Abstract:
An eyepiece member comprises an eye cup provided on the outer circumference of an eyepiece barrel that holds an eyepiece lens, the eye cup being movable relative to the eyepiece barrel along the direction of the optical axis of the eyepiece lens, and a positioning members for the eye cup provided on at least one of a portion of the eyepiece barrel and a portion of the eye cup that are opposed to each other, intervals of the positioning members being relatively smaller in the eye cup pull-out side in which the eye cup is pulled toward the user when used than in the eye cup push-in side.

Description:
[0001]     This application claims the benefit of Japanese Patent application No. 2004-065130 which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an eyepiece device and a binocular.  
         [0004]     2. Related Background Art  
         [0005]     Eyepiece devices of optical apparatuses such as binoculars are provided with an eye cup for the purpose of preventing entrance of exterior light or making it easy to keep the positional relationship between the eyepiece device and the eyes constant. Some eyepiece devices having an eye cup are equipped with a mechanism for allowing the eye cup to move along the optical axis relative to the eyepiece barrel.  
         [0006]     A known mechanism for allowing movement of the eye cup along the optical axis direction is provided with a twist-up ring that is movable along the optical axis direction relative to the eyepiece barrel, a twist-up adjusting pin provided on the eyepiece barrel and three pin engagement portions provided on the twist-up ring for retaining the twist-up pin (see Japanese Utility Model No. 3090513). With this mechanism, the eye cup can be retained steadily at three positions with respect to the optical axis direction.  
         [0007]     When a person wearing eyeglasses uses an eyepiece device that allows adjustment of the position of the eye cup, the eye cup will be used in the state in which it is pushed (or retracted) into the eyepiece barrel (see  FIGS. 1 and 2 ).  
         [0008]     Letting D be the distance from the surface of the eyepiece lens G 1  that constitutes the last lens in the optical system to the surface of the eyeglass lens G 4  (or G 5 ), t be the thickness of the eyeglass lens G 4  (or G 5 ), S 1  be the distance from the backside surface of the eyeglass lens G 4  (or G 5 ) to the surface of the cornea E, S 2  be the distance from the surface of the cornea E to the iris I, and X be the distance from the surface of the eyepiece lens G 1  that constitutes the last lens in the optical system to the iris I, the equation X=D+t+S 1 +S 2  holds.  
         [0009]     The distance from the surface of the eyepiece lens G 1  that constitutes the last lens in the optical system to the surface of the eyeglass lens G 5  for farsightedness is generally smaller than the distance from the surface of the eyepiece lens G 1  that constitutes the last lens in the optical system to the surface of the eyeglass lens G 4  for nearsightedness. In addition, the thickness t of the eyeglass lens G 5  for farsightedness is larger than the thickness t of the eyeglass lens G 4  for nearsightedness.  
         [0010]     Generally, the thickness t of the eyeglass lens G 4  (or G 5 ) is larger than 1.1 mm, the distance S 1  from the backside surface of the eyeglass lens G 4  (or G 5 ) to the surface of the cornea E is larger than 12 mm, and the distance S 2  from the surface of the cornea E to the iris I is approximately 3 mm (equivalent value in the air), and therefore in typical cases, the distance X from the surface of the eyepiece lens G 1  that constitutes the last lens in the optical system to the iris I is larger than 20 mm.  
         [0011]     The distance of the position of the eye point (i.e. the position at which a pupil is formed) EP of optical apparatuses such as binoculars from the most eye side surface of the eyepiece lens (that is, the surface of the eyepiece lens which surface is closest to the person using an optical apparatus.) is generally smaller than 20 mm. Accordingly, even when the eye cup is set to the fully retracted (or pushed in) state, the position of the eye point EP and the position of the iris of a person wearing eyeglasses do not coincide with each other. This means that eyeglass wearers cannot adjust the position of the eye cup to allow the position of their iris I to coincide with the eye point, and they cannot see whole the field of view.  
         [0012]     On the other hand, when a person who is not wearing eyeglasses (i.e. a person who observes with naked eye) uses an eyepiece device that allows adjustment of the position of the eye cup, the eye cup will be used in the state in which it is extended (or pulled out) from the eyepiece barrel (see  FIGS. 3 and 4 ).  
         [0013]     Each one has his own face shape and there are differences in the shape of the faces. Especially, there are differences in the shape of the eye pit (or differences between sunken eyes, clear-cut eyes etc.) depending on the racial difference between the Orientals and the Westerners, the difference in stages of growth between adults and children or the sexual difference between men and women.  
         [0014]     Accordingly, in the case that the eye cup is used in a state where it is pulled out from the eyepiece barrel, it is necessary for a person who observes with naked eye to finely adjust the position of the eye cup (by, for example, changing the distance L between the outer end of the eye cup and the iris I) to adjust the position of the iris I to coincide with the position of the eye point EP.  
         [0015]     However, the eyepiece device disclosed in the above-mentioned Japanese Utility Model No. 3090513 suffers from the problem that when the eye cup is pulled out from the eyepiece barrel, fine position adjustment cannot be carried out in the range that requires finer adjustment, since the three pin engagement portions are formed at equal intervals.  
       SUMMARY OF THE INVENTION  
       [0016]     The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible for a person observing with naked eyes who uses the eye cup in a state pulled out from the eyepiece barrel to adjust the position of the eye cup finely in the range that requires finer adjustment so that the eye cup can be set at a position optimum for observation.  
         [0017]     An eyepiece device according to the present invention that is intended to achieve the above object comprises an eye cup provided on the outer circumference of an eyepiece barrel that holds an eyepiece lens, the eye cup being movable relative to the eyepiece barrel in the direction of the optical axis of said eyepiece lens, a projection provided on one of a portion of the eyepiece barrel and a portion of the eye cup that are opposed to each other, and at least three retaining portions provided on the other of the portion of said eyepiece barrel and the portion of said eye cup that are opposed to each other for retaining said projection, wherein the pitch of the retaining portions is designed in such a way as to be relatively smaller in the eye cup pull-out side than in the eye cup push-in side.  
         [0018]     In the eyepiece device according to the present invention, it is preferable that the interval between a pull-out side retaining portion that is adapted to retain the aforementioned projection when the eye cup is fully pulled out and a first intermediate retaining portion that is adjacent to this pull-out side retaining portion is smaller than the interval between a push-in side retaining portion that is adapted to retain the aforementioned projection when the eye cup is fully pushed in and a second intermediate retaining portion that is adjacent to this push-in side retaining portion (each of the retaining portions mentioned here being one of said at least three retaining portions).  
         [0019]     In the eyepiece device according to the present invention, it is preferable that eye cup be rotatable about the optical axis relative to the eyepiece barrel, the aforementioned projection be a projecting portion formed by bending a leaf spring attached on the outer circumferential surface of the eyepiece barrel, and the at least three retaining portions be a plurality of grooves extending along the optical axis direction formed on the inner circumferential surface of the eye cup.  
         [0020]     A binocular according to the present invention is characterized by having the above-described eyepiece device according to the present invention.  
         [0021]     As per the above, according to the eyepiece device of the present invention, when a person who observes with naked eye uses the eyepiece device with the eye cup being extended, the position of the eye cup can be adjusted finely in the range in which finer adjustment is required. Accordingly, the eye cup can be set to a position optimum for observation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a schematic cross sectional view showing a state in which an eyepiece device according to a first embodiment of the present invention is used by a person wearing eyeglasses for nearsightedness.  
         [0023]      FIG. 2  is a schematic cross sectional view showing a state in which the same eyepiece apparatus is used by a person wearing eyeglasses for farsightedness.  
         [0024]      FIG. 3  is a schematic cross sectional view showing a state in which the same eyepiece device is used by a person who observes with naked eye.  
         [0025]      FIG. 4  is a schematic cross sectional view showing a state in which the same eyepiece device is used by a person who observes with naked eye.  
         [0026]      FIG. 5  is a perspective view showing a ring-shaped member that constitutes a part of the eye cup.  
         [0027]      FIG. 6  is a schematic cross sectional view showing the eyepiece device in the state in which the eye cup has been fully pushed in.  
         [0028]      FIG. 7  is a schematic cross sectional view showing the eyepiece device in the state in which the projecting portion  32  is at a position between click groove  26   a  and click groove  26   b.    
         [0029]      FIG. 8  is a schematic cross sectional view showing the eyepiece device in the state in which the projecting portion is received in click groove  26   d.    
         [0030]      FIG. 9  is a schematic cross sectional view showing the eyepiece device in the state in which the projecting portion  32  is received in click groove  26   e.    
         [0031]      FIG. 10  is a schematic cross sectional view showing a ring shaped member.  
         [0032]      FIG. 11  is a schematic cross sectional view showing a ring shaped member.  
         [0033]      FIG. 12  is a schematic cross sectional view showing a ring shaped member.  
         [0034]      FIG. 13  is a schematic cross sectional view showing a ring shaped member.  
         [0035]      FIG. 14  is a schematic cross sectional view showing a ring shaped member that constitutes a part of an eye cup of an eyepiece device according to a second embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]     In the following, embodiments of the present invention will be described with reference to the drawings.  
         [0037]      FIG. 1  is a schematic cross sectional view showing a state in which an eyepiece device according to the first embodiment of the present invention is used by a person wearing eyeglasses for nearsightedness.  FIG. 2  is a schematic cross sectional view showing a state in which the same eyepiece apparatus is used by a person wearing eyeglasses for farsightedness.  FIGS. 3 and 4  are schematic cross sectional views showing states in which the same eyepiece device is used by a person who observes with naked eye.  FIG. 5  is a perspective view showing a ring-shaped member that constitutes a part of the eye cup.  
         [0038]     In connection with the above,  FIG. 3  shows the state in which the eye cup  20  is in its fully pulled-out state, and  FIG. 4  shows the state in which the eye cup  20  is slightly pushed in from the fully pulled-out state.  
         [0039]     The eye cup  20  includes the ring-shaped member  21  rotatably fitted on the outer circumferential surface of an eyepiece barrel  30  and a rubber eye cup  22  that covers the outer circumference of the ring-shaped member  21 . The ring-shaped member  21  is made of a metal or a synthetic resin. The rubber eye cup  22  is attached on the ring-shaped member  21  using an adhesive (not shown).  
         [0040]     The eyepiece barrel  30  houses a lens holding frame  34  that holds eyepiece lenses G 1 , G 2  and G 3 . The eyepiece lenses G 1 , G 2  and G 3  functions to magnify an image to be observed.  
         [0041]     Female screw holes  36  are formed in the radial direction on the outer circumferential surface of the eyepiece barrel  30  at an interval of 180°. Screws  35  are screwed into the female screw holes  36  (only one of the screws  35  is shown in  FIG. 1 ). The female screw holes may be replaced by through holes so that pins are pressed into them.  
         [0042]     A leaf spring  31  for a click-stop mechanism is attached on the outer circumferential surface of the eyepiece barrel  30 . The leaf spring  31  is formed by a bending process to have a projecting portion (or a projection)  32  (see FIGS.  6  to  9 ) protruding in the radial direction away from the optical axis, formed at its center.  
         [0043]     The ring-shaped member  21  has two cam grooves  25   a  and  25   b  for slidably retaining the heads of the respective screws  35 , formed along the circumferential direction at equal intervals. The cam grooves  25   a  and  25   b  are extending linearly in the same oblique direction from one opening of the ring-shaped member  21  to the other.  
         [0044]     On the inner circumferential surface of the ring-shaped member  21 , five click grooves (or retaining portions)  26   a  to  26   e  extending along the optical axis AX direction, into which the projecting portion  32  of the leaf spring  31  for click is to be received, are formed (see  FIG. 5 ). The click grooves  26   a  to  26   e  are formed in such a way as to satisfy the following condition: the interval between click groove  26   e  (the pull-out side retaining portion) and click groove  26   d  (first intermediate retaining portion) in the push-in side is smaller than the interval between click groove  26   b  (the second intermediate retaining portion) and click groove  26   a  (the push-in side retaining portion) in the pull-out side.  
         [0045]      FIG. 6  is a schematic cross sectional view showing the eyepiece device in the state in which the eye cup  20  has been fully pushed in (or fully retracted).  FIG. 7  is a schematic cross sectional view showing the eyepiece device in the state in which the projecting portion  32  is at a position between click groove  26   a  and click groove  26   b .  FIG. 8  is a schematic cross sectional view showing the eyepiece device in the state in which the projecting portion  32  is received in click groove  26   d .  FIG. 9  is a schematic cross sectional view showing the eyepiece device in the state in which the projecting portion  32  is received in click groove  26   e.    
         [0046]     In the state shown in  FIG. 6 , the projecting portion  32  of the leaf spring  31  is received in click groove  26   a .  FIG. 6  corresponds to  FIGS. 1 and 2  that show the state in which the eye cup is fully pushed in. The distance from the eyepiece lens G 1  to the outer end of the eye cup  20  is shortest in the state shown in  FIG. 6 . Since the projecting portion  32  is fitted in click groove  26   a  by means of the leaf spring  31 , movement of the eye cup is prevented unless a force larger than a certain value is exerted in the rotational direction of the eye cup  20 . Consequently, the distance from the eye piece lens G 1  to the outer end of the eye cup  20  is kept constant.  
         [0047]     From this state, the eye cup may be rotated by exerting a force larger than a certain value on the eye cup in the anticlockwise direction to dislocate the projecting portion  32  out of click groove  26   a . In this process, since the projecting portion  32  is pressed against the inner circumferential surface of the ring-shaped member  21  by a biasing force exerted by the leaf spring  31  (see  FIG. 7 ), a resisting force acts on the operator&#39;s hand. With the rotation of the eye cup  20 , the distance from the eyepiece lens G 1  to the outer end of the eye cup  20  gradually increases.  
         [0048]     When the eye cup  20  is rotated by a predetermined angle, the projecting portion  32  fits into click groove  26   b . This gives a click feeling (that is, a feeling with which the fitting of the projecting portion into the click groove  26   b  can be recognized). In this state, since the projecting portion  32  is fitted in click groove  26   b , movement of the eye cup is prevented unless a force larger than a certain value is exerted in the rotational direction of the eye cup  20 . Consequently, the distance from the eye piece lens G 1  to the outer end of the eye cup  20  is kept constant.  
         [0049]     Similarly, the groove in which the projecting portion  32  is fitted can be changed sequentially from click groove  26   b  to click groove  26   c , and further changed from click groove  26   c  to click groove  26   d  (see  FIG. 8 ) by exerting a rotational force larger than a certain valued on the eye cup  20 . The state shown in  FIG. 8  corresponds to the state shown in  FIG. 4 . When the projecting portion  32  is fitted into click grooves  26   c  or  26   d , a click feeling is generated, and in addition, the distance from the eyepiece lens G 1  to the outer end of the eye cup  20  can be kept constant.  
         [0050]     The groove in which the projecting portion  32  is fitted can be changed further from click groove  26   d  to click groove  26   e  (see  FIG. 9 ) by exerting a rotational force larger than a certain value on the eye cup  20 . When the projecting portion  32  is fitted into click groove  26   e , a click feeling is generated. The state shown in  FIG. 9  corresponds to the state shown in  FIG. 3  in which the eye cup  20  is fully pulled out (or fully extended). The distance from the eyepiece lens G 1  to the outer end of the eye cup is longest in the state shown in  FIG. 9 . Since the projecting portion  32  of the leaf spring  31  is fitted in click groove  26   e , movement of the eye cup is prevented unless a force larger than a certain value is exerted in the rotational direction of the eye cup  20 . Consequently, the distance from the eye piece lens G 1  to the outer end of the eye cup  20  is kept constant.  
         [0051]     According to this embodiment, since the position of the eye cup  20  relative to the eyepiece barrel  30  can be adjusted finely, a person who observes with naked eye can adjust the position of the eye cup he or she uses to a position optimum for observation.  
         [0052]     The pitches of click grooves  26   a  to  26   e  illustrated above are not essential, but they may be modified into, for example, those shown in FIGS.  10  to  13  so long as the condition presented below is satisfied.  
         [0053]     That is, the condition that the interval between the pull-out side click groove in which the projecting portion  32  is to fit when the eye cup is fully pulled out and the click groove adjacent thereto is smaller than the interval between the push-in side click groove in which the projecting portion  32  is to fit when the eye cup  20  is fully pushed in and the click groove adjacent thereto.  
         [0054]     FIGS.  10  to  13  are schematic cross sectional view showing modifications of the ring-shaped member.  
         [0055]     A first modification of the ring-shaped member  121  shown in  FIG. 10  has three click grooves (or retaining portions)  126   a ,  126   b  and  126   c  formed on its inner circumferential surface.  
         [0056]     Letting A be the interval between click groove  126   b  (or the first intermediate retaining portion) and click groove  126   c  (or the pull-out side retaining portion) and B be the interval between click groove  126   a  (or the push-in side retaining portion) and click groove  126   b  (or the second intermediate retaining portion), the condition B&gt;A holds, namely the above-mentioned condition is met.  
         [0057]      FIG. 11  shows a second modification of the ring-shaped member  221 , which has five click grooves  226   a ,  226   b ,  226   c ,  226   d  and  226   e  formed on its inner circumferential surface. This ring-shaped member  221  has the structure same as the ring-shaped member  21  of the above-described embodiment.  
         [0058]     The interval between click groove  226   b  and click groove  226   c , the interval between click groove  226   c  and click groove  226   d  and the interval between click groove  226   d  (or the first intermediate retaining portion) and click groove  226   e  (or the pull-out side retaining portion) are equal (i.e. interval A). Letting B be the interval between click groove  226   a  (or the push-in side retaining portion) and click groove  226   b  (or the second intermediate retaining portion), the condition B&gt;A holds, namely the above-mentioned condition is met.  
         [0059]      FIG. 12  shows a third modification of the ring-shaped member  321 , which has five click grooves (or retaining portions)  326   a ,  326   b ,  326   c ,  326   d  and  326   e  formed on its inner circumferential surface.  
         [0060]     The interval between click groove  326   b  and click groove  326   c , the interval between click groove  326   c  and click groove  326   d  and the interval between click groove  326   d  (or the first intermediate retaining portion) and click groove  326   e  (or the pull-out side retaining portion) are D, C and A respectively. Letting B be the interval between click groove  326   a  (or the push-in side retaining portion) and click groove  326   b  (or the second intermediate retaining portion), the condition B&gt;A holds, namely the above-mentioned condition is met. In addition, the condition A≠C holds.  
         [0061]      FIG. 13  shows a fourth modification of the ring-shaped member  431 , which has six click grooves (or retaining portions)  426   a ,  426   b ,  426   c ,  426   d ,  426   e  and  426   f  formed on its inner circumferential surface.  
         [0062]     The interval between click groove  426   c  and click groove  426   d  is D, the interval between click groove  426   d  and click groove  426   e  is C, and the interval between click groove  426   e  (or the first intermediate retaining portion) and click groove  426   f  (or the pull-put side retaining portion) is A. Letting B be the interval between click groove  426   a  (or the push-in side retaining portion) and click groove  426   b  (or the second intermediate retaining portion), the condition B&gt;A holds, namely the above-mentioned condition is met. In addition, the condition A≠B, C holds. One or more additional grooves may be provided between click groove  426   b  and click groove  426   c , though such grooves are not shown in the drawings.  
         [0063]      FIG. 14  is a side view showing a ring-shaped member that constitutes a part of the eye cup of an eye piece device according to the second embodiment of the present invention.  
         [0064]     In this eye cup, the ring-shaped member  521  that constitutes a part of the eye cup is moved in the optical axis direction (in the vertical direction in  FIG. 14 ) by sliding an adjust pin (or a projection) formed on the eyepiece barrel (not shown) along a slot  525  formed on the ring-shaped member  521 .  
         [0065]     In this second embodiment, the pitch of four pin engagement portions (or retaining portions)  526   a ,  526   b ,  526   c ,  526   d  formed in the slot  525  for retaining the projection is designed in such a way as to be made smaller in the range in which the ring-shaped member  521  is pulled out (i.e. moved upwardly in  FIG. 14 ) more than a certain amount.  
         [0066]     According to the second embodiment, advantageous effects similar to those of the first embodiment can be achieved.  
         [0067]     Although in the above-described embodiments, the retaining portions in the form of the click grooves  126   a - 126   c ,  226   a - 226   e ,  326   a - 326   e ,  426   a - 426   f  or the pin engagement portions  526   a - 526   c  are provided on the ring-shaped member  21 ,  121 ,  221 ,  321 ,  421 , the click grooves and the pin engagement portions may be provided on the eyepiece barrel  30 .  
         [0068]     In the present invention, the projection may be provided as a separate member attached to the eyepiece barrel or the eye cup, or alternatively, the projection may be provided on the eyepiece barrel or the eye cup by directly machining the eyepiece barrel or the eye cup.