Rangefinder binoculars

The range binoculars include first and second observing optical systems, a laser beam-emitter for emitting a laser beam, a measuring optical system for collimating the laser beam and sending the collimated laser beam to a target. A laser beam-receiving device receives the laser beam reflected by the target, while a distance-determining device determines the distance between the observation place and the target from the flight time of the laser beam taken from the laser beam-emitter to the laser beam-receiver. A measurement-displaying device displays the measurements obtained by the distance-determining device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to range binoculars, more particularly, the invention relates to a pair of binoculars having an optical system that measures distance and an optical system for observation.

2. Background Art

Typically, conventional range binoculars emit an infrared ray as a distance-measuring laser beam, collimate and aim the emitted infrared ray at a target, then receive a reflected ray from the target, measure the flight time taken from the ray-emitting point to the reflected ray-receiving point, and determine the distance from the observation place, i.e., the ray-emitting point to the target.

Conventional range binoculars are provided with a beam splitter, which permits an infrared ray to be transmitted, but does not permit visible rays to be transmitted between the objective lens of the optical system for observation and the erecting prism. As such, the infrared ray beam goes to the beam splitter, is reflected, and returns to the objective lens. The beam is collimated by the objective lens and transmitted to the target. Furthermore, in the conventional range binoculars, visible rays entering the objective lens for observation go through the beam splitter and advance to the eyepieces at which an image is formed.

The beam splitter used in the conventional range binoculars is required to assure the reflection of the distance-measuring infrared ray thereon and, at the same time, the transmission of the observed visible rays through itself at a high transmittance. Thus, the beam splitter is required to have a high performance.

To produce such high performance beam splitters is technically difficult, thereby resulting in high production costs. Consequently, conventional range binoculars using such beam splitters are rather expensive.

Furthermore, such high performance beam splitters are not able to transmit all of the visible rays reaching the beam splitters. Thus, conventional range binoculars, due to the presence of the beam splitter, inevitably reduce the transmittance of the observed visible rays and the resolving power thereof. As a result, images are degraded using conventional range binoculars.

The focusing mechanism of binoculars is of an independent feeding type (IF Type) or a central feeding type (CF Type). It is well known in the industry that focusing is easier with the CF Type binoculars than with the IF Type binoculars. In CF Type binoculars, an internal focusing lens is inserted between the objective lens and the erecting prism. The user focuses by moving the focusing lens. Therefore, the CF Type binoculars must be provided with the internal focusing lens and a means for moving in a space between the objective lens and the erecting prism.

However, it is very difficult and almost impossible to find a space to place an internal focusing lens in such conventional range binoculars, because the beam splitter is already fixed between the objective lens and the erecting prism. Thus, conventional rangefinder binoculars can hardly use the CF Type focusing systems, which is disadvantageous.

SUMMARY OF THE INVENTION

An object of the invention is to overcome the above-described drawbacks of conventional range binoculars. It is also an object of the invention to provide a pair of range binoculars which can be produced at a lower cost, has a lower degree of image degradation, and uses CF Type focusing means.

In order to achieve the above-described objects, the invention provides a pair of range binoculars, which includes a first observing optical system separate from a second observing optical system. An emitting device emits a laser beam to measure a distance, while a rangefinder optical system, provided separately from the first and second observing optical systems, collimates the emitted laser beam and aims the laser beam at a target. A laser beam-receiver receives the laser beam reflected by the target so a distance-measuring device can determine a distance from the observation place to the target. A display indicates the distance obtained by the distance-measuring device.

The rangefinder optical system includes a reflecting mirror for reflecting the laser beam emitted by the emitting device to the distance-measuring device and a collimating lens for collimating the distance-measuring laser beam reflected from the mirror. The first observing optical system includes a first objective optical member, a first eyepiece optical member, and a first optical member for assembling an image of the visible rays from the first objective optical member and sending the image to the first eyepiece optical member. The second observing optical system includes a second objective member, a second eyepiece member, and a second optical member for assembling an image of the visible rays from the second objective optical member and sending the image to the second eyepiece optical member.

The first and second optical members are beam splitters, which separate the distance-measuring laser beam and the visible rays entering the observing optical system from each other to remove the distance-measuring laser beam from the light path of the observing optical system before it is sent to the distance-measuring device.

A body case and an attachment case are provided with the body case having the first observing optical system and the second objective optical member contained therein. The attachment case, which has the second eyepiece optical member and the second optical member, is connected with the body case to allow the attachment case to rotate around the axis of the second objective optical member. The distance-measuring laser beam can generate an infrared ray.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2illustrate the structural configuration of the range binoculars according to a preferred embodiment of the invention.FIG. 1is a cross-sectional plan view of range binoculars1.FIG. 2is a cross-sectional plan view of the left side of a part of the range binoculars1. The range binoculars1include body case11, attachment case21and outer case101.

The body case11and a body10of the range binoculars1are contained in the outer case101. The body10includes a first optical system. The range binoculars1also include an attachment20contained in the attachment case21, wherein the attachment20includes a second optical system.

The range binoculars1include a pair of observing optical systems, that is, first and second observing optical systems. The first observing optical system30includes a first objective optical member31, first eyepiece optical member32, first internal focusing lens63and first optical member33. The second observing optical system50includes a second objective optical member51, second eyepiece optical member52, second internal focusing lens64and second optical member53.

FIG. 3is a schematic diagram illustrating the first and second observing optical systems of the range binoculars1shown in FIG.1.

As shown inFIG. 1, the first objective optical member31, first internal focusing lens63, and first optical member33form an optical axis of a first objective optical system, and the first eyepiece optical member32and first optical member33form an optical axis of the first eyepiece optical system. The second objective optical member51, second focusing lens64, and second optical member53form an optical axis of the second objective optical system, and the second eyepiece optical member52and second optical member53form an optical axis of the second eyepiece optical system.

The body10of the binoculars1contains the first observing optical system30and the second objective optical member51of the second observing optical system50. The body case11surrounds the body10as an outer structural member.

The body case11includes the objective part12, which contains the first objective optical member31and the second objective optical member51, and the eyepiece part13, which contains the first eyepiece optical member32and the first optical member33. The eyepiece part13is integrally connected to the objective part12. The eyepiece part13includes a first eyepiece cylindrical frame14, which contains the first eyepiece optical member32. A face16provided on the eyepiece part13includes a hole15, wherein an axis of the hole15coincides with the optical axis of the second objective optical system.

The attachment20includes the second eyepiece optical member52and second optical member53of the second observing optical system50, which are contained by the attachment case21as an outer structural member.

The attachment case21includes a second eyepiece cylindrical frame24, which contains the second eyepiece optical member52at one end face thereof, and, at another end face23, a circular projection22, which can engage the hole15provided in the face16of the objective part12. The axis of the circular projection22coincides with the optical axis of the second objective optical member when the circular projection22engages the hole15. The circular projection22is provided with a connecting member25. The connecting member25contacts the inner wall of body case11when the circular projection22is inserted in the hole15and the face16of the body case11contacts the face23of the attachment case21. The connecting member25is a means for connecting the body case11and attachment21with each other, thereby allowing the attachment case21to rotate within the hole15of the body case11.

The body10further includes a laser diode17, which is a laser beam-emitting means, and a distance-measuring optical system18.

The distance-measuring optical system18is provided such that an optical axis of the system18is parallel to optical axes of the first observing optical system30and the second observing optical system50at a position between the second observing optical system50and a side wall of distance-measuring optical system18adjacent to the second observing optical system50in the objective part12of the body case11. The distance-measuring optical system18includes a mirror61and collimating lens62. The mirror61reflects a distance-measuring laser beam emitted by the laser diode17and sends the reflected distance-measuring laser beam to the collimating lens62, which collimates the distance-measuring laser beam reflected from the mirror61. Preferably, the collimating lens62includes two lenses, however, it is within the scope of this invention to vary the number of lenses used, so long as the above-described function is not lost. Similarly, it is within the scope of the invention to use any suitable lens capable of collimation as the collimating lens62.

Thus, the range binoculars1have a distance-measuring system18, first observing optical system30, and second observing optical system50.

The laser diode17is fixed under the mirror61can aim an infrared ray, also known as the distance-measuring laser beam, at the mirror61. The wavelength of the infrared ray emitted by the laser diode17is, for example, 905 nm, and may be any suitable wavelength as long as distance measurement is possible using the measuring method mentioned below.

In the range binoculars according to this invention, it is not necessary to always send the distance-measuring laser beam from the laser diode, through the mirror, to the collimating lens. Rather, the distance-measuring laser beam may be sent directly from the laser diode to the collimating lens, that is, without any mirrors therebetween.

Moreover, it is within the scope of the invention to position the laser beam-emitting part and distance-measuring optical system anywhere within the range binoculars.

The first objective optical member31and the second objective optical member51each includes a lens group having a plurality of objective lenses. It is within the scope of the invention to have the first objective optical member31and the second objective optical member51be substantially similar to objective optical members used in conventional range binoculars.

The first eyepiece optical member32and the second eyepiece optical member52each includes a lens group having a plurality of eyepieces. As mentioned above, the first eyepiece optical member32is mounted on the first eyepiece cylindrical frame14inserted in the eyepiece part13of the body case11. The second eyepiece optical member52is mounted on the second eyepiece cylindrical frame24inserted in the attachment case21. Similarly, it is within the scope of the invention to have the first eyepiece optical member32and the second eyepiece optical member52be substantially similar to eyepiece optical members used in conventional range binoculars.

The first internal focusing lens63is fixed between the first objective optical member31and the first optical member33wherein the optical axis of the first internal focusing lens63is aligned with the optical axis of the first objective optical member31. The second internal focusing lens64is provided between the second objective optical member51and the second optical member53wherein the optical axis of the second internal focusing lens64is aligned with the optical axis of the second objective optical member51. The first internal focusing lens63and second focusing lens64are fixed to a frame66of focusing lens-moving means65provided between the first observing optical system30and the second observing optical system50. Operating the focusing lens-moving means65moves the frame66, which, in turn, allows the first internal focusing lens63and second focusing lens64to travel together in a direction of the first objective optical member31and the second objective optical member51, or in the direction of the first optical member33and the second optical member53. Thus, the focus of the first observing optical system30and the second observing optical system50is controlled. That is, the range binoculars1use a CF Type of focusing method.

As shown inFIG. 3, the second optical member53, which is commonly known as a Porro II erecting prism, includes an assembly of a second upper prism55, second side prism56, and second lower prism57. The assembly of prisms is positioned such that a ray coming through the second objective optical system enters the second objective optical member51and passes sequentially through second upper prism55, second side prism56and second lower prism57, and is then sent to the second eyepiece optical system. Due to the structural arrangement of the second optical member53, the second eyepiece optical member52of the second observing optical system50has an optical axis that is not aligned with the optical axis of the second objective optical member51.

Similarly, the first optical member33, which is commonly known as a Porro II erecting prism, has a structure that is identical to the structure of the second optical member53. In particular, the structure of the first optical member33includes a first upper prism35, first side prism36, and first lower prism37, but further includes a rectangular prism38, as shown inFIG. 3. Abottom face of the rectangular prism38contacts a bottom face of the first lower prism37. The assembly of the first lower prism37and the rectangular prism38form a beam splitter39. Therefore, the first optical member33has, in addition to the same function as the second optical member53, the function of a beam splitter, which transmits an infrared ray and reflects visible light. Due to the beam splitting function of the first optical member33, an infrared ray, which is emitted by the laser diode away from the range binoculars1, reflected by an object back to the binoculars1and into the optical path of the first observing optical system30through the first object optical member31, is transmitted by the beam splitter39and guided to the outside of the first observing optical system30. On the other hand, visible light, which is reflected by the object back into the optical path of the first observing optical system30through the first object optical member31, is reflected by the beam splitter39and sent to the first eyepiece optical member32.

As shown inFIG. 3, the focusing plate67is provided between the first optical member33and the first eyepiece optical member32of the first observing optical system30.

The body10further includes a laser beam-receiving means41disposed near an inner wall on the side where laser diode17is placed. The laser beam-receiving means41is a photodetector which receives, for example, an infrared ray separated by the first optical member33, as mentioned above.

Furthermore, the body10has a range-finding means (not shown), connected to the laser diode17and laser beam-receiving means41for determining a distance between the observer and the target. The distance is determined based on the flight time of the infrared ray from the emission of the infrared ray by the laser diode17to reception by the laser beam-receiving means41. A range-finding means, for example, the range-finding means disclosed in JP Translated PCT Application Publication No. 10-512954(1998), U.S. Pat. Nos. 5,574,552, 5,612,779, 5,623,335, 5,652,651 or 5,740,952.

An LCD42is mounted on the focusing plate67for displaying the measurement result. The LCD42, which is connected to the range-finding means, displays the distance between the observation place and the target or object. The LCD42is disposed such that a display window69of the LCD42appears at a lower part of a view68formed on the focusing plate67.

Operation of the above-described range binoculars1is provided below.

A pupil distance is adjusted by rotating the attachment20. As mentioned above, the axis of the circular projection22is aligned with the optical axis of the second objective optical member51. Consequently, when the second optical member53is turned by rotating the attachment20, rays traveling along the optical axis of the second objective optical member51always enter the second optical member53at the same point. This means that the rotation of the attachment20does not change the image obtained in the second observing optical system50. Also, since the optical axis of the second objective optical member51is not aligned with the axis of the second eyepiece optical member52, when the attachment20is rotated, the optical axis of the second eyepiece optical member52included in the attachment20turns, drawing a circular arc having a center on the axis of the second objective optical member51and having a radius corresponding to a difference between the optical axis of the second objective optical member51and the optical axis of the second eyepiece optical member52. Since the optical axis of the second objective optical member51is provided in the body case11, separate from the attachment20, together with the optical axis of the first objective optical member31and the optical axis of the first eyepiece optical member32, when the attachment20is rotated, the distance between the optical axis of the second objective optical member51and the optical axis of the first eyepiece optical member32is not changed. In summary, when the attachment20is rotated, the distance between the optical axis of the second eyepiece optical member52and the optical axis of the first eyepiece optical member32is changed, which means the distance between the second eyepiece cylindrical frame24accommodating the second eyepiece optical system52, and the first eyepiece cylindrical frame14accommodating the first eyepiece optical member32, is changed. Thus, the pupil distance in the range binoculars1can be adjusted without affecting the visual field.

The user observes an object with the range binoculars1of the invention in the same way as with conventional binoculars. When an object is observed with the range binoculars1of the invention, visible light reflected by the object enters the binoculars through the first and second objective optical members31and51. The visible light entering the first observing optical system30through the first objective optical member31proceeds along the optical path determined by the first objective optical member31, and enters the first optical member33, which functions as a beam splitter. Since the beam splitter39of the first optical member33reflects visible light, the visible light is reflected by the beam splitter39and sent to the first eyepiece optical member32along the optical path determined by the first eyepiece optical member32. Visible light entering the second observing optical system50through the second objective optical member51proceeds along the optical path determined by the second objective optical member51to the second optical member53, advances through the second optical member53, and reaches the second eyepiece optical member52via the optical path determined by the second eyepiece optical member52. In this way, the same image of the object is made by each of the left and right optical systems.

As mentioned above, the range binoculars1do not have a beam splitter provided between the second objective optical member51and the second optical member53, as is typical in conventional binoculars. Therefore, the visible light entering the second observing optical system50through the second objective optical member51reaches the second eyepiece optical member52without passing through the beam splitter. Thus, the range binoculars1do not reduce the transmission amount of visible light or the resolving power. Consequently, the second observing optical system50also produces clear images.

The measurement of the distance between the observer and an object using the range binoculars1is carried out in the following way. First, the object is brought into focus. Then, the mirror61is irradiated with an infrared ray produced by the laser diode17. The mirror61reflects the infrared ray, which is then sent to the collimating lens62. The infrared ray, collimated with the collimating lens62, advances to the object. The infrared ray is reflected by the object and sent to the range binoculars1through the first objective optical member31. The incoming infrared ray proceeds along the path determined by the first objective optical member and enters the first optical member33, which performs a beam splitting function. Since the infrared rays travel through the beam splitter39of the first optical member33, the infrared ray is transmitted by the beam splitter39and guided to the outside of the first observation optical system30. Then, the infrared ray is received and detected by the laser beam-receiving means41. The distance between the observing point and the object is calculated by the range-finding means based on the length of time from the emission of an infrared ray by the laser diode17to the detection of the reflected ray by the laser beam-receiving means41.

When the calculation is finished, a signal indicating the distance is sent to the LCD42, wherein the distance is shown on the display window69of the LCD42. The displayed distance appears at a lower part of view68, which is obtained from the first observing optical system30. As a result, the user sees the distance on the display.

Hereinbefore has been explained an embodiment of the invention. Needless to say, the invention is not limited to the discussed embodiment only but can be suitably modified without departing from the scope of the invention.

For example, for the method of displaying the result of the measurement, a bright LED display may be formed in the view field68by a relay lens together with the beam splitter of the erecting prism. Alternatively, as disclosed in JP Utility Model 3074643, an LCD, reticle, relay lens, and reflecting mirror may be arranged so an image displayed on the LCD is reflected onto the reticle through the relay lens and reflecting mirror. The use of the relay lens prevents the LCD itself from coming into the view field, which results in the display of the measurement with little influence on observations.

The range binoculars1in accordance with the invention separate the observing optical systems from the distance-measuring system. Therefore, it is not necessary to have an expensive beam splitter to send a distance-measuring laser beam. Further, the collimating lens used to collimate a distance-measuring laser beam in the range binoculars1of the invention need not have any observation function. Therefore, a cost-effective lens, such as a plastic lens, may be used. These features of the invention advantageously reduce the production cost of the range binoculars1.

The range binoculars1in accordance with the invention do not provide a beam splitter between the objective optical member and the erecting prism. Therefore, visible light needed for observation reaches the eyepiece optical member without passing through any beam splitters. As such, the transmission of visible light or the resolving power is not reduced. A clear image is also obtained through the second observing optical system.

Since the range binoculars1in accordance with the invention does not have a beam splitter between the objective lens and the erecting prism, it is possible to place the internal focusing lens and corresponding moving means between the objective lens and the erecting prism. Thus, the CF type focusing mechanism, which can easily control the focusing, is used in the range binoculars1of the invention.