Patent Application
20090206859
The invention relates to electrical probe devices used to measure electrical signals on conductors of a device under test (DUT). More particularly, the invention relates to a probe device having a light source located thereon.
A probe device is a device having two arms, sometimes referred to as “substrates” or “blades”, which are mechanically coupled to each other at distal ends of the arms, and having electrically conductive tips secured to the proximal ends of the arms. During testing of a DUT, the tips are placed in contact with respective conductors of the DUT for sensing electrical signals propagating though the conductors of the DUT. The probe device is typically adjustable to allow the probe tips to be moved closer to and farther away from each other such that a span width between the tips is adjustable to accommodate varying DUT physical layouts. The electrical signals sensed by the tips are passed from the tips to other electrical circuits disposed on the arms that prepare the signals for input to a differential amplifier circuit. The arms are each electrically coupled at their distal ends to respective electrical wires, such as coaxial cables, which receive the amplified differential signals output from the amplifier circuit and pass the amplified signals to test and measurement equipment, such as an oscilloscope.
In order for the user to make physical contact between the tips of the probe device and the conductors of the DUT, the user visually observes the positions of the tips relative to the conductors and moves the tips until they are in physical contact with desired locations on the conductors of the DUT. This is becoming increasingly difficult due to the physical dimensions on the DUT components becoming increasingly smaller. In addition, modem high-speed probing is typically performed differentially, which requires that the tips be placed in contact with separate points on the DUT simultaneously. With pads on the DUT now being on the order of 1/4 millimeter (mm) in diameter, it is becoming almost impossible for the user to see well enough to make good contact between the probe tips and the pads.
Solutions to this problem have been proposed or implemented. For example, Agilent Technologies, Inc., the assignee of the present application, offers a 19600 series Logic Analyzer that uses a software indicator that detects when good contact is made between the probe tips and the pads of the DUT and triggers an on-screen indication that is displayed on the scope display screen of the Logic Analyzer to inform the user that good contact has been made. This system employs a user-adjustable threshold voltage and circuitry that detects when the voltage measured by the tips exceeds the threshold voltage level. When the measured signal exceeds the threshold level, the on-screen indication is triggered.
While this solution is satisfactory in many cases, one problem with this solution is that the user is required to look at the scope display screen to determine when good contact has been made between the probe tips and the DUT contact pads. Because of the dexterity required by the user when performing this task, it can be difficult for the user to watch the screen while trying to place the probe tips in contact with the DUT contact pads. In addition, once contact has been made, it can be difficult for the user to maintain contact while viewing the scope screen.
Accordingly, a need exists for a probe device having a visual indicator of connection status that is easily viewable by the user as the user is attempting to place the tips in contact with the contact areas on the DUT and as the user is attempting to maintain contact between the tips and the contacts on the DUT.
Yet another difficulty associated with current probe devices is that they provide no source of illumination for illuminating the probe tips or the contact points on the DUT. Currently, the only way to illuminate the tips and the contact points on the DUT is to have a person hold a flashlight or lamp over the area in question as the user attempts to navigate the probe device to bring the tips into contact with the contacts on the DUT. Often times, the hand holding the probe device, or large components on the circuit board, cast shadows over the area in question. Consequently, this solution is inadequate for its intended purpose. Accordingly, a need also exists for a way to satisfactorily illuminate the probe device tips and the areas on the DUT in question as the user attempts to place the tips in contact with the contact points on the DUT.
The invention provides a probe device having a light source, a system that incorporates the probe device, and a method for placing a light source in at least a first mode if a first control signal is sent to the probe device. The probe device comprises a probe device housing having a distal end connected to first and second conductive wires, first and second arms each having a proximal end and a distal end, first and second electrically conductive tips secured to the first and second arms, respectively, a light source secured to the probe device housing, and light source indicator driver circuitry in the housing. The driver circuitry is configured to cause the light source to be placed in a first mode if a first control signal is received in the driver circuitry.
The system comprises a probe device having a housing to which a light source is secured and a scope apparatus. The scope apparatus comprises processing circuitry configured to receive electrical signals sensed by first and second tips of the probe device and sent over the first and second conductive wires, respectively, to the scope apparatus. The scope apparatus determines whether or not the electrical signals sensed by the first and second tips indicate that the first and second tips are in good electrical contact with first and second contact areas, respectively, on the DUT. If the scope apparatus determines that the electrical signals sensed by the first and second tips indicate that the first and second tips are in good electrical contact with the first and second contact areas, respectively, on the DUT, the scope apparatus causes a first control signal to be sent over a communication link to light source indicator driver circuitry of the probe device. The driver circuitry of the probe device causes the light source to be placed in a first mode if the first control signal is sent by the scope apparatus to the probe device.
The method comprises receiving an indication of a difference between electrical voltage signals sensed by first and second probe tips of a probe device, determining whether or not the received indication indicates that the first and second tips are in good electrical contact with first and second contact areas, respectively, on the DUT, if a determination is made that the received indication indicates that the first and second tips are in good electrical contact with first and second contact areas, respectively, on the DUT, causing a light source on the probe device to be placed in a first mode and if a determination is made that the received indication indicates that the first and second tips are not in good electrical contact with first and second contact areas, respectively, on the DUT, causing a light source on the probe device to be placed in a second mode.
These and other features and advantages of the invention will become apparent from the following description, drawings and claims.
In accordance with the invention, a probe device is provided that has a light source thereon. In accordance with an embodiment, the light source operates as a visual indicator to provide a visual indication of whether a good connection exists between the tips of the probe device and the intended contact points on the DUT. In accordance with another embodiment, the light source operates as a source of illumination to illuminate the probe tips and the contact pads on the DUT as the user is attempting to place the probe tips in contact with the contact pads on the DUT. In accordance with another embodiment, the light source performs the dual functions of providing a visual indication of connection status and of illuminating the probe device tips and the intended contact points on the DUT.
A variety of probe device configurations are possible that will enable the goals of the invention to be achieved. A few examples of possible configurations will now be described with reference to the figures. It should be noted, however, that the invention is not limited to the probe device configurations described herein, as will be understood by persons of ordinary skill in the art in view of the following description and claims. For example, although the invention is being described herein with reference to a differential probe device for illustrative purposes, the invention is suitable for use with probe devices that are not differential probe devices. It should also be noted that the figures are not necessarily drawn to scale. The figures are intended to demonstrate the principles and concepts of the invention without being limited in terms of dimensions or shape.
The probe device 1 includes a light source 10 that provides an indication of the electrical connection status of the probe device 1. Preferably, the light source 10 is located on the upper surface of the probe device 1 as shown on the distal end 2A of the housing 2. Thus, the light source 10 is clearly visible to a person who is using the probe device 1 as that person is attempting to place the probe tips 3A and 4A in physical contact with the contact pads (not shown) of the DUT (not shown). This makes it unnecessary for the person using the probe device 1 to turn away from the probe tips 3A and 4A to look at the scope screen of the logic analyzer to ascertain whether an electrical connection has been made or is being maintained. This feature of the invention also allows persons with poor eyesight to know when the probe tips 3A and 4A have been correctly placed on contact areas of the DUT. This feature of the invention ensures that even as the physical dimensions of components on the DUT continue to decrease in size, and therefore become more difficult to accurately probe, the user will know when the tips 3A and 4A are in contact with the intended contact areas on the DUT.
The light source 10 is typically a light emitting diode (LED), but may be any type of suitable illumination device. LEDs are available that are very small in size, remain at relatively low temperatures during operation, and have relatively long life spans. These characteristics of LEDs make them highly suitable for placement on the probe device 1. In the case where an LED is used for this purpose, the LED 10 illuminates when an appropriate electrical connection has been made between the probe tips 3A and 4A and the contact points on the DUT. What constitutes an “appropriate” electrical connection preferably is user definable through the scope user interface. An “appropriate” electrical connection may be defined in several ways. For example, one technique is to simply cause the LED 10 to be illuminated when there is a non-zero voltage level between the probe tips 3A and 4A. Thus, in this case, an “appropriate” electrical connection is one that results in a non-zero voltage level between the probe tips 3A and 4A. A threshold voltage level may be defined through the user making an appropriate selection via the scope user interface. If the voltage measured between the tips 3A and 4A is equal to or exceeds this user-selected threshold voltage, the LED 10 may be activated (i.e., turned on). If the voltage measured between the tips 3A and 4A falls below the user-selected threshold voltage, the LED 10 may be deactivated (i.e., turned off).
In order to activate and deactivate the LED 10, a source of power is typically needed in the probe device 1. A suitable power source for this purpose is a small dc battery, which may be located in the housing 2 near its distal end 2A. Also, in order to provide user-customization to enable user-defined settings (e.g., the threshold voltage level) to be applied by the user, communication between the scope apparatus and the circuitry in the probe device 1 that controls the LED 10 is needed. The cables 6 and 7 that communicate signals from the probe device 1 to the scope apparatus generally are not suitable for sending control signals from the scope apparatus to the probe device 1. In order to allow the scope apparatus to control the Led 10 based on the voltage sensed by the tips 3A and 4A, the scope apparatus needs to have some way of communicating control signals to the circuitry in the probe device 1 that controls the LED 10. The manner in which this can be accomplished will now be described with reference to a few illustrative embodiments depicted in
In the scope apparatus 30, the sensed signals are received and processed in a known manner in accordance with the test or tests being performed by the scope apparatus 30. The scope apparatus 30 then causes signal traces corresponding to the sensed signals to be displayed on the display screen 31. Various selector switches 35 are provided on the control panel 32 to enable the user to select the manner in which the signals measured by the probe device 1 are to be processed and displayed on the display screen 31. Alternatively, the scope apparatus 30 may have a control panel that is part of a graphical user interface (GUI), in which case menus and buttons displayed on a display device (e.g., display screen 31) are provided to allow the user to make appropriate selections.
In accordance with this embodiment, the scope apparatus 30 includes a processor or controller (not shown) that performs an algorithm that determines whether the difference between the voltage levels sensed by the tips 3A and 4A (i.e., the differential voltage level) is equal to or greater than a particular threshold level, THDIFF. If so, then the algorithm performed by the scope apparatus 30 causes a first indicator control signal, SIN1, to be sent via a conductive wire 40 to the probe device 1. The conductive wire 40 may be, for example, an RF wire such as a coaxial cable. The coaxial cables 6 and 7 that are typically used to send the differential signals from the probe device 1 to the scope apparatus 30 sometimes include extra wires, one of which could be used as wire 40 to communicate the control signal SIN1 from the scope apparatus 30 to the probe device 1.
In the probe device 1, indicator circuitry, which is described below with reference to
Other characteristics associated with the signals measured by the probe device tips 3A and 4A could be used instead of, or in combination with, the voltage level to determine whether an appropriate electrical connection has been made between the tips 3A and 4A and the contact pads on the DUT. For example, the frequency of the measured signal could be used to determine whether an appropriate electrical connection has been made. The invention is not limited with respect to which characteristics of the measured signal are used to make this determination.
Also, although the algorithm that processes the signals sensed by the probe tips 3A and 4A to determine whether the light source 10 is to be illuminated or darkened is typically performed by the scope apparatus 30, this algorithm could instead be performed by processing circuitry contained within the probe device 1 itself. For example, probe devices sometimes include integrated circuits (ICs), such as application specific integrated circuits (ASICs), for example. In such cases, the algorithm described above could be performed within the ASIC of the probe device, in which case the wired communication link 40 would not be needed because the signals SIN1 and SIN2 would be produced by and used by circuitry within the probe device 1.
If the algorithm that processes the signals sensed by the probe device tips 3A and 4A and produces the indicator control signals SIN1 and SIN2 is to be performed within the probe device 1 instead of in the scope apparatus 30, the circuitry 50 shown in
The indicator control signals SIN1 and SIN2 may be signals that have different voltage levels. For example, control signal SIN1 may be a voltage signal having a high voltage level (e.g., 5 volts) and control signal SIN2 may be a voltage signal having a low voltage level (e.g., 0 volts). In this case, the indicator light source driver circuitry 51 will receive the signals SIN1 and SIN2 and produce corresponding high and low output signals, respectively, which, in turn, cause the indicator light source 10 to be activated and deactivated, respectively. Of course, the indicator light source driver circuitry 51 may be configured with inverter circuitry (not shown) such that a high-level input signal is converted into a low-level output signal, and vice versa. In the latter case, a low-level SIN1 signal received by the indicator light source driver circuitry 51 will result in a high-level driver signal being output from the indicator light source driver circuitry 51, whereas a high-level SIN2 signal received by the indicator light source driver circuitry 51 will result in a low-level driver signal being output from the indicator light source driver circuitry 51.
Alternatively, the indicator control signals SIN1 and SIN2 may be signals that have the same voltage level, in which case the indicator light source driver circuitry 51 contains toggle circuitry (e.g., flip-flop circuitry). In this case, if SIN1 is a signal having a high voltage level, the output signal produced by the indicator light source driver circuitry 51 is a signal having a high voltage level. If the next signal received by the indicator light source driver circuitry 51 is SIN2 having the same high level as the immediately preceding signal SIN1, the toggle circuitry contained in the indicator light source driver circuitry 51 will toggle its output, causing the output signal produced by the indicator light source driver circuitry 51 to have a low level. The indicator light source driver circuitry 51 may be configured in virtually an infinite number of ways to achieve the functions necessary for driving the indicator light source 10.
In the scope apparatus 70, the sensed signals are received and processed in a known manner in accordance with the test or tests being performed by the scope apparatus 70. The scope apparatus 70 then causes signal traces corresponding to the sensed signals to be displayed on the display screen 71. Various selector switches 75 provided on the control panel 72 are used by the user to select the manner in which the signals measured by the probe device 100 are processed and displayed on the display screen 71. Alternatively, the scope apparatus 70 may have a control panel that is part of a GUI, in which case menus and buttons displayed on a display device (e.g., display screen 71) are provided to allow the user to make appropriate selections.
The scope apparatus 70 performs an algorithm in accordance with the invention that determines whether the difference between the voltage levels sensed by the tips 103A and 104A (i.e., the differential voltage level) is equal to or greater than THDIFF. If so, then the algorithm performed by the scope apparatus 70 causes a first wireless indicator control signal, SIN1, to be generated by wireless transmitter 80 and sent over wireless link 90 to the probe device 100. In the probe device 100, indicator circuitry (described below with reference to
If the scope apparatus 70 determines that the sensed differential voltage level is less than THDIFF, then the scope apparatus 70 causes a second indicator control signal, SIN2, to be generated by the wireless transmitter 80 and sent via the wireless link 90 to the probe device 100. In the probe device 100, indicator circuitry (
As indicated above with reference to
Also, although the algorithm that processes the signals sensed by the probe tips 103A and 104A to determine whether the light source 110 is to be illuminated or darkened is typically performed by the scope apparatus 70, this algorithm could instead be performed by processing circuitry contained within the probe device 100. For example, the algorithm described above could be performed within an ASIC of the probe device 100, in which case the wireless communication link 90 would not be needed because the signals SIN1 and SIN2 would be produced by and used by circuitry within the probe device 100.
If the algorithm that processes the signals sensed by the probe device tips 103A and 104A and produces the indicator control signals SIN1 and SIN2 is to be performed within the probe device 100 instead of in the scope apparatus 70, the circuitry 120 shown in
The indicator light source driver circuitry 121 may have various configurations similar to those described above with reference to the indicator light source driver circuitry 51 shown in
It should be noted that the threshold voltage level, THDIFF, may be set by the user. For example, with reference to
If a determination is made at block 142 that an appropriate connection has been made, then the indicator light source on the probe device is caused to be placed in a first mode, as indicated by block 143. This first mode typically corresponds to the indicator light source being illuminated. If a determination is made at block 142 that an appropriate connection has not been made, then the indicator light source on the probe device is caused to be placed in a second mode, as indicated by block 144. This second mode typically corresponds to the indicator light source being darkened.
If the algorithm represented by the flowchart shown in
The processor that performs the algorithm represented by the flowchart shown in
In accordance with another illustrative embodiment of the invention, the light source 10 (
In accordance with yet another embodiment of the invention, the light source on the probe device performs the dual functions of providing a visual indication of connection status and of illuminating the DUT to enable the user to easily see the contact points on the DUT as the user attempts to place the probe tips in contact with the contact points on the DUT. For example, the light source 150A, 150B shown in
To provide an example of the manner in which this embodiment may be carried out, it will be assumed that a white light LED is used as the light source 150A, 150B. With reference to
It should be noted that the invention has been described with reference to illustrative embodiments for the purpose of describing the principles and concepts of the invention. Those skilled in the art will understand, in view of the description provided herein, that many modifications may be made to the embodiments described herein without deviating from the scope apparatus of the invention.
