Ocular optical system

Abstract

An ocular optical system includes a first lens element and a second lens element from an eye-side to a display-side in order along an optical axis. The first lens element and the second lens element each include an eye-side surface and a display-side surface. The eye-side surface of the first lens element has a convex portion in a vicinity of the optical axis. The second lens element has negative refracting power. The ocular optical system satisfies 1.5≤|f2/f1| and 250 millimeters/EFL≤10, wherein f2 is the focal length of the second lens element, f1 is the focal length of the first lens element, and EFL is the effective focal length of the ocular optical system.

What is claimed is: 
     
         1 . An ocular optical system, for imaging of imaging rays entering an eye of an observer via the ocular optical system from a display screen, a side facing towards the eye being an eye-side, a side facing towards the display screen being a display-side, the ocular optical system comprising a first lens element and a second lens element from the eye-side to the display-side in order along an optical axis, the first lens element and the second lens element each comprising an eye-side surface and a display-side surface;
 the eye-side surface of the first lens element having a convex portion in a vicinity of a periphery of the first lens element;   the eye-side surface of the second lens element having a convex portion in a vicinity of a periphery of the second lens element; and   lens elements having refracting power of the ocular optical system are only the first lens element and the second lens element;   wherein DLD is a diagonal length of the display screen corresponding to one single pupil of the observer, T 1  is a thickness of the first lens element along the optical axis, ER is a distance from a pupil of the eye of the observer to the first lens element along the optical axis, G 12  is an air gap from the first lens element to the second lens element along the optical axis, and the ocular optical system satisfies the equation:
   2.652≤((0.5× DLD )+ T 1)/( ER+G 12)≤4.517.
 
   
     
     
         2 . The ocular optical system according to  claim 1 , wherein T 2  is a thickness of the second lens element along the optical axis, and the optical imaging lens satisfies the equation:
   15.240≤( T 1+ G 12+(0.5× DLD ))/ T 2≤27.840.
 
 
     
     
         3 . The ocular optical system according to  claim 1 , wherein ALT is a sum of thicknesses of the first lens element and the second lens element along the optical axis, D 2  is a diameter of a clear aperture of the eye-side surface of the second lens element, ω is one half the field of view of the observer, and the ocular optical system satisfies the equations:
   0. 828 mm/°≤( ALT+D 2)/ω<1.572 mm/°.
 
 
     
     
         4 . The ocular optical system according to  claim 1 , wherein SL is a distance from a pupil of the eye of the observer to the display screen along the optical axis, T 2  is a thickness of the second lens element along the optical axis, and the ocular optical system satisfies the equation:
   5.253≤((0.5× DLD )+ SL )/( ER+T 2)≤7.631.
 
 
     
     
         5 . The ocular optical system according to  claim 1 , wherein D 1  is a diameter of a clear aperture of the eye-side surface of the first lens element, ω is one half the field of view of the observer, and the ocular optical system satisfies the equation:
   0.763 mm/°≤( D 1+ T 1)ω≤1.539 mm/°.
 
 
     
     
         6 . The ocular optical system according to  claim 1 , wherein G 2 D is a distance from the second lens element to the display screen along the optical axis, T 2  is a thickness of the second lens element along the optical axis, and the ocular optical system satisfies the equations:
   1.865≤( G 12+ G 2 D )/( ER+T 2)≤2.970.
 
 
     
     
         7 . The ocular optical system according to  claim 1 , wherein EFL is an effective focal length of the ocular optical system, T 2  is a thickness of the second lens element along the optical axis, and the ocular optical system satisfies the equation:
   2.271≤ EFL/ ( ER−FT 2)≤3.300.
 
 
     
     
         8 . An ocular optical system, for imaging of imaging rays entering an eye of an observer via the ocular optical system from a display screen, a side facing towards the eye being an eye-side, a side facing towards the display screen being a display-side, the ocular optical system comprising a first lens element and a second lens element from the eye-side to the display-side in order along an optical axis, the first lens element and the second lens element each comprising an eye-side surface and a display-side surface;
 the eye-side surface of the first lens element having a convex portion in a vicinity of a periphery of the first lens element;   the eye-side surface of the second lens element having a convex portion in a vicinity of a periphery of the second lens element; and   lens elements having refracting power of the ocular optical system are only the first lens element and the second lens element;   wherein DLD is a diagonal length of the display screen corresponding to one single pupil of the observer, T 1  is a thickness of the first lens element along the optical axis, ER is a distance from a pupil of the eye of the observer to the first lens element along the optical axis, and the ocular optical system satisfies the equation:
   2.785≤((0.5× DLD )+ T 1)/ ER≤ 4.800.
 
   
     
     
         9 . The ocular optical system according to  claim 8 , wherein G 12  is an air gap from the first lens element to the second lens element along the optical axis, T 2  is a thickness of the second lens element along the optical axis, and the optical imaging lens satisfies the equation:
   15.240≤( T 1+ G 12+(0.5× DLD ))/ T 2≤27.840.
 
 
     
     
         10 . The ocular optical system according to  claim 8 , wherein ALT is a sum of thicknesses of the first lens element and the second lens element along the optical axis, D 2  is a diameter of a clear aperture of the eye-side surface of the second lens element, ω is one half the field of view of the observer, and the ocular optical system satisfies the equations:
   0.828 mm/°≤( ALT+D 2)/ω≤1.572 mm/°.
 
 
     
     
         11 . The ocular optical system according to  claim 8 , wherein SL is a distance from a pupil of the eye of the observer to the display screen along the optical axis, T 2  is a thickness of the second lens element along the optical axis, and the ocular optical system satisfies the equation:
   5.253≤((0.5× DLD )+ SL )/( ER+T 2)≤7.631.
 
 
     
     
         12 . The ocular optical system according to  claim 8 , wherein D 1  is a diameter of a clear aperture of the eye-side surface of the first lens element, ω is one half the field of view of the observer, and the ocular optical system satisfies the equation:
   0.763 mm/°≤( D 1+ T 1)/ω≤1.539 mm/°.
 
 
     
     
         13 . The ocular optical system according to  claim 8 , wherein G 12  is an air gap from the first lens element to the second lens element along the optical axis, G 2 D is a distance from the second lens element to the display screen along the optical axis, T 2  is a thickness of the second lens element along the optical axis, and the ocular optical system satisfies the equations:
   1.865≤( G 12+ G 2 D )/( ER+T 2)≥2.970.
 
 
     
     
         14 . The ocular optical system according to  claim 8 , wherein EFL is an effective focal length of the ocular optical system, T 2  is a thickness of the second lens element along the optical axis, and the ocular optical system satisfies the equation:
   2.271≤ EFL/ ( ER−FT 2)≤3.300.