Output device for range information for use in an interchangeable lens

Claims

What is claimed is:

1. An output device for developing range information in an interchangeable lens, comprising:

an interchangeable lens detachably mounted on a camera body and having an objective lens movable in two directions toward or away from said camera body and including a rotatable range ring for moving said objective lens;

rotation detecting means for producing pulses corresponding to rotation of said range ring of the interchangeable lens;

extreme position preset means for moving said range ring to an extreme position prior to calculation of range information;

a first CPU disposed in the interchangeable lens and having data necessary for controlling the focussing of the individual lens of the interchangeable lens as part of a program, for calculating an absolute range value of the interchangeable lens at its focal point on the side of an object being photographed on the basis of the data and the pulses obtained from movement of the range ring from said extreme position; and

means for outputting said absolute range value to said camera body.

2. An output device according to claim 1, in which

said rotation detecting means comprises a comblike electrode of a comblike conductor pattern which is formed on the range ring along its rotational direction, a contact point which is slidably in abutment with said electrode and pulse generating means for producing pulses by turning on and off contact between said first electrode and said contact point in response to rotation of the range ring.

3. An output device according to claim 1, in which

said CPU stores said pulses and clears the stored contents whenever the range ring reaches the extreme position.

4. An output device according to claim 1, in which said first CPU is connected to a second CPU disposed within the camera body through bus lines which are capable of selectively transmitting absolute range information to said second CPU which is disposed in the camera body.

5. An output device according to claim 1, in which said first CPU includes data tables for converting a count value obtained from said pulses to an absolute range value representative of a distance to an object on the basis of data stored in said data table.

6. An interchangeable lens detachably mountable to a camera body, the interchangeable lens comprising:

focus movement detecting means for producing a series of pulses representative of the movement of a range ring of said interchangeable lens, said range ring movable in two directions;

counter means for providing a pulse count value of said pulses by selectively adding and subtracting said pulses from said pulse count value based on the direction of movement of said range ring;

detecting means for detecting the arrival of said range ring at an extreme position;

reset means for resetting said counter means in response to an output produced by said detecting means; and

calculation means for calculating an absolute range to an object on the basis of said pulse count value.

7. An interchangeable lens according to claim 6, wherein said focus movement detecting means includes a comblike electrode provided on said range ring and a contact point disposed in sliding abutment to said electrode.

8. An interchangeable lens according to claim 6, wherein said calculation means includes data tables which provide data for converting said count value to an absolute range to an object.

9. A camera system, comprising:

an interchangeable lens, a camera body, and bus lines;

said interchangeable lens being detachably mounted to said camera body, said lens having a focus position and including focus position detecting means for producing a series of pulses corresponding to movement of said focus position of said interchangeable lens;

detecting means for detecting the arrival of said focus position at an extreme position associated with said interchangeable at lens; and

a first CPU for calculating an absolute range value from said pulses on the basis of using said extreme position as a reference;

said camera body including:

a drive motor for moving the focus position of said interchangeable lens;

a second CPU for controlling said drive motor and at least one other camera element of said camera body;

said bus lines interconnecting said first and second CPUs and being effective for permitting information and other signals to be transmitted between said first and second CPUs.

10. A camera system according to claim 9, said interchangeable lens having a range ring and said focus position detector means being effective for detecting rotation of said range ring.

11. A camera system according to claim 9, wherein said bus lines include a clock line for delivering a clock signal, a REQ line for singalling whether a given system is transmitting or receiving data; an EN line for signalling whether a system is ready or is not ready to receive data; and a DB line for transferring said information serially over said DB line.

12. A camera system according to claim 9, further including a respective unique identification code respectively for each of said first and second CPUs.

13. An output device for outputting range information developed in an interchangeable lens, said output device comprising:

an interchangeable lens detachably mountable to a camera body and having a lens which is movable toward or away from said camera body and including a range ring;

rotation detection means for generating a series of pulses representive rotation of said range ring of said interchangeable lens;

counting means for producing a count of said pulses by adding and subtracting said pulses independence on the direction of rotation of said range ring;

initial position setting means for moving a focus position associated with said interchangeable lens to a predetermined position when a power source for said camera system is turned on;

calculation means for calculating an absolute range to an object on the basis of said count value; and

means for outputting said absolute range value to said camera body.

14. An output device according to claim 13, further including reset means for resetting said counting means whenever said focus position is at said predetermined position.

15. An output device for outputting range information developed in an interchangeable lens, said output device located in said interchangeable lens and comprising:

focus movement detecting means for producing a series of pulses representative of a focus position associated with said interchangeable lens;

counter means for producing a count of the number of said pulses by adding or subtracting said pulses in dependence on a direction of focussing of said focus position;

reset means for resetting said count of said counter means in response to the detection of the arrival of said focus position at a predetermined position;

data tables for converting said count to an absolute range value; and

reading out means for reading out said absolute range value from said data tables.

16. An output device according to claim 15, comprising a plurality of data tables, each data table being respectively dedicated for a given type of an interchangeable lens.

17. An output device according to claim 15, comprising a plurality of data sections, each data table section corresponding to a given type of an interchangeable lens and means for selecting a given one of said data table sections based on the type of interchangeable lens mounted to said camera body.

18. A method for producing absolute range information within an interchangeable lens, said method comprising the steps of:

producing a series of pulses representative of movement of a focus position of an interchangeable lens toward or away from a camera body and producing an indication of the direction of movement of said interchangeable lens;

counting the number of said pulses by adding or subtracting said pulses in dependence on the direction of movement of said focus position;

resetting a count value obtained for said pulses at the detection of the arrival of said focus position to a predetermined position;

calculating an absolute range value to an object on the basis of said count value, said calculating of said absolute range value including reading out an absolute range value from a data table by finding in said data table a corresponding absolute range value for a count value obtained from said counting step; and

outputting said absolute range value to a camera body.

19. A camera system, comprising:

rotatable and manually operable operating members disposed on a camera accessory;

pulse generating means for generating pulses in response to rotation of said operation members;

rotation detection means for detecting rotation of said operating members on the basis of said pulses received from said pulse generating means; and

a motor drive control circuit for focussing an interchangeable lens in response to an output of said detecting means.

20. A camera system, comprising:

a first CPU for receiving a series of pulses produced in response to movement of a focus position of an interchangeable lens in first and second directions and calculating an absolute range value by respectively adding or subtracting the pulses to or from a count value on the basis of the direction of movement of said interchangeable lens;

a second CPU for controlling camera elements in a camera body;

a third CPU disposed within a camera accessory; and

bus lines for interconnecting said first, second and third CPUs, said bus lines being effective for transmitting said absolute range value therethrough.

21. A camera system, comprising:

first CPU for receiving a series of pulses produced by the movement of a focus position of an interchangeable lens which is movable along two directions, said first CPU being further effective for calculating an absolute range by counting said pulses;

a second CPU disposed in a camera body for controlling camera elements of said camera body; and

a third CPU disposed in an electronic flash unit for transmitting information characteristic of said electronic flash unit, said information including information indicative of the state of said electronic flash unit and said information being transmitted to said second CPU; said second CPU being effective for determining exposure factors on the basis of said absolute range information delivered by said first CPU and said electronic flash information delivered from said third CPU.

22. A camera system, comprising:

an interchangeable lens and an absolute range detecting means disposed within the interchangeable lens for producing a count value by counting electric pulses produced in response to movement of a focus position of the interchangeable lens with respect to a given position and means for generating an absolute range value from the count value;

outputting means for outputting said absolute range value from said interchangeable lens;

calculation and control means, located outside said interchangeable lens and coupled to said outputting means, for determining an exposure value; and

evaluation means for evaluating the status of an electronic flash unit and delivering an electronic flash unit status signal to said calculation and control means, said calculation and control means being effective to determine an exposure value on the basis of said absolute range information and said electronic flash unit status signal.

23. An output device for developing and outputting range information, the output device comprising:

an interchangeable lens barrel detachably mounted on a camera body and variable in focal length and including a rotatable ring;

movement detection means for producing electric pulses corresponding to movement of a lens of said interchangeable lens barrel;

extreme position preset means for moving said lens of said interchangeable lens barrel to an extreme position prior to calculation of range information;

focal length detection means for detecting focal length information in which said interchangeable lens is set;

a first CPU, disposed in said interchangeable lens barrel and having data effective for controlling for focusing of individual lens of said interchangeable lens under control of a program, for calculating an absolute range value of the interchangeable lens at its focal point on the side of an object being photographed on the basis of the data, the focal length information and the electric pulses obtained from movement of the lens from extreme position; and

means for outputting said absolute range value to a camera body.

24. An output device according to claim 23, in which said movement detection means comprises a comblike electrode of a comblike conductor pattern which is formed on the rotatable ring along its rotational direction, a contact point disposed in sliding abutment to said electrode and pulse generating means for producing pulses by turning on and off contact between said electrode and said contact point in response to rotation of the rotatable ring.

25. An output device according to claim 23, in which said first CPU stores said pulses and clears the stored contents whenever the lens reaches the extreme position.

26. An output device according to claim 23, in combination with a camera body including a second CPU, said first CPU being connected to said second CPU disposed within said camera body through bus lines which are capable of selectively transmitting absolute range information to said second CPU.

27. An output device according to claim 23, in which said first CPU includes data tables for converting a count value obtained from said pulses to an absolute range value representative of a distance to an object on the basis of data stored in said data tables.

28. An interchangeable lens barrel detachably mountable to a camera body and variable in focal length, the interchangeable lens comprising:

a lens movable in two directions toward or away from the camera body;

focus movement detection means for producing electric pulses corresponding to movement of said lens;

counter means for counting said electric pulses by addition or subtraction according to a direction of movement of said lens;

extreme position detection means for detecting that said lens has reached an extreme position;

reset means for resetting said counter means on the basis of an output of said extreme position detection means;

focal length detection means for detecting focal length setting information of said lens; and

calculation means for calculating an absolute range on the basis of a count value of said counter means and said focal length setting information.

29. An interchangeable lens according to claim 28, wherein said focus movement detection means includes a comblike electrode provided on said range ring and a contact point disposed in sliding abutment to said electrode.

30. An interchangeable lens according to claim 28, wherein said calculation means includes data tables containing data for converting said count value to an absolute range to an object.

31. An interchangeable lens barrel according to claim 28, further including means in the interchangeable lens for receiving a demand from a camera body to transmit absolute rang information, and transmitter means, in the interchangeable lens, for transmitting the absolute range information to the camera body responsive to said demand.

32. An interchangeable lens barrel according to claim 31, wherein said focus movement detection means includes a comblike electrode provided on said range ring and a contact point disposed in sliding abutment to said electrode.

33. An interchangeable lens barrel according to claim 31, wherein said calculation means includes data tables containing data for converting said count value to an absolute range to an object.

34. An output device for developing and outputting range information, the output device comprising:

an interchangeable lens barrel detachably mounted on a camera body and variable in focal length and including a rotatable ring;

movement detection means for producing electric pulses corresponding to movement of a lens of said interchangeable lens barrel;

extreme position preset means for moving said lens of said interchangeable lens barrel to an extreme position prior to calculation of range information;

focal length detection means for detecting focal length information in which said interchangeable lens is set;

a first CPU disposed in said interchangeable lens barrel and having data effective for controlling the focusing of individual lens of said interchangeable lens under control of a program, for calculating an absolute range value of the interchangeable lens at its focal point on the side of an object being photographed on the basis of the data, the focal length information and the electric pulses obtained from movement of the lens from said extreme position;

means for outputting said absolute range value to said camera body; and

wherein said first CPU is responsive to a second CPU disposed within a camera body to deliver absolute range information in response to a demand from said second CPU.

35. An output device according to claim 34, in which said movement detection means comprises a comblike electrode of a comblike conductor pattern which is formed on the rotatable ring along its rotational direction, a contact point disposed in sliding abutment to said electrode and pulse generating means for producing pulses by turning on and off contact between said electrode and said contact point in response to rotation of the rotatable ring.

36. An output device according to claim 34, in which said first CPU stores said pulses and clears the stored contents whenever the lens reaches the extreme position.

37. An output device according to claim 34, in combination with a camera body and a second CPU disposed in said camera body, said first CPU being connected to said second CPU through bus lines which are capable of selectively transmitting absolute range information to said second CPU.

38. An output device according to claim 34, in which said first CPU includes data tables for converting a count value obtained from said pulses to an absolute range value representative of a distance to an object on the basis of data stored in said data tables.

39. An output device for developing range information, comprising:

a camera body;

an interchangeable lens barrel detachably mounted to said camera body;

focus point status detection means disposed within the camera body for detecting a focus point status of a lens of said interchangeable lens barrel;

drive means for driving said lens in response to an output of said focus point status detection means;

movement detection means for producing electric pulses corresponding to movement of said lens disposed within said interchangeable lens barrel;

extreme position preset means for moving said lens of said interchangeable lens barrel prior to calculation of range information; and

a first CPU disposed in the interchangeable lens barrel and having data necessary for controlling the focusing of individual lens under control of a program, for calculating an absolute range value of the interchangeable lens at its focal point on the side of an object being photographed on the basis of the data and the electric pulses obtained from movment of the lens from said extreme position.

40. An output device according to claim 39, including variable focal length means for changing a focal length of the interchangeable lens;

focal length detection means for detecting focal length information which is changed by said variable focal length means; and

wherein said first CPU is effective for calculating said absolute range value also on the basis of said focal length information.

41. An output device according to claim 39, further including a bus line for connecting said first CPU to a second CPU disposed within said camera body;

an absolute range information output demand being transmitted from said second CPU to the first CPU when the second CPU receives the demand from the first CPU.

42. An output device for developing range information, comprising:

a camera body;

an interchangeable lens barrel having a lens movable in two directions toward or away from said camera body;

focus point status detection means disposed within said camera body for detecting a focus point status of the lens of said interchangeable lens barrel;

drive means for driving said lens in response to an output of said focus point status detection means;

focus movement detection means for producing electric pulses corresponding to movement of said lens;

counter means for counting said electric pulses by addition or subtraction in response to a direction movement of said lens;

extreme position detection means for detecting that said lens has reached an extreme position;

reset means for resetting said counter means in response to an output of said extreme position detection means;

calculation means for calculating an absolute range on the basis of a count value of said counter means; and

said interchangeable lens barrel further includes terminal means for receiving a demand from the camera body to transmit to the camera body absolute range information and transmitter means in the interchangeable lens barrel for transmitting the absolute range information to the camera body in response to said demand.

BACKGROUND OF THE INVENTION

The present invention relates to a single lens reflex camera, and more particularly, to an output device for range information for use in an interchangeable lens adapted to be detachably mounted on a camera.

In a single lens reflex camera, range information is required for effecting an automatic focussing operation. A mechanical transfer device has been widely utilized in the past to obtain range information from the lens side. However, such device has the disadvantage of being large-sized, complicated and inaccurate. A a result, an arrangement in which information signals are transmitted to a camera body has been proposed (Japanese Laid-Open Patent Publication Sho 54/1979-108628). The proposed arrangement, however, lacks the capability of expanding the scope of information since signals are limited to only that information which is transmitted from the lens side and a prescribed sequence for transmitting signals can not be varied. When it is desired to obtain information from a camera system other than a lens in the same way, a number of input lines are required, resulting in that the arrangement increases in size and becomes complicated.

In view of the foregoing, camera systems in which an arithmetic unit of a microcomputer (hereinafter referred to as a CPU) is separately disposed in each of the systems have been proposed by the assignee of the present invention (Japanese Laid-Open Patent Publication Sho 60/1985-26324). Even in this proposal, however, there is no practical solution to the problem of reading range information of an interchangeable lens and transmitting the range information to a camera body.

Outputs relating to range information of an interchangeable lens fall into two categories, absolute and relative range information. Absolute range information in an autofocussing operation is represented by an output of a signal corresponding to a range obtained by reading a rotation preset position of a range ring as shown in, for example, Japanese Laid-Open Patent Publication Sho 50/1975-67650. Relative range information refers to the amount by which a present position is away from a reference position. The use of relative range information, which can be produced only by a comblike electrode, for example, advantageously simplifies a construction of an output device for range information of an interchangeable lens. On the other hand, although absolute range information may be conveniently used in a single lens reflex camera serving as a system camera, it leads to a complicated structure and therefore is rarely used.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an output device for range information for use in an interchangeable lens which is simple in structure and produces an output of an electrical signal in a precise manner as absolute range information to a CPU disposed in a camera body and other attachments associated therewith.

According to the present invention, the focussing operation of higher accuracy can be achieved with both of a CPU provided on the side of a lens barrel and a detector for delecting an amount of rotation, and range information of the lens can be obtained in the form of information from the rotation detector, which can be also used for a system other than the lens, such as in a flashmatic control of an electronic flash unit or a strobo unit.

Transfer of electrical signals between a lens barrel and camera body is effected through bus lines, so that a time sharing processing with signal transfer to other systems can be performed, resulting in a miniaturized device.

In addition, since absolute range information of an interchangeable lens can be produced only by a comblike electrode of a simple structure, it may be only necessary to read the absolute range information from the electrode without coding it and it is possible to accurately deliver the absolute range information to a CPU provided in a camera body, resulting in a reduction in the numbers of terminals for input and output of an electric circuitry for dealing with the absolute range information.

A further camera system embodiment according to the present invention comprises: rotatable and manually operable operating members disposed on a camera accessory; pulse generating means for generating pulses in response to rotation of said operating member; rotation detection means for detecting rotation of said operating members on the basis of said pulses received from said pulse generating means; and a motor drive control circuit for focussing an interchangeable lens in response to an output of said detecting means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the overall concept of the present invention;

FIG. 2 is a sectional view of an interchangeable lens barrel to which the present invention is applied;

FIG. 3 is a perspective view of a range ring drive device of the lens barrel shown in FIG. 2;

FIG. 4 is a perspective view of a focal length change drive device of the lens barrel shown in FIG. 2;

FIG. 5 is a perspective view illustrating a structure of a comblike electrode of the lens barrel shown in FIG. 2;

FIG. 6 is a perspective view illustrating a structure of a slide electrode of the lens barrel shown in FIG. 2;

FIGS. 7A and 7B are a side and a rear view of a camera provided with an device of the present invention, respectively;

FIG. 8 is a circuit of a device according to the present invention;

FIG. 9 is a schematic diagram illustrating of a gray scale comprised of a slide terminal and a contact piece which are shown in FIG. 6;

FIG. 10 is a circuit depicting of transistors at output stages of an EN line between CPUs;

FIG. 11 is a signal waveform diagram of actions of range information in an embodiment according to the present invention;

FIG. 12 is an exploded perspective view illustrating a structure of a rotary knob;

FIG. 13 is a flow chart illustrating operations of the embodiment according to the present invention;

FIG. 14 is a flow chart illustrating data transfer in a data interruption process; and

FIG. 15 is a signal waveform diagram explanatory of signal actions in a data interruption process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, an output device for range information of an interchangeable lens according to the present invention has a basic arrangement in which a range ring 201 of the interchangeable lens is rotated to an extreme position, that is, a position at infinity or at close range by an extreme position preset means 502 which is disposed within a camera body 100 or an interchangeable lens barrel 200 substantially at the same time that the lens barrel 200 is mounted on the camera body 100 or a power switch not shown on the camera body 100 is turned on, to obtain a range information based on a rotational angle of the range ring 201 from the extreme position. Specifically, the lens barrel 200 comprises a rotation detector 202 for producing pulses corresponding to a rotational angle of the range ring 201 and a CPU 211 which is an arithmetic unit of a microcomputer containing data necessary for control of focussing individual interchangeable lenses, as part of a program. The CPU 211, after the range ring 201 has been set to the position at infinity or close range which is a reference position of the range ring 201, delivers an output which provides absolute range information for the range ring 201 which is calculated by the data contained in the CPU 211 and the pulses from the detector 202 to a CPU 111 disposed within the camera body 100, thereby a range being set by a drive means 501 provided within the lens barrel 200 or the camera body 100.

A preferred embodiment of the present invention will be described hereinafter with reference to FIGS. 2 through 15.

FIG. 2 is a sectional view of an interchangeable lens barrel 200 to which an output device for outputting range information obtained from an interchangeable lens according to the present invention is applied. The interchangeable lens, which is a zoom lens, comprises a focussing lens L.sub.1 and lenses L.sub.2 and L.sub.3 which are movable for obtaining zooming operation. The focussing operation is effected by transmitting the drive force of a lens drive motor 101 provided within the camera body 100 through a coupler to the lens barrel 200 in a camera mount 28. Details of the transmitting mechanism are shown in FIG. 3. An output shaft 102 of the motor 101 constitutes part of the coupler which engages one end of a shaft 203 provided on the side of the lens barrel 200. The drive force of the motor 101 is transmitted to the range ring 201 through a gear 204 which is fixed to the other end of the shaft 203 and a gear 205 which meshes with the gear 204, further through a pinion 207 which is provided on the end of a shaft 206 of the gear 205 and a rack which is provided on the inner periphery of the range ring 201 so as to mesh with the pinion 207, to move the focussing lens L.sub.1 by rotating the range ring 201 and urging a pin 208 which is provided on a holding frame 202 of the lens L.sub.1.

The zooming operation is effected by a drive force of a motor 209 which is disposed within the lens barrel 200. As seen in FIG. 4, a rack is provided on the outer periphery of a zoom ring 213 which rack meshes with a pinion 212 provided on an output shaft of the motor 209. A groove is