Systems and methods are provided for predicting a circadian state of an individual. The methods comprise: providing a model representative of the response of the circadian state to light stimulus, the model comprising at least one model variable representative of a probability distribution function (PDF) of a phase offset of the circadian state of the individual; and using the model to estimate an updated PDF of the phase offset, wherein using the model to estimate the updated PDF of the phase offset comprises performing a Bayesian estimation process commencing with an initial PDF of the phase offset and iterating toward the updated PDF of the phase offset.

The word "circadian" is derived from the Latin words circa, meaning about, and dies, or day and refers to processes with 24 hour rhythms. Circadian physiological rhythms are present in organisms across the animal and plant kingdoms. Circadian rhythms are thought to be driven by an internal pacemaker that maintains a self-regulating oscillation with a 24 hour period. Recent research has revealed the molecular structures which form the core of the human circadian pacemaker. The pacemaker serves as a central timing mechanism which synchronizes the rhythms of a wide array of physiological systems.
Circadian Pacemaker Mechanism
Daily fluctuations in human physiology, such as sleeping and body temperature changes, have long been observed; however, it was not until the 1970s that strong experimental evidence of the existence in humans of an endogenous circadian pacemaker emerged. Subsequently, in the 1990s the molecular basis of a central human circadian pacemaker was identified. More specifically, research indicates that a molecular clock located in the suprachiasmatic nucleus (SCN) in the hypothalamus region of the brain maintains an approximate 24 hour rhythm. While evidence of additional peripheral oscillators exists, such as in the liver, the SCN pacemaker is believed to play the central role in regulating circadian timing signals for other physiological systems.
Although the circadian pacemaker has an intrinsic period close to 24 hours, precise synchronization to the external environment is maintained by external stimuli referred to as "zeitgebers" (from German zeit (time) and geber (giver)). For most organisms, including humans, the strongest known zeitgeber is light. The daily transitions between light and dark caused by the earth's rotation relative to the sun create a strong environmental stimulus to which organisms naturally synchronize.
Synchronization of the circadian pacemaker to light occurs through photoreceptors in the retina which have a neural pathway to the SCN that is distinct from the neural pathway of the visual system. Signals arriving to the SCN modify both the phase and amplitude of the pacemaker's oscillations. The duration, intensity, timing of light exposure relative to circadian phase and the pattern of light exposure are all factors which have been observed to influence an organism's circadian pacemaker.
Studying the effects of circadian rhythms is generally not as straight forward as considering 24 hour physiological oscillations. Daily patterns of physical activity and sleep-wake also generally occur on a 24 hour schedule, so it is desirable to distinguish between behavior-induced rhythms (e.g. body temperature rising during the day because of walking) and endogenously driven rhythms (e.g. body temperature rising based on internal circadian thermoregulatory signals).
Two predominant experimental techniques for isolating circadian effects are referred to as the "forced desynchrony" and "constant routine" protocols. Both occur in time isolation laboratories. The forced desynchrony technique forces an individual's sleep and wake schedules to desynchronize from their internal circadian pacemaker. The constant routine technique eliminates sleep/wake effects by keeping individuals awake in a constant environment for more than 24 hours. Based on studies conducted with these protocols, a number of relationships between the circadian pacemaker and various physiological systems has been identified. Non-limiting examples of physiological systems that are, or may be, effected by, or otherwise related to, the circadian pacemaker include: core body temperature (CBT), hormonal melatonin concentration, hormonal cortisol concentration, rate of cell proliferation, the cardiac regulatory system, chemoreceptive respiratory feedback system and cognitive performance (alertness).
Indirect Measurement of Circadian State
Since the human central circadian pacemaker mechanism is inaccessibly located in the brain, its state cannot be measured directly. Some researchers have attempted to indirectly measure a subject's circadian state by inferring the subject's circadian state from measurements of downstream physiological systems. A complication arising out of such indirect inference is that systems with an observable circadian modulation, such as CBT and melatonin secretion for example, are also responsive to other physiological systems and/or environmental stimulus. From the perspective of attempting to infer a subject's circadian state, such physiological systems and/or environmental stimulus are considered to mask the circadian contribution to the observed physiological system. Accordingly, most indirect measurements of a subject's circadian state require methods to "demask" the circadian signal components of an observable system from the other, non-circadian components. Two demasking approaches which have been used in the past involve: physical elimination of time-varying exogenous stimulus; and extraction of exogenous factors using signal processing techniques. Laboratory protocols associated with holding all exogenous stimuli constant may be referred to as "constant routine" techniques. Signal processing methods for extracting exogenous factors may be referred to as "purification" techniques.
The Constant Routine Technique
CBT and hormonal melatonin levels are two physiological systems that tend to exhibit consistent and observable circadian rhythms. However, CBT also responds to physical activity, posture, ambient temperature, and sleep and melatonin secretion is also responsive to ambient light exposure. A constant routine demasking procedure developed by Czeisler (Czeisler, C., J. Allan, S. Strogatz, E. Ronda, R. Sanchez, C. Rios, G. Freitag, G. Richardson, and R. Kronauer, Bright light resets the human circadian pacemaker independent of the timing of the sleep-wake cycle. Science 233:4764, 667-671; 1986 (Czeisler 1986)) attempts to minimize such confounding effects on CBT and melatonin levels, by placing subjects in a strictly controlled laboratory environment. To reduce the effects of sleep-wake transitions and posture changes, the Czeisler technique typically involves: keeping subjects awake for long periods of time (e.g. up to 40 hours) in a semi-recumbent position; setting light exposure to a low level (e.g. to 10 lux); introducing meals at regular intervals (e.g. one hour intervals); and limiting physical activity.
During the constant routine technique, CBT may be measured continuously and the circadian contribution to the CBT (a roughly sinusoidal oscillation with an amplitude of approximately 2° C.) may be monitored. The timing of the minimum of this approximately sinusoidal CBT oscillation typically occurs between 4:00 AM and 5:00 AM and is may be used as an indicator of the circadian state of a subject. The natural circadian melatonin cycle includes an onset in secretion approximately at one's typical sleep time. The timing of this onset is driven by the circadian pacemaker; however, melatonin secretion is also affected by exposure to ambient light. The dim light conditions of the constant routine technique facilitate measurement of the Dim Light Melatonin Onset (DLMO) time.
The constant routine technique is currently accepted as a state of the art method for experimentally assessing the circadian state of a subject and is the primary method by which data have been collected about the circadian-phase-shifting effects of light. Despite the success of the constant routine technique, its application is limited to laboratory environments and often involves subject discomfort (e.g. having to be awake for 40 hours).
The Purification Technique
The "purification" demasking approach is another method of circadian state estimation which attempts to use signal analysis techniques to remove masking contributions from observed physiological phenomena (i.e. to extract the circadian contribution from the observed physiological phenomena). Typically, purification techniques attempt to avoid the restrictive physical constraints of the constant routine technique. Physical activity and sleep represent two well-known masking factors associated with the observable phenomena of CBT. Consequently, prior art purification methods have focused on the separation of the effects physical activity and sleep contributions to CBT from the circadian component contribution to CBT. In contrast to the constant routine technique, participants in purification studies have been allowed to follow regular sleep/wake schedules with free ambulatory movement during waking periods.
Waterhouse has developed statistical methods of purification utilizing data from activity sensors. One method involves categorizing activity during waking and sleep periods and then calculating an associated temperature effect from each activity category (Waterhouse, J., D. Weinert, D. Minors, S. Folkard, D. Owens, G. Atkinson, D. Macdonald, N. Sytnik, P. Tucker, and T. Reilly, A comparison of some different methods for purifying core temperature data from humans. Chronobiology International 17:4, 539-566; 2000 (Waterhouse 2000A)). A second method uses a linear regression based on direct mean scores from activity sensors (Waterhouse 2000a). Recent developments in purification-based methods have introduced some basic thermoregulatory models (Weinert, D., A. Nevill, R. Weinandy, and J. Waterhouse, The development of new purification methods to assess the circadian rhythm of body temperature in mongolian gerbils. Chronobiology International 20:2, 249-270; 2003).
While results using purification techniques have been shown to be comparable to constant routine techniques in some cases (Waterhouse, J., S. Kao, D. Weinert, B. Edwards, G. Atkinson, and T. Reilly, Measuring phase shifts in humans following a simulated time-zone transition: Agreement between constant routine and purification methods. Chronobiology International 22(5), 829-858; 2005), there remains contention among experts about the accuracy of purification approaches relative to constant routine techniques. A significant limitation of the statistical purification approach is that during periods of significant desynchrony between sleep-wake times and circadian phase, linear methods to separate the two effects from CBT data are inherently unreliable.
Actigraphy
Another approach to indirectly measuring the circadian state of an individual is referred to as actigraphy and is based on the assumption that there is a direct correlation between an individual's rest-activity rhythm and their sleep-wake rhythm and thus their circadian state. Actigraphy involves recording of rest-activity patterns using sensors which record gross physical movement. Typically, actigraphs are implemented using wrist-worn accelerometers.
Actigraphy has been used to indirectly measure the circadian state of cancer patients for timing the delivery of chronomodulated chemotherapy drugs. The type of circadian variation present in actigraph measurements has also been shown to provide an indicator of 'health status' of cancer patients. Actigraphy appears attractive for use in field applications, since it is portable and generally non-invasive. However, studies to date have yet to produce strong evidence demonstrating the link between actigraphy and more direct physiological systems known to be correlated to circadian state (e.g. CBT or melatonin). Actigraphy-based techniques have been applied only to individual's following a regular diurnal schedule. As such, confounding factors such as inter-individual variations in circadian phase, differences in behavioral patterns, and irregular schedules, such as arise with shift-work or the like, limit the accuracy and precision of actigraphy-based techniques.
Modeling and Predicting Circadian Dynamics
An alternative to measurement of observable physiological phenomena and using such physiological measurements to estimate an individual's circadian state involve the use of predictive models of circadian pacemaker physiology. Mathematical models describing the dynamic response of the circadian pacemaker have been used to predict the behavior of the circadian pacemaker under specific light exposure scenarios.
Mathematical Models of Circadian State
The most widely accepted model of the circadian pacemaker was developed by Kronauer et al in 1987 based on observations of dose-response relationships between light exposure and circadian phase shifts. Kronauer inferred from experimental data that the model should have both a self-regulating oscillator component representing the internal circadian pacemaker, and a light input response component representing the pathway from light in the eye to a synchronizing input on the oscillator. Subsequent discovery of the molecular functionality of the circadian pacemaker has supported the general physiological basis of the Kronauer model. A refined version of the Kronauer model (the Kronauer-Jewett model) was published in 1999 (Jewett, M., D. Forger, and R. Kronauer, Revised limit cycle oscillator model of human circadian pacemaker. Journal of Biological Rhythms 14:6, 493-499; 1999 (Jewett 1999b)).
FIG. 1 represents a schematic, block-diagram depiction of the Kronauer-Jewett model 10, which comprises a dynamic model including a circadian pacemaker component 12 and a physiological marker component 14 for comparison to a measurable physiological parameter. In the prior art Kronauer-Jewett model 10 of FIG. 1, the measurable physiological parameter is the subject's CBT. Circadian pacemaker component 12 of the Kronauer-Jewett model 10 receives a light input I together with a set of initial conditions xinit, xc init and ninit corresponding to its model variables x, xc and n and uses this information together with its model equations to generate output model variables x, xc. Typical profiles of output model variables x, xc are shown in FIG. 2. It may be observed that output model variables x, xc are approximately sinusoidal in shape with a period of approximately 24 hours and that output model variables x, xc are approximately 90° out of phase with one another.
Physiological marker component 14 of the Kronauer-Jewett model 10 incorporates a minimizer component 16. Minimizer component 16 receives the output model variable x and returns a time at which output model variable x is a minimum xmin. As shown in FIG. 2, the minimum xmin (also referred to as a nadir of the model variable x) occurs once every period of output model variable x or approximately once every 24 hours. The time at which output model variable x is a minimum xmin is referred to FIGS. 1 and 2 as φmin{x}.
The Kronauer-Jewett model 10 also incorporates the experimentally determined observation that the time φmin{x} that the model variable x is a minimum xmin is correlated to the time of the CBT minimum CBTmin. The time that physiological marker component 14 predicts to be the time of CBTmin is referred to in FIG. 1 as φmin{CBT}. As can be seen by observation of summing junction 18, the Kronauer-Jewett model 10 incorporates the experimentally determined relationship that the time φmin{CBT} typically occurs 0.8 hours after the time φmin{x}. Physiological marker component 14 of the Kronauer-Jewett model 10 outputs the time φmin{CBT} of the CBT minimum CBTmin which in turn permits comparison of the Kronauer-Jewett model 10 to measured CBT values. Since the time φmin{x} that the model variable x is a minimum xmin is only output once every approximately 24 hours, it follows that physiological marker component 14 only outputs the time φmin{CBT} of the CBT minimum CBTmin once every approximately 24 hours.
The Kronauer-Jewett circadian pacemaker model 10 has been used with differential-equation-solving algorithms to generate simulations predicting the phase shift of the circadian pacemaker, starting from known initial conditions (xinit, xc init, ninit), in response to a given light exposure pattern (I). This predictive capability has been successfully used to design of experimental protocols and confirm experimental observations of circadian phase shifts in a laboratory context. Despite the apparent usefulness of the Kronauer-Jewett model 10, it has not actually been widely applied in broader contexts—e.g. outside of an experimental laboratory environment.
A number of drawbacks have tended to limit widespread adoption of the prior art Kronauer-Jewett model 10 as a general modeling framework. By way of non-limiting example, such limitations include: (i) the circadian phase of the subject is not presented as a continuous variable which can be monitored (e.g. as an output of model 10) or updated (e.g. as an initial condition of model 10); (ii) the correlation between the circadian phase and physiological marker 14 is not defined in a statistical manner (i.e. Kronauer-Jewett model 10 does not incorporate statistical uncertainties); and (iii) the Kronauer-Jewett model 10 only specifies a correlation to CBT and not to other physiologically observable phenomena.
Alertness Models
One use of circadian physiology models is in the field of human alertness modeling and prediction. Human alertness may also be referred to as human performance. Current models of human alertness incorporate both a sleep-related component and a circadian component; however, most of the widely used human-alertness models assume a fixed circadian phase—e.g. a series of sinusoidal harmonics with a predetermined and constant phase. With such constant phase assumption, scenarios in which the actual circadian phase of a subject may be non-stationary, e.g. shift work or transmeridian travel, cannot be accurately modeled. Some human-alertness models incorporate the potential for changing circadian phase. One such human-alertness model uses a version of the Kronauer model for accommodating variations in the circadian phase (Jewett, M. and R. Kronauer (1999). Interactive mathematical models of subjective alertness and cognitive throughput in humans. Journal of Biological Rhythms 14:6, 588-597; 1999 (Jewett 1999a)). Another such human-alertness model uses a "rule of thumb" for shifting the circadian phase in response to time-zone changes—e.g. a constant rate of change of the circadian phase until the subject is entrained to the new time zone (Akerstedt, T., S. Folkard, and C. Portin, Predictions from the three process model of alertness. AVIATION SPACE AND ENVIRONMENTAL MEDICINE March 75:3, Suppl., A75-A83; 2004). The lack of dynamic circadian modeling has been identified as a general need in the context of human alertness prediction.
One of the challenges in applying a human-alertness model incorporating a detailed dynamic circadian pacemaker model to real world scenarios is that current simulation methods require precise specification of initial conditions and complete knowledge of light levels during the course of the simulation. In uncontrolled environments, such as in an actual workplace or in almost any scenario outside of a laboratory, it is difficult to assess both the circadian phase and ambient light levels for a specific individual. It may be this reason that the Kronauer-Jewett model 10 has found application in simulating laboratory environment scenarios, where circadian phase and light levels can be controlled, but has not been widely used in operational scenarios. This inability to apply circadian predictions to real world environments may be partially responsible for the fact that despite a well-established model of the circadian pacemaker, it remains difficult for scientists to provide definitive advice concerning specific circadian adjustment countermeasures.
There is a general desire for systems and methods for predicting a belief in or probability of the circadian state of a subject which may overcome or ameliorate some of the aforementioned issues with the prior art.

Methods and systems for circadian physiology predictions


A memory device with a switchable clock output. The memory device has a data pin, a clock input pin, and a clock output pin. The memory device is designed to be wired up to a plurality of other memory devices in a daisy chain manner. The clock input pin of the first memory device would be serially coupled to the first memory device. The clock output pin of each memory device would be serially coupled to the clock input pin of a directly successive memory device. The processor can then interrogate the first memory device for the identification information it contains. Once this information is obtained, the processor can issue a command to deactivate the first memory device from responding to bus commands, as well as to output the clock signal via the clock output pin to a directly successive memory device. The processor may then interrogate the next memory device.

1. Field of the Invention
This invention relates generally to memory devices and, more specifically, to a memory device having a switchable clock output pin which will allow for board identification in systems having a plurality of circuit boards.
2. Description of the Prior Art
Presently the standard I.sup.2 C serial Electrical Erasable Programmable Read Only Memory (EEPROM) device has data and clock inputs. The EEPROM device is designed to have the clock and data signals bussed to each EEPROM device in parallel. Addressing of each individual EEPROM device is accomplished by three address pins which couple each EEPROM device to the computer system. The problem with this approach is that the three address pins limit the total number of EEPROM devices that may be coupled to the clock and data lines to eight. A further problem with I.sup.2 C devices being used for board identification for electronic circuit boards is the requirement for the three address pins to be routed to the electronic circuit board connector. This requirement consumes extra connector pins which could be used for different and more important functions.
Therefore, a need existed to provide an improved electronic circuit board and method therefor. The addressing of the improved electronic circuit board must not require the three address pins which are currently being used. This will allow more electronic circuit boards to be placed on the clock and data bus lines. The removal of the requirement of the three address pins will also free up extra connector pins which may be used for different and more important functions. A need further existed to provide an improved method for board identification in systems which use a plurality of electronic circuit boards. The new method must increase the total number of electronic circuit boards which may be placed on the clock and data signal lines.

Memory device having a switchable clock output and method therefor


An imaging apparatus includes an imaging element including a pixel portion having a plurality of photoelectric conversion units with respect to one micro lens and color filters which are regularly arranged for each micro lens. The imaging apparatus generates a first signal and a second signal for phase difference-type focus detection based on an output of the imaging element. Each of the first signal and the second signal consists of a plurality of unit signals, and the unit signal of each of the first signal and the second signal is a signal obtained by mixing image signals from the same combination of the color filters.

Field of the Invention
The present invention relates to an imaging apparatus and a method for controlling the same.
Description of the Related Art
As a focus detection method for controlling the focusing of an imaging apparatus, there is a technique that performs phase difference-type focus detection simultaneously with imaging by applying a configuration such that a pixel in an imaging element receives light from a different pupil plane of an imaging lens.
Japanese Patent Laid-Open No. 2001-083407 discloses an imaging apparatus in which a light-collecting photodiode (hereinafter referred to as "PD") is divided into a plurality of PDs under one micro lens and each of the PDs receives light from a different pupil plane of an imaging lens. The imaging apparatus compares outputs from the two PDs to thereby perform focus detection. The imaging apparatus disclosed in Japanese Patent Laid-Open No. 2001-083407 performs focus detection using the output of an imaging element for imaging an image. Thus, when the imaging apparatus is applied to a typical color camera or the like, each pixel of the imaging element has a color filter. In this case, a color signal which is different for each arrangement of color filters is obtained as a focus detection signal.
Here, there has been proposed a technique that performs focus detection using an output signal from an imaging element in which a color filter is provided for each pixel. Japanese Patent Laid-Open No. 2000-292686 discloses an imaging apparatus that includes an imaging element having pixel portions in which a color filter is provided for each phase-difference detection pixel and performs phase difference detection using an output signal from the pixel portion.
However, the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2000-292686 calculates a focus detection signal by using focus detection data from a blue filter and a green filter, separately, which are adjacent in the horizontal direction to thereby average the calculation result. In the method, calculation needs to be performed for each color filter, resulting in an undesirable increase in the amount of calculation for focus detection.
In addition, the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2000-292686 has an output line in only one row as the output line of a focus detection signal. Thus, in the imaging apparatus, when the output line of a focus detection signal is set in plural and focus detection signal calculation processing is performed in the vertical direction in the same manner as that in the horizontal direction, the amount of calculation further undesirably increases. Furthermore, in the imaging apparatus, a color filter of the same color is arranged in every second pixel, so that the amount of data for focus detection reduces, resulting in a decrease in focus detection performance.

Imaging apparatus and method for controlling same


A device to protect surgical tables that incorporates a horizontal base and a vertical flange that meet creating a vertex, where the vertex may have a radius. The horizontal base is supported by at least one foot providing a stable platform for the surgical table guard. The vertical flange is spaced away from the vertical base of the surgical table providing adequate clearance to the vertical base to allow the vertical base to compress in normal operation.

1. Field of the Invention
The present invention relates to the field of surgical tables. More specifically, protection for the housings of surgical tables used by hospitals and clinics throughout North America and Europe.
2. Description of the Prior Art
U.S. Pat. No. 6,497,233 by DeAngelis discloses a Surgical Drape for use on Surgical carts. Specifically, this drape is used to maintain a sterile field, and to provide protection for multi level access of surgical instruments for complex operations. This drape has the purpose of preventing fluids from leaking through to the surface of the surgical cart. This drape is comprised of molded plastic, woven, and non-woven material. One main purpose of this invention is that it be made from a series of flexible materials to aid the drape in covering the surgical cart.
U.S. Pat. No. 6,189,459 by DeAngelis discloses an auxiliary shelf that is attachable to existing operating room carts. This invention uses adjustable clamps to allow removal of the invention from existing inventories of operating room carts.
U.S. Pat. No. 5,429,058 by Miller discloses a Heart/Lung Machine Base. This invention is very specific to the operating parameters for reducing the distance between the arterial pump and the surgical table. This invention performs this operation by providing a lift that will mimic the movement of the surgical table. This is accomplished with the use of a mechanical lift mechanism.
US Patent Number Publication US 2012/0137935 by Hodges et al. discloses an Adjustable Bi-Level Surgical Accessory Table. This invention is to allow a nurse to place instruments that are used for a particular surgery in a more readily accessible position for the surgeon. Both of the moveable table tops are specifically designed for sterilized medical instruments and supplies during a medical procedure. The rearmost table top can be tilted, while the forward most table top cannot tilt but can be moved up and down as well as in and out.
U.S. Pat. No. 6,038,718 by Rennington, et. al, discloses a Surgical Table. This is a common type of table. Of particular note to this table, and many others on the market by different companies, is item number (26) support column. The support column (26) is vertically extendable and includes telescoping sections (26a), (26b), and (26c) for providing upward and downward movement of the table top (12); column 5, lines 6 through 8. It is this component, support column (26) that is damaged by persons placing other equipment onto the base. When the table is lowered, the telescoping sections (26a), (26b), and (26c), are damaged and need to be replaced at great cost. It is very common for the hospital, clinic, etc., to return the table to a repair station, where the components are replaced. This places the table out of commission for weeks.
What is needed and has never been disclosed or described in the prior art is an device that will protect surgical table shrouds and support columns from damage by placement of equipment on the base of the table.


In a method and system for testing a device, a tester is operable to generate a first set of test signals for testing the device. The tester is electrically coupled to a test head, which in turn provides electrical coupling to the device. A test assembly is operable to generate a second set of test signals for testing the device. The test assembly is electrically coupled to an interface apparatus, which is adapted to be removably secured to the test head. The interface apparatus is operable to communicate the first and second set of test signals to the device.

The present disclosure relates generally to test systems, and more particularly to a system and method for testing electrical devices requiring a variety of test signals.
Manufacturers of electrical/electronic devices such as integrated circuits, radio frequency (RF) circuit devices, printed circuit boards, and other circuits, typically use automatic test equipment (ATE) or similar other test systems to test the devices during the production process, preferably before they are installed by a user. The test systems are generally configured to apply a test signal to the device and measure its response. A device under test (DUT) is typically mounted on a test board, which in turn is secured to a test head. Depending on the size of the test system, the test head may include several thousand electrical connectors for electrically coupling the test system to the DUT. Test signals generated by the test system are communicated to the DUT via the test head and the test board. Different DUT's may require a corresponding matching test board. The size, layout and arrangement of the test head may vary by manufacturer but is generally fixed for a particular test system.
Today, many commercially available, advanced, multi-function ATE systems generate several types of test signals for testing various attributes of the DUT. However, many of these test systems are very complex, bulky, often require additional heat removal systems and typically cost several million dollars thereby making them unattractive for use in a cost driven manufacturing environment. In addition, the test systems often lack the flexibility to cost effectively integrate one or more test signals, which may be required to test the DUT but may not be supported by the test system manufacturer. For example, many test systems may not support RF signals and/or high speed digital (HSD) signals which may be required for testing a DUT. It may take the test system manufacturer a longer-than-desirable time period to support the required test signals in the test system, and it may be supported at an unaffordable cost.
In a manufacturing/production line environment, complex and bulky test systems often decrease production efficiency and increase costs since they often require elaborate set up and dismantling procedures. In addition, some of the test systems may not be suitable for use in production areas having limited accessibility and tighter space clearances.
Therefore, a need exists to provide an efficient method and system for testing electrical devices requiring a variety of test signals. Additionally, a need exists to provide an improved technique to cost effectively and timely integrate a required test signal into an existing or legacy test system for testing the DUT. Accordingly, it would be desirable to provide an improved test system for testing devices, absent the disadvantages found in the prior methods discussed above.


A sheet conveying device, which is incorporated in an image forming apparatus, includes a pair of sheet holding rollers and a regulator. The pair of sheet holding rollers disposed along a sheet conveying path rotates and conveys the recording medium while holding a recording medium in a nip region thereof. The pair of sheet holding rollers includes a stopper that rotates with the pair of sheet holding rollers between a closing position at which the sheet conveying path is closed and an opening position at which the sheet conveying path is open. The regulator is movably disposed between a contact position and a retracted position with respect to the pair of sheet holding rollers. The pair of sheet holding rollers corrects a positional shift of the recording medium in the sheet conveying direction with the stopper at the closing position, and further conveys the recording medium after correction.

1. Technical Field
This disclosure relates to a sheet conveying device to correct positional shifts of a recording medium while the recording medium is traveling in a sheet conveying path, and an image forming apparatus including the sheet conveying device.
2. Related Art
Various types of electrophotographic image forming apparatuses include copiers, printers, facsimile machines, or multifunction machines having two or more of copying, printing, scanning, facsimile, plotter, and other capabilities. Such image forming apparatuses usually include a sheet holding roller that has a stopper (a contact member) attached thereto. The stopper rotates with the sheet holding roller to correct a positional shift and a skew with respect to a sheet conveying direction of a recording medium in a sheet conveying path.
Specifically, in such image forming apparatuses, for example, the sheet holding roller includes two rollers, one of which mounts the stopper thereon to rotate together with the stopper. As the sheet holding roller rotates, the stopper closes the sheet conveying path. With this action, a leading edge of the recording medium that travels in the sheet conveying path contacts the stopper. Consequently, a positional shift in the sheet conveying direction of the recording medium is corrected, which is for convenience referred to as a "positional registration correction". At the same time, the a positional direction to an oblique side in the sheet conveying direction of the recording medium is corrected, which is for convenience referred to as a "skew correction". After completion of the positional registration correction and the skew correction, as the sheet holding roller rotates, the stopper opens the sheet conveying path, so that the recording medium further travels toward a downstream side of the sheet conveying path.
As described above, when the positional registration correction and the skew correction are performed, the recording medium contacts the stopper of the sheet holding roller. Impact or shock caused by the contact of the recording medium to the stopper vibrates the stopper in a rotational direction together with the sheet holding roller, and therefore it is likely that the degree of precision of the positional registration correction and the skew correction is reduced.
When the sheet holding roller is driven by gear drive transmission, the stopper easily vibrates in the rotational direction together with the sheet holding roller within a range not exceeding a backlash range.

Sheet conveying device and image forming apparatus incorporating the sheet conveying device


Packaging for optical components. A package for packaging multiple fiber optical components can include a bottom portion comprising at least two cavities. The cavities can include a first cavity that is sized and configured to receive a first fiber optic component, and a second cavity that is sized and configured to receive a different fiber optic component. The package can also include a lid portion. The lid can be secured in a closed position with the bottom portion. The cavity can receive a first optical component and a second optical component. The package can also include identification information integrated with at least one of the bottom portion and the lid portion for describing the package or a component held within the package.

1. The Field of the Invention
The present invention relates generally to packaging systems and methods. More specifically, embodiments of the present invention relate to systems and methods for packaging fiber optic communication components including optical transceivers.
2. The Relevant Technology
Some of the fundamental components in fiber optic technologies are the components used to transmit and receive the optical signals. These components are typically referred to as transceivers. Transceivers often use lasers to generate the optical signals. Because the transceivers contain lasers, they are often subject to various packaging and labeling requirements.
Conventionally, the packaging of fiber optic components such as transceivers is often carried out using a separate cardboard box for each component. Each box typically includes packaging foam for cushioning the fiber optic component. During the packaging process, each cardboard box is sealed independently of the others using tape or glue. In addition, each box receives a label that is attached to the outside of the box. The labels identify the product in the box and may also include an address to which the component is sent. The resulting packages have typically been expensive to ship and to store at least because of the size of the individual packages, the labor required to assemble the packages, and the amount of material required for each separate component. In addition, the materials that have been historically used for the packaging have not been easily reused or recycled resulting in excess waste and cost in the disposal of the used packaging.
FIGS. 1A, 1B, and 1C illustrate a conventional package for storage and shipment of a transceiver. The package includes a rectangular cardboard box 100 including a flap 110 and tabs 120 for securing the lid 130 of the box in a closed position as shown in FIGS. 1B and 1C. Tape 155 or glue is typically used to close the box 100 and a label 160 for shipping, providing electrostatic discharge (ESD) caution, or for identification and regulatory purposes can be attached to the outside of the box 100.
The box typically includes foam 140 attached to the inside of the box 100 for cushioning the fiber optic component 150 housed therein. Often, these packaging boxes 100 cannot be reused and the box 100 itself cannot be recycled without removing the cushioning foam 140 from within. The current packaging of fiber optic components tends to be bulky and is relatively expensive to ship, store and recycle. Further, it is not readily apparent what part is contained within the packaging without a label or external indication of some sort. The fact that a component was actually placed inside of a conventional package cannot be visually ascertained without opening the package.


A method for making a carbon nanotube-based field emission display device includes the following steps: providing an insulative layer (22) having a first surface; depositing a layer of catalyst (26) on the first surface of the insulative layer; forming a spacer (28) having a number of openings therein such that patterned areas of the layer of catalyst are exposed in the openings; forming arrays of carbon nanotubes (30) extending from the layer of catalyst in the openings; forming a cathode electrode (34) on a top of each of the arrays of carbon nanotubes; forming gate electrodes (40) on a second, opposite surface of the insulative layer offset from the patterned areas; removing portions of the insulative layer corresponding to the arrays of carbon nanotubes so as to expose the arrays of carbon nanotubes; and attaching an anode electrode (50) having a phosphor screen (52) to the above obtained structure.

1. Field of the Invention
The present invention relates to a method for making a field emission display device, and more particularly to a method for making a carbon nanotube field emission display device.
2. Description of Prior Art
Carbon nanotubes are a novel carbonaceous material discovered by Iijima, a researcher of NEC corporation, in 1991. Relevant information was reported in an article by Iijima, entitled "Helical Microtubules of Graphitic Carbon" (Nature, Vol. 354, P56, 1991). Carbon nanotubes can transmit an extremely high electrical current and emit electrons easily at a very low voltage of less than 100 volts, which make it a very promising potential material for field emission applications.
Referring to FIG. 13, U.S. Pat. No. 6,232,706, invented by Hongjie Dai et al., discloses a field emission device using aligned parallel bundles of carbon nanotubes 100 extending from patterned catalyst layers 130 deposited on a layer of porous silicon 120 which is formed on a substrate 110 using a chemical vapor deposition (CVD) process. The carbon nanotubes produced by the CVD process have a variety of heights in a wide range so that the bundles of carbon nanotubes each forms a top which may be flat, concave, or in different pattern since the grown height is neither predictable nor controllable. Furthermore, a thin layer is formed on the top of the bundle which includes nanotubes with a variety of sizes, a number of remaining catalyst particles and amorphous carbon. These defects usually result in uniformity and unreliability of the field emission from the bundles of carbon nanotubes.
In order to optimize electron emissions, a triode-type field emission device is used. U.S. Pat. No. 6,515,415 discloses a typical triode-type field emission device, which generally includes a cathode electrode having carbon nanotube array emitters, an anode electrode with a phosphor screen, and a gate electrode positioned between the cathode electrode and the anode electrode to control emission of electrons from the carbon nanotube array emitters. The carbon nanotube arrays are usually produced using a chemical vapor deposition process.
In order to lower the emission turn-on voltage, a precisely controlled distance between the emitters and the gate electrode is required. Although the carbon nanotubes array growth higher with longer the reaction time, it is very difficult to control the growth height precisely. Therefore, the distance between the emitters and the gate electrodes is difficult to control merely by growth.

Method for making a carbon nanotube-based field emission display


A semiconductor integrated circuit with low power consumption is provided. In one embodiment, the semiconductor integrated circuit includes a logic circuit portion that is connected between a first power line and a virtual ground line. The logic circuit portion includes at least one NMOS transistor having a first threshold voltage and at least one PMOS transistor having a second threshold voltage. The semiconductor integrated circuit further includes a first MOS transistor, which is connected between the virtual ground line and a ground voltage, where the first MOS transistor has the first threshold voltage and applies the ground voltage to the virtual ground line in an active state. Also included in the semiconductor integrated circuit is a controller that is connected to the first MOS transistor, where the controller applies the ground voltage to the first MOS transistor in the active state and applies a bulk voltage supplied from a bulk power line in a standby state to control a threshold voltage of the first MOS transistor.

1. Field of the Invention
The present invention relates to a semiconductor integrated circuit and, more particularly, to a semiconductor integrated circuit with low power consumption.
2. Description of the Related Art
Portable electronic devices are different from general electronic devices because they are driven by a battery. Thus, it is important to reduce power consumption in the portable electronic device. In a large scale integrated circuit (LSI) chip employed in the portable electronic device, the power consumption is one of the important design factors. The power consumption problem with the portable electronic device which employs the LSI chip generally has two classifications.
One is the power consumption which occurs in an active state of the LSI chip, and the other is the power consumption that occurs in a standby state. For example, in case of a personal digital assistant (PDA), its LSI chip stays in the active state when a user continuously inputs data or executes a certain application program. However, when there is no data input or no execution of the application program during a certain time period, the LSI chip enters the standby state in which only internal requisite data necessary for returning to a normal operation are kept.
In the standby state, a clock necessary for the operation of the LSI chip turns off, and only a power voltage VDD is applied. Thus, hardware and software is designed such that even in the standby state the internal state of the LSI chip and stored data are maintained until the LSI chip returns to an active state.
In the case of the portable electronic device, standby time is generally longer than operation time. Thus, it is important to reduce the power consumption in the standby state. For the foregoing reason, LSI chips are being developed to provide various standby modes and minimize electric currents in the standby state.
In order to maintain data in the standby state, the LSI chip for the portable electronic device can be implemented with static logic. When the portable electronic device is designed with static logic, most of the power consumption is caused from leakage currents, such as a leakage current between the power voltage and the ground voltage, a leakage current in the PN junctions, and the like. Conventional methods for reducing the power consumption and improving the performance of the LSI chip have depended on a scaling down technique. That is, as a device is scaled down, the performance is improved by the shorter channel of a MOS transistor and the corresponding reduced capacitance. This, in turn, leads to lower power consumption and reduced operation voltage.
However, if a device is scaled down past a predetermined level, the operation speed can be significantly lowered due to an increase in the threshold voltage of a transistor. Therefore, in order to solve the problem, the threshold voltage of the transistor needs to also be lowered. However, if the threshold voltage of the transistor is low, the transistor may not be completely turned off in an off state resulting in a large amount of leakage current.
In order to solve the problem, a multi-threshold CMOS (MTCMOS) technique has been suggested.
FIG. 1 is a circuit diagram illustrating a conventional semiconductor integrated circuit.
The semiconductor integrated circuit of FIG. 1 includes a transistor having a low threshold and a transistor having a high threshold voltage. Transistors which constitute a logic circuit portion 10 are transistors having a low threshold voltage, and a transistor having a higher threshold voltage than the transistors of the logic circuit portion 10 is an NMOS transistor NM1.
One end of the NMOS transistor NM1 is connected to a ground voltage VSS, the other end is connected to a virtual ground V-GND, and a gate is connected to an active signal ACT. The logic circuit portion 10 which comprises the transistors having a low threshold voltage is arranged between a power voltage VDD and the virtual ground V-GND.
When the active signal ACT having a high level is applied in the active state of the MTCMOS circuit, the NMOS transistor NM1 having a high threshold voltage is turned on, and the virtual ground V-GND functions as an actual ground voltage and the resistance of the circuit is reduced.
On the other hand, when the active signal ACT has a low level in the standby state, the NMOS transistor NM1 is turned off, and the virtual ground V-GND is floated so that the ground voltage is blocked, which prevents leakage current from flowing.
That is, the MTCMOS turns on the NMOS transistor NM1 having a high threshold voltage to allow the electric current to flow before the logic circuit portion 10 enters the active state and turns off the NMOS transistor NM1 to block the leakage current when the logic circuit portion 10 enters the standby state.
The conventional semiconductor integrated circuit described above reduces the power consumption in the standby state, but since the MOS transistor having a high threshold voltage is used as a switch for controlling the power, when the NMOS transistor NM1 is turned on, the virtual ground V-GND and the ground voltage VSS are momentarily connected, which creates noise such as ground bounce noise in the supplied electric current, which may inhibit smooth transitional operation.


A system and method for two-way relaying with beamforming are provided. A method for relay operations includes estimating communications channels between a relay and communications devices coupled to the relay, storing data contained in the transmissions, storing data contained in the transmissions, precoding a transmission including a subset of the stored data with a precoding matrix, and transmitting the precoded transmission. The estimating is based on transmissions made by the communications devices in the subset of communications devices, and the precoding matrix is based on estimates of the communications channels.

A relay node (RN), or simply relay, is considered as a tool to improve, e.g., the coverage of a base station, group mobility, temporary network deployment, the cell-edge throughput and/or to provide coverage in new areas. The RN is wirelessly connected to a wireless communications network via a donor cell (also referred to as a donor enhanced Node B (donor eNB or D-eNB)) through network resources donated by the D-eNB.
Generally, there may be several different types of RNs, including an amplify-and-forward RN, wherein a RN receives a transmission and then transmits the received transmission without performing any attempt at demodulating and/or decoding the received transmission. The RN may receive and transmit the transmission over different frequency bands or over different intervals of time to reduce self-interference. An amplify-and-forward RN may amplify and/or apply additional signal processing on the received transmission to help improve communications system performance. Another type of RN is a decode-and-forward RN: such a RN receives a transmission, demodulates and decodes it, re-encodes and re-modulates it (possibly using a different modulation and coding scheme) and then transmits it.
Another concept applicable to RNs, either amplify-and-forward or decode-and-forward, is a two-way RN. In a two-way RN, there is typically no concept of uplink and/or downlink transmission. Instead, there may be multiple transmission phases. For example, there may be a first transmission phase (referred to herein as Multiple Access Phase (MA) wherein communications devices coupled to the two-way RN, such as an eNB and User Equipment (UE), transmit simultaneously, and a second transmission phase (referred to herein as Broadcast Phase (BC), wherein the two-way RN broadcasts signals to the eNB and UEs coupled to the two-way RN.
Information theory indicates that two-way RNs may provide better link efficiency than traditional one-way RNs (e.g., amplify-and-forward RNs and decode-and-forward RNs) that still use the concept of uplink and downlink transmission, thereby improving overall communications system performance.

This patent is subject to a terminal disclaimer.

System and method for two-way relaying with beamforming


This application relates to apparatus and methods for automatically determining and providing, for a given anchor item, a ranking of items. The ranking may include sponsored items. In some examples, a computing device receives a request for items for an anchor item. The computing device determines a relevancy of a plurality of recommended items and sponsored items. The computing device also determines a cost value for the sponsored items. The computing device determines ranking values for the plurality of recommended items and sponsored items based on the relevancy values and the cost values, and ranks the items based on the ranking values. In some examples, the computing device updates the final item ranking based on the application of one or more rules. The computing device transmits the final item ranking to a web server. The web server displays advertisements for the items in ranked order.

At least some websites, such as retailer websites, display item advertisements. The item advertisements may include an image of an item, and a price of the item. For example, a website may display item advertisements, and may further allow a customer to click on the advertisement. The website may also allow the customer to purchase the advertised items. In some examples, websites advertise items sponsored by advertisers. The advertisers may pay a cost to the retailers when a customer clicks on a sponsored item advertisement. In some examples, the displayed advertisements are provided by advertisement recommendation systems.
At least some item advertisements, however, may be for items that are irrelevant to a customer, or for items the customer is not interested in. As a result, a retailer may lose sales of items to a customer. For example, the customer may not buy an advertised item, and may leave the website without having purchased an item that, if shown an advertisement for, the customer would have purchased. In some examples, if a customer perceives an advertisement as irrelevant, the customer may go elsewhere, such as another website, to make a purchase. In addition, if a customer is not interested in an advertisement, such as a sponsored advertisement, the customer may not click on the advertisement. As such, there are opportunities to address item advertisements.

Methods and apparatus for electronically determining item advertisement recommendations


A communication method of MTC devices in the field of communication technologies, including: grouping, by a network side, first MTC devices according to time when the first MTC devices access a network, where the grouping is so performed that MTC devices accessing the network at same time are grouped into different groups, and MTC devices accessing the network at different time are grouped into a same group; and sending, after the first MTC devices access the network, group information to the first MTC devices, so that the first MTC devices receive and/or send data according to the group information. Embodiments of the present invention further provide a related communication apparatus of MTC devices. Embodiments of the present invention realize scattering time for MTC devices to access a network for sending data, thereby avoiding collisions and effectively easing the burden resulted from MTC devices accessing the network concurrently.

A machine type communication (MTC, Machine-Type Communication) application refers to network communications performed by one network element or between multiple network elements without human involvement, that is, a machine to machine (M2M, Machine To Machine) application, such as applications for traffic control and management, factory monitoring, and remote metering. In an M2M application, multiple machine to machine equipment (M2ME, Machine To Machine Equipment) having same M2M application functions form a unit, which is referred to as a group (Group) for short.
In embodiments of the present invention, a user equipment involved in an MTC application is referred to as an MTC device, which may also be referred to as an MTC user, an M2M user, or an M2M device etc. This type of MTC devices are devices of which physical layers, access Stratum, and non-access Stratum are specially simplified for an MTC application. The characteristics of this type of MTC devices include: the interaction traffic of every MTC device may be very small and the interaction may burst; the location of an MTC device may be relatively fixed or seldom changed; and an MTC device implements relatively simple function, where only specific information transmission and interaction needs to be completed; and behavior of the MTC devices under a specific application is consistent. For example, in a smart metering service, all MTC devices upload data to a specific server at specific time.
In an M2M application, there are a large number of MTC devices. Massive MTC devices, if they access a network and compete for network resources, bring a new burden to the existing network, especially in some application scenarios such as a smart metering service. In many countries, a smart grid requires a large number of MTC devices upload metering data frequently at an interval of 5 minutes, and the size of the metering data is relatively small. A large number of MTC devices need to periodically and frequently initiate uplink data transmission, the data size is small, and the sending occasion is relatively fixed, which result in a serious burden on the network.
In the prior art, in order to prevent massive MTC devices from simultaneously accessing a network and causing a serious burden on the network, a solution for grouping on the application layer is proposed. That is, MTC devices are grouped on the application layer according to users' quality of service (QoS, Quality of Service) requirements, uploading destination addresses, or location information, and the like, and the number of MTC devices simultaneously accessing the network is controlled by using group paging, thereby avoiding the cases of massive MTC devices accessing the network simultaneously.
However, the application layer cannot obtain information about a cell in which an MTC device camped; therefore, the grouping on the application layer cannot ensure that users in different cells are balanced.
Therefore, the existing grouping solution based on the application layer cannot ensure that users in different cells are balanced, and the circumstance of concurrent accessing by users in a cell still persists.

Communication method of MTC devices and related apparatus


Provided are a charge/discharge control circuit having a self-test function, which can dispense with a complicated test device, and a battery device. The battery device includes the charge/discharge control circuits each including a pull-up/pull-down circuit provided at a terminal to which a secondary battery is to be connected. When a self-test start signal is input so as to enter a self-test state, a self-test control circuit controls the pull-up/pull-down circuit, to thereby perform a test on a voltage detection circuit provided at the terminal to which the secondary battery is to be connected. When the self-test is finished, a self-test start signal is output to a next-stage charge/discharge control circuit, to thereby perform a test sequentially on the voltage detection circuits of the cascade-connected charge/discharge control circuits.

1. Field of the Invention
The present invention relates to a charge/discharge control circuit for controlling charge/discharge of a secondary battery, and a battery device, and more specifically, to a charge/discharge control circuit having a self-test function for a voltage detection circuit for detecting a voltage of a secondary battery, and a battery device.
2. Description of the Related Art
A battery device is used as a voltage supply source for circuits of various electronic devices. In recent years, the battery device has been required to output a high voltage as a power supply for automobiles and electric tools. Therefore, there is needed a battery device in which a plurality of secondary batteries are connected in series and which includes a plurality of cascade-connected charge/discharge control circuits for controlling charge/discharge of the secondary batteries (see, for example, Japanese Patent Application Laid-open No. 2009-17732).
FIG. 4 illustrates a block diagram of a conventional battery device including series-connected secondary batteries and cascade-connected charge/discharge control circuits for controlling the secondary batteries.
The conventional battery device includes a plurality of cascade-connected charge/discharge control circuits 401a to 401n, a plurality of series-connected secondary batteries 402a to 402n, a charge control FET 403, a discharge control FET 404, resistors 405a to 405n each connecting a charge control terminal CO and a charge control signal input terminal CTLC, and resistors 406a to 406n each connecting a discharge control terminal DO and a discharge control signal input terminal CTLD.
In the conventional battery device, the charge/discharge control circuits 401a to 401n are connected to each other via the charge control terminal CO and the charge control signal input terminal CTLC and via the discharge control terminal DO and the discharge control signal input terminal CTLD, thus enabling reciprocal communication. In this manner, the plurality of charge/discharge control circuits can be connected in series, and hence a necessary number of series-connected secondary batteries for outputting a high voltage can be controlled.
In the above-mentioned battery device, however, the number of voltage detection circuits increases as the number of secondary batteries increases. Therefore, there has been a drawback that a device for testing each voltage detection circuit becomes complicated in the state of being assembled as a battery device.

Charge/discharge control circuit and battery device


The present invention concerns a process for detecting the spatial structure of a three-dimensional surface by projection of a pattern on to the surface along a projection direction which defines a first axis, and by pixel-wise detection of at least one region of the pattern projected on to the surface, by means of one or more sensors in a viewing direction of the sensor or sensors, which defines a second axis, wherein the first and the second axes (or a straight line parallel to the second axis) intersect at an angle different from 0xc2x0 so that the first and the second axes (or the straight line parallel thereto) define a triangulation plane, wherein the pattern is defined at least upon projection into a plane perpendicularly to the first axis by a varying physical parameter which can be detected by the sensor (sensors), and wherein the pattern is such that the difference in the physically measurable parameter, measured between predeterminable image pixels or pixel groups, along a predeterminable pixel row which is preferably parallel to the triangulation plane, assumes at least two different values. In order to provide a process for detecting the spatial structure of a three-dimensional surface, which is substantially independent of different inclinations with respect to a normal to the triangulation plane and also independent of the other surface properties which independently of the spatial extent of the surface can influence the physical parameter to be measured, in accordance with the invention it is proposed that, for the purposes of evaluation of the imaged pattern structure only changes in the physical parameter between the predetermined pixels or predetermined pixel groups of one or more pixel rows which are preferably parallel to the triangulation plane are detected and converted into spatial co-ordinates of the surface.

The present invention concerns a process for detecting the spatial structure of a three-dimensional surface by projection of a pattern on to the surface along a projection direction which defines a first axis, and by pixel-wise detection of at least one region of the pattern projected on to the surface, by means of one or more sensors in a viewing direction of the sensor or sensors, which defines a second axis, wherein the first and the second axes (or a straight line parallel to the second axis) intersect at an angle different from 0xc2x0 so that the first and the second axes (or the straight line parallel thereto) define a triangulation plane, wherein the pattern is defined at least upon projection into a plane perpendicularly to the first axis by a varying physical parameter which can be detected by the sensor (sensors), and wherein the pattern is such that the difference in the physically measurable parameter, measured between predeterminable image pixels or pixel groups, along a predeterminable pixel row which is preferably parallel to the triangulation plane, assumes at least two different values.
Such a process is known for example from U.S. Pat. No. 5 615 003.
The pattern which is specifically disclosed in that patent specification has a very high degree of similarity to bar codes as have already long been in use for example in the retail trade for identifying products and prices, wherein the sequence of lines or bars of different thicknesses defines a series of binary numbers which is clearly associated for example with a product and its price. For the purposes of detecting the spatial structure of a three-dimensional surface however the bar widths and the spacings between bars of that kind are distorted according to the respective specific structure of the surface involved and the known process is distinguished by devices and measures which, in spite of the distortion effect, permit identification of given regions of the bar pattern so that the first distorted pattern can be adapted to the projected pattern, wherein the parameters of such adaptation afford the structure of the surface which produces the above-mentioned distortion effects.
Another similar process which uses an encoded pattern is known from German patent application No 196 38 727, in which respect that process is not limited to encoding of a pattern only in one direction but is composed of individual distinguishable pattern elements each of similar respective structure and size, wherein the pattern elements also differ alternately from each other in mutually perpendicular directions. An encoded pattern is characterised in that at least portions of the pattern which are of a given minimum size are not repeated at any point in the entire pattern surface. Even if that requirement is not satisfied in the strict sense, this means that repetitions of pattern structures can certainly also occur as long as those repetitions are only sufficiently far apart on the pattern surface that, upon evaluation of an imaged pattern structure, there is practically no possibility of confusion between two randomly identical regions of the pattern.
All previously known processes however basically operate on the principle of pattern recognition, that is to say imaging, implemented by calculation, of the flat pattern on to the distorted pattern of which the image is formed from the viewing direction on a non-flat surface. Problems always occur in that respect however when the information content of the projected pattern element can vary in the imaging procedure, depending on the spatial extent or other configuration of the surface. If for example the physical parameter which is to be measured and which varies and by which the pattern structure is defined includes the color of the pattern or of individual pattern elements, then interpretation of color information in the projected pattern can be interfered with or even made impossible, by virtue of the surface being colored in nature. When using different line widths for a pattern the line width in the image depends not only on inclinations of the surface in a direction parallel to the triangulation plane but also inclinations of the object or the surface with respect to a line normal to the triangulation plane. This means that, upon the projection of lines of different width, by virtue of the spatial extent of the surface being of a disadvantageous configuration, for example a narrow line in the image is represented in a width which is of the order of magnitude of the image of a line which is wide in the projected pattern, and accordingly can result in an incorrect item of information in the evaluation procedure.
In addition the evaluation of encoded patterns involving a differing geometrical configuration of pattern elements imposes very high demands on the evaluating data processing procedure as the geometry of the projected pattern elements can recur in severely deformed condition in the image.
In comparison with the above-depicted state of the art, the object of the present invention is to provide a process for detecting the spatial structure of a three-dimensional surface, which is substantially independent of different inclinations with respect to a line normal to the triangulation plane and also independent of the other surface properties which independently of the spatial extent of the surface can influence the physical parameter to be measured.
That object is attained in that, for the purposes of evaluation of the imaged pattern structure only changes in the physical parameter between the predetermined pixels or predetermined pixel groups of one or more pixel rows which are preferably parallel to the triangulation plane are detected and converted into spatial co-ordinates of the surface.
In that respect the changes in the physical parameter are detected at least in the component thereof parallel to the triangulation plane and converted into spatial co-ordinates.
The fact that only changes in the physical measurement parameter of the pattern, which is to be detected, are detected, preferably between adjacent pixels or adjacent pixel groups, means that specific surface properties are so-to-speak eliminated as the surface regions which are imaged or reproduced in particular by adjacent pixels generally have the same properties. The inclination of the surface with respect to a line normal to the triangulation plane also has no effect on detection and possibly identification of the pattern structure as it is not the pattern that is detected in respect of its specific dimensions and shapes and compared to the original projection pattern and adapted thereto, but only the values of the physical parameter which is of interest, being measured in predetermined preferably adjacent pixels or pixel groups, are compared to each other, more specifically by forming the difference thereof. In that case the specifically imaged pattern is then produced simply on the basis of characteristic changes in the physical parameter from given pixels to other predetermined pixels, in particular their adjacent pixels, or from given pixel groups to other predetermined and preferably adjacent pixel groups, or along another suitable sequence of pixels which are to be compared together.
As in accordance with the invention the change in the values, which are detected or reproduced in the image pixels, of the specifically evaluated physical parameter, can assume at least two different values, those differing values in respect of the change, which can occur from one pixel to another or from one pixel group to another, make it possible to define and recognise structures without the specific properties of the surface playing a part in that respect.
Desirably the pattern is so oriented that, in a predetermined measurement direction along which pixels or pixel groups are compared to each other, there are change values which are at a maximum in respect of amount at least in part while the other change values which occur are comparatively small in respect of amount or are of the value zero.
In a preferred variant of the present invention a respective plurality of pixels, which are disposed in mutually superposed relationship in a column, of pixel rows which are adjacent in the column direction, are assembled to form a pixel group, and the changes in the physical parameter are evaluated between respective ones of such pixel groups which are adjacent in the line direction. It would however also be possible to compare groups of adjacent pixels which each comprise a plurality of pixels disposed in juxtaposed relationship in the line direction. In a variant of that configuration, the pixels which are assembled to form a respective group, from a plurality of lines, can also be displaced relative to each other, that is to say they can originate from different columns which however are preferably in close proximity with each other.
It will be appreciated moreover that the xe2x80x98linesxe2x80x99 and xe2x80x98columnsxe2x80x99 of pixels of an image sensor or image, as those terms are used in the context of the present application, do not necessarily have to extend along straight lines which intersect in mutually perpendicular relationship.
A particularly preferred embodiment of the invention is one in which the pattern is in the form of an encoded pattern, in which respect that requirement is not to be interpreted in a strict sense.
Desirably the pattern structures are relatively small in comparison with the overall extent of the pattern and also the minimum size of the surface regions which have a pattern structure which is not repeated should be as small as possible in comparison with the overall surface area of the pattern as in that way the respective clearly identifiable pattern structures can be suitably accurately located. Pattern repetitions however may also occur at a sufficiently large spacing in many situations of use.
A further preferred embodiment of the invention is one in which the pattern is formed by individual pattern elements which each occupy approximately equal areas in a plane perpendicular to the projection direction. The equal-size surface regions of individual elements facilitate the evaluation procedure if for example transitions from one pattern element to another are particularly pronounced and are thus clearly detected or if given regions of individual pattern elements have substantial changes in the physical parameter to be measured, in the line direction of the image pixels, and thus serve as a pattern recognition point which can be well located.
In that respect a particularly preferred embodiment of the present invention is one in which there are at least two types of pattern elements, in the region of which the physical parameter is respectively of a constant level or a constant value, wherein that value of the physical parameter in question respectively clearly measurably differs between the two types of pattern elements. In that way it is very easily possible to establish the transitions from a pattern element of the first type to a pattern element of the second type and vice-versa. The differences which are formed between adjacent pixels or pixel groups assume the value zero, in regard to pattern elements of that kind, if the pixels or pixel groups which are to be compared are within the same pattern element and assume the clearly measurable distinguishing value as between the two types of pattern elements when the one pixel or the one pixel group forms the image of one of the two pattern elements while the adjacent pixel or the adjacent pixel group does so for the respective other pattern element. In that way, respective clearly measurable changes occur at the transitions from one pattern element to another and in that respect also measurement points for identification of the pattern structure and the position of such transitions. That applies even if the surface properties of the article being investigated change considerably in the projected pattern region so that the same transitions between identical pattern elements but at different locations on the surface show clearly different differences and are nonetheless recognised as similar transitions because the difference in both cases always still clearly differs from other difference values which occur (for example the difference value zero).
In addition a preferred embodiment of the present invention is one in which there is provided at least one type and at least one further type respectively of a pattern element, in the surface region of which the value of the physical parameter to be detected continuously changes in a predetermined direction. With a pattern element of that kind, the changes in the physical parameter between adjacent pixels or pixel groups are generally relatively small, while by virtue of the continuous change in the physical parameter in the region or in a sub-region of that pattern element those change values are respectively equal between all adjacent pixels or pixel groups. It is only in the event of a transition to another pattern element or if a region of the pattern element is reached in which the physical parameter no longer changes continuously in accordance with the previously defined rule that a greater difference in respect of the physical parameter can occur between adjacent pixels or pixel groups, which difference is in turn characteristic of a given region of the pattern.
In that respect a particularly preferred embodiment of the present invention is one in which there are provided two types of such pattern elements with a continuous change in the physical parameter within at least a sub-region of those pattern elements, wherein those two types differ from each other in that, in the predetermined direction, with respect to the progressive comparisons of adjacent pixels or pixel groups, the sign of the change in the physical measurement parameter is precisely reversed. In the surface region in question of the pattern element of a first type therefore the value of the physical parameter which is of interest increases for example from one pixel to another by the same value in each case, while, in regard to the other type of pattern element, that value decreases from one pixel to another by a corresponding amount in each case.
It will be appreciated that, in the transition to an adjacent pattern element, considerably greater differences can occur in the values of the physical parameter between adjacent pixels or pixel groups.
The pattern elements with a change in the physical parameter, which is more or less continuous at least in a region-wise manner, make it possible, in regard to the transition to adjacent pixels or pixel groups, to obtain at the transition to a further pattern element a clear jump in the physical parameter in the same direction in each case, while in regard to the previously defined types of pattern elements within whose surface region the physical measurement parameter is of a constant respective value, the sign of the change in regard to the transition to the next pattern element, if there is any change at all, is clearly established by the value of the physical parameter in the preceding pattern element.
In that respect, the change may admittedly assume two different values which respectively differ from each other by their sign, depending on from which of the two types of pattern elements the transition to the respective other type occurred, but after a previously implemented positive change in the value of the physical measurement parameter, in regard to pattern elements of that kind, at the transition to the next pattern element there can be only a negative or no change, and vice-versa. In contrast, with the types of pattern elements which have a change which is continuous in a region-wise manner but which is relatively small between respectively adjacent pixels within those ranges and which therefore can be ignored, the value of the physical parameter is continuously repeatedly restored to a value which has already been achieved previously and which then, at the transition to the next pattern element or also within the given pattern element, is abruptly changed, in which respect that abrupt change is detected as a characteristic structure element of the pattern and involves a given direction or a given sign, wherein changes involving the same sign or for example opposite signs can then readily follow, depending on which respective type of pattern element is the next following and the next but one.
It will be appreciated that, in regard to various types of pattern elements of that kind, it is desirable if those types are arranged in an encoded distribution on the surface of the projected pattern, in which respect the notion of encoded distribution has already been discussed above. A preferred example of encoded distribution is simply random distribution of the various types of pattern elements on the entire projection surface. It is particularly preferred in that respect if all the above-defined types of pattern elements, that is to say both those within whose surface region the physical parameter is of a respective constant level and also those which involve a surface region within which the physical parameter respectively continuously changes, are used for the production of such a pattern.
Desirably the surface region of a pattern element in the imaging plane should correspond at a maximum to a number of mxc3x97n pixels, wherein m and n are each greater than 2, but at the same time m is markedly smaller than M and n is markedly smaller than N, when Mxc3x97N is the total number of the detected or imaged image pixels.
In that respect it is further desirable if, for pattern encoding and identification of pattern elements or characteristic regions of the pattern, the procedure only involves evaluating changes which are greater than the changes between adjacent pixel groups within those types of pattern elements which at least in part have a continuous change in the physical parameter. It has already been mentioned hereinbefore that the small changes in the physical parameter, which occur along that region between adjacent pixels or pixel groups, in comparison with the relatively great changes which can occur between adjacent pattern elements, can be ignored.
Furthermore a preferred embodiment of the invention is one in which two measurement procedures are implemented with triangulation planes which are angled relative to each other, wherein in the two measurement procedures the triangulation planes are preferably angled relative to each other through about 90xc2x0.
Evaluation of the image data is substantially facilitated if, upon projection of the pattern on to a reference plane, imaging of the lines of the pattern on the image converter is effected substantially parallel to the lines of the image converter. The term reference plane is used herein to denote that plane which is formed in the following manner: (i) an auxiliary straight line is defined, which extends parallel to the optical axis of the projection unit and which intersects the optical axis of the receiving or recording unit, wherein the plane defined by that straight line and the optical axis of the recording unit, in accordance with the invention, is identified as the xe2x80x98triangulation planexe2x80x99; (ii) the bisector of the optical axis of the recording unit and the auxiliary straight line is established as a normal vector of the reference plane (the reference plane is thus perpendicular to the triangulation plane); (iii) the reference plane is so disposed that the spacing between the points at which the two optical axes pass through the reference plane is at a minimum. That definition takes account of the fact that the two optical axes, in a real apparatus, will not exactly intersect, even if that is structurally intended. If now the lines of the pattern extend parallel to the triangulation plane, the image of those lines on the image converter will extend parallel to the lines of the image converter. Upon projection of that pattern on to a surface which does not correspond to the reference plane, the deviation from parallelism will only be small of second order.
It is also advantageous if the pattern is such and projection of that pattern is effected in such a way that, upon projection of the pattern on to a flat surface which is perpendicular to the triangulation plane, with a unitary surface configuration, the result is a structure which is organised in lines, those lines are parallel to the triangulation plane and the characteristic above-specified measurements of the change occur along those lines.
It is further desirable if (i) the pattern is projected using a beam source and suitable optical means on to the object to be measured; (ii) the pattern to be projected is of a flat or a real configuration, with substantially mutually perpendicular lines and columns involving a respectively uniform pitch division and arranged in the resulting pitch division are different geometrical elements which are optically transparent, non-transparent or partially transparent; (iii) the transparency of the partially transparent elements both increases in the line direction steadily from non-transparent to transparent or steadily decreases from transparent to non-transparent; (iv) the geometrical elements are arranged in the pattern to be projected, in such a way that in the pitch division of the columns, as between the geometrical elements, there is a change from transparent to non-transparent or from non-transparent to transparent, in such a way that the different sign, which is distributed over the pattern, of the size of the change in the pitch division grid or raster of the columns, on the basis of image recording of the projected pattern of interrelated surface segments of the object, which are delimited in any desired fashion, of sufficient size, makes it possible to determine a clear association with the respective projected part of the pattern; (v) the radiation reflected by the object, at least in parts, is projected by suitable optical means on to a flat CCD image converter whose radiation-sensitive elements are also organised in lines and columns, and is converted thereby into an electrical signal and contained in that electrical signal is the information content of the components, reflected by the object, of the projected pattern, at least in parts thereof; (vi) the directions of the optical axes for projection of the pattern and for formation of the image of the object on the image converter are different from each other; (vii) the lines of the pattern to be projected are oriented parallel to the plane which is formed by the optical axes for projection and for imaging of the reflected radiation on to the image converter; (viii) the electrical signals of the image converter are converted into discrete data and passed to a unit for processing and storage of data; (ix) the data of the radiation-sensitive elements of the image converter are evaluated in lines which are parallel to the triangulation plane, in regard to the size of the change in the intensity of radiation; (x) the resulting flanks upon substantially sharp changes, in accordance with the respective sign of the size of the change, are associated with the binary information elements zero and one; and (xi) the resulting binary sequences serve to distinguish parts of the pattern from other parts of the pattern.
If for example a pattern (i) comprises checkered black and white elements, (ii) the pattern is projected using visible light and suitable optical means on to a white object of any three-dimensional extent, (iii) an image is produced from the object using suitable optical means on a flat image converter, (iv) the projection direction is different from the receiving or recording direction, (v) the signal of the image converter is digitised, put into intermediate store in an electronic memory or storage device and fed to a data processing unit, (vi) the image converter is organised in mutually perpendicular lines and columns, (vii) the pattern is positioned in the projection device in such a way that the lines of the checkered pattern extend in the direction of the lines of the image converter, (viii) both the projection device and also the receiving or recording device are of such a configuration and position that the triangulation angle extends to a recording of the image of the checkered pattern in the column direction of the image converter (in other words: the plane defined by the triangulation angle extends in the direction of the columns of the projected pattern and also the image converter), (ix) the configuration of the pattern elements is greater than the resolution of the image converter, then values can be found in the image store, which represent the line information of the image converter and which correspond to the brightness values of the white and black elements of the checkered pattern. If (x) those items of information are evaluated along the corresponding line of the image converter, the result is sudden changes in the items of brightness information corresponding to the grid or raster of the projected pattern. The deviations in the dimensional relationships of the sudden changes in brightness along an image line with respect to the corresponding projected pattern represent the spatial extent of the object, with the beam path being known. If (xi) the object in the region being viewed is sufficiently steady and is optically accessible both from the projection direction and also from the receiving or recording direction, then the sequence of line information alternately involves sudden changes in brightness from light to dark and from dark to light. If (xii) the items of brightness information are represented by the digitisation procedure as digital values with an association proportional to the brightness values and if (xiii) the change in brightness along the designated column of the image converter is calculated from the difference between the respective brightness value at a given location and the brightness information of the image location which follows in the direction of the line, that alternately gives positive and negative values which correspond to the size of the change in brightness. If that discrete sequence of values is interpreted as a brightness signal, it is then possible to refer to positive or negative flanks or edges of that signal.
In the preferred embodiment of the invention the image data which represent the projected pattern with the stated statistical distribution of the pattern elements and thus the corresponding encoding are checked in respect of the individual pattern elements to ascertain whether the information content of the individual element can be unambiguously recognised on the basis of the recording. If that unambiguity is not guaranteed then the corresponding pattern element is to be excluded from further data processing. The pattern elements which are to be unambiguously recognised, by signal edge recognition and evaluation, form the basis thereafter for generation of the information elements, and adjacent unambiguously recognised information elements are attributed to so-called clusters. A cluster in the sense of the present invention is a group of adjacent information elements. The comparison of the decoded items of information of the recorded pattern which is projected on to the object, with the pattern content to be projected, makes it possible to check the plausibility of the arrangement of the decoded items of information. If deviations occur in that situation, the deviating information element is falsified and separated out. If the corresponding information element is at the edge of the cluster, a suitably corrected delimitation is produced. If the information element is in the middle of a cluster, then under some circumstances the cluster is to be divided and the unambiguous association of the two resulting cluster portions is to be re-checked. If the smaller clusters cannot be unambiguously associated, then all corresponding elements are to be falsified and separated out. Accordingly, represented in the clusters are interrelated surface segments whose pattern elements of the projected pattern, by virtue of the information content available in the cluster in respect of the mutually adjoining pattern elements, can be unambiguously associated with the corresponding pattern element in the pattern to be projected. On the basis of the position for example of the center of gravity or the resulting edges or flanks in the image, in comparison with the arrangement in the pattern to be projected, it is possible by means of triangulation to calculate three-dimensional coordinates as support points of the surface of the object. In accordance with the invention three respective adjacent support points which are not disposed in a row can advantageously be defined as a triangle and thus also as a triangular surface so that there is no need for surface retrieval from a cloud of points, as is required in the case of other processes. As a result of that analysis and calculation of the items of image information from an individual image digital images of interrelated surface segments of the object, which are unambiguously determined in respect of their configuration, are available. These segments which are possibly not interrelated are however known in terms of their three-dimensional position and orientation relative to each other.

Evaluation of projection pattern for transitions in pattern to determine spatial structure of 3D surfaces