data Control Circuit or write the information received from the CPU via the Data Control Circuit onto thE~ Optical Storage Medium. In the context of operation with the CPU of a computer' system each optical element of the SOSD reads or writes one bit of information from or to the Optical Storage Medium.
Kabeer A. Sayeed page 5 of pages 9
SPECIFICATION
_ This invention relates to a device for the optical storage and retrieval of information.
Devices for optically storing and retrieving information normally consist of a medium on which the information is stored and a head to read information from or write information onto the storage medium. In most optical storage devices the storage medium is in the form of circular disks which rotate about a central axis. The head moves radially across the disk surface. The combination of the two motions permits inform<~tion to be read from or written to various points on the surface of the disk. In certain other types of devices, there is no rotational motion but instead the head and/or the medium move linearly, thus enabling information to be transferred between the head and the medium from various points on the surface of the storage medium. In such devices the storage medium is in the form of rectangular cards, strips, or tapes.
All the devices described above use relative motion between the head and the optical storage medium in order to read from or write to various points on the medium. Consequently such devices have several disadvantages. Since the relative motion has to be provided by mechanical or electromechanical components contained in t'he device, wear and tear of the mechanisms may result in misalignment. Shock or vibration may cause errors or damage to the mechanisms. These can result in erroneous operation or failure of the device.
Also, since information has to be transferred while there is relative motion between the head and thE~ storage medium, this limits the speed at which information can be read from or written onto the optical storage medium.
These disadvantages can be removed by the elimination of relative motion between the head and the storage medium. In order to eliminate relative motion, the single head is replaced by an array of optical elements which covers the surface of the optical storage medium. Each optical element is capable of performing read and write functions similar to the single head, except that the optical element is stationery with respect to the optical storage medium. The shape of this array corresponds to the shape of the storage medium. The array and the medium are stationary with respect to each other. Each optical element reads from or writes to a single point on the surFace of the storage medium.
The amount of information stored on the medium is directly proportional to the number or optical elements associated with the surface of the storage medium.
Kabeer A. Sayeed page 2 of pages 9 200 pan 23 STATIC OPTICAL STORAGE DEVICE
Since there is no relative motion between the optical elements and the storage medium, there is no need for any mechanical or electromechanical components in this type of storage devicE~ thus eliminating all the problems described above.
Due to the absence of relative motion, the rate of information transfer between the optical elements and the storage medium is limited only by their respective response times and not by the response times of mechanical components. Since no relative motion is involved this device is hereinafter referred to as Static Optical Storage Device.
Figures 1, 2, 3, 4, and 5 illustrate the construction of the Static Optical Storage Device. Figure 6 illustrates one possible application of the device.
Figure 1 shows a single sided implementation of the Static Optical Storage Device, which hereinafter will be referred to by its abbreviation, namely, SOSD.
In this implementation, the device consists of a two dimensional array of optical elements of square or rectangular shape which is positioned over an optical storage medium having a sirnilar shape.
The optical storage medium may consist of media such as read only media, write-once/read-many, or erasable media. The optical storage medium may use magneto-optic technology, phase change technology, dye polymer technology, or any other technology which may be used for optical or magneto-optical storage and retrieval of information. The optical storage medium is usually in the form of square or rectangular sheets which may be either permanently installed in the SOSD or may be removable.
Each optical element in the array of optical elements consists of one or more sources of electromagnetic radiation of suitable wavelength such as a laser, and one or more detector of Electromagnetic radiation. Alternatively, the optical element may consist of one or more optical waveguides and one or more detectors and may be supplied with electromagnetic radiation having the required frequency from sources internal or external to the optical element which may be contained within the SOSD. The laser sources in conjunction with the detectors are used to read information from or write information onto the optical storage media.
In the case of a SOSD using magneto-optic storage media, the array of optical elements will also contains electromagnets associated with the optical element to magnetise the medium a~t the required point with magnetism of the required polarity.
Kabeer A. Sayeed page 3 of pages 9 200 pan 23 STATIC OPTICAL STORAGE DEVICE
The actual details of the methods of transferring information to and from the optical storage medium are extremely complex and have been documented extensively. Hence, it will b~e sufficient for the purposes of this specification to say that the SOSD will use the currently available methods for the optical storage and retrieval of information, such as those listed above, and any other suitable methods which may be developed in the future. Consequently, there may be as many implementations of the SOSD, as there are optical storage media. However, all these irnplementations will embody the main features which distinguish the SOSD from other optical storage devices, namely, the absence of relative motion between they medium and the reading/writing elements, and the use of arrays of reading/writing elements.
The optical elements in the two dimensional array may be as closely spaced as is possible with the currently available technologies for optical and optoelectronic devices and their integration. Currently available technologies may permit the spacing between each optical element to be 100 micrometers or less. Future advancements in these technologies may permit higher densities to be achieved.
The fabrication of the array of optical elements may be done using a combination of integrated circuit technology, integrated optics technology, and related technologies.
Figure 2 shows a double sided implementation of the SOSD. The double sided implementation is similar to the single sided one except that the optical storage medium used is capable of being written on both sides using two dimensional arrays of optical elements positioned on each side of the medium. This increases the amount of information which may be stored per unit volume of the device.
Figure 3 shows several SOSDs stacked together to increase the information storage capacity. Several stacks of these devices may be used together to provide even greater information storage capacity.
Figure 4 shows the external block diagram of the SOSD. This diagram shows the power inputs, signals for control and communication with the SOSD, signals for selection of the required optical element or elements, and data (information) signals associated with the SOSD. These signals enable the SOSD to be used in conjunction with other devices which require the storage and retrieval of information.
Kabeer A. Sayeed page 4 of pages 9 200 pan 2s STATIC OPTICAL STORAGE DEVICE
Figure 5 shows the internal block diagram of the SOSD. This diagram shows the various internal circuits which may be used in the operation of the SOSD. The power distribution circuit supplies power to the optical elements and other devices within the SOSD. The optical element selection circuit selects one or more optical devices which will be used to transfer information to or from the optical storage medium. The signals for control of and communication with the optical storage device are used to determine the nature of the data transfer, that is, whether information is to be stored on the optical storage medium or retrieved from it. The data control circuit controls the transfer of information to and from external devices which make use of the SOSD for information storage and retrieval.
Figure 6 shows a block diagram of one possible application of the SOSD. In this example, the SOSD is used for information storage and retrieval in a computer system. Control signals (Chip Select, ReadMlrite) from the CPU (Central Processing Unit} of the cornputer system are supplied to the optical element control circuit of the SOSD. From these signals the optical element control circuit determines whether information is to be written on the optical storage medium or retrieved from it. Address signals from the address bus of the CPU are supplied to the optical element selection circuit which may use these signals to select one or more optical elements. Depending on whether a read or write operation has been requested by the CPU (determined as above by the Optical Element Control Circuit), the selected optical elements either read the information from the Optical Storage Medium and supply them to the CPU via the Data Control Circuit or write the information received from the CPU via the Data Control Circuit onto thE~ Optical Storage Medium. In the context of operation with the CPU of a computer' system each optical element of the SOSD reads or writes one bit of information from or to the Optical Storage Medium.
Kabeer A. Sayeed page 5 of pages 9
Claims (25)
1 A device for the storage and/or retrieval of information consisting of a two dimensional array of optical writing and reading elements (hereinafter referred to as the "Array"), a two dimensional optical storage medium (hereinafter referred to as the "Medium"), one or more sources of electromagnetic radiation connected, attached, or built into the Array, electronic and/or optical circuits and devices for controlling the optical reading/writing elements of the Array, and electronic and/or optical circuits for communicating with the device in which, during the process of information transfer between the Array and the Medium. the Array is completely stationary with respect to the Medium while the Array writes to or reads from individual or multiple locations on the two dimensional surfaces of the Medium concurrently or sequentially.
2 A device for the storage and/or retrieval of information as defined in claim in which each element of the Array consists of a generator of electromagnetic radiation and a detector of electromagnetic radiation, the entire Array consisting of a multiplicity of such elements arranged in a two dimensional pattern.
3 A device for the storage and/or retrieval of information as defined in claim in which each element of the Array consists of a generator of electromagnetic radiation and a detector of electromagnetic radiation which is shared between a multiplicity of adjacent elements, the entire Array consisting of a multiplicity of such elements arranged in a two dimensional pattern.
4 A device for the storage and/or retrieval of information as defined in claim in which each element of the Array consists of a transmitter of electromagnetic radiation wherein such transmitter transmits electromagnetic radiation generated by one or more generators which are connected to a muliplicity of transmitters, and a detector of electromagnetic radiation, the entire Array consisting of a multiplicity of such elements arranged in a two dimensional pattern.
A device for the storage and/or retrieval of information as defined in claim 1 in which each element of the Array consists of a transmitter of page 6 electromagnetic radiation wherein such transmitter transmits electromagnetic radiation generated by one or more generators which are connected to a muliplicity of transmitters, and a detector of electromagnetic radiation which is shared between a multiplicity of adjacent elements, the entire Array consisting of a multiplicity of such elements arranged in a two dimensional pattern.
6 A device for the storage and/or retrieval of information as defined in claims 4 or 5 in which the Array consists of one or more generators of electromagnetic energy which are connected to and shared by a multiplicity of elements of the Array.
7 A device for the storage and/or retrieval of information as defined in claims 2, 3, or 6 in which the Medium consists of a two dimensional sheet of optically sensitive material
8 A device for the storage and/or retrieval of information as defined in claims 2, 3, or 6 in which the Medium consists of a two dimensional sheet whose surface consists of optically sensitive material.
9 A device for the storage and/or retrieval of information as defined in claims 2, 3, or 6 in which the Medium consists of a two dimensional sheet, both sides of which consist of optically sensitive material.
A device for the storage and/or retrieval of information as defined in claims 7, 8, or 9 in which information is stored on the Medium by changing the state of the Medium at one or more locations of the Medium.
11 A device for the storage and/or retrieval of information as defined in claims 7, 8 or 9 in which information stored at one ore more locations on the Medium may be retrieved by detecting the state of the Medium at these locations.
12 A device for the storage and/or retrieval of information as defined in claim 10 in which changes to the state of the Medium at one or more locations of the Medium are effected by applying electromagnetic radiation of sufficient intensity from the Array to these locations, the Medium and the Array being held parallel to one another at a predetermined distance or in contact with one another as required.
13 A device for the storage and/or retrieval of information as defined in claim 11 in which information is retrieved from one or more locations of the Medium by illuminating these locations with electromagnetic radiation of sufficient page 7 intensity from the Array, and detecting the state of the Medium at these locations from the radiation reflected from these locations, the Medium and the Array being held parallel to one another at a predetermined distance or in contact with one another as required.
14 A device for the storage and/or retrieval of information as defined in claim 11 in which information is retrieved from one or more locations of the Medium by illuminating these locations with electromagnetic radiation of sufficient intensity from the Array, and detecting the state of the Medium at these locations from the radiation transmiited through these locations, the Medium and the Arrays being held parallel to one another at a predetermined distance or in contact with one another as required.
15 A device for the storage and/or retrieval of information as defined in claims 12 and 13 or 12 and 14 in which information can be either sequentially or concurrently stored to or retrieved from a multiplicity of locations distributed over the surfaces of the Medium.
16 A device for the storage and/or retrieval of information as defined in claim 15 in which elements of the Array can be individually or collectively controlled to store information to or retrieve information from the Medium.
17 A device for the storage and/or retrieval of information as defined in claims 16 in which the Array may also contain electromagnets in addition to optical elements, in order to effect changes to the magnetic state of locations on the Medium, in conjuction with electromagnetic radiation from the Array if the medium used is magneto-optic in nature
18 A device for the storage and/or retrieval of information as defined in claims 16 or 17 in which the Array is completely devoid of any form of relative motion with respect to the Medium at the instant at which information transfer takes place between the Array and the Medium.
19 A device for the storage and/or retrieval of information as defined in claims 18 in which one or more Arrays may be used in conjunction with one or more surfaces of the Medium to transfer information between the surfaces of the Medium and the corresponding Arrays.
20 A device for the storage and/or retrieval of information as defined in claims 19 in which the Medium used is such that information can only be retrieved from the Medium (read only).
page 8
page 8
21 A device for the storage and/or retrieval of information as defined in claims 19 in which the Medium used is such that information can be stored only once and retrieved a multiple number of times from the Medium (write once and read many times)..
22 A device for the storage and/or retrieval of information as defined in claim 19 in which the Medium used is such that information can be both stored and retrieved a multiple number of times from the Medium (erasable and/or re-writable).
23 A device for the storage and/or retrieval of information as defined in claims 20, 21, or 22 in which the Medium is permanently attached to the device.
24 A device for the storage and/or retrieval of information as defined in claims 20, 21 and 22 in which the Medium can be removed from, re-inserted into the device, or replaced with another Medium a multiple number of times as required.
25 A device for the storage and/or retrieval of information as defined in claims 23 or 24 in which both the Array and the Medium may conform to various physical shapes including square or rectangular but are not necessarily restricted to the aforementioned shapes.
26 A device for the storage and/or retrieval of information as defined in
25 A device for the storage and/or retrieval of information as defined in claims 23 or 24 in which both the Array and the Medium may conform to various physical shapes including square or rectangular but are not necessarily restricted to the aforementioned shapes.
26 A device for the storage and/or retrieval of information as defined in
claim 25 in which are included optical and/or electronic circuits, components, and interfaces to select the required elements of the Array, control them to store (write) information to the Medium, and/or retrieve (read) information from the Medium, and perform information transfer between the device and external systems.
page 9
page 9
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2091107 CA2091107C (en) | 1993-03-05 | 1993-03-05 | Static optical storage device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2091107 CA2091107C (en) | 1993-03-05 | 1993-03-05 | Static optical storage device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2091107A1 CA2091107A1 (en) | 1994-09-06 |
| CA2091107C true CA2091107C (en) | 2002-05-14 |
Family
ID=4151261
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2091107 Expired - Lifetime CA2091107C (en) | 1993-03-05 | 1993-03-05 | Static optical storage device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2091107C (en) |
-
1993
- 1993-03-05 CA CA 2091107 patent/CA2091107C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2091107A1 (en) | 1994-09-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20130305 |
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| MKEC | Expiry (correction) |
Effective date: 20131009 |