Encoder for controlling measurements in the range of a few angstroms

A position detecting apparatus comprising:

• a reference element having a surface to be detected having regular scales;
• a probe disposed to face the surface to be detected with a gap therebetween and movable relative to said reference element along the surface to be detected;
• means for applying a voltage between said probe and said reference element;
• means for detecting a tunnel current flowing between said probe and said reference element;
• an actuator for changing the gap between said probe and the surface to be detected;
• means for generating a control signal for controlling said actuator so as to provide a constant tunnel current detected by said current detecting means;
• means for detecting the relative position of said probe relative to said reference element along the surface to be detected on the basis of changes in the control signal caused by relative movement across the scales of said probe upon the occurrence of relative movement between said probe and the reference element;
• and
• means for detecting, upon the occurrence of the relative movement, the direction of the relative movement.

A position detecting apparatus comprising:

• a reference element having a surface to be detected having regular scales;
• a first probe disposed to face the surface to be detected and movable relative to said reference element along the surface to be detected;
• a second probe disposed to face the surface to be detected and movable, together with said first probe, relative to said reference element along the surface to be detected;
• means for applying voltage between said first and second probes and said reference element;
• means for detecting first and second tunnel currents flowing between said first and second probes and said reference element, respectively;
• means for detecting the relative position of said first and second probes relative to said reference element along the surface to be detected on the basis of changes in the first and second tunnel currents of said current detecting means caused by relative movement across the scales of said first and second probes upon the occurrence of relative movement between said first and second probes and said reference element;
• and
• means for detecting, upon the occurrence of the relative movement, the direction of the relative movement on the basis of a difference in phase between the first and second tunnel currents.

A position detecting apparatus comprising:

• a reference element having a surface to be detected having regular scales;
• a first probe disposed to face the surface to be detected with a gap therebetween and movable relative to said reference element along the surface to be detected;
• a second probe disposed to face the surface to be detected with a gap therebetween and movable, together with said first probe, relative to said reference element along the surface to be detected;
• means for applying voltage between said first and second probes and said reference element;
• means for detecting first and second tunnel currents flowing between said first and second probes and said reference element, respectively;
• a first actuator for changing the gap between said first probe and the surface to be detected;
• a second actuator for changing the gap between said second probe and the surface to be detected;
• means for generating first and second control signals for controlling said first and second actuators so as to provide first and second constant tunnel currents detected by said current detecting means, respectively;
• means for detecting the relative position of said first and second probes relative to said reference element along the surface to be detected on the basis of changes in the first and second tunnel currents detected by said current detecting means caused by relative movement across the scales of said first and second probes upon the occurrence of relative movement between said first and second probes and said reference element;
• and
• means for detecting, upon the occurrence of the relative movement, the direction of the relative movement on the basis of a difference in phase between the first and second tunnel currents.

A position detecting apparatus comprising:

• a first reference element having a surface to be detected having scales at first regular intervals;
• a first probe disposed to face the surface to be detected of said first reference element and movable relative to said first reference element along the surface to be detected;
• a second reference element having a surface to be detected having scales at second regular intervals;
• a second probe disposed to face the surface to be detected of said second reference element and movable, together with said first probe, relative to said second reference element along the surface to be detected of said second reference element;
• means for applying voltage between said first and second probes and said first and second reference elements;
• means for detecting first and second tunnel currents flowing between said first and second probes and said first and second reference elements, respectively;
• means for detecting the relative position of said first and second probes relative to said first and second reference elements, respectively, along the surface to be detected of said first and second reference elements on the basis of changes in the first and second tunnel currents detected by said current detecting means caused by relative movement across the scales of said first and second reference elements of said first and second probes upon the occurrence of relative movement between said first and second probes and said first and second reference elements, respectively.

A position detecting apparatus comprising:

• a first reference element having a surface to be detected having regular scales;
• first position detecting means, disposed to face the surface to be detected of said first reference element, for detecting first positional information on the basis of said first reference element;
• a measuring head movable along the surface to be detected of said first reference element and movably supporting said first position detecting means;
• a second reference element having a surface to be detected having regular scales and mounted on one of said first position detecting means and said measuring head;
• a probe disposed to face the surface to be detected of said second reference element and mounted in the other of said first position detecting means and said measuring head;
• means for applying voltage between said probe and said second reference element;
• means for detecting a tunnel current flowing between said probe and said second reference element;
• and
• means for detecting second positional information indicative of the relative position of said first position detecting means relative to said measuring head on the basis of changes in the output of said current detecting means caused by relative movement by said probe across the scales of said second reference element upon the occurrence of relative movement between said probe and the second reference element.

Recording and/or reproducing apparatus comprising:

• a recording medium having a recording portion and a reference portion having a surface to be detected having regular scales;
• a probe disposed to face the surface to be detected and movable relative to said reference portion along the surface to be detected;
• means for applying a voltage between said probe and said reference portion;
• means for detecting a tunnel current flowing between said probe and said reference portion;
• means for detecting the relative position of said probe relative to said reference portion along the surface to be detected on the basis of changes in the output of said current detecting means caused by relative movement by said probe across the scales upon the occurrence of relative movement between said probe and the reference portion;
• and
• means for recording and/or reproducing information via a rotatable member from the relative movement using the position detected by said relative position detecting means.

Recording and/or reproducing apparatus comprising:

• a recording medium having a recording portion and a reference portion having a surface to be detected having regular scales;
• a first probe disposed to face said recording portion of said recording medium;
• a second probe disposed to face the surface to be detected of said reference portion and movable relative to said reference portion along the surface to be detected in interrelation with said first probe;
• means for applying a voltage between said second probe and said reference portion;
• means for detecting a tunnel current flowing between said second probe and said reference portion;
• means for detecting the relative position between said second probe and said reference portion along the surface to be detected on the basis of changes in the output of said current detecting means caused by relative movement across the scales by said second probe upon the occurrence of relative movement between said second probe and said reference portion;
• and
• means for recording and/or reproducing information via a rotatable member from said relative movement by said first probe using the position detected by said relative position detecting means.

A position detecting apparatus comprising:

• a reference element having a surface to be detected having irregular scales;
• a memory for storing interval information of the scales;
• a probe disposed to face the surface to be detected and movable relative to said reference element along the surface to be detected;
• means for applying a voltage between said probe and said reference element;
• means for detecting a tunnel current flowing between said probe and said reference element;
• means for detecting the relative position of said probe relative to the reference element along the surface to be detected on the basis of changes in the output of said current detecting means caused by relative movement by said probe across the scales upon the occurrence of relative movement between said probe and the reference element and on the basis of the interval information stored in said memory;
• and
• means for detecting, upon the occurrence of the relative movement, the direction of the relative movement.