JP2002289411A - Sliding resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding resistor which is capable of reducing wear and keeping electrical continuity stably. SOLUTION: A sliding resistor 1 is equipped with sliding resistors 2 (21 and 22) provided on the surface of a board 20, and contacts 3 (31 and 32) sliding on the sliding resistors 2 (21 and 22), where each sliding resistor 2 (21 and 22) is formed of a carbon deposited film DLC having higher hardness than that of the contact 3 (31 and 32). The carbon deposited film DLC has an amorphous structure where a diamond structure and a graphite structure are mixedly present at a prescribed ratio, and the amorphous structure is improved in density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding resistor, and more particularly to a sliding resistor having wear resistance and electrical conduction stability, and a sliding resistor using the same.

[0002]

2. Description of the Related Art There is known a sliding resistor provided with a resin-made sliding resistor for making a variable resistance by sliding a so-called contact contact made of a metal brush (JP-A-4-187).
03 publication).

This sliding resistor is a thick film resistor obtained by kneading carbon black in a resin. As the carbon black, conductive carbon such as acetylene black or furnace black is used. Is an epoxy resin or the like.

[0004] As a result, as a result of the sliding friction between the contact contact and the sliding resistor continuously, the sliding resistor as a composite material is completely separated into carbon black and resin in the course of abrasion. In some cases, if the abrasion powder, especially resin, of the sliding resistor adheres and accumulates on the sliding track, the electrical contact between the contact contact and the sliding resistor becomes unstable, that is, the electrical conductivity becomes unstable It may be.

As a countermeasure against this, according to Japanese Patent Application Laid-Open No. Hei 4-18703, an inorganic component such as alumina is added to the sliding resistor to suppress the wear of the sliding resistor and to reduce the life of the sliding resistor. We are improving.

[0006]

In any of the conventional structures, when the wear progresses to some extent, the resin adheres on the sliding locus,
As a result, the electrical conductivity becomes unstable.

That is, a dramatic improvement in service life cannot be expected within a practical range.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a sliding resistor capable of stably maintaining electrical conductivity while reducing abrasion.

[0009]

According to a first aspect of the present invention, there is provided a sliding resistor having a sliding resistor disposed on a surface of a substrate and a contact sliding on the sliding resistor. ,
The sliding resistor is made of a carbon deposited film having a hardness equal to or higher than the hardness of the contact.

[0010] Since the sliding resistor is formed of a carbon vapor deposited film having a hardness equal to or higher than the hardness of the contact, even if the contact slides continuously on the sliding resistor, wear of the sliding resistor is prevented. Is possible.

According to a second aspect of the present invention, in the sliding resistor provided with the sliding resistor disposed on the surface of the substrate and the contact sliding on the sliding resistor, the contact is made of a noble metal. The sliding resistor is formed of a carbon vapor deposited film, and the surface of the contact is coated with a carbon vapor deposited film.

That is, while the sliding resistor is formed from a carbon vapor deposited film, the surface of the contact of the noble metal is coated with the carbon vapor deposited film, that is, formed into a thin film.

For this reason, since the surfaces on which the sliding resistor and the contact slide are made of the same material, wear of both the sliding resistor and the contact can be prevented, and the surface of the contact is formed. Since the carbon deposited film is formed into a thin film, the influence of the carbon deposited film on the conductive properties of the contact can be extremely reduced.

The carbon deposited film according to claim 1 or 2 has an amorphous structure in which a diamond structure and a graphite structure are mixed at a predetermined ratio, as described in claim 3 of the present invention. The amorphous structure has been densified.

For this reason, if the mixing ratio is within a predetermined range due to the amorphous structure in which the diamond structure as the insulator and the graphite structure as the conductor are mixed, the amorphous structure existing at the molecular level can It is possible to have desired hardness and conductivity as a resistor.

As a result, the carbon vapor-deposited film has predetermined hardness and conductive properties at the molecular level, so that even if abrasion occurs, the abrasion powder does not separate into a conductive material and an insulating material.

Moreover, since the carbon deposited film, that is, the amorphous structure is densified, it is possible to improve the surface hardness and the surface roughness of the carbon deposited film, that is, to reduce the friction coefficient.

According to claim 4 of the present invention, the densified carbon deposited film has a coefficient of friction of 0.2 or less.

For this reason, since the surface of the sliding resistor on which the contact slides can keep the sliding friction resistance low, it is possible to prevent wear caused by surface roughening due to sliding friction.

According to a third aspect of the present invention, the predetermined mixture ratio corresponds to the G band (155) in the Raman spectrum of the Raman spectroscopy.
Raman intensity ratio of 0 cm ^-1 vicinity) and D-band (1350 cm ^-1 vicinity) is desirably ratio in the range of 0.6 to 1.2.

As a result, the carbon deposited film satisfies at least conductivity, which is a basic characteristic as a sliding resistor,
Furthermore, as the abrasion resistance and the sliding frictional resistance are suppressed low, the slidability can be improved.

According to claim 6, the carbon deposition film has an impurity containing hydrogen, and the remaining amount of hydrogen is 10%.
% By weight or less.

If the above-mentioned impurities are excluded from the additives intentionally added to improve the wear resistance, the impurities generally cause a decrease in hardness. Therefore, the hydrogen as an impurity has a residual amount of 10% by weight or less. Is desirable.

Thus, for example, the conductivity, abrasion resistance, and slidability of the amorphous carbon deposited film having the predetermined mixture ratio can be stably obtained.

According to claim 7, the conductivity of the deposited carbon film is in the range of 0.01 to 10 Ω · cm as the volume resistivity.

Thus, the carbon deposited film is suitable as a sliding resistor for a sliding resistor.

[0027] The contact according to claim 1 is a contact according to claim 8.
As described above, the surface of the contact may be subjected to rhodium plating.

[0028] Thus, with the sliding resistor having improved wear resistance, it is possible to prevent the amount of contact wear from increasing.

[0029]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a sliding resistor according to an embodiment of the present invention.

FIG. 1 is a plan view showing a potentiometer incorporating a sliding resistor according to an embodiment of the present invention. FIG.
FIG. 2 is a sectional view of the potentiometer of FIG. 1 as viewed from II-II.

FIGS. 3A and 3B are configuration diagrams showing the configuration of a sliding resistor according to an embodiment of the present invention. FIG. 3A is a plan view, and FIG. FIG. 3 (c)
Is a side view.

As shown in FIGS. 1 to 3, a sliding resistor 1 according to the present invention includes a sliding resistor 2 provided on the surface of a resistor substrate 20 and a sliding resistor on the sliding resistor 2. Moving contact 3
And

An embodiment in which the sliding resistor 1 of the present invention is applied to a potentiometer for an automobile will be described below.

As shown in FIGS. 1 and 2, the potentiometer 10 includes a sliding resistor 1, a rotary cylinder 30 to which rotation from the outside is transmitted, and a case 11, and has a rotational position. To detect.

As shown in FIGS. 1 to 3, the sliding resistor 1 is provided with a sliding resistor 2 made of a conductive carbon vapor-deposited film on a substrate 20 of a potentiometer 10.

As shown in FIGS. 2 and 3, the sliding resistor 2 is centered on a fitting hole 202 provided on the resistor substrate 20 side corresponding to the rotation center projection 302 of the rotary cylinder 30. A first sliding resistor 21 (for inner current collection) formed concentrically and a second sliding resistor 22 (for outer output) formed on the outer periphery of the first sliding resistor 21 Become. In other words, the sliding resistor 2 has an inner first sliding resistor 21 and an outer second sliding resistor 21 arranged in two rows in an arc shape corresponding to a sliding trajectory in which two contacts 3 described later move. Sliding resistor 2
2 is comprised.

One end of the inner first sliding resistor 21 and both ends of the outer second sliding resistor 22 are electrically connected to three electrical terminals 12 arranged in the case 11. A contact portion 23 for achieving conduction is formed. Case 1
Reference numeral 1 denotes an outer shell of the potentiometer 10.

The two sliding resistors 21 and 22
Are formed of a carbon vapor-deposited film having an amorphous structure in which a diamond structure and a graphite structure described later are mixed.

The first and second sliding resistors 21 and 22
That is, the details of the carbon deposited film forming the sliding resistor 2 will be described later.

Next, the contact 3 is shown in FIG.
As shown in (c), the rotary cylinder 30 is fixedly provided on the side facing the resistor substrate 20. See Figure 3 for details.
As shown in (a), the contact 3 is made up of a first contact 31 and a second contact branched from the conductive plate 39.
Of the rotating cylinder 3
It is fixed on the upper part of the “0” via a conductive plate 39.

This contact 3 (specifically, the first and second contacts
Are made of a noble metal such as a hexagonal alloy or a noble metal alloy, and the hardness (specifically, Vickers hardness) is in the range of Hv200 to 300.

As shown in FIG. 2, the potentiometer 10 has a contact chamber 4 surrounded by a case 11 and a substrate 20 on which the sliding resistor 2 is disposed. A rotary cylinder 30 having the contact 3 is rotatably disposed in the contact chamber 4.

In the potentiometer having the above-described configuration, the voltage corresponding to the position of the contact 3 is applied to the terminal 23 by sliding on the sliding resistor 2 as the rotary cylinder 30 rotates.
Output.

Here, the sliding resistor 2 (specifically, the first and second sliding resistors 21 and 22) made of a carbon vapor-deposited film, which is a feature of the sliding resistor 1 of the present invention, will be described below. I do.

First, the carbon deposited film DLC forming the sliding resistor 2 has a hardness equal to or higher than the hardness of the contact 3 (specifically, the first and second contacts 31 and 32). The carbon vapor deposited film DLC can have a hardness (specifically, Vickers hardness) of Hv300 or more due to an amorphous structure in which a diamond structure and a graphite structure described later are mixed.

For this reason, the hardness of the contact 3 (Hv20
0 to 300), the sliding resistor 2 has an amorphous structure in which a diamond structure and a graphite structure are mixed, and has a hardness of Hv300 or more and has a hardness of Hv300 or more.
Therefore, the sliding resistor 2 can have a hardness equal to or higher than the hardness of the contact 3.

Therefore, the sliding resistor 2 having a hardness higher than the hardness of the contact 3 can prevent the sliding resistor 2 from being worn even if the contact 3 slides on the sliding resistor 2 continuously. It is.

Next, an amorphous structure in which a diamond structure and a graphite structure forming the sliding resistor 2 of the carbon vapor deposited film DLC are described below. In the present embodiment, DLC refers to Diamond.
-Called as an abbreviation for Like Carbon.

The main component of the carbon deposited film DLC is carbon (C), and contains hydrogen (H) and oxygen (O) as the contained impurity components. This carbon deposited film DLC forms an amorphous structure in which a crystalline diamond structure and a graphite structure are mixed in the molecular structure of carbon by a film forming method using plasma such as PVD or P-CVD described later.

The diamond structure is a so-called diamond as a single crystal, is a perfect insulator (resistance value> 10 ¹³ Ω), and has a feature of being very hard. On the other hand, the graphite structure is a so-called graphite as a single crystal body, has characteristics of high conductivity (resistance value> 10 ^-13 Ω) and good slipperiness.

Therefore, due to the amorphous structure in which the diamond structure and the graphite structure are mixed,
By setting the mixture ratio in a predetermined range described later, it is possible to have a desired hardness and conductivity as a resistor due to the amorphous structure existing at the molecular level.

Thus, the contact 3 is connected to the sliding resistor 2
Even if the sliding resistor 2 is worn by continuous sliding on the upper side, that is, even if the carbon deposited film DLC is worn out, the carbon deposited film DLC has a molecular level. In this case, the abrasion powder does not separate into a conductor and an insulator.

Therefore, in a conventional resin-made sliding resistor in which carbon black is kneaded in a resin, the conductive carbon black and the insulating resin are separated during the abrasion process. Due to the resin adhering to the trajectory, the electrical contact between the contact and the sliding resistor may be unstable, that is, the electrical conductivity may be unstable. In the resistor 2, such a phenomenon can be reliably prevented.

The carbon deposited film DLC is formed by a manufacturing method using plasma such as PVD or P-CDV.

PVD (Physical Vapor)
Abbreviation of Deposition, so-called physical vapor deposition
), For example, as a source gas
(C ₆H₆) Ionized plate
Method or solid carbon (C) as a target
For example, an ion sputtering method can be applied. The above
The ion plating method reduces the residual amount of hydrogen described later.
It is desirable because it has a feature that can be reduced.

Further, P-CVD (Plasma-Che)
As a film forming method (abbreviation of physical vapor deposition, which is a so-called plasma chemical vapor deposition method), a method of forming by plasma using a source gas such as methane (CH ₄ ) can be applied.

Next, the carbon deposited film DLC of the sliding resistor 2 of the present invention, that is, the above-mentioned amorphous structure is densified by performing the film forming conditions in the above film forming method, for example, by increasing the bias voltage. May be formed.

Thus, it is possible to improve the surface hardness of the carbon vapor deposited film DLC and to improve the surface roughness, that is, to reduce the friction coefficient.

More specifically, the densified carbon vapor-deposited film DLC can easily have a surface hardness of Hv 300 or more and a surface roughness of RZ 3 μm or less.

At this time, the friction coefficient (specifically, the friction coefficient in a dry state) can be 0.2 or less due to the surface roughness of RZ 3 μm or less.

For this reason, the surface of the sliding resistor 2 on which the contact 3 slides can keep the sliding friction resistance low according to the friction coefficient, so that the abrasion caused by the surface roughening due to the sliding friction can be prevented. It is possible.

Here, the method of specifying the physical properties, particularly the structure, of the carbon vapor deposited film DLC having the above-described characteristics will be described with reference to FIG.

FIG. 4 is a graph of the Raman spectrum by Raman spectroscopy showing the physical properties of the sliding resistor, ie, the carbon deposited film DLC, which is the main part of the embodiment of the present invention. The horizontal axis in FIG. 4 indicates the Raman shift, that is, the so-called wave number (cm ^-1 ), and the vertical axis indicates the relative intensity.

The portion reflecting the graphite structure appears near the wave number of 1550 cm ^-1 (so-called G band), while the amorphous portion appears near the wave number of 1350 cm ^-1 (so-called D band).

For Raman spectroscopy, NRS-1000 manufactured by JASCO Corporation was used to measure the G band (155).
The Raman intensity ratio of 0 cm ^-1 vicinity) and D-band (1350 cm ^-1 vicinity) from the results obtained experimentally, the physical properties of the carbon deposited film DLC in the range of the intensity ratio, were identified.

[0066] That is, the intensity ratio of the wave number 1550 cm ^-1 vicinity and the wave number 1350 cm ^-1 peak portion near, i.e. the Raman intensity ratio is in the range of 0.6 to 1.2 is desirable.

If the intensity ratio is less than 0.6, the desired conductivity of the carbon deposited film DLC cannot be obtained. In order to secure conductivity in this state (strength ratio is 0.6 or less), a non-conductive substance contained in the carbon deposited film DLC,
For example, reducing hydrogen (H) as much as possible, or conversely,
It becomes necessary to add a conductive metal component, resulting in impaired slidability.

On the other hand, when the intensity ratio exceeds 1.2,
The conductivity of the carbon vapor deposited film DLC becomes too low, and the film quality becomes fragile.

Therefore, the Raman intensity ratio is set to 0.6 to
Since it is set in the range of 1.2, the carbon deposited film DLC
Satisfies at least the following predetermined conductivity, which is a basic characteristic of the sliding resistor 2, and further improves the abrasion resistance (specifically, increases the hardness and reduces the friction coefficient) and reduces the sliding friction resistance. It is possible to improve the slidability to be suppressed (specifically, to reduce the friction coefficient).

The conductivity of the sliding resistor 2 of the sliding resistor 1 of this embodiment is different from that of the carbon deposited film DLC.
Is 0.01 to 10 Ω expressed by volume resistivity.
-Obtained in the range of cm. Thereby, it is suitable as the sliding resistor 2 of the sliding resistor 1 applied to the automotive potentiometer 10 and the like.

Here, in the carbon deposited film DLC,
It is desirable that the residual amount of hydrogen (H) contained as an impurity is 10% by weight or less. Conversely, when the residual amount is large, the volume specific resistance of the carbon deposited film DLC becomes large, and the hardness is reduced, that is, the wear resistance is reduced.

For this reason, the remaining amount of hydrogen (H) is reduced to 10% by weight or less. Therefore, for example, the amorphous structure with the above-mentioned predetermined mixture ratio (specifically, the Raman intensity ratio is in the range of 0.6 to 1.2) is used. The properties of conductivity, abrasion resistance and slidability of the carbon deposited film DLC can be stably obtained.

Next, the sliding resistor 1 of the present invention was subjected to a life acceleration test to confirm the effect of improving the wear resistance and the like.

As the life accelerating test, a cooling operation endurance test and the like were repeated at an ambient temperature between 120 ° C. and −30 ° C., and the wear amount and the life were evaluated.

Note that, in FIGS. 5A and 5B, Example-1, Example-2,
Example-3 corresponds to the Raman spectra obtained by the respective Raman spectroscopy methods shown in FIG. As a comparative example, a conventional polymer-based resin resistor was used.

As shown in FIG. 5, Embodiment-1 and Embodiment-
2. In Example-3, each hardness was Hv523, 542, 58.
0, which satisfies the hardness (Hv 300 or more) of the carbon deposited film DLC as the sliding resistor 2 of the present invention. On the other hand, the hardness of the polymer resin resistor of the comparative example is Hv
It is extremely low at 55.

For this reason, while the comparative example is worn out by 5 μm, the sliding traces of the sliding resistors 2 in Examples 1, 2, and 3 are such that the sliding locus can be slightly confirmed in the sliding resistor 2. In addition, the amount of abrasion was only within a measurement error range of 0.1 μm or less, and it can be determined that the abrasion was substantially not caused.

Therefore, as shown in FIG. 5, in comparison of the life acceleration test results, the comparative example was limited to 1,000,000 cycles, whereas the carbon deposited film DLC of the sliding resistor 2 of the present invention was limited to 1,000,000 cycles. In either case, the life can be dramatically improved to 2 million cycles or more.

(Modification) In the above embodiment, in order to provide a sliding resistor capable of stably maintaining electrical conductivity while reducing abrasion, the sliding resistor 2 is made of a carbon vapor deposited film DLC.
However, from the viewpoint of providing a maintenance-free product that has been required in recent years, a carbon vapor deposition film DLC or a rhodium plating so-called Rh plating film is formed on the surface of the contact 3 as a modification. You may.

The carbon deposited film DLC provided on the surface of the contact 3 is formed by coating, that is, forming a thin film.

For this reason, since the respective surfaces on which the sliding resistor 2 and the contact 3 slide are formed of the same material,
The carbon-deposited film DLC forming the surface of the contact 3 is formed into a thin film while preventing the abrasion of both the sliding resistor 2 and the contact 3, so that the influence of the carbon-deposited film on the conductive properties of the contact is extremely reduced. It is possible.

Example 2 was used as the sliding resistor 2, and the contact 3 was coated without coating, with a carbon deposited film DLC (Hv542), R
Using each of the h-plates (Hv700), a durability test was performed under the test conditions of the life acceleration test described above.
The wear of the contact 3 was higher than that of the case without the coating, in which the carbon deposited film DLC (Hv542) and Rh plating (Hv
700), and the wear of the Rh-plated contact 3 having the highest hardness is particularly small.

[Brief description of the drawings]

FIG. 1 is a plan view showing a potentiometer incorporating a sliding resistor according to an embodiment of the present invention.

FIG. 2 is a sectional view of the potentiometer of FIG. 1 as viewed from II-II.

3A and 3B are configuration diagrams illustrating a configuration of a sliding resistor according to an embodiment of the present invention. FIG. 3A is a plan view, and FIG.
Is a cross-sectional view from AA, and FIG. 3C is a side view.

FIG. 4 is a graph of a Raman spectrum by Raman spectroscopy showing physical properties of a sliding resistor, ie, a carbon deposited film DLC, which is a main part of an embodiment of the present invention.

FIG. 5 is a table showing evaluation results of a life acceleration test performed to confirm the effect of the carbon deposited film DLC of the sliding resistor according to the present invention, and comparing hardness, wear amount, life, and the like.

[Explanation of symbols]

1 sliding resistor 2, (21, 22) sliding resistor, (first sliding resistor, first sliding resistor) 3, (31, 32) contact, (first contact, 2 contacts) 10 potentiometer 20 substrate DLC carbon deposited film

Claims (8)

[Claims] A sliding resistor provided on a surface of a substrate;
A sliding resistor provided with a contact that slides on the sliding resistor, wherein the sliding resistor is made of a carbon vapor-deposited film having a hardness equal to or higher than the hardness of the contact. . 2. A sliding resistor disposed on a surface of a substrate,
In a sliding resistor provided with a contact that slides on the sliding resistor, the contact is made of a noble metal, and the sliding resistor is formed of a carbon vapor-deposited film, and the surface of the contact is A sliding resistor characterized by being coated with a carbon deposition film. 3. The carbon deposited film has an amorphous structure in which a diamond structure and a graphite structure are mixed at a predetermined ratio, and the amorphous structure is densified. 3. The sliding resistor according to 2. 4. The sliding resistor according to claim 3, wherein the densified carbon deposited film has a friction coefficient of 0.2 or less. 5. The Raman spectrum of Raman spectroscopy is used to determine the predetermined mixture ratio in G band (1550c
The sliding according to claim 3 or 4, wherein the Raman intensity ratio between the m- ¹ ) and the D band (1350cm- ¹ ) is in the range of 0.6 to 1.2. Resistor. 6. The carbon deposited film has impurities containing hydrogen, and the residual amount of hydrogen is 10% by weight or less. A sliding resistor according to item 1. 7. The method according to claim 1, wherein the conductivity of the carbon vapor-deposited film is in a range of 0.01 to 10 Ω · cm as a volume resistivity. Sliding resistor. 8. The sliding resistor according to claim 1, wherein the surface of the contact is rhodium-plated.