Patent Description:
Another solution to the volatility of stored data under high temperature conditions is to save the data to a programmable ROM memory (a programming step). However, the programming step may draw down backup battery power better reserved for other purposes, such as a radio beacon contained in a flight data recorder. Additionally, a special burn voltage may be required to perform the programming step which is higher than the standard voltages within the read-write memory. Further, there may not be a reliable means to assess the ambient conditions so that a timely programming decision is made. Also, the memory controller performing read-write operations on the read-write memory may have failed, disabling any memory backup procedure. And finally, there may not be enough time to transfer data from a read-write memory to a programmable ROM before ambient conditions are too harsh for preserving data integrity.

<CIT> is concerned with multi-level video processing within a vehicular communication network. In particular, a system is provided for performing multi-level video processing within a vehicle includes a pre-processing module for determining an encoding mode and enabling one or more levels of encoding based on the encoding mode. The pre-processing module further receives a video stream from a camera attached to the vehicle via a vehicular communication network and encodes the video stream based on the encoding mode to produce a packet stream output. The system further includes a video decoder for receiving the packet stream output and decoding the packet stream output in accordance with the encoding mode to produce a decoded video output.

Claim <NUM> defines a data recorder for permanently storing pre-event data and claim <NUM> defines a method of permanently storing pre-event data in a data recorder. In the following, apparatus and/or methods referred to as embodiments that nevertheless do not fall within the scope of the claims should be understood as examples useful for understanding the invention.

As may be appreciated, based on the disclosure, there exists a need in the art for permanently saving pre-event data stored in a read-write memory when conditions ambient to a data recorder containing the read-write memory pose a risk to a recovery of the data. Also, there exists a need in the art for a means to detect a high ambient temperature independently of system power and a method for generating power for burning in a permanent copy of the pre-event data stored in bit cells of the read-write memory. Further, there exists a need in the art for quickly saving read-write data without the step of copying and without a need for a memory controller.

Referring to <FIG>, in various embodiments, a data recorder <NUM> for permanently storing pre-event data <NUM> when the pre-event data is at risk of becoming unrecoverable by exposure to an ambient environment <NUM> may comprise a read-write memory <NUM> having a plurality of bit cells <NUM>. Memory <NUM> may be housed within a durable casing <NUM>, such as in a flight data recorder whose contents are thermally insulated (not shown) from ambient environment <NUM>. Each bit cell <NUM> may have a bit state of at least one of a high value or a low value. A fusible memory structure <NUM> may reside in the data recorder <NUM> and may comprise a morphable element <NUM> associated with each of the plurality of bit cells <NUM>. Read-write memory <NUM> may comprise one array of bit cells <NUM> and the fusible structure <NUM> may be a second array of a write-only memory comprising morphable elements <NUM>. Read-write memory <NUM> may be connected to a memory controller <NUM>. Memory controller <NUM> may be coupled to a temperature-triggered module <NUM>. Module <NUM> may be thermally coupled to ambient environment <NUM> and may be configured to electrically couple to each morphable element <NUM>.

Referring to <FIG>, temperature-triggered module <NUM> may be configured to determine if a parameter of ambient environment <NUM>, such as an ambient temperature <NUM>, exceeds a predetermined threshold <NUM>, such as a temperature threshold <NUM> (<FIG>). The parameter may include time in addition to temperature, or the parameter may include additional metrics such as acceleration, humidity, electromagnetics, and other metrics that indicate risk to preserving pre-event data. For example, the parameter may be one or more temperature signatures <NUM> (<FIG>) predicting the imminent loss of data stored in read-write memory <NUM> prior to an event. If the parameter exceeds the predetermined threshold, temperature-triggered module <NUM> may be configured to transmit a burn signal <NUM> to fusible structure <NUM> so that each morphable element permanently secures the bit state for each bit cell (<FIG>, <FIG>, and <FIG>). A commit signal <NUM> may actuate the release of burn signal <NUM> to various morphable elements <NUM> (<FIG> and <FIG>).

Referring now to <FIG>, in various embodiments, a data recorder <NUM> for permanently storing pre-event data <NUM> may comprise a read-write memory <NUM> having a plurality of bit cells (not shown) grouped into pages <NUM> and blocks <NUM>. Memory <NUM> may be housed within a durable casing <NUM> of the data recorder and may be thermally insulated (not shown) from ambient environment <NUM>. A fusible memory structure <NUM> may reside in the data recorder <NUM> and may comprise a morphable element (not shown) for each of the plurality of bit cells. Read-write memory <NUM> may comprise one array and fusible structure <NUM> may be a second array of a write-only memory comprising morphable elements <NUM>. Both arrays may be connected to a memory controller <NUM> and the memory controller <NUM> may be coupled to a temperature-triggered module <NUM>. Module <NUM> may be thermally coupled to ambient environment <NUM> and may be configured to electrically couple to fusible memory <NUM>. Module <NUM> may include thermoelectric generator <NUM> generating output amplitude <NUM> and may include trigger controller <NUM> sensing ambient temperature <NUM> through temperature sense line <NUM> and may communicate burn signal <NUM> to memory controller <NUM>. The read-write memory may be a non-volatile memory such as a flash memory, and may be subject to data loss due to extreme conditions in ambient environment <NUM>.

Continuing with the embodiment of <FIG>, if the parameter exceeds the predetermined threshold, memory controller <NUM> may be configured to copy pages <NUM> or blocks <NUM> of pre-event data from read-write memory <NUM> through read-write lines <NUM> to write-only memory <NUM> and, after copying the data, may convey the burn signal <NUM> from module <NUM> to the write-only memory <NUM> to permanently secure pre-event data <NUM>. A commit signal <NUM> may actuate the release of burn signal <NUM>.

Referring to <FIG>, in an embodiment, temperature-triggered module <NUM> may comprise a thermoelectric generator (TEG) <NUM> having a hot plate <NUM> and a cold plate <NUM> and generating the burn signal <NUM> with an output amplitude <NUM> substantially proportional to a temperature difference between the hot <NUM> and cold <NUM> plates. TEG <NUM> may be integrated into the casing <NUM> in order to thermally couple the hot plate <NUM> to ambient environment <NUM>, and cold plate <NUM> may be configured to impress a large temperature difference across the TEG in order to maximize output amplitude <NUM> and burn signal <NUM>. For example, cold plate <NUM> may face an interior (not shown) of the data recorder insulated from ambient environment <NUM>. Alternately, hot plate <NUM> may be thermally coupled to ambient environment <NUM> through a heat pipe or thermal conduction element from an exterior of the casing <NUM> to a TEG <NUM> situated interior to the memory <NUM> (not shown). The TEG <NUM> may harvest electrical energy from precisely the environmental conditions (heat) which pose a risk to pre-event data <NUM>, and may convert the heat energy into electrical power usable for generating burn signal <NUM> and for supplying operating power to the data recorder <NUM>.

Continuing, in various embodiments, the output amplitude <NUM> of TEG <NUM> may be on the order of several volts, and may be exceed <NUM> volts or may exceed <NUM> volts, depending on the size of the thermoelectric array and the available temperature difference. TEG <NUM> may provide a voltage sufficient to change a conductivity of morphable element <NUM> such that morphable element <NUM> permanently records the bit state for the morphable element associated with it. Morphable element may be one of an anti-fuse or a fuse, and may require a burn signal to have a voltage higher than that readily available in a flash memory or a data recorder, but which may be available from a TEG. The embodiments depicted in <FIG> and <FIG> represent anti-fuse configurations. However, fuse configurations are also possible and this disclosure extends to embodiments constructible with fuses using the principles disclosed herein with a simple reversal of polarity. An anti-fuse may exhibit a relatively high impedance prior to impressing the burn signal <NUM> across it, and may exhibit a relatively low impedance after burn signal <NUM> is passed through element <NUM>.

Referring still to <FIG>, in various embodiments, temperature-triggered module <NUM> may include a trigger controller <NUM> coupling burn signal <NUM> to fusible structure <NUM> (<FIG>) and to each morphable element <NUM> (<FIG>). Controller <NUM> may test ambient temperature <NUM> against threshold <NUM>. Controller <NUM> may include signal conditioning (not shown) for regulating the voltage and/or current of burn signal <NUM> to an effective and non-damaging condition. In the distributed embodiments of <FIG> and <FIG>, where a morphable element <NUM> is positioned near each bit cell <NUM>, controller <NUM> may also be in communication with memory controller <NUM> for coordinating a burn-in process with the read-write operations. Alternatively, burn signal <NUM> may be directed to conduct through morphable element <NUM> without any coordination with memory controller <NUM>. Referring to <FIG>, trigger controller <NUM> may issue a commit signal <NUM> to a tri-state buffer <NUM> to deliver burn signal <NUM> to morphable element <NUM> when selected by a commit signal <NUM>. Burn signal <NUM> may flow from TEG <NUM> through trigger controller <NUM> and onto morphable elements <NUM>. Or, burn signal <NUM> may bypass controller <NUM> and flow from TEG <NUM> to morphable elements <NUM>, where controller <NUM> performs only sensing and control functions, such as selecting tri-state buffer <NUM>.

Referring again to <FIG>, in this modular embodiment of the present disclosure, measuring a parameter of ambient environment <NUM> against a threshold may determine whether to initiate a burn-in process for protecting pre-event data <NUM> in a read-write memory <NUM> by copying the pre-event data though a memory controller <NUM> to a write-only memory <NUM> of morphable elements <NUM>. Following the copying, the pre-event data <NUM> may be permanently secured (recorded) by passing a burn signal <NUM> from temperature-triggered module <NUM> to the appropriate morphable elements <NUM>. For example, it may be necessary to send burn signal <NUM> only to morphable elements associated with bit cells having a bit state of either the high value or the low value, where the other bit state is secured by virtue of element <NUM> having an unchanged electrical characteristic. Memories <NUM> and <NUM> may be arranged on a common semiconductor platform <NUM>, or may be on separate semiconductor platforms or may be in separate modules within the data recorder <NUM>.

Continuing with <FIG>, when data recorder <NUM> is a flight data recorder of an aircraft, pre-event data <NUM> may be sequentially recorded onto memory pages <NUM> of flash memory <NUM> until there is no more free memory space, whereupon the oldest data is written over. Therefore, a burn-in process for permanently storing pre-event data <NUM> may preferably entail copying the most recently recorded portion of pre-event data first, followed by copying a less recent portion of pre-event data. In this way, the most important data may be permanently stored in case the copy and burn process cannot be completed. Alternatively, read-write memory <NUM> may be copied and burned one memory page <NUM> at a time in some predetermined order. Burn period <NUM> (<FIG>) may be the time required to permanently secure pre-event data for all of the plurality of bit cells, and threshold <NUM> may be chosen to complete burn period <NUM> prior to there being a risk of not recovering the data.

Referring now to <FIG> and <FIG>, in various embodiments showing a fusible structure distributed within a read-write memory, data recorder <NUM> may include a burn gate <NUM> disposed on a terminal <NUM> of the bit cell <NUM> and connected to temperature-triggered module <NUM>. Terminal <NUM> may receive the bit state <NUM> of bit cell <NUM> and may thereby make the bit state available to burn gate <NUM>. Bit state <NUM> may be a high electrical value or a low electrical value. Burn gate <NUM> may switch burn signal <NUM> to change morphable element <NUM> only when the bit state is the high electrical value. For example, referring to <FIG>, the read-write memory <NUM> may be a flash memory and burn gate <NUM> may be disposed on a floating gate <NUM> of bit cell <NUM> being a MOSFET device, and morphable element <NUM> may comprise an oxide layer <NUM> on burn gate <NUM>. The high electrical value may be an excess negative charge accumulated in floating gate <NUM> such that when burn signal <NUM> is applied, the combination of signal <NUM> and the excess negative charge breaks down the oxide layer, and may thereby change a conductivity of morphable element <NUM> and may cause a low input impedance at the burn gate. In contrast, a low electrical value for the bit state may represent an absence of charge in floating gate <NUM> such that the application of burn signal <NUM> may not cause a breakdown in oxide layer <NUM>, and may leave morphable element <NUM> unchanged. Advantageously, the combination of burn gate <NUM> and oxide layer <NUM> may form both a switch and a morphable element <NUM> for permanently securing the bit state for all of the plurality of bit cells when the ambient environment <NUM> exceeds the predetermined threshold <NUM>.

Continuing with <FIG>, a high electrical value may correspond to an excess charge in floating gate <NUM> which may also correspond to a logical "<NUM>" for bit cell <NUM>, where the high electrical value refers to a high turn-on threshold voltage for a flash cell. In an embodiment, the oxide layer <NUM> on burn gate <NUM> may be thinner than an oxide layer <NUM> between floating gate <NUM> and MOSFET channel <NUM>, which may ensure that oxide layer <NUM> is the only layer that breaks down under the influence of burn signal <NUM> having a voltage much higher than typical read-write memory voltages. Memory controller <NUM> may connect to a control gate of flash cell <NUM> for reading and writing to the flash cell. The source and drain terminals of flash cells <NUM> may be connected in a NAND, a NOR, or in other configurations (not shown), and various means may be employed to recover the permanently stored pre-event data. For example, a low impedance at burn gate <NUM> may be detected by a test line (not shown) connecting the burn gate <NUM> of each bit cell <NUM> to a special recovery terminal (not shown). Or, a low impedance at burn gate <NUM> may be detected by a test line connecting burn gate <NUM> of each bit cell <NUM> to memory controller <NUM>. Once the low-impedance burn gates in read-write memory <NUM> are determined to indicate a particular bit state, one may assume that the remaining bit cells have the opposite bit state, thereby recovering all of the pre-event data.

Continuing, in various embodiments, bit state <NUM> may comprise more than two electrical values, such as may be found in multi-level cells (MLC) of some flash memories. In the case of MLC flash memory, burn gate <NUM> and morphable element <NUM> may be configured to record two of the bit states of an MLC and additional circuitry may be provided to capture the remaining bit states in the event commit signal <NUM> releases burn signal <NUM>. In an example not shown, a second burn gate having a second oxide layer may be added to a terminal of bit cell <NUM> for detecting a middle bit state, where a second burn signal testing for a middle electrical value utilizes a different voltage. Impedance measurements of the first and second burn gates may be logically combined to determine three or four bit states permanently stored in fusible structure <NUM>.

In <FIG> there is another embodiment showing a fusible structure distributed within a read-write memory. The data recorder <NUM> may further comprise a switch <NUM> switchable by burn gate <NUM> and interposed between burn gate <NUM> and temperature-triggered module <NUM>. For example, the switch <NUM> may be a transistor switch for enabling the burn signal to flow through a morphable element <NUM> connected between switch <NUM> and temperature-triggered module <NUM>. Morphable element <NUM> may be an anti-fuse connected to the switch and may contain an insulating layer which breaks down under the influence of a sufficiently large voltage. Burn signal <NUM> may change a conductivity of the anti-fuse <NUM> to a low impedance when the high electrical value closes the switch <NUM>. For example, anti-fuse <NUM> may be a high impedance prior to a passage of burn signal <NUM> and may have a low impedance after the passage of burn signal <NUM>. Switch <NUM> may be a MOSFET, bipolar junction, or other switching device controllable by gate <NUM>, and may have one terminal connected to a ground or may be connected to some other return path <NUM> for burn signal <NUM>. Alternatively, the positions of switch <NUM> and morphable element <NUM> may be reversed.

Continuing with <FIG>, in various embodiments, terminal <NUM> of the bit cell may connect to memory controller for reading the state of morphable element <NUM> during a post-event memory recovery process. Switch <NUM> may be turned on by memory controller <NUM> to test for a current flow in morphable element <NUM> and which may thereby determine whether element <NUM> is in a low impedance or high impedance state. The high electrical value may be a high voltage value available at terminal <NUM> for actively switching burn gate <NUM>. Alternatively, switch <NUM> may be configured to enable burn signal <NUM> to change morphable element <NUM> when the bit state is a low electrical value. The high electrical state may be defined as one in which the combination of the high electrical state and the burn signal create a higher potential for changing the morphable element than the low electrical state, as shown in <FIG>. In embodiments not shown, a morphable element may be placed in shunt across a terminal of the bit cell for responding both to the bit state and to the burn signal, thereby permanently recording the bit state of the pre-event memory. Furthermore, emergency events meriting permanent burn-in of the bit states in a read-write memory may include detecting extreme ambient temperatures or an ambient electromagnetic condition that threatens the integrity of read-write data <NUM>.

In other embodiments not shown, morphable element <NUM> may comprise a phase-changing material that melts due to an application of the burn signal, where the melting may substantially change the physical characteristics for permanently representing the high electrical value of the bit cell. For example, a phase-changing element subjected to the burn signal may be detected by electrical measurement, by an electron microscope showing an altered molecular or crystalline structure, or by other means to detect a shift in physical properties. In particular, damage to the read-write memory during an event may include inoperable electrical pathways, an inoperable memory controller, and other impediments to traditional measurements of bit state. Alternatively, the melting may be configured to permanently represent the low electrical value.

Many other possible embodiments and configurations in addition to that shown in the above figures are contemplated by the present disclosure. To the extent not already described, the different features and structures of the various embodiments can be used in combination with each other as desired. That one feature cannot be illustrated in all of the embodiments is not meant to be construed that it cannot be, but is done for brevity of description. Thus, the various features of the different embodiments can be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. Moreover, while "a set of" or "a plurality of' various elements have been described, it will be understood that "a set" or "a plurality" can include any number of the respective elements, including only one element. Combinations or permutations of features described herein are covered by this disclosure.

Claim 1:
A data recorder for permanently storing pre-event data, the data recorder comprising:
a read-write memory (<NUM>);
a plurality of bit cells (<NUM>) in the read-write memory, each bit cell having a bit state of at least one of a high value (<NUM>) or a low value (<NUM>), characterized by:
a fusible structure (<NUM>) in the data recorder and comprising a morphable element (<NUM>) associated with each bit cell (<NUM>); and
a temperature-triggered module (<NUM>) thermally coupled to the ambient environment (<NUM>) and configured to be electrically coupled to each morphable element (<NUM>), wherein the temperature-triggered module (<NUM>) comprises a thermoelectric generator (<NUM>) having a hot plate (<NUM>) thermally coupled to the ambient environment and having a cold plate (<NUM>), the generator is configured to generate the burn signal with an amplitude substantially proportional to a temperature difference between the hot and cold plates;
wherein the temperature-triggered module (<NUM>) is further configured to determine if a parameter of the ambient environment exceeds a predetermined threshold, and then to transmit a burn signal (<NUM>) to the fusible structure (<NUM>) when the parameter of the ambient environment exceeds the predetermined threshold so that each morphable element (<NUM>) permanently secures the bit state for each bit cell (<NUM>) in response to the burn signal (<NUM>).