In a semiconductor integrated circuit provided with a circuit for testing an input buffer threshold voltage, an output node of a first logic gate having its output logic value determined by an output signal of an input buffer, and an output node of a second logic gate having its output logic value determined by a condition setting signal from an external source, are connected to a common signal line. When a standardized voltage for discriminating the threshold voltage is applied to the input buffer, if the input buffer malfunctions, the output signal of the first logic gate collides with the output signal of the second logic gate on the common signal line, so that a power supply current greatly increases.

1. Field of the Invention
The present invention relates to a digital semiconductor integrated circuit of a CMOS (complementary metal oxide semiconductor field effect transistor) structure, and more specifically to a semiconductor integrated circuit provided with a test circuit for checking whether or not a threshold voltage of an input buffer is within a predetermined range.
2. Description of Related Art
Ordinarily, a semiconductor integrated circuit (called an "LSI" hereinafter) is so configured that a plurality of digital data signals and control signals are simultaneously received, and a predetermined signal processing is performed by an internal logic circuit (called an "internal circuit" simply hereinafter). In this case, before a signal supplied to each of external terminals for receiving a signal (input terminals) is applied to the internal circuit, each input signal is current-amplified by an input buffer to have a sufficient driving power, and thereafter, the input signal is actually applied to the internal circuit. Therefore, in order to cause the LSI to execute an expected signal processing, each input buffer is required to transfer a logic value of the input signal to the internal circuit without error. As one requirement for fulfilling this request, it is very important that a threshold voltage of the input buffer is in a predetermined range.
In a conventional test for the threshold of the input buffer in the LSI, a test signal is applied to an input terminal (an input point of the input buffer) so as to perform a function test of the LSI. If the LSI operates normally, namely, if an expected output signal is obtained from an external output terminal of the LSI, it is discriminated that the threshold voltage of the input buffer meets with the standard value. In this case, however, depending upon a combination of input signals applied to a plurality of input buffers, it is in some cases that a signal applied to an input buffer to be tested is used only for the signal processing in the internal circuit, and the change of the input signal is not externally outputted as any change of a signal outputted from an output terminal. In this case, the input threshold of the input buffer in question cannot be tested. Therefore, in order to surely test the threshold of the input buffer in question, it was necessary to repeat the function test while variously changing a combination of the input signals applied to a plurality of input terminals. Recently, with a remarkable advance of the integration density and the multi-function of the LSI, the number of the input terminals has increased, and therefore, a function test pattern for testing the input threshold voltage of all input buffers becomes very complicated and large and long. Therefore, the number of steps for preparing and actually performing the function test pattern has increased, and this increased number of steps has become a large problem.
Under this circumstance, the prior art has proposed various methods and apparatuses for efficiently performing the input threshold voltage. Japanese Patent Application Pre-Examination Publication JP-A-3-214079 proposes one approach (called a "first prior art" hereinafter). Referring to FIG. 1A, there is shown a block diagram of the input threshold voltage measuring apparatus shown in JP-A-3-214079. FIG. 1B illustrates an operation waveform at the time of the measurement.
In the input threshold voltage measuring apparatus shown in FIG. 1A, a sweep voltage generating circuit 801 generates an analog sweep voltage waveform "s" shown in an upper part of FIG. 1B. This voltage waveform "s" is a truncated conical shape having two ramp voltages, which, with lapse of a time, firstly elevates constantly at a predetermined rate, and then, becomes flat, and finally, drops constantly at a predetermined rate. This sweep voltage generating circuit 801 is constituted of a ROM 802, a D/A converter 803, and a control circuit 804 accessing the ROM 802.
In the ROM 802, digital data to be converted into an analog voltage at each moment in order to generate the analog sweep voltage waveform "s" is stored in a sequential address in order.
The control circuit 804 is composed of a clock generator and a program counter (both not shown) for generating an address used to access the ROM 802, so that the ROM 802 is accessed in accordance with the address generated. The access address is sequentially incremented in response to the clock. Thus, the digital data to be converted into an analog value is read out from respective addresses of the ROM, with lapse of time in units of a clock period, so that the read-out digital data is supplied to the D/A converter 803. As a result, the analog sweep voltage waveform "s" is outputted from the D/A converter 803.
In addition, if the control circuit 804 receives a sweep stop signal from a peak current detecting circuit 808 explained hereinafter, the control circuit stops the increment of the address counter in response to the clock generated by the clock generator. In this condition, the address in a stopped position of the ROM 802 is repeatedly continuously accessed in response to the clock, so that the digital data at the stopped address is continuously supplied to the D/A converter 803. Thus, the analog voltage generated at the moment the sweep stop signal is received, continues to be outputted from the sweep voltage generating circuit 801.
The analog voltage thus generated by the sweep voltage generating circuit 801 is applied through a switch circuit 805 to one of input terminals IN of an integrated circuit 806, namely, a device under test (abbreviated "DUT" hereinafter). The switch circuit 805 is a change-over switch controlled by a switch change signal from the peak current detecting circuit 808, so as to switch the output voltage of the sweep voltage generating circuit 801 from the DUT 806 to a voltage measuring circuit 807.
The peak current detecting circuit 808 is a current level detecting circuit composed of a comparator, and operates to generate a detection signal when a current IDD flowing from a power supply circuit 809 to a power supply terminal VDD of the DUT 806 exceeds a predetermined reference level ITH (See FIG. 1B). This detection signal is supplied as the sweep stop signal D to the sweep voltage generating circuit 801, and also as the switch change signal to the switch circuit 805. In addition, the detection signal D is supplied as a peak detection signal to a measurement control circuit 810.
The measurement control circuit 810 supplies a start signal to the sweep voltage generating circuit 801, and receives and processes a measured voltage value obtained in the voltage measuring circuit 807. Thus, it is a control circuit for the whole of the input threshold voltage measuring apparatus.
Now, operation of the first prior art having the above mentioned construction will be described with reference to FIG. 1B.
First, the measurement control circuit 810 outputs the start signal to the sweep voltage generating circuit 801. In response to the start signal, the sweep voltage generating circuit 801 generates the analog sweep voltage waveform "s" shown in FIG. 1B, so that the input voltage Vin of the DUT 806 linearly elevates with a lapse of time. When the analog voltage "s" exceeds an input threshold voltage of the input buffer of the DUT 806, the internal circuit receiving this input signal is put in an operating condition. At this time, depending upon the operation of the internal circuit, a transient current flows as an operating current for example in a CMOSIC. This operation current IDD is measured as a characteristics current curve "p" having a peak shown in FIG. 1B.
This current value IDD is monitored by the peak current detecting circuit 808. The moment the current value IDD exceeds the reference current value ITH, corresponds to the moment an inverter (constituting the input buffer in the DUT 806) flips. Therefore, this means that the voltage waveform "s" exceeds the input threshold voltage. In the shown example, the peak current detecting circuit 808 generates the peak current detecting signal at a time T901. The sweep voltage generating circuit 801 receiving the detecting signal as the sweep stop signal D, stops the sweep operation, and at the same time, the switch circuit 805 is switched over so that the analog voltage generated by the sweep voltage generating circuit 801 at that time is measured through the switch circuit 805 by the voltage measuring circuit 807. The result of the measurement is fetched into the measurement control circuit 810 receiving the peak the detecting signal D.
At this time, the measurement control circuit 810 supplies a control signal to the sweep voltage generating circuit 801 so as to cancel the clock stop signal. As a result, after the sweep voltage has become a constant value, the sweep voltage starts to drop.
In the course of the drop of the sweep voltage, when the value of the voltage waveform "s" becomes lower than the input threshold voltage of the DUT 806, a peak current appears again in the current IDD. With this, it is possible to measure a low level VIL of the input threshold voltage.
Incidentally, this first prior art is so configured that the reference value ITH used as the comparison reference in the peak current detecting circuit 808 can be adjusted externally so as to be changed in accordance with the characteristics of the DUT 806.
Next, another example of the conventional input threshold voltage testing method disclosed in Japanese Patent Application Pre-Examination Publication JP-A-4-194667 (called a "second prior art" hereinafter).will be described with reference to FIG. 2A.
Referring to FIG. 2A, an input circuit 1021 of a Bi-CMOS LSI is supplied with a supply voltage VDD through an ammeter 1023, and an input voltage Vin is applied to an input terminal 1020 from a DC voltage supply 1022.
Here, when the input voltage Vin is for example at a low level, a pnp transistor 1006 is in an on condition, and therefore, a p-channel MOS (pMOS) transistor 1007 is also in an on condition and an n-channel MOS (nMOS) transistor 1008 is in an off condition, so that an output voltage at a terminal 1024 is at a high level. Thereafter, if the input voltage Vin is caused to gradually elevate as shown in FIG. 2B, the pnp transistor 1006 is brought to an off condition from the on condition. At this time, before the pMOS transistor 1006 is completely turned off, the nMOS transistor 1008 is turned on, so that a passthrough current flows from the voltage supply terminal VDD to a ground terminal GND as shown in FIG. 2C. Thereafter, the pMOS transistor 1007 is turned off, and the nMOS transistor 1008 is turn on, so that the output voltage on the terminal 1024 is brought to a low level.
Thus, the input voltage Vin when the ammeter 1023 detects the above mentioned passthrough current, corresponds to the threshold voltage Vth. Accordingly, the input threshold voltage is measured by detecting the passthrough current which flows in the input circuit operation when the input voltage Vin is gradually changed.
Now, a third example of the conventional input threshold voltage testing method will be described on the basis of the disclosure of in Japanese Utility Model Application Pre-Examination Publication JP-UA-2-007580 (called a "third prior art" hereinafter).
Referring to FIG. 3A, there is shown an apparatus for discriminating a non-defective/defective of a DUT incorporating a plurality of electronic circuits therein, on the basis of an input threshold voltage. This apparatus includes an input voltage generator 1214 for supplying an input voltage into each of input circuits 1212 of the DUT 1210, a passthrough current detecting circuit 1215 for detecting a passthrough current which instantaneously flows in the input circuits when an output level of each input circuit 1212 changes in response to the input voltage, and a threshold voltage discriminator 1222 for discriminating on the basis of the passthrough current, whether or not the threshold voltage of the input voltage is in a standardized range.
As shown in FIG. 3B, the input voltage generator 1214 receives a test start signal 1213 and gradually elevates the input voltage Vin from a low level to a high level. In this process, when the input voltage Vin exceeds the input threshold of the input circuit 1212 internally provided in the DUT 1210, the output voltage Vout of the input circuit 1212 is brought from a low level to a high level. At this time, a passthrough current as mentioned hereinbefore is detected by the passthrough current detecting circuit 1215, which outputs a passthrough current detecting signal 1211 to the threshold voltage discriminator 1222. This threshold voltage discriminator 1222 receives the passthrough current detecting signal 1211, and discriminates whether or not the threshold voltage of the input voltage is in the standardized range. Namely, the threshold voltage discriminator 1222 outputs the result of the discrimination. Thus, the input threshold voltage test is performed.
All of the first, second and third prior arts explained above are so configured to measure the input threshold voltage of the input circuit by detecting the increase of the power supply current (generation of the passthrough current in the input circuit) when the input voltage exceeds the threshold voltage of the input buffer and the circuit including the input buffer changes its condition. Differently from the above mentioned prior arts, another approach is to set, a mode generally called a test mode, different from a mode in which inherent signal processing is performed in which a threshold voltage of the input buffer is tested and measured by using an input voltage testing circuit provided in the LSI. In the following, some of this type approach will be described.
Now, as a fourth example of the conventional input threshold voltage testing approach, a construction of the LSI disclosed in Japanese Patent Application Pre-Examination Publication JP-A-4-359175 (called a "fourth prior art" hereinafter).will be described with reference to FIGS. 4A and 4B.
Referring to FIG. 4A, there is shown a block diagram of the LSI incorporating therein a circuit for measuring the input threshold voltage of the input buffer and for outputting the result of the measurement. As shown in FIG. 4A, an input signal applied to an input terminal 1408 is supplied to an input buffer 1402. An output signal of the input buffer 1402 is supplied to an internal circuit 1401 where various electric circuits are caused to operate. At the same time, the output signal of the input buffer 1402 is supplied to a selector 1404 as one signal to be selected.
The selector 1404 receives, as another signal to be selected, an output signal 1406 from the internal circuit 1401, and is controlled by a selector selection signal 1407 generated in the internal circuit 1401, so as to select and output one of the two "signals to be selected" supplied to the selector 1404. The selected signal is supplied to an output buffer 1403, which in turn outputs the supplied signal through an output terminal 1409 to an external of the LSI.
When the input threshold value is tested, the selector selection signal 1407 controls the selector 1404 to select the signal 1405 to be selected and to output it to the output buffer 1403. In a normal signal processing operation, the selector selection signal 1407 controls the selector 1404 to select the signal 1406 to be selected so that information is transferred from the internal circuit 1401 to the output buffer 1403.
When the input threshold voltage test is executed, a standardized voltage VIH of a high level input threshold voltage is applied to the input terminal 1408, as shown in an upper column of FIG. 4B. This input signal causes the input buffer 1402 to operate, so that the output signal 1405 of the input buffer is selected by the selector 1404 to be transferred to the output buffer 1403. If the input threshold voltage of the input buffer 1402 meets with the above mentioned standardized voltage VIH of the high level input threshold voltage, an output signal in the same phase as that of the input signal appears on the output terminal 1409, as shown in a middle column of FIG. 4B. However, when the input threshold voltage of the input buffer 1402 does not meet with the standardized voltage, namely, when the input buffer 1402 malfunctions, an output signal in a phase opposite to that of the input signal appears on the output terminal 1409, as shown in a lower column of FIG. 4B. In this manner, whether or not the input threshold voltage fulfills the standard, can be discriminated on the basis of whether the input signal and the output signal are in the same phase or in the opposite phase.
Next, as a fifth example of the conventional input threshold voltage testing approach, a construction of the LSI disclosed in Japanese Patent Application Pre-Examination Publication JP-A-2-291164 (called a "fifth prior art" hereinafter).will be described with reference to FIGS. 5A and 5B.
Referring to FIG. 5A, an input node of an input buffer 1604 is connected to an input terminal 1601, and an input node of input buffers 1605 and 1606 are connected to input terminals 1602 and 1603, respectively.
An output node of the input buffer 1604 is connected to an internal circuit 1610 and one input "A" of a two-input NAND gate 1607, which in turn has the other input "B" connected to a voltage supply terminal VDD. An output node of the input buffer 1605 is connected to the internal circuit 1610 and one input "A" of another two-input NAND gate 1608, which in turn has the other input "B" connected to an output of the NAND gate 1607. An output node of the input buffer 1606 is connected to the internal circuit 1610 and one input "A" of a further two-input NAND gate 1609, which in turn has the other input "B" connected to an output of the NAND gate 1608. An output of the NAND gate 1609 is connected to an external output terminal 1617.
Now, an input threshold voltage testing method in this LSI will be described with reference to a timing chart shown in FIG. 5B. The input threshold of the input buffer 1604 is tested during a period T171 in FIG. 5B. During this period, the input terminals 1602 and 1603 are fixed to a high level (supply voltage), and the input level of the input terminal 1601 is brought to a standardized voltage VIH of a high level threshold voltage. At this time, if the input buffer 1604 operates normally, the output signal 1611 of the input buffer 1604 becomes a high level, and therefore, the output of the NAND gate 1607 becomes a low level. Here, since the input terminals 1602 and 1603 are at the high level, both the output signal 1612 of the input buffer 1605 and the output signal 1613 of the input buffer 1606 are at the high level. Therefore, the NAND gates 1607, 1608 and 1609 become equivalent to an inverter chain receiving the signal 1611 as an input signal and for outputting a signal 1616 as an output signal.
In the shown example, since the three input terminals are provided, the output signal 1616 is in a phase opposite to that of the input terminal 1601, and the output terminal 1617 outputs a low level signal as shown in a fourth row of FIG. 5B. Similarly, when the input level of the input terminal 1601 is brought to a standardized voltage VIL of a low level threshold voltage, if the input buffer 1604 operates normally, the output terminal 1617 outputs a high level signal as shown in the fourth row of FIG. 5B.
On the contrary, if the input buffer 1604 malfunctions, the signal 1611 becomes in a phase opposite to that of the input level, and therefore, the output terminal 1617 outputs a signal having the same phase as that of the input level, as shown in a fifth row of FIG. 5B.
Next, during a period T172 in FIG. 5B, the input threshold of the input buffer 1605 is tested. At this time, the input terminal 1603 is maintained at the high level, but the input terminal 1601 is maintained at the low level. By setting the input terminals as mentioned above, the output 1611 of the input buffer 1604 becomes the low level, so that the output 1614 of the NAND gate 1607 becomes the high level. Thus, the NAND gates 1608 and 1609 becomes equivalent to an inverter chain of two stages receiving the signal 1612 as an input signal and for outputting the signal 1616 as an output signal.
Therefore, if the input buffer 1605 operates normally, a signal appearing on the output terminal 1617 is in the same phase as that of the input signal applied to the input terminal 1602. On the contrary, if the input buffer 1605 malfunctions, the signal appearing on the output terminal 1617 is in a phase opposite to that of the input level applied to the input terminal 1602.
Next, during a period T173 in FIG. 5B, the input threshold of the input buffer 1606 is tested. At this time, the input terminal 1602 is maintained at the low level, but the input terminal 1603 may be at the low level or at the high level. By setting the input terminals as mentioned above, the output 1612 of the input buffer 1605 becomes the low level, so that the output 1615 of the NAND gate 1608 becomes the high level. Thus, the NAND gate 1609 becomes equivalent to an inverter receiving the signal 1613 as an input signal and for outputting the signal 1616 as an output signal.
Therefore, if the input buffer 1606 operates normally, the signal appearing on the output terminal 1617 is in a phase opposite to that of the input signal applied to the input terminal 1603. On the contrary, if the input buffer 1605 malfunctions, the signal appearing on the output terminal 1617 is in the same phase as that of the input signal applied to the input terminal 1602.
Thus, it is possible to discriminate whether or not each of the input buffer operates normally, on the basis of whether the output signal is in the same phase as that of the input signal or in the opposite phase to that of the input signal.
In the conventional examples mentioned above, the input threshold voltage test methods of the first to third prior arts are configured to applying a ramp voltage to the input node of the input buffer and to detect the passthrough current flow when the ramp voltage exceeds the threshold of the input buffer, as an increase of the power supply current. However, when these methods are applied to the testing of an LSI having a plurality of input terminals, it is impossible to clearly define a reference current value used for discriminating the increase of the power supply current. Actually, there is no LSI having only one input terminal. Namely, if it is considered that actual LSIs have a number of input terminals, it can be said that the input threshold voltage test methods of the first to third prior arts cannot actually discriminate the non-defective/defective of the input threshold voltage of the LSIs. The reason for this is as follows:
Now, assume that, in accordance with the first to third prior arts, the input threshold voltage test is performed for input buffers of an LSI having two external input terminals A and B. Here, the two input buffers will be called an input buffer A and an input buffer B, respectively.
FIG. 6A illustrates an operation at the time of the measurement. In FIG. 6A, the axis of abscissas shows a time, and the axis of ordinates indicates an input voltage applied to the input terminals A and B. In addition, it is assumed that a high level input threshold voltage of the input buffer A is VA, a high level input threshold voltage of the input buffer B is VB, and a standardized value of the high level input threshold voltage is VH Therefore, the input buffer A fulfills the standardized value VH, and on the other hand, the input buffer B does not fulfill the standardized value VH. The voltage waveform "s" shows that the voltage applied to the input buffers A and B gradually elevates with the lapse of time. In FIG. 6B, on the other hand, the axis of abscissas shows a time with the same scale as that of the axis of abscissas of FIG. 6A, and the axis of ordinates indicates the power supply current of the LSI. The current value ITH is a reference current value used for the comparison in order to discriminate whether or not an increase of the power supply current occurs when the input voltage applied to each input terminal exceeds the input threshold of a corresponding input buffer.
Referring to FIGS. 6A and 6B, at a time t18A, the input buffer B flips for the first time, so that an operation current flows, and therefore, the power supply current increases. In the first to third prior arts, the value of the power supply current at the time t18A must be compared with the reference current value. In other words, as the input threshold voltage, the input voltage at the time that the operation current is detected the voltage applied to the input terminals A and B gradually elevates. Because, during a period t18E after the first input buffer flips, an internal circuit receiving an output signal of the input buffer B and its succeeding circuits operate so that the power supply current further increases. Therefore, it is not possible to recognized that, in the change of the power supply current after the time t18A, the power supply current at a time t18B is attributable to the operating current of the input buffer A which flips lastly since it have the highest input threshold. However, in the high level input threshold voltage testing, it is necessary to discriminate whether or not the input buffer having the highest input threshold fulfills the standardized value. Therefore, the test in accordance with the first to third prior arts cannot make a proper discrimination.
The above mentioned situation is not any special case. Rather, it can be said that there is no LSI having only one input terminal. Therefore, it must be said that the first to third prior arts cannot be used for an ordinary GO/NOGO testing, nor can it be used to measure a "true capability value" of the worst input threshold voltage (a distribution of the worst input threshold voltage of LSIs when a number of LSI is tested).
Next, the fourth prior art shown in FIG. 4A is so configured that the output buffer 1403 for outputting the signal 1406 indicative of the result of the signal processing in the normal mode is used as the output buffer even in the test mode, so that the output signal 1405 of the input buffer 1402 is outputted through the output buffer 1403 to the external. In this method, in the case that the number of output buffers is smaller than the number of input buffers, extra output buffers which are not required for the signal processing in the normal mode, must be added for only the input threshold voltage test. This results in an increase in the number of external terminals, and therefore, makes the size of the LSI large and lowers the package density of the LSI.
On the other hand, in the fifth prior art, the expected value of the output logic value for discriminating the non-defective/defective changes dependently upon an input buffer to be tested. In addition, for each input buffer to be tested, it is necessary to change the logic value applied to the input terminals other than to the input terminal connected to the input buffer to be tested. Therefore, how to change the input signal to be applied to the input terminal and the expected output value for the discrimination depend upon how the NAND gate 1609 receiving the output of the respective input buffers to be tested is connected in relation to the respective input terminals. In other words, a test pattern used for the input threshold voltage testing by use of an LSI tester, must be individually prepared for each of products, on the basis of the circuit connection information of each product. As a result, the number of steps for preparing the test pattern will increase the manufacturing cost of the LSI.

Semiconductor integrated circuit with a test circuit for input buffer threshold


An endovascular system for arresting a patient's heart and maintaining the patient on cardiopulmonary bypass. A venous cannula, venting catheter and an aortic occlusion device are all coupled together so that the blood drawn into each of these catheters may be fed to a pump. A manifold has valves which control flows through the venous cannula, venting catheter and aortic occlusion device. A blood storage element is also provided so that the amount of blood in the perfusion circuit may be varied if necessary. The blood storage element is preferably positioned in parallel with the pump so that the pump may be used to add and remove blood to and from the blood storage element.

The present invention relates to systems for arresting a patient's heart and maintaining a patient on cardiopulmonary bypass. Such systems are used when performing surgical procedures, such as coronary artery bypass grafting, on an arrested heart.
In conventional open-heart surgery, the patient's breast bone is sawed open, the chest is spread apart, and the heart is accessed through the large opening created in the patient's chest. The patient is placed on cardiopulmonary bypass and the patient's heart is then arrested using catheters and cannulae which are inserted directly into the large arteries and veins attached to the heart through the large opening in the chest. The arterial cannula typically passes through the wall of the ascending aorta and a cross-clamp is applied to the ascending aorta to isolate the coronary arteries from the remainder of the arterial system. A venous cannula passes through the right atrium for withdrawing blood from the patient.
Recent developments in cardiac surgery have enabled surgeons to perform coronary artery bypass grafting and valve repair and replacement procedures without creating a large opening in the patient's chest. These developments have significantly reduced trauma to the patient by eliminating the need for sawing open the breast bone and opening the patient's chest. Such procedures are disclosed in U.S. Pat. Nos. 5,452,733 and 5,571,215 which are hereby incorporated by reference.
In order to perform such surgical procedures, the patient's heart must be arrested and the patient placed on cardiopulmonary bypass without direct access to the heart. Catheters and cannulae for arresting the patient's heart and establishing bypass without requiring direct access to the patient's heart are disclosed in U.S. Pat. Nos. 5,584,803 and 5,558,644 which are hereby incorporated by reference.
The systems described in U.S. Pat. Nos. 5,584,803 and 5,558,644 include an aortic occlusion device which has a balloon to occlude the ascending aorta and a lumen to deliver cardioplegic fluid for arresting the patient's heart. The aortic occlusion device replaces the conventional external cross-clamp and advantageously reduces the amount of displacement and distortion of the aorta. Minimizing distortion of the aorta may reduce the amount of emboli released and, therefore, may reduce stroke incidents.
A venous cannula withdraws blood from the patient and blood is returned to the patient through an arterial cannula which is placed at a peripheral artery such as the femoral artery. In a preferred embodiment, the aortic occlusion device passes through the arterial cannula thereby minimizing the number of penetrations in the patients vascular system.
The systems described in U.S. Pat. Nos. 5,584,803 and 5,558,644 also include an endovascular coronary sinus catheter for retrograde perfusion of a cardioplegic agent, preferably blood cardioplegia, via the coronary sinus. The coronary sinus catheter preferably passes through the internal jugular vein and has an inflatable balloon for occluding the coronary sinus. An endovascular venting catheter extends through the tricuspid and pulmonary valves for venting the pulmonary artery.
Although the endovascular bypass system has performed admirably and has enabled surgeons to perform less invasive cardiac procedures, the extracorporeal bypass circuit which couples the catheters and cannulae to the cardiopulmonary bypass elements may be optimized.
Thus, a specific object of the present invention is to provide an extracorporeal flow circuit for use with endovascular cardiopulmonary bypass systems.

Methods and devices for maintaining cardiopulmonary bypass and arresting a patient's heart


A teething rail which can be snapped on and off of the handle of a shopping cart and can be chewed safely by a teething baby when riding in the seat of the shopping cart. The teething rail is a split tube which preferably has a center portion with raised elements on which the baby can chew pleasantly.

This invention relates to a teething rail for use on the handle of a shopping cart.
Teething rings for babies are well-known. They usually consist of a ring of soft rubber which the baby can chew to relieve the sensations associated with teething. However, when a baby accompanies its mother on a grocery shopping trip, the baby is often carried in a seat in a shopping cart facing the cart's handle. The baby often leans over and chews on the handle, especially if it is teething, and this can be unsanitary. Covers for shopping cart handles are known, for example in U. S. Pat. No. 3,866,649--Bringmann, but such covers do not have special provisions for a teething baby and are typically fastened by means of a zipper.

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This invention pertains to a multipass retroreflector and to a method for its operation. In a preferred embodiment, the retroreflector comprises three reflecting surfaces arranged at an angle to each other in the form of a prism that is triangular in cross-section and 1 to 2 ports through which an optical beam enters and/or exits. The method includes the step of admitting an optical beam into the retroreflector where the optical beam is reflected from the reflecting surfaces and exits parallel to the path of the incoming optical beam. The method also includes the steps of spacing and adjusting angular disposition and dimensions of the reflecting surfaces in order to change path length of the optical beam passing through the retroreflector. This spacing can be continuously scanned causing a large change in optical path length due to a small change in the position of the moving surface.

1. Field of the Invention
This invention pertains to the field of collinear and non-collinear retroreflectors and to methods for their operation.
2. Description of Related Art
Multipass optical cells have been used for many years in the field of gas and atmospheric absorption spectroscopy so that a small volume can be interrogated by making multiple passes through the volume. This achieves a long optical path length in a very compact structure, or similarly, amplifies via multiple passes a weak optical response of a single pass.
Retroreflection of an optical signal is very important in optical systems since it not only reflects the light, but also causes the return optical path to be parallel to the incident path. This has many applications such as optical delay line scanning, optical alignment, and bright passive reflections such as road signs, to name a few.
Combining the trait of a multipass optical cell with a retroreflector creates a flexible tool for use in compact laser amplifier gain stages, communication, spectroscopy, and remote sensing.
Donald R. Herriott and Harry J. Schulte in an article entitled "Folded Optical Delay Lines" in the journal Applied Optics, for August 1965, vol. 4, No. 8, starting on p. 883, disclose that a long optical path has been folded between two 7.5 cm diameter spherical or aspherical mirrors to provide an output optical beam which can be well separated from previous reflections with 1000 or more passes between the mirrors. The 3000-m path provides 10 μsec of delay. This system can be used as a dispersionless optical delay line for use in filtering or storage of information modulated onto the light beam. The pattern of beams between the two mirrors is obtained in one of two ways. A small perturbing mirror may be inserted to give a series of offset ellipses, or one or both of the mirrors can be made astigmatic to give a Lissajous pattern of spots on each mirror. The output beam can be separated from others by discriminating in both angle and position. The diffraction losses of the system are much lower than those for an open beam because of the periodic focusing of the spherical mirrors. The extreme dependence of the loss of the delay line upon the absorption and scattering loss of the mirrors makes the system a suitable method for measuring mirror loss.
U.S. Pat. No. 5,973,864 to Lehman et al discloses a stable resonator for a ring-down cavity spectroscopy cell having an optic axis. The resonator includes two Brewster's angle retroreflector prisms, each having a plurality of total internal reflection surfaces. The prisms are disposed in alignment along the optic axis of the resonator. One or both of the prisms can be rotated so that light rays enter a surface of the prism nearly at Brewster's angle to the normal of the prism surface. This feature maintains alignment between the prisms and allows the resonator to be tuned. One of the internal reflection surfaces of at least one of the prisms may be a curved surface. Alternatively, an astigmatic lens may be centered in one arm of the resonator and tilted at Brewster's angle with respect to the optic axis of the resonator.

Multipass optical retroreflector and method of using

The United States of America as represented by the Secretary of the Navy


A cutting tool includes a main body suitable to be mounted pivotably about an axis of rotation. A cutting head is carried by a carrying member. The carrying member is mounted displaceably in translation on the main body along an axis perpendicular to the axis of rotation. A counterweight is displaceably mounted in translation on the main body along an axis perpendicular to the axis of rotation. The cutting tool also includes an adjusting spindle for the simultaneous adjustment of the carrying member with respect to the counterweight, arranged on either side of the axis of rotation of the main body.

Currently, rotary cutting tools are formed by one or more cutting heads mounted rotatably around an axis of rotation of the cutting tool driven by the motor of a machine tool.
When the cutting tool is suitable to allow the setting of the cutting surface of the device, the cutting head is mounted on the cutting tool in such a way as to allow its radial displacement with respect to the axis of rotation of the cutting tool. This radial displacement of the cutting head towards or away from the axis of rotation thus allows a reduction or increase of the radius of rotation of the cutting head and therefore of the diameter obtained.
In order to avoid the generation of an imbalance during the rotation of the cutting head that might pose a risk of putting the cutting tool out of true, the cutting tool is traditionally equipped with a counterweight suitable for offsetting the centrifugal force of the cutting head during the operation of the tool. According to a known manner of construction, such a counterweight is also arranged to be radially displaceable and to allow a setting appropriate to the position of the cutting head on the tool.
The document US 2006/3239787 proposes an example of construction of such a tool comprising a counterweight that is radially adjustable so as to allow an offsetting of the weight of the cutting head. However, it should be noted that the mechanism for positioning and adjusting the counterweight on the cutting tool is structurally independent from the adjustment of the cutting head. Such a mechanism therefore has the disadvantage of requiring a double setting for a given cutting surface, namely, on the one hand, the adjustment of the cutting head according to a defined cutting radius, and, on the other hand, the balancing of the counterweight according to the position of the cutting head with respect to the axis of rotation.

Cutting tool suitable to allow a balanced setting


A stereoscopic image display device for providing a stereoscopic image by displaying images with a parallax on a viewer's left and right eyes is disclosed. The display device comprises the following. (1) A light source with selectively variable light-emitting regions for emitting light, wherein the light-emitting regions are disposed at various positions from a center of the light source. (2) An optical element having an optical axis extending through the center of the light source for condensing light emitted from the light source to each of the viewer's left and right eyes. (3) Spatial modulation means, disposed on an optical path from the light source to the viewer, for spatially modulating the light emitted from the light source. (4) Control means for controlling the light-emission state of the light source so that brightness of the light-emitting regions increases as the positions of the light-emitting regions become distant from the optical axis, in order to obtain a uniform viewing illuminance of the light viewed by the viewer even when a viewing point of the viewer changes and the positions of the light-emitting regions move.

This invention relates generally to a stereoscopic image display device which displays an image from a plurality of points of view with a stereoscopic vision, and more particularly to a stereoscopic image display device which converges spatially modulated light of left and right images having binocular parallax on the vicinities of the corresponding left and right eyes of a viewer to make the viewer recognize a stereoscopic image.
Recently, stereoscopic image display devices which use images having binocular parallax to make a viewer recognize them as a stereoscopic image are reported. Among them, attention has been paid to stereoscopic image display systems which do not require special spectacles since viewers can easily enjoy stereoscopic images.
Jpn. Pat. Appln. KOKAI Pub. No. 6-225344 discloses such a stereoscopic image display system which displays images while following the motion of a viewer, without requiring special spectacles. In this system, back-light for left and right sides is emitted through a large-sized convex lens to the position, or thereabouts, of the viewer's face or the viewer's left or right eyes. Therefore, since the position of light sources of back-light change as the viewer moves, a good tracking is achieved.
However, in this conventional art, as the viewer moves leftwards or rightwards from the front position, an angle .phi. formed between the light axis of incident light passing through the spatial modulation element and the surface of a liquid crystal board used as the spatial modulation element increases, and the amount of an orthogonal-projection component of incident light reduces. Further, in this conventional art, a black-and-white television wherein a phosphor-coated surface is used as a luminous member is used. The luminescent section of this light source can be regarded as a perfect diffusion light source whose luminance is uniform even if it is viewed from any angle. When the luminous intensity in the vertical direction is Io, the luminous intensity in the oblique direction is Io cos .phi.. Therefore, the luminous intensity has such characteristics that the luminous intensity reduces according to the degree of obliqueness of the direction in which the light source is viewed. Further, the liquid crystal board used as the spatial modulation element has such general characteristics that its transmissivity lowers when the light incident direction shifts from the vertical axis.
As explained above, in the conventional stereoscopic image display device, there were the problems that the image to be viewed becomes dim as the viewer moves leftwards or rightwards from the central position, and that the stereoscopically viewable region is narrow. Further, even when the viewer does not move, a peripheral portion of an image to be viewed is dimmer than a central portion.


A method can be used for charging a battery of a vehicle. The method includes performing a first charging process in which the battery is charged with a maximum amount of charges corresponding to a current temperature of the battery, the battery being heated while performing the first charging process. The method also includes performing a heating process in which the battery is heated without charging of the battery, and performing a second charging process in which, when the maximum amount of charges of the battery increases by heating of the battery, the battery is further charged with the increased maximum amount of charges.

In pure electric vehicles designed to use a battery as an energy source, and engine hybrid electric vehicles and fuel-cell hybrid vehicles designed to use a battery as an energy buffer, the battery is one of the principal constituent elements for determining vehicle quality.
Therefore, a Battery Management System (BMS), which is configured to manage overall conditions of the battery, prevents early reduction in battery lifespan and transmits State of Charge (SoC) information of the battery to a vehicle controller configured to perform integrated control, thereby supporting electricity generation control and vehicle traveling control.
The principal function of the BMS may be to perform SoC estimation and a fully charged state of the battery, balanced voltage maintenance between cell modules, maximum charging and discharge voltage control based on battery SoC information, safety management, cooling control, and the like.
The amount of electric energy stored in the battery of the electric vehicle may denote an available range of the electric vehicle. In order to increase the range of electric vehicles, many electric vehicle manufacturers mainly increase battery capacity or enlarge an available SoC region of the battery.
The battery may have different performances according to battery temperature. Generally, a lithium (Li) battery has high resistance at a low temperature. Accordingly, since high resistance occurs when the battery is charged with electricity at a low temperature, the battery may be charged with a smaller charge as compared to the case in which the battery is charged with electricity at a normal or high temperature. In the electric vehicles, reduction in the electric charge stored in the battery may indicate reduction in the range of the electric vehicle.

Vehicle and method for controlling the same


A constant-head soil permeameter for determining hydraulic conductivity of earthen materials is inserted into a borehole at the desired test depth. A calibrated reservoir, disposed on the ground surface, is attached thereto with a suitable length of hose. Water is added to the calibrated reservoir and allowed to flow freely into the borehole until an equilibrium level is reached in the borehole and inside the soil permeameter. The water flowing to the permeameter is throttled by buoyant float pressure that is greatly increased by a lever-and-link valve control assembly which provides considerable mechanical advantage, thereby allowing better constant head control and much greater depths of testing than previously attained by known permeameters. A filtered vent system, backflow check valve, and seals restrict entry of soil particles and debris, thereby minimizing cleaning and maintenance of the invention. The soil permeability is determined by solving appropriate mathematical equations which utilize the equilibrium height of water, rate of water flow, and dimensions of the borehole as input parameters.

1. Field of the Invention
This invention relates to the hydraulic conductivities of liquids through permeable materials and particularly relates to the conductivity of water through earth. It also relates to testing such conductivity from the surface of the earth to great depths beneath the surface and above the water table while preventing contamination by falling soil and debris. It more particularly relates to instruments that establish a static head of water within a borehole and maintain the water at this predetermined level by use of a float and valve system. It specifically relates to a float and valve system that provides a mechanical advantage ratio enabling use at such great depths.
2. Review of the Prior Art
It is often important to estimate the hydraulic conductivities of earthen materials in order to safely and economically develop lands for urban and agricultural uses. Hydraulic conductivity values are important considerations in design and construction of building and roadway foundations, on site sewage wastewater treatment systems, and storm water infiltration facilities. These values are important for artificial treatment of wetlands, and for estimating the rate of transport of liquid contaminants from waste disposal sites and leaking storage tanks. Hydraulic conductivity values are additionally important in design of irrigation systems and drainage of agricultural lands.
Soil hydraulic conductivity can be used to describe the ability of earthen materials to transmit water. Darcy""s Law describes the relationship of the volume of water, moving through a cross sectional area of soil (commonly known as flux) along the hydraulic gradient of the water flow path, to the hydraulic conductivity. Under saturated conditions, such as below a water table, hydraulic conductivity is referred to as saturated hydraulic conductivity. Even though Darcy""s law was originally developed to describe saturated flow, the principles of the law can be applied to water movement in partially saturated soils above the water table.
The determination of hydraulic conductivity under field conditions can be complicated because of the natural variation of soil properties and the specific need for which the test is being conducted. Soils typically contain multiple contrasting layers and often exhibit significantly differing hydraulic conductivity values along preferential flow paths within the soil matrix.
Prior art instruments developed for measuring hydraulic conductivity of soils above the water table in the field have generally fallen into three groups. The first group introduces either a ponded static (i.e., constant) or a variable (i.e., falling) head of water into the bottom of an unlined borehole below the ground surface or into a confining ring in contact with the ground surface. Instruments that establish a static head of water within a borehole maintain the water at a predetermined level, usually by use of either a float and valve system or a marriott tube system. The rate of water flow necessary to maintain a constant water level in the borehole at the predetermined level is utilized to estimate hydraulic conductivity of the soil. Methods used to measure the saturated hydraulic conductivity in a borehole utilizing a constant head of water have been referred to as the shallow well pump-in technique or constant-head well permeameter. Instruments in this first group that utilize a falling head procedure usually measure the drop of water from a predetermined level in a lined or unlined borehole as it dissipates into the soil to estimate hydraulic conductivity.
The second group of instruments applies water through a semi-permeable membrane to a soil surface, which is under negative pressure (tension), to measure unsaturated hydraulic conductivity. The third group of instruments utilizes various methodologies, which include electrical resistivity procedures and gas or liquid injection into the soil through penetrating probes. The instruments in the third group typically require a power source, fluid or gas pumps, multiple chambers, borehole packers, electronic data loggers, and complex analysis procedures.
U.S. Pat. No. 6,105,418 discloses a constant-head float valve assembly which includes a J-shaped fluid conduit for intermittently delivering water from a supply container to a borehole. As the float moves downward with dissipating water levels, a shutoff valve is contacted and thereby opened to replenish the water in the borehole. The rising water moves the float upward and away from the valve, thereby allowing pressure of the incoming water to close the valve again.
U.S. Pat. No. 4,561,290 utilizes a float valve assembly, connected to a water supply reservoir, to regulate water inflow and obtain a constant water level within a borehole. The float responds to a rising water level by regulating water flow through a valve and thereby maintaining a constant water level.
However, neither of these devices incorporates an apparatus for magnifying the vertical force of the float body that is necessary for valve regulation at large depths and flow volumes, nor do they incorporate a backflow check valve to prevent incident entry of suspended soil particles and other contaminates into the float chamber. In addition, neither of these devices includes a means for eliminating the entry of contaminants through its air equalizing passage into the interior of the device.
Soil hydraulic conductivity has been historically measured on a smaller scale in the laboratory, utilizing a falling or constant head of water applied to soil core samples retrieved from the field or on remolded soil samples. Laboratory centrifugal force methods are also utilized to estimate hydraulic conductivity. Laboratory measurements are often significantly at variance with in situ field measurements because of the differing methodologies and the inherent difficulty of obtaining undisturbed soil samples and replicating natural environmental and stress conditions in the laboratory.
It is desirable to have the capability to conduct hydraulic conductivity tests at any depth in earthen materials above the permanent water table. Such depths may range from zero to many meters below the ground surface. In addition, it is desirable to have adequate flow capacity for maintaining flow equilibrium in a wide range of soils. Clay soils often have slow permeability, whereas sandy or gravelly soils often have high permeability and, therefore, a greater equilibrium flow rate.
Prior art inventions that utilize a float system alone do not provide a mechanical advantage ratio, thereby limiting testing to relatively shallow depths. Inventions utilizing the marriott tube principle to establish a constant water level are also limited to relatively shallow depths of testing.
A buoyant force is provided by a float in accordance with Archimedes""s Principle which states that the buoyant force on a body immersed in a fluid is equal to the weight of the fluid displaced by that body. The displacement volume of any float of practical geometric shape that can fit in a small-diameter borehole is relatively small, therefore the depth at which such float can provide throttling of a valve by direct buoyant force alone is limited to relatively shallow depths and small flow rates. There is accordingly a need for an apparatus that is sufficiently rugged and versatile to measure hydraulic conductivities of soils inside a borehole at a variety of depths above the water table, ranging from shallow to deep. There is also a need for a device that can be used inside a borehole, wherein the device is subject to being struck by falling soil particles and debris, without contamination by such particles and debris through the air vent hole at its top or through water outlets at its bottom.
It is an object of the invention to provide a simple and sturdy apparatus which functions as a constant-head soil permeameter for estimating saturated hydraulic conductivity of in situ earthen materials above the water table by establishing a constant head of water at a predetermined level in a borehole that is dug below the ground surface with ordinary hand auger equipment or with power equipment.
It is a further object to provide a soil permeameter that can, without incorporation of electronics, be effectively used to estimate hydraulic conductivity at desired test depths normally encountered above the water table and at depths much greater than the depths at which known devices that utilize a float system can be employed.
It is an additional object to provide a constant-head soil permeameter that can be effectively used to determine hydraulic conductivity within a wide range of soil permeability.
It is also an object to provide a soil permeameter that avoids malfunction in the field by minimizing contamination from soil particles and debris falling from the side of the borehole.
In accordance with these objects and the principles of the invention, the soil permeameter of this invention is an apparatus which incorporates a float and a mechanical linkage system that greatly increases the forces applied by the float to throttle water flow at the control valve.
The constant-head soil permeameter of this invention seeks to overcome disadvantages of other float systems by greatly increasing the buoyant force resulting from submergence of a float alone. The permeameter increases the buoyant force by use of a compound lever and link assembly, as a part of its float system, which provides a mechanical advantage ratio ranging from approximately 10:1 at full valve opening to approximately 60:1 at full valve closure. The resultant available maximum throttling force is, therefore, approximately 60 times greater than simple buoyant force at full valve closure. The effective testing depth range of the permeameter is from 15 centimeters to about 30 meters. The permeability testing range of the apparatus is from 10xe2x88x926 centimeters/second to 10xe2x88x922 centimeters/second. The range of water flow volume through the apparatus is from zero to 2000 milliliters/minute or more at depths greater than one meter.
This constant-head soil permeameter comprises a tubular cylinder having a top end, a bottom end, means for introducing a liquid into the top end, means for selectively closing the bottom end, and means for preventing falling debris and soil from entering the top end while enabling air to flow into and out of the cylinder, the top end and the bottom end being defined in relation to usage within a vertically disposed borehole in materials permeable to the liquid. The cylinder contains a float system that provides a mechanical advantage ratio for shutting off the introduction of liquid.
This float system comprises a compound lever and link assembly that functions as a valve control assembly and is hereinafter thus identified. It is particularly operative when:
A) the liquid is water, the materials are earthen, and the borehole has a bottom disposed above a water table in the earthen materials; and
B) the mechanical advantage ratio ranges from approximately 10:1 at full valve opening to approximately 60:1 at full valve closure.
The valve control assembly, described hereinafter with water as the liquid, comprises the following lever and link assembly:
A) a valve support bracket which is longitudinally disposed and rigidly supported within the cylinder, adjacent to the inner side thereof;
B) an actuating lever arm, having two ends, which is attached at one end to a first pivot which is attached to the valve support bracket;
C) a link, having two ends, which is attached at its lower end to a second pivot which is attached to but spaced apart by a selected distance from the first pivot; and
D) a valve seat retaining lever arm, having two ends, which is pivotally attached at one end to the valve support bracket and is pivotally attached at its other end to a pivot attached to the upper end of the link.
The top end of the cylinder comprises a top stopper, having an upper side and a lower side, which is rigidly attached to the cylinder and is encircled by an o-ring in sealing contact with the cylinder. The means for introducing water into the top end of the cylinder comprises a reservoir for containing water, a hose connection which is rigidly attached to the top stopper and projects outwardly from its upper side and has a bore therewithin, a hose for connecting the reservoir to the hose connection, and a valve body which is rigidly attached to the lower side of the stopper and has a bore therewithin in fluid communication with the bore within the hose connection.
The valve seat retaining lever arm comprises a valve seat which is attached thereto in facing relationship to the valve body and is adapted for selectively shutting off the introducing of water from the reservoir.
The cylinder additionally contains a buoyant float body that is axially movable within the cylinder and has upper and lower surfaces. The upper surface exerts pressure against the other end of the actuating lever arm when the float is supported by water within the cylinder.
The constant-head soil permeameter may be described as comprising the following lever and link assembly which provides a mechanical advantage ratio:
A) a valve support bracket having an upper pair and a lower pair of spaced-apart lugs attached perpendicularly thereto and projecting toward the center of the cylinder;
B) an actuating lever arm having one pair of spaced-apart lugs attached perpendicularly thereto at its pivot end and projecting upwardly, being attached to the lower pair by the first pivot;
C) a link having two pairs of the spaced-apart lugs attached perpendicularly thereto at the upper and lower ends thereof and projecting toward the valve support bracket, one pair being attached by the second pivot to the one pair of spaced-apart lugs on the pivot end of the actuating lever arm and being spaced from the first pivot by a selected distance; and
D) a valve seat retaining lever arm having two pairs of spaced-apart lugs attached perpendicularly thereto at the ends thereof and projecting in opposite directions, one pair being pivotally attached to the upper pair on the valve support bracket and the other pair being pivotally attached to the pair of spaced-apart lugs on the upper end of the link.
The means for preventing falling debris and soil from entering the top end of the cylinder while enabling air to flow into and out of the cylinder comprises an inverted J-shaped tube, having a long portion which passes through the stopper and a short portion having a filter screen at its outer end, the filter screen being disposed to face toward the upper side of the stopper and being spaced from the upper side.
The means for selectively closing the bottom end of the cylinder comprises a bottom stopper, having an upper surface and a lower surface, which is rigidly attached to the cylinder, an o-ring encircling the stopper and in sealing contact with the cylinder, an axially disposed bolt attached to the stopper and extending upwardly beyond its upper surface, at least one longitudinally disposed hole extending through the bottom stopper, and a check valve disposed beneath the lower surface, whereby reverse flow of water from the borehole toward the stopper lifts the check valve and closes the hole and the bottom end.
This constant-head soil permeameter, adapted for operational use within a borehole in earthen materials, comprises a cylindrical housing having a top end and a bottom end which has a flow-through means for allowing water entering the top end to form a first water level within the housing and then to flow through the bottom end into the borehole to form a second water level therewithin when the second water level is lower than the first water level and having a closing means for preventing water from flowing into the cylindrical housing when the second water level is higher than the first water level.
This flow-through means comprises a bottom stopper which is rigidly attached to the cylindrical housing, has a countersunk bottom surface forming a downwardly extending skirt that contacts the bottom of the borehole when the permeameter is resting thereupon, has at least one longitudinally disposed hole through the stopper, and has at least one laterally extending hole through the skirt.
This closing means comprises a check valve guide which is axially and rigidly attached to the countersunk bottom surface of the stopper, a disk-shaped check valve which is loosely and axially fitted to the check valve guide, and a disk-shaped baffle, having a plurality of longitudinally disposed holes therethrough, which is rigidly and perpendicularly attached to the check valve guide and disposed beneath the check valve, whereby backflow of water from the borehole toward the bottom stopper passes through the plurality of holes in the baffle and lifts the check valve to block the at least one longitudinally disposed hole in the bottom stopper.
The rate of water flow into the borehole that is necessary to maintain the constant head is recorded at appropriate intervals during the test period. The information recorded during the test, which also includes height of constant water column, rate of flow, and borehole geometry, is factored into an appropriate mathematical equation to provide an estimate of hydraulic conductivity.

Constant-head soil permeameter for determining the hydraulic conductivity of earthen materials


Production equipment for oil and gas wells has features that allow accumulated liquid to be removed from the well without the need for a low pressure system. This equipment also isolates the perforations from accumulated liquid back pressure, even if there is insufficient hole depth below the perforations. The well has a tubing string located inside the casing, with the tubing in contact with the accumulated liquid. Both the tubing and the casing are connected to the sales line. Periodically, both the casing and tubing are shut-in, allowing formation pressure to build up in the casing. Then the tubing is opened to the sales line to discharge its accumulated liquid, it being driven by the higher formation pressure that has built up. To isolate the perforations from accumulated liquid, a standpipe is mounted in the casing above the perforations by a packer. The standpipe receives the lower end of the tubing which is closed except for a passage connecting it to the annular area between the standpipe and the casing. Produced fluid flows up the standpipe in a restricted area adjacent the tubing. At the top of the standpipe, liquid droplets drop out and accumulate above the packer between the standpipe and the casing.

1. Field of the Invention
This invention relates in general to oil and gas well production, and in particular to a system for removing accumulated liquid from gas producing wells.
2. Description of the Prior Art
Many gas wells product both gas and liquids such as water, oil and condensate. The gas is often flowed from the casing to a sales line. Part of the liquid, initially entrained as droplets in the gas flow, drops out of the flow because of insufficient velocity of gas. The liquid accumulates in the bottom of the well, and as accumulation increases, exerts an increasingly large back pressure on the formation. This back pressure, which equals the hydrostatic head of the liquid column, may be large enough to reduce the production rate or completely stop production.
It is therefore advantageous to periodically remove accumulated liquid from gas wells. A typical gas well has casing through which the gas flows through the perforations at the gas producing formation to a production or sales line at the surface or well head. Tubing inside the casing is used to remove accumulated liquids. The tubing usually has an open lower end extending close to the producing formation and into the accumulated liquid. Normally, the tubing is closed by the valve at the surface, and the casing is opened to permit gas to flow into the sales line. Accumulated liquid rises in the casing and in the tubing to the same level. To remove liquid the valve at the top of the tubing is opened to reduce the pressure inside the tubing to a value less than the pressure inside the casing and in the sales line. Thus, the pressure of the gas inside the casing forces liquid through the tubing toward the well head. The liquid and gas from the tubing is discharged into a low pressure storage and disposal system.
In the above method, liquid removal is facilitated by use of a loose fitting plunger which separates the liquid and the gas. This helps prevent the gas from migrating through the liquid and prevents the liquid from dropping through the gas.
There are a number of variations of the above described methods. Two such variations may be seen in U.S. Pat. Nos. 3,053,188 and 3,203,351. One disadvantage of such systems is that they require a second pipe system on the surface leading to the lower pressure storage or disposal facility. This represents a considerable additional amount of pipe and equipment that must be installed and maintained. Also, the gas discharged in the lower pressure system may not be usable unless pressurized to the sales line pressure, which may not be economical.

Surface controlled liquid removal method and system for gas producing wells


According to the present invention, a process which comprises bringing polyethylene terephthalate having an intrinsic viscosity of at least 0.50 dl/g and a density of 1.38 g/cm.sup.3 or more into contact with water is provided.. In the water-treated polyethylene terephthalate obtained in the present invention, amounts of oligomers and acetaldehyde formed at the time of molding said polyethylene terephthalate into molded articles are small, and the contamination of the mold therewith is difficult to occur and further the contents of said molded articles does not change in flavor and fragrance.

Various resins have heretofore been used as materials for containers of seasonings, oils, beverages, cosmetics and detergents according to the kind of contents with which the containers are filled and to the purpose which the containers are used.
Because of its excellent mechanical strength, heat resistance, transparency and gas barrier properties, polyethylene terephthalate is a useful material for forming containers to be filled particularly beverages such as fruit juices, cooling drinks and carbonated drinks.
Such polyethylene terephthalate as referred to above may, for example be prepared by esterifying terephthalic acid or its ester-forming derivative with ethylene glycol or its ester forming derivative in the presence of an esterification catalyst, and polymerizing the esterified product in liquid phase in the presence of a polymerization catalyst, followed by solid phase polycondensation. In general, polyethylene terephthalate thus prepared is fed to a molding machine such as an injection molding machine and molded into a blow-molding preform, and thereafter the preform is inserted into a mold of a predetermined shape and stretch blow-molded into a blown container, and if necessary followed by heat setting.
However, known polyethylene terephthalate obtained by the conventional procedure as mentioned above contains oligomers such as cyclic trimer, with the result that the oligomers attach to the inner surface of blow-molding mold and contaminate the mold therewith or attach to the vent portion of mold of the injection machine as mentioned above and contaminate the mold therewith.
Such contamination of the mold as mentioned above forms the determining cause for surface roughness or chalking of the resulting bottle. If the bottle obtained is chalked, either partly or wholly, it has to be discarded. Owing to such circumstances, in molding bottles out of the known polyethylene terephthalate, there was such a serious problem that contaminants attached to the mold must be removed therefrom at frequent intervals and hence productivity of the bottle markedly decreases.
In light of such existing circumstances as mentioned above, the present inventors extensively studied with the view of obtaining polyethylene terephthalate, by the use of which the contamination of the mold therewith is difficult to occur, and have found that the contamination of the mold at the time of molding polyethylene terephthalate is mainly attributable to an increased amount of oligomers such as cyclic trimers contained in the polyethylene terephthalate, said oligomers being formed in large amounts at the time when said polyethylene terephthalate is molded.
The present inventors further studied on the basis of the above-mentioned finding, and eventually have found that the increase in amount of the oligomers in polyethylene terephthalate at the time of molding may be inhibited by bringing the polyethylene terephthalate into contact with water, and they have accomplished the present invention.
Furthermore, the present inventors have found that there is an intimate relationship between a rate of polycondensation at the time when polyethylene terephthalate used for molding is subjected under specific conditions to solid phase polycondensation treatment and an increasing amount of oligomers formed at the time of molding, and that if the rate of polycondensation treatment of the polyethylene terephthalate is less than a specific value, the contamination of the mold at the time of molding is difficult to occur, on the basis of which finding the present invention has been accomplished.
In this connection, Japanese Patent L-O-P Publn. No. 25815/1984 discloses a process which comprises treating particulate polyethylene terephthalate, prior to solid phase polycondensation thereof, with water vapor heated to above 110.degree. C. so as to crystallize the polyethylene terephthalate.
Further, Japanese Patent L-O-P Publn. No. 219328/1984 discloses a process for preparing polyesters of high polymerization degree, which comprises a step of moisture conditioning a polyester having ethylene terephthalate units as the main repeating units and having an intrinsic viscosity of at least 0.4 dl/g and a density of less than 1.35 g/cm.sup.3 so as to have the moisture content of at least 0.2% by weight, a step of precrystallizing the polyester thus treated, and a step of solid phase polymerizing the precrystallized polyester at a temperature of above 180.degree. C. and below 240.degree. C. in an inert gas atmosphere or under reduced pressure.

Process for treatment of polyethylene terephthalate, polyethylene terephthalate for molding purposes and process for preparation thereof


An electromagnetic flowmeter wherein a liquid to be metered is conducted through a flow tube to intersect a transverse magnetic field produced by an electromagnet, the resultant signal induced in the liquid being transferred to a pair of electrodes mounted at diametrically-opposed points on the tube. To avoid spurious signal components arising from stray couplings between the electromagnet and the loop constituted by the electrodes and the liquid bridging the electrodes, the coil of the electromagnet is energized by a low-frequency wave whose frequency is well below the standard a-c power line frequency. And, to avoid noise components produced when the liquid being metered is a slurry containing solid particles which impinge on the surface of the electrodes, the electrodes are fabricated of or coated by a carbide metal or an alloy thereof whose metallurgical hardness is such as to substantially reduce the generation of such noise components.

Field of Invention
This invention relates generally to electromagnetic flowmeters, and more particularly to a flowmeter in whose excitation current for the electromagnetic coil is a low-frequency wave and in which the electrodes have a metallurgical hardness which minimizes the generation of a noise component when the liquid is a slurry having solid particles that impinge on the electrode surfaces.
In an electromagnetic flowmeter, the liquid whose flow rate is to be measured is conducted through a flow tube provided with a pair of diametrically-opposed electrodes, a magnetic field perpendicular to the longitudinal axis of the tube being established by an electromagnet. When the flowing liquid intersects the field, a voltage is induced therein which is transferred to the electrodes. The voltage, which is proportional to the average velocity of the liquid and hence to its average volumetric rate, is then amplified and processed to actuate a recorder or indicator.
The magnetic field may be either direct or alternating in nature, for in either event the amplitude of voltage induced in the liquid passing through the field will be a function of its flow rate. However, when operating with direct magnetic flux, the D-C signal current flowing through the liquid acts to polarize the electrodes, the magnitude of polarization being proportional to the time integral of the polarization current. With alternating magnetic flux operation, polarization is rendered negligible, for the resultant signal current is alternating and therefore its integral does not build up with time.
Through A-C operation as disclosed in the Cushing U.S. Pat. No. 3,693,439 is clearly advantageous in that polarization is obviated and the A-C flow induced signal may be more easily amplified, it has distinct drawbacks. The use of an alternating flux introduces spurious voltages that are unrelated to flow rate and, if untreated, give rise to inaccurate indications. The two spurious voltages that normally are most troublesome are:
1. stray capacitance-coupled voltages from the coil of the electromagnet to the electrodes, and PA1 2. induced loop voltages in the input leads. The electrodes and leads in combination with the liquid extending therebetween constitute a loop in which is induced a voltage from the changing flux of the magnetic coil.
The spurious voltages from the first source may be minimized by electrostatic shielding and by low-frequency excitation of the magnet to cause the impedance of the stray coupling capacitance to be large. But the spurious voltage from the second source is much more difficult to suppress.
The spurious voltage resulting from the flux coupling into the signal leads is usually referred to as the quadrature voltage, for it is assumed to be 90.degree. out of phase with the A-C flow-induced voltage. Actual tests have indicated that this is not true in that a component exists in-phase with the flow-induced voltage. Hence, that portion of the "quadrature voltage" that is in-phase with the flow-induced voltage signal constitutes an undersirable signal that cannot readily be distinguished from the flow induced signal, thereby producing a changing zero shift effect.
Pure "quadrature" voltage has heretofore been minimized by an electronic arrangement adapted to buck out this component, but elimination of its in-phase component has not been successful. Existing A-C operated electromagnet flowmeters are also known to vary their calibration as a function of temperature, fluid conductivity, pressure and other effects which can alter the spurious voltage both with respect to phase and magnitude.
Hence it becomes necessary periodically to manually re-zero the meter to correct for the effects on zero by the above-described phenomena.
All of the adverse effects encountered in A-C operation of electromagnetic flowmeters can be attributed to the rate of change of the flux field (d.phi.)/dt, serving to induce unwanted signals in the pick-up loop. If, therefore, the rate of change of the flux field could be reduced to zero value, then the magnitude of quadrature and of its in-phase component would become non-existent. Zero drift effects would disappear.
When the magnetic flux field is a steady state field, as, for example, with continuous d-c operation, the ideal condition d.phi./dt=0 is satisfied. But, as previously noted, d-c operation to create a steady state field is not acceptable, for galvanic potentials are produced and polarization is encountered.
In the patent to Mannherz et al., U. S. Pat. No. 3,783,687, whose entire disclosure is incorporated herein by reference, there is disclosed an electromagnetic flowmeter in which the excitation current for the electromagnetic coil is a low-frequency wave serving to produce a periodically-reversed steady state flux field, whereby unwanted in-phase and quadrature components are minimized without giving rise to polarization and galvanic effects. This low frequency wave is derived by means of a presettable scaler coupled to the standard a-c power line (60 Hz) and is at a frequency in the order of 17/8 , 33/4 , 71/2 or 15 Hz.
When the fluid being metered is in the form of a slurry containing solid particles which impinge on the surface of the electrodes as the slurry flows through the tube, we have found that a substantial noise component is generated which may make detection of the signal more difficult. Noise is any voltage that does not convey measurement information. Under the most favorable circumstances where noise has been minimized by filtering or other expedients, there are still certain sources of noise present resulting from the granular nature of matter and energy.
While noise fluctuations may be small compared with the total energy transfer involved in most measurements, the existence of a noise background limits the ultimate sensitivity to which a measurement can be carried. Sensitivity-limiting noise factors include Brownian motion, the Johnson noise in a resistance element and the Barkhausen effect in a magnetic element.
In the case of an electromagnetic flowmeter having a coil excited by an alternating current or a periodically interrupted direct current, it has been found that when the fluid being metered is a slurry containing solid particles, a spectrum of noise voltages is generated as a result of impingement of the solid particles on the surfaces of the electrodes. However, the frequency components of this spectrum does not include the frequency of the standard a-c power line (i.e. 50 or 60 Hz). Hence in a system of this type in which the excitation current is at the line frequency no difficulty is experienced in discriminating between the flow-induced signal and noise components to provide a favorable signal-to-noise ratio.
But in the case of an electromagnetic flowmeter of the above-described Mannherz type in which the excitation frequency is well below 60 Hz, we find that the frequency components of the noise spectrum do lie in the excitation frequency range; hence discrimination between noise and signal cannot be effected, and the signal-to-noise ratio is unfavorable. Indeed, in some instances, the magnitude of the noise relative to that of the flow-induced signal is such as to render the meter useless.

Noise-reducing electrodes for electromagnetic flowmeter


A control apparatus and associated method for a refrigeration system are provided. The control apparatus includes sensors capable of detecting controlled refrigerator zone temperatures and superheat levels of refrigerant vapour exiting an evaporator. The control module receives input from the sensors, compares the input to a determined controlled refrigerator zone set point and a learned superheat level, and generates an output with respect thereto. In particular the output modulates an electronic evaporator pressure regulating (EEPR) valve between an open and a closed position in response to detecting abnormal operation of the thermostatic expansion valve or electronic expansion valve.

Generally, a refrigeration system includes a compressor, a condenser, an expansion valve, and an evaporator. Refrigerant vapor is compressed to a high pressure by the compressor and is conducted through the condenser where it is cooled to form a liquid under high pressure. This high pressure liquid is then adiabatically expanded through the expansion valve into the evaporator. In the evaporator, the refrigerant absorbs heat from the surroundings of the evaporator, which transforms the low pressure liquid refrigerant into a vapor. In this process, the environment surrounding the evaporator, for example, a refrigerator case, is cooled. The refrigerant vapor is then returned to the compressor via a suction line.
Generally, it is desirable to control the amount of liquid refrigerant returning to the inlet of the compressor from the evaporator. In some cases, liquid refrigerant may dilute the lubricating oil in a typical hermetic compressor and thus cause damage to the compressor. Also, liquid refrigerant may damage certain of the compressor components, such as the compressor reed valves.
Another concern with many refrigeration systems is the presence of ice on the evaporator coils. During normal operation of many refrigeration systems, the evaporators may operate at temperatures low enough for water vapor to crystallize on the evaporator coils. This can produce a "frost" on the coils, which may reduce the efficiency of the refrigeration system and may result in liquid refrigerant flooding the compressor. As a result, the surfaces of the evaporator coils must periodically be defrosted.
Various techniques for defrosting refrigeration systems are known. For example, one method for defrosting refrigeration systems is to reverse the refrigeration cycle. When the refrigeration cycle is reversed, hot refrigerant vapor from the compressor is directed into the evaporator outlet, through the evaporator, into the condenser inlet, through the condenser, and back into the compressor. A problem with this method is that often the temperature of refrigerant entering the compressor is so low that some liquid is introduced into the compressor. As discussed above, the presence of liquid in the compressor may damage or destroy the compressor. In addition, the temperature of the refrigerant entering the evaporator may be too low for rapid or complete defrosting of the evaporator. Thus, the defrost cycle may be very time consuming or the evaporator may not be completely defrosted.
As such, there is a need for improved refrigeration systems, in particular, for refrigeration systems in which the amount of liquid refrigerant entering the compressor is controlled and/or in which the amount of ice build up on the evaporator coils is controlled.


Syringe/conduit combination with a syringe part (1) and a conduit part (2). The parts have a male slip fitting (4) and a female slip fitting (5) for press fitted connection. The syringe part (1) has a hollow barrel (22) and a plunger (23) inserted into the barrel (22). The plunger (23) and the hollow barrel (22) have abutments (25, 27) defining a maximally inserted position of the plunger (23). The male slip fitting (4) fits in the female slip fitting (5) such that the male slip fitting (4) is at an axial distance of less than 0.1 mm from an internal end of the female slip fitting (5). The plunger (23) in its maximally inserted position is then at an axial distance from an opposite one of the slip fittings (5) that is equal to or less than the axial distance between the male slip fitting (4) and the internal end (9) of the female slip fitting (5).

The present invention generally relates to syringe/conduit combinations having a frustoconical male slip fitting and a frustoconical female slip fitting, the male slip fitting being inserted or insertable into the female slip fitting establishing a press fitted connection. The conduit part may for instance be a needle assembly or via which a fluid can be injected into a medical tubing, a bag or a catheter.
Syringes are typically joined to downstream tubing by connecting matching fittings on the distal end of the syringe and a proximal end of the conduit part. One common connector type has matching male and female fittings each having conical surfaces that, when the fittings are connected, provide a sealed press fit connection between tubes. Conical fittings that form a seal by pressing the fittings together are often referred to as "slip fittings" Conical fittings that also include a form locked axial load transfer, such as threaded elements or a bayonet fitting are often referred to as "lock fittings."
Standards have been developed to permit compatibility of standard fittings. An example of specifications for conical fittings used for medical applications may be found, for example, in the International Standard ISO 594-1 titled "Conical fittings with 6% (Luer) Taper for syringes, needles and certain other medical equipment," and referred to herein as the "ISO Luer Standard."
FIGS. 1 through 3 slip fitting conforming to the ISO Luer Standard are shown, where FIG. 1 is a side view of a male slip fitting 10 and a matching female slip fitting 20, and FIG. 2 is a sectional view along the line II-II in FIG. 1.
The male slip fitting 10 has an external frustoconical surface 11 and a distal end 16 for inserting into female slip fitting 20. The female slip fitting 20 has an internal frustoconical surface 21 matching at least a portion of the external frustoconical surface 11 of the male slip fitting 10.
The slip fittings 10 and 20 each have conical surfaces resulting in a conical angle θ, as shown. According to the ISO Luer Standard, the value of this conical angle is 6°. The external frustoconical surface 11 of the male slip fitting 10 has a height A from a proximal base 17 to the distal end 16 having a diameter B. The internal frustoconical surface 21 of the female slip fitting 20 has a depth D extending from an opening with a diameter C to a bottom end 26. The height A, diameters B and C and depth D, are mandated by the ISO Luer Standard, and define contacting surfaces.
FIG. 3 is a sectional view along the line II-II in FIG. 1, but with the male and female slip fittings 10 and 20 connected by applying an axial pressure force of 27.5 N for 5 s whilst twisting action if any is limited to a torque value not exceeding 0.1 Nm to give rotation not exceeding 90°. Such an engagement force is also called an axial engagement force or normalized axial engagement force, and is applied such that a portion of frustoconical surfaces 11 and 21 are in contact, where the contact portion is indicated by the length X. The ISO Luer Standard mandates that the distal end 16 and bottom end 26 be separated by a distance, which is indicated as E=X−D. The value of E is not specified by the ISO Luer Standard, but is required to be greater than zero. In practice, in ISO Luer Standard compliant fittings, the distance E is typically about 2 mm or more and the diameter B is approximately 4 mm, so that, a "dead space" 300 within connected fittings 10 and 20 of approximately 40 μl is left, in addition to the dead space constituted by the channels in the syringe part and in the conduit part. Medicament volumes left in this dead space constitute a waste of medicament and associated costs, in particular when expensive drugs are administered. Medicament leftovers in the dead space may also constitute an environmental and/or health hazard.
Other, functional requirements of the ISO Luer Standard are that after a slip type connection has been made, to prevent inadvertent disconnection, the slip type connection should resist an axial removal force of 35 Newton and unscrewing torque of up to 0.02 Nm without disconnection. In addition, slip type connections should also hold a seal against 3 bar after a connection has been made. In slip fitting connections this resistance and sealing is supplied by the friction between the opposing conical surfaces.

Low residual volume syringe/conduit combination and syringe for such a syringe/conduit combination


An apparatus and a method for measuring the flexural characteristic of a golf club shaft. The apparatus includes a table having a clamping structure for clamping the golf club shaft thereto. A data collection system having a computer coupled to an image recording device measures the amount of deflection of the golf club shaft before and after a bending moment is applied to the golf club shaft. The stiffness of the golf club shaft is determined from the amount of deflection.

This invention relates, in general, to an apparatus for measuring physical properties of golf club shafts and, more particularly, to a method and apparatus for measuring a flexural characteristic of a golf club shaft.
In the field of designing, modifying, and fitting golf clubs, it is advantageous to know the physical properties of the golf club shaft as well as the physical properties of the golf club head. It is common in the industry to rate clubs based on the flexural stiffness designated typically by the terms: Extra Stiff (XS); Stiff (S); Firm (F); Regular (R); Average (A); and Ladies (L). The flexural stiffness is important because it determines the maximum bending as well as the first bending mode frequency of the shaft and, therefore by selecting the appropriate shaft stiffness, the club can be optimized for the swing speed of the particular golfer. The torsional stiffness of the golf club is also important because it determines the maximum windup of the club head relative to the shaft and the torsional frequency at which the club head oscillates about the axis of the golf club shaft during the swing. For optimum performance, in addition to matching the flexural stiffness of the shaft to the player""s swing speed, the torsional stiffness of the shaft should also be matched to the club head swing weight and the player""s swing speed. Another important physical property of the golf club shaft is its frequency of oscillation because it provides a reproducible and reliable index of shaft flexibility. Further, the frequency of oscillation allows frequency matching of golf clubs to form a set of golf clubs which have a substantially uniform xe2x80x9cfeelxe2x80x9d to the golfer.
A common prior art apparatus for determining the deflection of a golf club shaft is illustrated in FIG. 1. What is shown in FIG. 1 is a flex board 10 having a golf club shaft clamping structure 11, a plurality of mirrors 12, and a golf club shaft 13. Golf club shaft 13 has a butt end 14, i.e., a grip end, and a tip end 15, i.e., a head end. Clamping structure 11 includes a receptacle 17 for receiving butt end 14 of golf club shaft 13 and a clamp 18 for securing golf club shaft 13 to flex board 10. Flex board 10 further includes calibrated scales 19 along each mirror 12. Calibrated scales 19 are marked in inches and are used to measure the deflection or flexure of golf club shaft 13 when a mass 20 is attached to tip end 15 of golf club shaft 13. Typically, golf club shaft 13 is manually adjusted by an operator after insertion into clamping structure 11 to ensure that it is properly mounted to flex board 10. The operator then adds mass 20 to tip end 15 and records the number of inches golf club shaft 13 is deflected at a predetermined distance along the golf club shaft. For example, the deflection can be measured at the location indicated by reference number 21 or at the location indicated by reference number 22. Although this technique has been used for many years, it is dependent on human operators who may introduce variation into the measurements because of parallax error and operator fatigue. In addition, this technique does not permit making continuous flex measurements along the golf club shaft, i.e., the measurement is made at a discrete point along the golf club shaft.
The present invention provides a method and an apparatus for accurately determining the flexure of stiffness of a shaft by measuring the deflection of the shaft. In a preferred embodiment of an apparatus for measuring the deflection of a golf club shaft incorporating features of the present invention, a clamping mechanism is provided for securing one end of a shaft to a support structure of the apparatus. A flexing mechanism is provided to create a bending moment on the shaft by moving one end of the shaft. In one embodiment, the flexing mechanism comprises a pulley system in which a mass is coupled to the end of the shaft not secured to the support structure. In another embodiment, the flexing mechanism comprises a stop against which the end of the shaft not secured to the support structure is pushed. An image recording device creates an image of the shaft before and after the creation of the bending moment on the shaft. The image is transmitted to a computer which creates a model that mathematically describes the deflection of the golf club shaft. A plot in accordance with the mathematical model can be displayed on a computer screen. The flexure of stiffness of the golf club shaft is determined from the deflection.

Method and apparatus for measuring a flexural characteristic of a golf club shaft