TW201337920A - Resistive temperature sensors for improved asperity, head-media spacing, and/or head-media contact detection - Google Patents

Abstract

A sensor supported by a head transducer has a temperature coefficient of resistance (TCR) and a sensor resistance. The sensor operates at a temperature above ambient and is responsive to changes in sensor-medium spacing. Conductive contacts connected to the sensor have a contact resistance and a cross-sectional area adjacent to the sensor larger than that of the sensor, such that the contact resistance is small relative to the sensor resistance and negligibly contributes to a signal generated by the sensor. A multiplicity of head transducers each support a TCR sensor and a power source can supply bias power to each sensor of each head to maintain each sensor at a fixed temperature above an ambient temperature in the presence of heat transfer changes impacting the sensors. A TCR sensor of a head transducer can include a track-oriented TCR sensor wire for sensing one or both of asperities of the medium.

Description

Resistive temperature sensor for improved roughness, probe-to-medium spacing, and/or probe-to-medium contact detection Related patent documents

This application claims the priority of the provisional patent application number 61/414,733 and 61/414,734, filed on November 17, 2010, in accordance with 35 USC § 119(e), and therefore, such applications They are incorporated herein by reference in their entirety.

The present invention relates to apparatus and methods for resistive temperature sensors for improving roughness, probe-to-medium spacing, and/or probe-to-medium contact detection.

Embodiments of the present invention are directed to an apparatus including a probe transducer that is to interact with a magnetic recording medium. The sensor is placed at the probe transducer and has a temperature coefficient of resistance and a sensor resistance. The sensor system is operative to operate at temperatures above ambient temperature and is responsive to changes in the distance between the sensor and the medium. The conductive contacts are connected to the sensor and have contact resistance. The contact has a cross-sectional area that is adjacent to the sensor and larger than the cross-sectional area of the sensor such that the contact resistance becomes smaller relative to the sensor resistance and negligibly contributes to the signal generated by the sensor .

Embodiments are directed to a method comprising: moving a magnetic recording medium relative to a probe transducer, sensing using a sensor having a temperature coefficient of resistance The temperature at the point of proximity of the probe converter. The sensor is connected to a conductive contact having a contact resistance. The contact has a cross-sectional area that is adjacent to the sensor and larger than the cross-sectional area of the sensor such that the contact resistance becomes smaller relative to the resistance of the sensor and negligibly contributes to the generation by the sensor signal. The method further includes outputting the sensor signal and detecting the roughness of the medium using the sensor signal.

According to various embodiments, the apparatus includes: a plurality of probe transducers that are configured to interact with the magnetic recording medium; and a plurality of sensors having a temperature coefficient of resistance. At least one sensor is disposed on the respective probe transducer and is responsive to a change in the distance between the sensor and the medium. The power source architecture supplies bias power to each of the respective probe converters and adjusts the bias power to maintain each sensor at ambient temperature in the presence of thermal transfer changes that affect the sensor At a fixed temperature above.

In other embodiments, the method includes moving the magnetic recording medium relative to the plurality of probe transducers, using a sensor having a temperature coefficient of resistance to sense a change in the distance between the probe transducer and the medium. The method further includes supplying a bias power to the sensor and adjusting the bias power to maintain each of the sensors at a fixed temperature above the ambient temperature in the presence of a change in thermal transfer affecting the sensor.

Embodiments are directed to an apparatus including a probe transducer that is to interact with a magnetic recording medium having a plurality of tracks. The device also includes a sensor having a temperature coefficient of resistance and configured in the probe transducer such that the longitudinal axis of the sensor is substantially flat relative to the trajectory The row orientation, the sensor is responsive to one or both of the roughness of the medium and the change in the distance between the sensor and the medium.

In a further embodiment, the method includes moving the magnetic recording medium relative to the probe transducer, using a sensor having a temperature coefficient of resistance to sense the roughness of the medium and the change in the distance between the probe transducer and the medium One or both. The sensor has a longitudinal axis that is oriented substantially parallel with respect to the trajectory.

These and other features and aspects of various embodiments will be apparent from the description and drawings.

A data storage system typically includes one or more recording probe transducers that read and write information to the magnetic recording medium. It is always desirable to have a relatively small distance or spacing between the recording probe transducer and its associated medium. This distance or spacing is known as the flying height 〞 or the spacing of the probe to the medium. By reducing the pitch of the probe to the medium, the recording probe transducer can typically write data to and read data from the medium. Moreover, reducing the pitch of the probe to the medium allows measurements such as the roughness and other characteristics of the surface of the recording medium to be used to record the condition of the recording medium.

In accordance with various embodiments, and with reference to Figures 1 through 3, the slider 100 supported by the suspension 101 is shown to be in close proximity to the rotating magnetic recording medium 160. The slider 100 supports the recording probe transducer 103 and the heater 102, which is thermally coupled to the probe transducer 103. The heater 102 can be a resistive heater and generate heat when current passes through the heater 102. the amount. Heater 102 is not limited to resistive heaters and may include any type of heat source. Thermal expansion of the probe transducer 103 is caused by thermal energy generated by the heater 102. This thermal expansion can be used in a data storage system to reduce the probe-to-medium spacing 107. It is noted that in certain embodiments, non-thermal actuators can be used to reduce the probe-to-medium spacing 107.

The resistive temperature sensor 105, located on the probe transducer 103, is shown at or near the approach point. Preferably, the resistive temperature sensor 105 is a sensor having a temperature coefficient of resistance (TCR) and is referred to herein as a TCR sensor 105. As explained previously, actuation of the probe transducer 103 can be accomplished by a thermal actuator such as heater 102, or other actuator (e.g., a writer). The bias power is applied to the TCR sensor 105 to increase the surface temperature of the sensor 105 and the abutting portion of the probe converter 103 to be substantially higher than the temperature of the magnetic recording medium 160.

Preferably, the TCR sensor 105 is configured to sense changes in the heat flow for detecting the beginning of contact of the probe to the medium. The details of the determination of the probe-to-medium spacing and contact in accordance with various embodiments of the present invention are disclosed in co-owned U.S. Patent Application Serial No. 12/941,461, filed on Nov. 8, 2010. It is incorporated herein by reference.

As depicted in FIG. 3, there is an air gap 107 defined between the hot probe surface and the relatively cold disc 160 prior to the probe-to-medium contact. Probe transducer 103, air gap 107, and magnetic recording disc 160 define one of the levels of thermal transfer rate. When the probe transducer 103 is in contact with the disc 160 after actuation, such as by a thermal actuator or heater 102, then between the probe transducer 103 and the high thermal conductivity material of the disc 160 Direct contact can greatly increase the rate of heat transfer. Thus, the TCR sensor 105 on the probe transducer 103 senses the drop in temperature or the amplitude of the temperature track, allowing probe-to-medium contact detection.

Figure 4A depicts a representative temperature profile for the recording probe transducer 103 of the type shown in Figures 1 through 3 before, during, and after contact between the probe transducer 103 and the surface of the magnetic recording disk 160. . In this non-limiting illustrative example, the temperature profile is indicative of a steady state DC signal for the purpose of illustration. When the probe transducer 103 is actuated by the thermal actuator 102, the probe transducer surface temperature will increase with actuation due to the heat generated by the thermal actuator 102. The probe converter temperature will be higher than the temperature of the disc 160. Therefore, in this scenario, the disc 160 acts as a heat sink. When the probe transducer 103 contacts the disc 160, the probe transducer surface temperature will drop due to a change in the thermal transfer rate caused by the contact. Due to thermal actuator heating and friction heating, the surface temperature of the probe transducer will continue to increase. The change in temperature or the amplitude in the temperature track can be used to indicate the probe to medium contact.

Figure 4B depicts a representative temperature profile for a recording probe transducer 103 that is actuated by a non-thermal actuator. In this illustrative example, the TCR sensor bias power self-heats the TCR sensor 105, causing the probe to increase the temperature at the disc interface to a temperature substantially higher than the temperature of the disc 160. In this scenario, the disc 160 acts as a heat sink. When the probe transducer 103 is actuated downward toward the disk 160, the heat transfer rate is gradually increased, causing the temperature of the sensor 105 to gradually decrease. When the probe transducer 103 becomes in contact with the disc 160, there will be a change in the thermal transfer rate. , which causes the amplitude of the surface temperature of the probe converter. The TCR sensor 105 on the surface of the probe transducer measures this temperature amplitude and detects the contact of the probe to the medium. If the actuation of the probe-to-medium contact will occur further, the temperature will eventually increase due to frictional heating.

In the following description, the temperature coefficient of the resistance wiring will be referred to to illustrate an embodiment of a suitable resistive temperature sensor in accordance with various embodiments. It should be understood that the term "wire" is used herein for the purpose of illustration and does not limit the resistive temperature sensor or sensor element to a wiring structure. Other TCR configurations and sensor configurations can also be imagined.

Referring now to Figure 5, there is depicted a wide variety of processes for sensing probe-to-medium spacing changes and contact events in accordance with various embodiments. Moving 140 through the probe transducer relative to the magnetic recording medium, the method depicted in FIG. 5A includes sensing the temperature of the proximity point of the probe 142 using a resistive temperature sensor coupled to the low resistance contact. . Moreover, the method includes outputting 144 a sensor signal that is not confused by the components of the signal facilitated by the contacts. A wide variety of processing can be performed using the sensor signals, including detecting the roughness of the medium 146, measuring the change in the pitch of the probe 147 to the medium, and detecting the contact of the probe 148 to the medium.

When the TCR wiring that drives the resistive temperature sensor heats up (eg, above ambient temperature, and in particular above the temperature of the associated magnetic recording medium), then a portion of the heat generated by the wiring Will disappear from the adjacent conductive contacts. Typically, conventional implementations have a relatively high electrical resistance in the junction of the sensor adjacent to the heat. Thus, in the TCR wiring The junction of the next wall also ultimately contributes to the measured signal, and the 〝 effective sensor 〞 is greater than the geometry of the designed TCR wiring sensor.

This has several issues, including but not limited to the following. The effective size of the TCR sensor is greater than desired. In the case of roughness detection, the characteristics of the roughness size smaller than the effective length of the TCR cannot be accurately displayed. Since the resistance of the contact also contributes to the measured change in resistance, it is not possible to set a true TCR-only wiring/sensor overheating ratio OHR. This will vary from design to design, unless the resistance of the contacts or the temperature to which the contacts are exposed is negligible. Finally, large contacts will have greatly different frequency responses relative to small TCR wiring. If the contacts also contribute to the measured signal, then the contacts will contaminate the measured response of the TCR wiring itself.

Typically, the TCR wiring sensor is driven to heat up, i.e., a sufficient electrical bias is placed over the TCR wiring to heat it to its surroundings, as desired. The sensor signal is then obtained by measuring a change in temperature due to a change in thermal transfer of the resistive element sensor. Because the material has a temperature coefficient of electrical resistance, a change in temperature causes a change in the resistance of the sensor. Equation (1) below shows how the resistance of the TCR wiring changes with temperature for a given TCR ( α ₀ ):

Ideally, only the change in resistance due to temperature changes in the TCR sensor itself is measured. However, the TCR sensor is attached to the conductive contacts in the probe converter and also external to the probe converter that also has resistance Leads. Equation (2) below shows how the measured resistance contains interest, that is, the TCR wiring resistance to be measured, and also includes the contact resistance (ie, it can be exposed to the TCR sensing in the probe converter). The resistance of the device or the temperature from the heater element, and the lead resistance (ie, the resistance outside the probe that is not exposed to the TCR sensor temperature or heater temperature).

In the following equation (2), the first symbols M, W, C, and L written below represent the resistances of the measurement, wiring, contacts, and leads, respectively. The second symbols H and C, written below, represent the thermal and cold wiring resistance measurements, respectively.

R _{M , H} = R _{W , H} + R _{C , H} + R _{L , H} R _{M , C} = R _{W , C} + R _{C , C} + R _{L , C} equation (2)

The following program (3) shows how the TCR wiring OHR depends on the measured resistance and contact resistance. Equation (4) below uses equation (1) above to replace the temperature difference and TCR of the junction's thermal resistance. Here, a constant and small lead resistance is ignored.

It can be found that the wiring OHR (or TCR sensor signal) depends on the temperature (T _H T _C ) to which the contact is exposed, the TCR ( α _C ) of the contact, and the cold resistance (R _{C, of the} contact) _{. C} ). Consider a resistor that is desirable to reduce the contact exposed to the temperature from the TCR sensor. When the resistor is at zero, then the portion of the OHR (or TCR sensor signal) of the junction becomes zero.

Referring now to Figures 6A and 6B, there is shown a finite element analysis model of a conventional resistive temperature sensor 200 that displays thermal TCR wiring voltage/resistance across the TCR wiring 202 and its conductive contacts 204 (6A) Figure) and temperature profile (Fig. 6B). Figures 6A and 6B show the voltage/resistance and corresponding temperature profile across a wiring design when the wiring to contact system is operating at 150 millivolts (mV) of bias (230 milliwatts (mW)). 6A and 6B are intended to show voltage/resistance and temperature profiles across conventional TCR wiring 202 and its contacts 204. This particular TCR wiring 202 has a resistance of approximately 34 ohms and a resistance of 18 ohms in the two contacts 204 (approximately the crossing track width of the wiring) directly adjacent to the TCR wiring 202 where the voltage profile can be seen. At a bias of 150 millivolts, the average TCR wiring temperature is 100 °C. The average temperature in the region of the contact 204 having an 18 ohm resistance adjacent to the TCR wiring 202 is 90 °C. The ambient temperature of the probe transducer in this case is 76 °C.

Equation (5) below shows how the change in junction temperature adjacent to the TCR wiring 202 at a given contact resistance adjacent to the TCR wiring 202 affects the measured OHR. Due to the influence of the contacts 204, the wiring OHR is 17% higher than the measured OHR. In addition, Equation (6) below shows that the incremental from the resistance of the contact 204 is 25% of the total increment in the resistance of the TCR wiring 202 and the contact 204. Thus, the signal from contact 204 represents 25% of the total TCR sensor signal.

Embodiments of the present invention are directed to reducing the implementation of non-sensor contact resistance just in the thermal TCR wiring sensor bulkhead for improved generation of only sensor signals. According to various embodiments, the region adjacent to the junction of the hot TCR wiring is expanded to effectively lower the resistance, and thus, the amount of signal from the contact is lowered.

In several embodiments, a joint having a very large cross-sectional area adjacent to the sensor is used to lower the resistance of the joint in the region. The resistance of the TCR wiring is given in Equation (7) below. The terminology of X is the resistivity, the length of the TCR wiring, and the cross-sectional area of the A _w system. According to equation (7), increasing the cross-sectional area reduces the resistance of the TCR wiring or junction profile.

FIG. 7 shows a descriptive example of a conventional TCR sensor 301 having a TCR wiring 325 and its adjacent contacts 327. Table of TCR wiring 325 The face and contacts 327 are located on the air bearing surface 320 of the probe transducer. Conventionally, contact 327 has the same downstream track thickness of TCR wiring 325 and a slowly increasing entry slider depth. Figure 8 shows a representative example of a resistive temperature sensor 302 having a low contact sensitivity TCR wiring sensor 335 in accordance with various embodiments, wherein the downstream track width of the contact 337 and the entry slider depth are This is greatly increased, resulting in a decrease in the resistance of the contact 337. In the embodiment shown in FIG. 8, the TCR sensor 302 includes a leading edge 340 and a trailing edge 350. The TRC wiring 325 and the contact 327 have individual leading and trailing edges that are aligned with the leading and trailing edges 340 and 350 of the TCR sensor 302 in parallel with each other. The leading edge of the TCR wiring 335 is recessed with respect to the leading edge of the contact 337. The relative alignment and positioning of the individual TCR wires 335 and contacts 337, as well as the approximate shape of the elements, can be varied to achieve specific roughness and probe to media spacing, and/or contact detection performance characteristics.

According to various embodiments, the TCR sensor 302 is disposed at the probe transducer and the probe transducer assembly is configured to interact with the magnetic recording medium. The TCR sensor 302 has sensor resistance and is configured to operate at temperatures above ambient temperature. For example, the TCR sensor 302 is responsive to the spacing between the sensor 302 and the media, the rough collision with the media, and the probe-to-media contact. Conductive contacts 337 are connected to TCR sensor 302 and have contact resistance. Contact 337 has a cross-sectional area that is adjacent to sensor 302 and larger than the cross-sectional area of sensor 302 such that the contact resistance becomes smaller relative to the sensor resistance and negligibly contributes to the TCR sensor 302 generated signal. Preferably, the contact 337 The resistance is negligible with respect to the resistance of the TCR sensor 302.

Implementing the TCR sensor 302 including the low resistance contact 337 can provide the effective size of the sensor 302 that contributes to the sensor signal to be substantially the same as the physical size of the sensor 302. The TCR sensor 302 with the low resistance contact 337 produces a sensor signal that is not confused by the components of the signal facilitated by the contact 337. In some embodiments, the area of the contacts 337 is exposed to thermal energy generated by one or both of the TCR sensor 302 and the heater (not shown) of the probe transducer. In this scenario, the contact resistance of the contact region 337 is reduced relative to the sensor resistance and negligibly contributes to the signal generated by the TCR sensor 302.

It can be appreciated that in various embodiments, the sensor elements 335 and contacts 337 of the TCR sensor 302 can define different regions of a single TCR structure. For example, the TCR sensor 302 can have opposite ends with the TCR sensor element 335 disposed therebetween. The opposite ends of the TCR sensor 302 have a cross-sectional area that is greater than the cross-sectional area of the sensor element 335. In these embodiments, the contacts 337 include or include opposite ends of the sensor 302.

In accordance with various embodiments, the contacts 337 can have a cross-sectional area adjacent to the TCR sensor 335 that is greater than the one of the sensors 335 by a factor ranging between 1 and 1000. In various embodiments, the contact resistance is less than the sensor resistance by a factor ranging between 1 and 1000. In various embodiments, the TCR sensor 335 is configured to operate at temperatures between about 25 and 300 ° C, while typical operations The temperature is about 100 ° C. In other embodiments, the TCR sensor 335 is configured to operate at a temperature between about 0 and 300 ° C above the ambient temperature of the magnetic recording medium and the ambient environment; typically, the range is between 25 and 75. Between °C.

In Fig. 7, a conventional TCR wiring sensor 301 is shown to have a narrow joint 327. Figure 8 shows a TCR wiring sensor 302 having a large cross-sectional area contact 337 to greatly reduce the contact resistance in accordance with an embodiment of the present invention. The particular geometry given in Figure 8 shows a possible implementation, and it should be understood that any geometry that increases the cross-sectional area of the contact 337 relative to the cross-sectional area of the TCR wiring 335 can be used. A finite element analysis model can be used to define the optimal geometry for any particular sensor design. Preferably, the TRC sensor 302 is located at or near the proximity of the probe transducer. In various embodiments, the TCR wiring 335 is sized to sense the roughness of the magnetic recording medium.

Figures 9A and 10A are schematic diagrams of the relative resistance of the two TCR wiring sensors 301 and 302 and their associated contacts 327 and 337 shown in Figures 9B and 10B as a function of track position. Figure 9A shows the resistance profile across the trajectory of a conventional TRC sensor 301 having a contact 327 having a relatively small cross-sectional area. Figure 10A shows a cross-sectional resistance profile of a TRC sensor 302 having a low sensitivity TCR wiring contact having a relatively large cross-sectional area in accordance with an embodiment of the present invention.

The theoretical contact resistance of the conventional sensor of Figure 9B is monotonically reduced from the sensor resistance value. The theoretical contact resistance of the low sensitivity contact of the TCR sensor 302 of FIG. 10B is immediately lowered and is better than in a conventional design. Reduce more quickly. Thus, the signal from contact 337 is greatly reduced to between 0 and 40 dB, or greater, depending on the geometry.

Typically, when using a hot TCR wiring sensor for a fixed electrical bias (ie, a fixed current, power, or voltage), there is a very large probe to probe in the roughness and contact detection signals. variation. Part of this signal variation comes from probe-to-probe variation due to geometry and temperature of the TCR wiring caused by thermal transfer changes across the sensor and probe transducers. This probe-to-probe variation will cause signal amplitude variations from the probe-to-probe fixed detection event.

Figure 11 is a flow diagram showing the use of a plurality of resistive temperature sensors for maintaining a plurality of probe transducers in the presence of thermal transfer affecting the sensor in accordance with various embodiments. Various treatments of temperature. Moving 180 through the probe transducer relative to the magnetic recording medium, the method depicted in FIG. 11 includes using a TCR wiring sensor to sense a change in the 182 probe-to-media spacing, while the bias power is supplied 183 to the TCR Wiring sensor. The method also includes adjusting 184 bias power to maintain the respective sensors at a fixed temperature above the ambient in the presence of a change in thermal transfer affecting the sensor. If the probe transducer is thermally actuated 186, the method further includes adjusting 188 bias power to maintain the TCR wiring sensor at a fixed temperature in the presence of a change in thermal transfer affecting the sensor, the thermal transfer changes comprising These are due to the thermally actuated probe transducer.

Figures 12A and 12B show the contact detection response of a representative multi-probe TCR wiring sensor as the wiring bias current (Fig. 12A) and in phase The function of the wiring OHR/temperature (Fig. 12B) on the same bias range. At hotter temperatures (higher bias or OHR), when the TCR wiring sensor is operating across a fixed OHR/temperature across the probe transducer, the contact detection response across the TCR wiring sensor is mixed. More consistent than the response (SNR) system.

Figures 13A and 13B show representative TCR wiring sensor roughness SNR data on a multi-probe converter. Figures 13A and 13B show representative representative probe TCR wiring sensor roughness detection SNR data as a function of TCR wiring bias power (Figure 13A) and wiring sensor OHR/temperature (Figure 13B). It can be seen that when the TCR wiring sensor is operated at a fixed OHR/temperature across the probe transducer, the roughness detection response across the TCR wiring sensor is more consistent.

Embodiments of the present invention are directed to apparatus and methods for biasing each TCR wiring sensor to provide a fixed temperature across all of the TCR wiring sensors of the probe transducer. According to various embodiments, the respective TCR wiring sensors operate at a fixed temperature to eliminate probe-to-probe roughness and contact detection signals due to varying temperatures across the TCR wiring sensor. variation. A TCR wiring sensor can be used to measure the temperature by measuring a change in the resistance of the TCR wiring, wherein the change in the resistance of the TCR wiring is a function of the change in the temperature of the TCR wiring, as in Equation (8) below Shown as follows: In the above equation (8), R _w and T _w are respectively a thermal resistance and a temperature; R ₀ and T ₀ are a cold resistance and a temperature, respectively, and a temperature coefficient of a resistance of the α _0- based TCR wiring. TCR, α ₀ , is a material property, and therefore, the value of the OHR for the fixed TCR wiring temperature will vary with the material.

Equation (8) is a linearized form, and higher order terms can exist in non-standard materials. Furthermore, it is assumed here that uniform temperature and resistance span the TCR wiring sensor. If the TCR wiring and resistance are not uniform, only the small element differential form of this equation is maintained, as shown in equation (9) below: Where dR _{(x, y, z)} and dT _{(x, y, z)} are the resistance and temperature of a small uniform element. If the temperature distribution or resistance across the TCR wiring changes, then the differential equation will have to be integrated in the sensor and the exact relationship using the maximum or average TCR wiring temperature established by the model.

In the envisaged case of several operations, it is advantageous to heat the TCR wiring above the ambient temperature by applying bias power to the wiring. Figure 14 shows an example of a descriptive thermal transfer balance for a wire suspended in air consistent with the hotline anemometer from Bruun; principle and signal response, similar to the 1995 pattern. Here, it is apparent that the temperature of the TCR wiring is not only dependent on Joule heating (I ² R), but also in accordance with various modes of heat transfer from the TCR wiring.

Since the temperature of the TCR wiring is dependent on Joule heating and heat transfer from the wiring, the temperature of the TCR wiring is not fixed across a different probe with a fixed wiring bias power. Therefore, in order to operate each TCR wiring sensor at the same temperature, the bias power must be adjusted so that the overheating has the same value (for the fixed material) than the OHR. For designs with uniform temperature and resistance across the sensor, use equation (10) below: For designs with large temperature and/or resistance gradients, strictly speaking, the functional form is only kept at small elements, as shown in equation (11) below: It should be noted that using this uniform equation (Equation (10) above) will produce an acceptable or possibly unacceptable error.

Figure 15 shows a graph of the wiring bias power of the OHR pair of clustered probe transducers (e.g., five probe transducers). In Figure 15, the respective probe converters are operated at multiple heater power (HP scan) and OHR = R _w /R _0-1 . Here, the temperature of the TCR wiring comes from both the wiring bias (horizontal axis) and the heater (the OHR is increased when the wiring current is fixed). Variations in the OHR across the probe transducer at fixed TCR wiring bias power and heater power can be immediately found in Figure 15 and can cause significant differences in TCR wiring temperatures across the probe transducer.

Note that the zero heater power situation is the lowest point of the respective TCR wiring bias power. For example, the OHR of the probe transducer S6Q0 at 345 μW and zero heater power is approximately 0.2. The OHR of the probe transducer S2W0 at 345 μW and zero heater power is approximately 0.09. In other words, the probe converter S6Q0 has 2.2 times the OHR of the probe converter S2W0. OHR. This becomes a temperature difference of 73 ° C at the TCR wiring that does not have heater power for the probe converters.

In order to obtain consistent probe-to-probe operation and reliability of the thermal TCR sensor, operate the respective TCR wiring sensor at a fixed OHR (eg, in the horizontal line in Figure 15), rather than not calculating The thermal transfer of the TCR wiring sensor across the probe transducer changes the fixed wiring bias power (eg, the vertical line in Figure 15), or a fixed wiring bias current or voltage, as desired.

The following is a representative example of a method for setting a fixed OCR for a uniform TCR wiring temperature and resistance (see, for example, equation (10) above):

Example 1

Representative field methods are given as follows: 1. Measure the TCR wiring resistance (R ₀ ) of the crucible or the surrounding environment, 2. Increase the TCR wiring bias power and simultaneously measure the increased 〞 〞 wiring resistance (R _w 3. Use Equation (10) above to calculate the OHR, 4. Use the TCR wiring bias power, or current, or voltage for a given OHR.

Example 2

The simpler interpolation or extrapolation method is given as follows: 1. Measure the resistance of the TCR wiring at two (or more) wiring bias powers, 2. Fit a line to the data, and determine the R _w to the wiring. Slope and intercept of the pressure power, 3. Use the intercept as R ₀ , 4. Use the inverse equation in equation (9) above and the desired OHR, the calculated slope, and the calculated intercept to resolve the operation. TCR wiring power.

However, R ₀ in the representative methods of Examples 1 and 2 above may have a large error due to measurement accuracy at a low bias voltage. For example, at 100 μA, the measured resistance has a large change (about 2 ohms). On this same system, the current system of the heated TCR wiring required to obtain a more accurate resistance measurement is 500 μA. The following is another representative method for finding a bias voltage for a fixed OHR with a short test time and a low R ₀ error.

Example 3

1. Pre-biased scan: The TCR wiring resistance is measured in a 100 μA step from a 100 μA scan to a target current (TC), which is the initial value of the current required to obtain the desired OHR.

2. Obtain the target bias power for the fixed OHR: plot the _Rw versus wiring bias power as shown in Figure 16. Note that at low bias voltages, curve 601 is not linear because of poor resistance measurement accuracy. Three points can be taken at a bias current of TC, TC-100, TC-200 for linear fitting 603 to achieve an equation of R _w = aP + b. Here, R _w is a TCR wiring resistance, a P-system bias power, a-system slope, and a b-intercept. Since the power system is proportional to the differential temperature (T _w -T ₀ ), the aforementioned linear fitting equation can be rewritten as equation (12) below: Comparing equation (10) above with the linear fit equation R _w = aP + b shows a function of slope a, TCR, and finally, intercept b is at zero bias cold resistance. The following calculations can be used to obtain the bias power for the fixed OHR:

a) Obtain the target TCR wiring sensor resistance at fixed OHR: R _w =b*(OHR+1)

b) Substituting R _w into the linear fit equation (12) above for the target bias power given by P = (R _w -b) / a.

3. According to the feasibility of the operation, the conversion target bias power is the bias current or voltage.

4. Optionally limit the target bias within a range of reliability such as the voltage range from the TCR wiring sensor life test.

Please refer to Figure 16 for an example. This figure shows an example of setting a fixed OHR for a probe transducer from a special wafer. The following equation is obtained: R = 127.803 + 0.092994 * P. Here, the slope a=0.092994±0.000796, and the intercept b=127.803±0.348. For example, if the above method is used and the fixed OHR is 0.3, the bias power should be set at P = 412.294 ± 2.406 μW.

In addition, setting the OHR across the TCR wiring sensor can also be extended to set the OHR across other parameters in the system such as radius/oblique axis. When using multiple heat source thermomechanical models (MXTM), you can find The drop in the contact detection response of the oblique axis results from when the probe converter is operating at a fixed TCR wiring bias power. Moreover, the results from the MXTM have shown that the change in the resistance of the TCR wiring is a function of the heater power across the oblique axis. It is observed that the OD (outer diameter) oblique axis case is more deviated than the ID (inner diameter) oblique axis case, and it can be considered that a relatively large amount of cooling occurs at the OD. The increment in cooling at the OD is observed to become three times higher than at the ID. Similarly, the contact detection response at the OD is observed to be three times that of the ID. If the OHR is adjusted across the oblique axis, the static heat transfer across the oblique axis can be made more consistent.

It should be noted that because of the multiple heat sources in the converter and the different resistivities and TCRs of the sensors and contacts, these simple methods described above can be used when trying to fix a constant temperature for conversion across all probes. The use of the TCR wiring sensor results in an understandable error. Additional implementations such as the following can be used to enhance the technology:

1. The temperature increment from the heater and/or surrounding can be included in the calculation; that is, the fixed OHR is set due to the TCR wiring bias and the heater's resistance increment.

2. The OHR can be recalculated and set according to how the system changes; for example, across a radius or time, if the TCR wiring sensor response decays over time.

3. If the junction changes across the resistance of the parameter that is being normalized using the OHR, then the change in contact resistance must be calculated.

4. Models can be used to understand how non-uniform temperature and resistance gradients change the accuracy of the desired temperature setting.

According to various embodiments. A more accurate method of setting OHR and consistent wiring temperature involves using a model to calculate non-uniform sensor temperature, resistance, and temperature from the probe transducer. Figures 17A through 17D show different ways of estimating the maximum temperature in a TCR wiring sensor in accordance with various embodiments. As can be seen in these figures, the most accurate method of estimating the maximum temperature is by monitoring the OHR and heater power in the TCR wiring (see Figure 17D, 17G, or 17I). For reliability purposes, especially for DLC integrity, it is important to accurately estimate the maximum power.

Figures 17A through 17I show the modeled maximum TCR wiring temperature versus different variables as follows: Figure 17A shows the maximum TCR wiring temperature versus wiring power; Figure 17B (and larger pattern 17E) shows the maximum TCR wiring temperature versus total Overheat ratio (lead and wiring); Figure 17C (and Figure 17F of the larger version) shows the maximum TCR wiring temperature versus wiring overheat ratio; and Figure 17D (and larger version 17G) shows the maximum TCR wiring temperature The wiring overheat ratio and the writer heater power.

Figures 17A through 17G show the regression of the maximum wiring temperature predicted by the MXTM model for different input variables. The modeling using the MXTM model is performed on a clustered probe that spans the maximum manufacturing parameter distribution including the height of the TCR wiring sensor to simulate a probe made in reality. Therefore, the necessary heater power to contact the medium changes the probe to the probe ground.

The maximum temperature of the wiring is due to both the energized TCR wiring sensor and the writer heater. Thus, higher flight and/or lower efficiency The probe requires a large heater power to contact the medium, so a large maximum wiring temperature can be produced when the voltage across the TCR wiring sensor is maintained constant.

The regressions in Figures 17A through 17D are ordered with increasing correlation levels, and the best way to predict the temperature in the TCR wiring is via the OHR in the wiring and the heater power (Figure 17D and larger) Figure 17G, which is the same as Figure 17I). This result, along with the fact that the TCR wiring contact detection SNR is more consistent with the OHR, indicates that the SNR consistency across the probe is enhanced by setting the TCR wiring sensor temperature across all probes to be constant.

Figures 17H and 17I show the modelled maximum wiring temperatures as follows: Figure 17H shows the maximum TCR wiring temperature versus wiring voltage and heater power; and Figure 17I shows the maximum TCR wiring temperature versus OHR and heater power. The regression of the modeled maximum wiring temperature shown in Fig. 17H with respect to the wiring voltage and the heater power indicates that the TCR wiring temperature prediction using the wiring voltage and the heater power is very good. However, this wiring temperature prediction is not as accurate as when using OHR and heater power (Fig. 17I), as indicated by the square root of the error of the two methods (RMSE), and is roughly a factor of 5.

Another important observation from the calculated value of the parameter is that the sign of the coefficient associated with the wiring temperature versus voltage is a positive value (Fig. 17H), and the sign of the coefficient associated with the wiring temperature for the OHR is negative (17I) Figure). This indicates that in order to obtain a constant maximum temperature across all components, the higher power of the component to be contacted is set to be greater than the component to be contacted. Lower power and higher OHR.

Figure 18 shows a graph of the modeled maximum wiring temperature vs. OHR for different heater powers. The reason for the illogical data chart on the surface of Figure 18 is due to the fact that OHR is also a function of heater power. That is, the temperature distribution across the TCR wiring sensor changes with heater power. In order to maintain a constant maximum temperature as the heater power increases, the ratio of OHR must also increase. For example, to achieve a constant maximum wiring temperature of 80 °C when the heater power is increased from 0 mW to 30 mW to 70 mW, the OHR should be increased from 0.062 to 0.09 to 0.11% and the wiring voltage should be lowered from 125 mW to 95. mW to 52 mW.

Conventional TCR wiring sensors for roughness and probe-to-medium contact detection are oriented in a direction across the track with the length of the TCR wiring. There are at least three problems associated with this geometry. First, the cross-track length of the TCR routing defines a roughness profile that spans a minimum across the width of the track. The roughness, which is less than the length of the wiring across the track, cannot be accurately characterized in the direction across the track. This will result in more trajectory than necessary and will result in unnecessary loss of drive capacity. Trajectory padding in this context means that the trajectory of the feature (or, generally, the disc) cannot be accurately displayed, and thus, may include roughness or other media defects. Such uncharacteristic regions of the track or disc surface are evaded during active flight of the recording probe transducer, resulting in reduced storage capacity.

Second, once the roughness is detected and characterized, it exceeds More trajectories of roughness across the width of the track are padded to calculate the span trajectory width of the functional elements of the probe transducer. Because conventional TCR wiring sensors are oriented in a direction that traverses the track, the number of tracks required to plug the TCR wiring sensor is greater than the number of tracks required by the writer and reader. Third, the first and second issues discussed above all consider the advantageous direction for the length of the TCR wiring to be shorter. However, from the viewpoint of sensor SNR, the longer the TCR wiring is, the better. Therefore, for the detection of roughness/contact and the characterization of accurate roughness across the trajectory, the TCR wiring sensor cannot be fully optimized.

Embodiments of the present invention are directed to TCR wiring sensors oriented parallel to the trajectory that provide increased roughness resolution and reduced track pad for increased drive capacity. According to various embodiments, the TCR wiring sensor is oriented parallel to the trajectory as compared to conventional TCR wiring sensors oriented in a cross-track direction.

Figure 19 is a flow diagram showing the use of a TCR wiring sensor for sensing the roughness, probe to media spacing using a vertical axis having a parallel orientation with respect to the trajectory of the magnetic recording medium, in accordance with various embodiments. Various changes to the change, and / or probe to medium contact. Moving 702 through the probe transducer relative to the magnetic recording medium, the method depicted in FIG. 19 includes sensing the 704 sensing probe to the TCR wiring sensor using a longitudinal axis having a parallel orientation with respect to the trajectory of the medium. A change in the distance between the media. The method also includes using a TCR sensor to generate 706 sensor signals, for example, which can be used for a variety of purposes, including detecting the roughness of the 712 medium, measuring 710 probe-to-medium spacing changes, And detecting the contact of the 714 probe to the medium.

Figure 20 shows an image of a conventional cross-track oriented TCR wiring sensor 801 comprising a TCR wiring 825 connected to a conductive contact 827. As can be seen in Fig. 20, in the conventional TCR wiring sensor 801, the TCR wiring 825 and the contact 827 are substantially parallel to each other. Figure 21 shows an image of a trajectory-parallel TCR wiring sensor 802 in accordance with various embodiments of the present invention. The TCR wiring sensor 802 shown in Fig. 21 includes a TCR wiring 835 having an orientation in which tracks are parallel. As can be seen in Fig. 21, the TCR wiring 835 is connected to the first contact 837' and the second contact 837". Each of the first and second contacts 837' and 837" is connected to The opposite ends of the TCR wiring 835 are formed at an angle of approximately 90 degrees therebetween. Conventional TCR wiring 825 is substantially parallel with respect to its contact 827; however, TCR wiring 835 in accordance with various embodiments is substantially orthogonal to its individual contacts 837' and 837".

Figures 20 and 21 further show the number of pads required to ensure that TCR wirings 825 and 835 do not interact with roughness during active operation. The number of pads required for the respective TCR wires 825 and 835 is indicated by dotted lines extending down the opposite ends of the individual TCR wires 825 and 835 along the page. A comparison of the regions within the dotted lines shown in Figures 20 and 21 demonstrates that the trajectory parallel oriented TCR wiring sensor 802 provides comparison to the conventional track-oriented TCR wiring sensor 801. A substantial decrease in the number of plugs required and an accompanying increase in storage capacity.

The case of the conventional TCR wiring sensor 801 shown in Fig. 20. The standard sensor is 500 nm across the length of the track and the width of the down track is 35 nm. At the zero oblique axis, this means that the roughness width of the smallest trajectory that can be determined is about 500 nm (that is, the effective sensor spans the width of the track by about 500 nm). When an additional approx. 500 nm is added for padding, the width of the conventional TCR wiring sensor 801 means that the respective roughness will need to be padded about 1 micron on each side.

Conversely, for the same size of the TCR wiring sensor 801 in the same situation, the trajectory parallel TCR wiring sensor 802 (and as shown in FIG. 21) in accordance with an embodiment of the present invention can display the characteristics of roughness Up to about 35 nm, and only an additional 35 micron pad plug will be required, resulting in a 0.07 micron pad plug on each side. At zero bevel, the trajectory-parallel TCR wiring sensor 802 in accordance with various embodiments produces 7% of the conventional traversal traverse TCR wiring sensor 801 pad. This large reduction in the plug and the accompanying increase in drive capacity is due to the true cross-track width of the roughness and the reduced number of pads required for narrower sensors. The reason for the characterization.

At the high bevel, the effective sense width of the trajectory parallel TCR wiring sensor 802 shown in Fig. 21 is increased by the following equation (13): w _eff = w + lsinα Equation (13) Here, w _eff is the effective cross-track width of the TCR wiring sensor 802, w is the physical width of the TCR wiring 835, l is the TCR wiring length, and the alpha system oblique angle. However, even with an oblique angle of up to 20 degrees, the effective sensor of the trajectory parallel TCR wiring sensor 802 is still much smaller than the trajectory width w _eff of the TCR wiring sensor 801 of the conventional cross-track.

For the above example, the effective sensor width w _eff of the trajectory parallel TCR wiring sensor 802 at 20 degrees is 206 nm, which is a standard cross-track TCR wiring sensing with the same size and probe orientation. 44% of the one of the 801. The specific pad retention will depend on the individual sensor design and operating the skew axis.

The following is a non-limiting method of constructing a trajectory-parallel TCR wiring sensor 802 in accordance with various embodiments:

1) Etching the trench (for example, in SiO ₂ or Al ₂ O ₃ ) and etching the blocking layer on the underlying contact. Then, a damascene plating process is used to fill the trench. Next, the top contacts are deposited or plated and covered with a dielectric and chemical mechanical polishing (CMP).

2) Again, the trench is etched as in 1) above. An atomic layer deposition (ALD) process is then used to fill the trench (this will be slow without depositing on the sidewalls of the trench). Some chemicals can be deposited directly on the dielectric. In such cases, CMP will be required prior to deposition/plating of the top contacts.

3) Produce large steps instead of ditches. Then, a directional deposition process such as ion beam deposition (IBD) is used, and is deposited obliquely (illegal line incidence), and sidewalls routed to the steps are established. Next, a dielectric is deposited on the other side of the trench and CMP is returned to the metal at the top of the first step (this can be used as a blocking layer for CMP). The top contact is then deposited and covered with a dielectric and CMP.

Figure 22 is a diagram of apparatus 900 for detecting roughness, probe-to-medium contact, and probe-to-medium spacing changes in accordance with various embodiments. It should be understood that, for the sake of brevity, several components of device 900 illustrated in FIG. 22 are not shown. Apparatus 900, shown in Fig. 22, depicts a wide variety of components that can be operated in concert to implement the various roughness, probe-to-medium contact, and probe-to-media spacing changes described herein. . In this illustration, control system 902 is shown coupled to a primary storage device containing any number of hard disk drives 904.

Fig. 22 includes a reproduction of the slider 100 shown in Fig. 1 supporting the recording probe transducer 103 equipped with the TCR sensor 105 spaced apart from the surface of the rotary magnetic storage medium 160. Control system 902 is shown to include controller 914, detector 912, and power supply 910. The controller 914 is configured to operate in conjunction with the various components of the device 900 to control the rotation of the media 160 and the movement of the slider 100 during such operations as reading and writing.

Power supply 910 provides power to a wide variety of components of device 900. In the case of various embodiments, the power supply 910 is configured to provide bias power to the TCR sensor 105 and the actuation power of the actuator for the probe transducer. For example, power supply 910 provides power to heater 102 that operates as a thermal actuator of probe transducer 103. In the case of the various embodiments described above, the power supply 910 is configured to supply bias power to each of the plurality of probe converters 103, and to adjust the bias power. Influencing the TCR sensor In the presence of a thermal transfer change of 105, each TCR sensor 105 is maintained at a fixed temperature above the ambient temperature.

The TCR sensor 105 is located near or near the probe transducer 105 and measures temperature at this location. Preferably, the TCR sensor 105 is a sensor having a temperature coefficient of resistance (TCR). The TCR sensor 105 can have a positive TCR or a negative TCR. As discussed above, the measured temperature changes in response to a change in the distance between the probe transducer 103 and the magnetic recording medium 160. The detector 912 is coupled to the TCR sensor 105, and the fabric is configured to detect changes in the measured temperature components, and to indicate roughness, probe-to-medium contact, and probe-to-medium spacing change. One or more of them.

According to various embodiments, the TCR sensor 105 is disposed at the probe transducer 103 such that the longitudinal axis of the TCR sensor 105 is oriented substantially parallel with respect to the trajectory of the magnetic recording medium. The TCR sensor 104 is responsive to a change in the distance between the TCR sensor 105 and the medium 160, and in particular, in response to the roughness of the medium 160. In an embodiment using a trajectory-parallel TCR sensor 104, the detector 912 is configured to substantially reduce the number of trajectory pads as compared to conventional cross-track oriented TCR wiring sensors. The roughness of the medium 160 is measured.

According to several embodiments, power is supplied to the TCR sensor 105 by a power supply 910 to heat the probe to a temperature above the temperature of the media interface 160. In other embodiments, power is provided to both the TCR sensor 105 and the heater 102 by a power supply 910 to provide heating of the probe to the disc interface. Detector 912 is based on the probe To the type of disc interface (modulated HDI vs. non-modulated HDI), and detecting changes in the AC or DC component of the signal generated by the TCR sensor 105 to indicate response to roughness, probe The rate of increase in heat transfer from the self-heating probe to the media interface 160 to the media contact, or from probe to media spacing.

It will be appreciated that many of the various features of the various embodiments have been described in the above description together with the details of the structure and function of the various embodiments. And, the changes may be made in detail to the full extent of the broad meaning of the terms used in the appended claims, particularly in the structure and arrangement of the components depicted by the various embodiments.

100‧‧‧Sliding parts

101‧‧‧suspension

102‧‧‧heater

103‧‧‧ Probe Converter

105‧‧‧TCR sensor

107‧‧‧ Probe to media spacing

160‧‧‧ Magnetic recording media

Processing 140-148‧‧

200, 301, 302, 801‧‧ ‧known TCR sensor

202,325,335,825‧‧‧TCR wiring

204,327,337,827‧‧‧Contacts

340‧‧‧ leading edge

350‧‧‧ trailing edge

402-412‧‧‧Process

900‧‧‧ Equipment

902‧‧‧Control system

904‧‧‧ hard disk drive

910‧‧‧Power supply

912‧‧‧Detector

914‧‧‧ Controller

Figure 1 is a schematic side elevational view of a heater-actuated probe transducer configuration incorporating a temperature sensor in accordance with various embodiments; Figure 2 is a heater-actuated probe conversion as shown in Figure 1 Front view of the configuration; Figure 3 shows the heater-actuated probe transducer configuration of Figures 1 and 2 in a pre-actuated configuration and actuation configuration; Figure 4A depicts the probe transducer and magnetic A representative temperature profile for a heater-actuated recording probe transducer of the type shown in Figures 1 through 3 before, during, and after recording the contact between the surfaces of the disc; Figure 4B depicts the probe transition For non-thermally actuated recording probes before, during, and after contact with the surface of the magnetic recording disc A representative temperature profile of the converter; FIG. 5 is a flow chart showing the use of a resistive temperature sensor having a low resistance contact to detect the roughness of the magnetic recording medium in accordance with various embodiments. Various treatments; Figure 6A shows the voltage profile across a resistive temperature sensor that does not have a low resistance contact; Figure 6B shows the temperature profile across a resistive temperature sensor that does not have a low resistance contact; Figure 7 depicts a conventionally designed resistive temperature sensor; Figure 8 depicts a resistive temperature sensor with low resistance contacts in accordance with various embodiments; Figure 9A is a graphical representation of the display The cross-track resistance profile of the resistive temperature sensor; FIG. 9B is an air bearing surface view of a conventional resistive temperature sensor having a cross-track resistance profile as shown in FIG. 9A; FIG. 10A A graphical representation showing the reduction in cross-track resistance of a resistive temperature sensor due to an increase in cross-sectional contact area in accordance with various embodiments; Figure 10B is implemented in accordance with various embodiments For example, as shown in Figure 10A The air bearing surface view of the resistive temperature sensor across the trajectory resistance profile is shown; Figure 11 is a flow chart showing the presence of heat transfer in the sense sensor according to various embodiments. Maintaining a plurality of resistive temperature sensors across a plurality of probe transducers at various fixed temperatures Example 12A shows that the contact detection response of a plurality of resistive temperature sensors is a function of the sensor bias current; and FIG. 12B shows the contact detection response of a plurality of resistive temperature sensors. The detector overheating ratio (OHR)/temperature function; Figure 13A shows the roughness detection response of a plurality of resistive temperature sensors as a function of the sensor bias current; Figure 13B shows a plurality of resistive temperature senses The roughness response of the detector is a function of the sensor's superheat ratio (OHR)/temperature; Figure 14 is used for the heat of the anemometer from Bruun: principle and signal response, similar to the similar pattern of 1995 A descriptive example of the thermal transfer balance of a resistive temperature sensor wiring; Figure 15 shows a graph of OHR versus bias voltage for a resistive temperature sensor for a plurality of probe transducers, illustrating the operation of multiple resistors with a fixed OHR Temperature sensor rather than a fixed bias power, bias current, or bias system; Figure 16 shows the resistance versus bias power of a resistive temperature sensor in accordance with various embodiments. Figure; Figure 17 shows the basis The regression of the maximum wiring temperature predicted by the multiple heat source thermomechanical model (MXTM) for different input variables is used in various embodiments; Figure 18 is the maximum resistive temperature sensor resistance for different probe converter heater powers. Figure of OHR; Figure 19 is a flow chart showing the use of various embodiments A TCR wiring sensor having a longitudinal axis oriented parallel to the trajectory of the magnetic recording medium to sense various effects of roughness, probe-to-media spacing, and/or probe-to-medium contact Figure 20 is an image of a conventional resistive temperature sensor across a track orientation; Figure 21 is an image of a trajectory parallel resistive temperature sensor according to various embodiments; and Figure 22 shows A pattern of equipment for detecting roughness, probe-to-medium contact, and probe-to-medium spacing changes in accordance with various embodiments.

100‧‧‧Sliding parts

101‧‧‧suspension

102‧‧‧heater

103‧‧‧ Probe Converter

105‧‧‧TCR sensor

107‧‧‧ Probe to media spacing

160‧‧‧ Magnetic recording media

Claims (25)

An apparatus comprising: a probe converter configured to interact with a magnetic recording medium; a sensor disposed at the probe converter and having a temperature coefficient of resistance and a sensor resistance, the sensor system The configuration is to operate at a temperature above the ambient temperature and in response to a change in the distance between the sensor and the medium; and a conductive contact is coupled to the sensor and has a contact resistance, the contacts having Adjacent to the sensor and greater than the cross-sectional area of the cross-sectional area of the sensor such that the contact resistance becomes smaller relative to the sensor resistance and negligibly contributes to the generation by the sensor Signal. The device of claim 1, wherein the contact resistance is negligible with respect to the sensor resistance. The apparatus of claim 1, wherein the effective size of the sensor that contributes to the sensor signal is substantially the same as the physical size of the sensor. The device of claim 1, wherein the sensor signal is not confused by the composition of the signal caused by the contacts. The device of claim 1, wherein: the regions of the contacts are exposed to thermal energy generated by one or both of the sensor and the heater of the probe transducer; and such The contact resistance of the contact region is reduced relative to the sensor resistance and negligibly contributes to the signal generated by the sensor. For example, the equipment of claim 1 of the patent scope, wherein: The sensor includes a sensor element and an opposite end of the sensor element therebetween; the opposite ends of the sensor have a cross-sectional area greater than a cross-sectional area of the sensor element; and the sense The detector contacts comprise the opposite ends of the sensor. The device of claim 1, wherein the contacts have a cross-sectional area adjacent to the sensor, the factor of between 1 and 1000 being greater than the sensor. The device of claim 1, wherein the contact resistance is less than the sensor resistance by a factor ranging between 1 and 1000. The device of claim 1, wherein: the contacts and the sensor each comprise a leading edge and a trailing edge; and the leading edge of the sensor is relative to the front of the contacts The edge is recessed. The apparatus of claim 1, wherein the sensor system is to operate at a temperature of between about 0 ° C and 300 ° C. The device of claim 1, wherein the sensor is located at or near an access point of the probe transducer. The apparatus of claim 1, wherein the sensor is sized to sense the roughness of the medium. A method comprising: moving a magnetic recording medium relative to a probe transducer; sensing a temperature of an approach point of the probe converter using a sensor having a temperature coefficient of resistance, the sensor being connected to having a contact resistance Guide Electrical contacts having a cross-sectional area adjacent to the sensor and greater than a cross-sectional area of the sensor such that the contact resistance becomes smaller relative to the resistance of the sensor and is negligible Generating a signal generated by the sensor; outputting the sensor signal; and detecting the roughness of the medium using the sensor signal. The method of claim 13, wherein the sensor signal is not confused by a component of the signal facilitated by the contacts. An apparatus comprising: a plurality of probe transducers, the fabric is to interact with a magnetic recording medium; a plurality of sensors having a temperature coefficient of resistance, wherein at least one of the sensors is disposed on a respective probe transducer, and Responding to a change in the distance between the sensor and the medium; and a power source, the fabric is configured to supply bias power to each of the respective probe converters, and the bias power is adjusted Each sensor is maintained at a fixed temperature above the ambient temperature in the presence of a change in thermal transfer that affects the sensors. The device of claim 15 wherein the at least one sensor is disposed at an approximate point of the respective probe transducer. The apparatus of claim 15, wherein the power source system adjusts the bias power such that a substantially fixed overheat ratio (OHR) affects heat transfer changes of the sensors. The existence of the sensor is maintained across all sensors. The device of claim 15 further comprising: a heater disposed at each of the probe converters, and the system is configured to actuate the probe converter, wherein the power source system is to be adjusted The bias power maintains each of the sensors at the fixed temperature in the presence of a change in thermal transfer affecting the sensors, the heat transfer changes including the power supplied to the heater Those who are. A method comprising: moving a magnetic recording medium relative to a plurality of probe transducers; sensing a change in a distance between the probe transducers and the medium using a sensor having a temperature coefficient of resistance; supplying a bias voltage Power to the sensors; and adjusting the bias power to maintain each sensor at a fixed temperature above ambient temperature in the presence of a change in thermal transfer affecting the sensors. The method of claim 19, further comprising: thermally actuating the probe transducers to cause the probe transducers to move toward the medium; and adjusting the bias power to affect thermal transfer of the sensors Each sensor is maintained at the fixed temperature in the presence of a change that includes those caused by thermal actuation of the probe transducers. An apparatus comprising: a probe transducer configured to interact with a magnetic recording medium having a plurality of tracks; a sensor having a temperature coefficient of resistance and configured in the probe converter such that a longitudinal axis of the sensor is oriented substantially parallel with respect to the tracks, the sensor being responsive to roughness of the medium And one or both of the changes in the distance between the sensor and the medium. The device of claim 21, wherein the sensor is operated at a temperature above ambient temperature. The device of claim 21, wherein the sensor system is configured to sense contact between the sensor and the medium. The device of claim 21, wherein the sensor comprises a wiring having a temperature coefficient of resistance (TCR), the wiring being connected to the first contact and the second connection at opposite ends The first and second contacts are oriented approximately orthogonal to the TCR wiring and are axially offset from one another. A method comprising: moving a magnetic recording medium having a track relative to a probe transducer; and sensing a roughness of the medium using a sensor having a temperature coefficient of resistance and a distance between the probe converter and the medium The sensor has one or both of the changes, the sensor having a longitudinal axis that is oriented substantially parallel with respect to the trajectory of the medium.