Abstract:
An automatic focusing camera includes a shutter; a range finding circuit for measuring the distances to a plurality of objects and for providing time base electrical signals corresponding thereto, the circuit including n parallel luminous elements which transmit light to the objects; a range and element position data arithmetic circuit for producing range data to the objects and element position data of active ones of the n elements, in response to the time base electrical signals; an object speed arithmetic circuit for producing time base speed signals corresponding to the object speeds, in response to the range data and the element position data; a shutter control circuit for controlling operation of the shutter in accordance with the object speeds at such time; object speed processors for supplying output signals corresponding to optimum exposure times and stop values of respective objects in response to the time base speed signals and luminances of the objects; and object speed rank order decision circuit for comparing the output signals from the object speed processors and for determining the order of ranking of the object speeds relative to each other and an object speed data organizing circuit for controlling the shutter control circuit in response to the object speed rank order decision circuit so as to control the shutter control circuit means in accordance with the highest speed object.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an automatic focusing camera, and more particularly, is directed to an automatic focusing camera in which the shutter speed corresponding to the opening and closing of the shutter aperture is determined from the speeds of a plurality of moving objects. 
     Conventionally, as disclosed in Japanese Patent Application No. SHO61-309531, entitled &#34;Automatic Focusing Unit for Still Camera&#34;, the distance to a moving object is observed at a plurality of predetermined times and the position of the object at the time of opening and closing the shutter aperture is determined from the observed range data. 
     Also, a method in which ranges to the center, as well as to left and right, objects are observed and the focal point is determined based on these ranges to the center, left and right objects, has been disclosed in Japanese Patent Application No. SHO63-199368 entitled &#34;Automatic Focusing Camera&#34;. 
     Furthermore, in Japanese Patent Publication No. 57-153610, incident light from an object is received at two light-receiving points and the light path of the object is determined by solid state elements disposed in parallel, thus forming a range-finding circuit having no mechanical driving system for focusing a lens. 
     In Japanese Patent Application No. SHO63-199368 and the Japanese Patent Publication, a plurality of light-receiving elements or luminous elements which are disposed in parallel are used as one side of a range finder and the active state on a light path of light-receiving elements or luminous elements which are disposed in parallel for the light is used as another side of the range finder, and a measured value is determined by the active states of elements provided on one side and the other side which are in accord with each other. 
     In the abovementioned three patent applications, the desired automatic focusing operation is performed from obtained range data or range data of a plurality of objects. 
     The arrangement of Japanese Patent Application No. SHO63-199368 has been provided for the purpose of preventing so-called center missing when the release button is pushed down to a first stroke to obtain a focused state for both left and right objects so as to perform a focusing operation, even in the case where an object does not exist at the center, and when the pertinent shutter opration cannot be performed when the object is moving. 
     Also, in Japanese Patent Application No. SHO63-309531 the distance to a moving object at the time of opening and closing the shutter aperture may be determined from the previously-determined distance to the moving object, and in the Japanese Patent Publication, the distance to an object may be obtained but the speed of the object cannot be obtained. Accordingly, a still picture of an object cannot be taken at an appropriate shutter speed. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an automatic focusing camera which is able to perform a pertinent focusing operation, and opening and closing of a shutter aperture for a plurality of moving objects by creating range data on a time base to a plurality of objects and speed data from element position data and by opening and closing the shutter aperture with the speed data for a desired object. 
     An automatic focusing camera according to the present invention is provided with a range-finding means in which the distance to an object is measured with first, second . . . and nth elements which are disposed in parallel and is output as an electrical signal on a time base, comprising: range and element position data arithmetic means which outputs range data to the object and element position data of the first, second, . . . and nth elements under active state from an electrical signal on the time base; and object speed arithmetic means that outputs speed data obtained by computing the speed of the object from the range data and element position data on the time base. 
     An automatic focusing camera according to the present invention is provided with a range-finding means in which the distance to an object is measured with first, second, . . . and nth elements which are disposed in parallel and is output as an electrical signal on a time base, comprising: range and element position data arithmetic means which outputs range data to the object and element position data of the first, second, . . . and nth elements under active state from an electrical signal on the time base; object speed arithmetic means that outputs speed data obtained by computing the speed of the object from the range data and element position data on the time base; and object speed rank order judging means which compares a plurality of speed data related to a plurality of objects that are output from the object speed arithmetic means with one another, thereby to judge the speed rank order of the plurality of objects. 
     An automatic focusing camera according to the present invention is further composed of shutter control means which controls a shutter in accordance with the speed of the object and which is capable of image pickup at the time of opening and closing a shutter aperture. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of an automatic focusing camera according to one embodiment of the present invention; and 
     FIG. 2 is a data area composition drawing of a range and element position data storage circuit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of an automatic focusing camera according to the present invention will be described in detail hereafter with reference to the drawings. 
     An automatic focusing camera according to the present invention is composed of a range-finding means 1, a range and element position data arithmetic circuit 2, a range and element position data storage circuit 3, an object speed arithmetic circuit 4, an object speed rank order decision circuit 6, an object speed data organizing circuit 7 and a shutter control IC 9. 
     The range-finding means 1 is formed of first, second, . . . and nth luminous elements Q1, Q2˜Q6 and an element position detecting light-receiving element Ph. For purposes of explanation only, n=6. Further, L is the base length between the luminous elements and element Ph. The luminous elements Q1, Q2˜Q6 emit light in succession by a scanning pulse (not shown) in a period of 60 nS which is sent out from a microcomputer (hereinafter referred to as just a CPU) within each time period, for example, period ΔT0˜ΔT1, from each zero time point ΔT0, ΔT1 . . . to the n time point ΔTn. For purposes of explanation only, n ranges from 0 to 127, and each period is 2,160 nS. As an aside, the CPU controls, through control lines Cn (n is at 1˜9 and 13˜16), each circuit shown with a numeral as a subscript. When the light projected onto objects S1, S2, . . . and S6 by the emission of luminous elements Q1, Q2˜Q6 is reflected by the objects S1, S2, . . . and S6 and received by the element position detecting light-receiving element Ph, electrical signals TD1˜TD6 are sent out to the range and element position data arithmetic circuit 2. In this case, when the object S1 moves toward the object S2, an electrical signal TD3 is output between time points ΔT1˜ΔT2. Electrical signals TD1 and TD2 correspond to the object on the left side, TD3 and TD4 correspond to the object at the center and TD5 and TD6 correspond to the object on the right side. The electrical signals TD1 . . . TD6 include element position data shown with subscripts corresponding to the objects and range signals, depending on the intensity of electrical signals TD1 . . . TD6. 
     Alternatively, if the luminous elements of an alternative range-finding means 1&#39; are composed of light-receiving elements Q&#39;1˜Q&#39;6, reflected light (shown with a dotted arrow) from the object S1 is scanned by a scanning pulse and detected by light-receiving elements Q&#39;1˜Q&#39;6. The element position detecting element Ph is constructed to operate with the reflected light at first . . . sixth incident angles, and the scanning pulse is sent out 6 times with six pulses as one set. Accordingly, they become digital electrical signals TD1˜TD36 (not shown) created within the period ΔT0˜ΔT1. 
     Referring to the first-described embodiment in FIG. 1, input electrical signals TD1˜TD6 are input to the range and element position data arithmetic circuit 2. The intensities of the electrical signals TD1˜TD6 are converted to digital signals by an A/D conversion circuit (not shown) provided in range and element position data arithmetic circuit 2 and become range data YD1˜YD6. The range data YD1˜YD6 have attributes of element position data XD1˜XD6, and the range and element position data YD1, XD1 . . . YD6, XD6 are stored in range and element position data storage circuit 3. Smaller numbers among the subscripts of the range data YD1 . . . YD6 and the element position data XD1 . . . XD6 correspond to the object on the left side. 
     In the alternative embodiment of light-receiving elements Q&#39;1˜Q&#39;6, there are 36 scanning pulses, and electrical signals TD1˜TD36 (not shown) are sent to a range and element position data arithmetic circuit 2&#39;. The object S1 is assigned with electrical signals TD1˜TD6, the object S2 is assigned with electrical signals TD7˜TD12, and so on. Among respective sets of electrical signals, smaller numbers of the subscripts is for long range, and there are provided 6 stages of long and short zones. 
     In the range and element position data storage circuit 3, one word is composed of 0˜31 bits, and 0˜767 words are included, as shown in FIG. 2. 
     Each memory area ΔT0˜ΔT127 on the time base has a memory capacity of 0˜5 words and is retrieved with subareas YD1˜YD6. The subareas YD1˜YD6 have range data YD1˜YD6 having the same names stored therein, and each has a storage capacity of approximately 40 m at one bit per one centimeter, but 15 m or over is practically processed as the most remote object. 
     When the light-receiving elements Q&#39;1˜Q&#39;6 are used, the range data having the same names are stored in subareas XD1˜XD36 provided at every 15˜20 bits. In the memory, the 15th bit is XD6, the 20th bit is XD1, and XD6 is the shortest zone. Respective bits in the subareas XD1˜XD36 become range data YD&#39;1˜YD&#39;6 and stored word positions show the element position data XD1˜XD36. For example, when XD14 is stored in the third scanning, XD14 is stored at the second word in the range data YD&#39;3 (zone for longer range), so it becomes element position data XD3 (word composition is started from 0 word). 
     Further, bits 21 to 31 of each word are used as a work memory. 
     The object speed arithmetic circuit 4 reads the range data YD1 . . . and the element position data XD1 . . . stored in the range and element position data storage circuit 3 and computes the change of position of the objects S1˜S6 with the change on the time base. Computed speed data v1, v2 and v3 are sent to first, second and third object speed processors 5a, 5b and 5c. The first object speed processor 5a processes the object on the left side, the second object speed processor 5b processes the object at the center, and the third object speed processor processes the object on the right side. The first, second and third object speed processors 5a, 5b and 5c receive speed data v1, v2 and v3 that are input from the object speed arithmetic circuit 4 and object luminances IB1, IB2 and IB3 that are measured photometrically with a photometric IC 14, and output optimum exposure times TV1 . . . and stop values AV1 . . . of respective objects to the object speed data organizing circuit 7, taking precedence of those that have higher speed rank order. 
     Also, the object speed arithmetic circuit 4 sends computed speed data to a range forecasting circuit 15. The range forecasting circuit 15 receives input speed data and the position of the object, and forecasts the location of the object existing in a scene at a predetermined time (using element position data XD1 . . . ). 
     The object speed rank order decision circuit 6 receives the speed data v1, v2 and v3 from the first, second and third object speed processors 5a, 5b and 5c, and decides the rank order of the speed data v1, v2 and v3. 
     The shutter control IC controls the opening and closing of the shutter aperture and also sends out data for focusing to a focus decision circuit 16. Those input data that are required for creating data for control and focusing are organized in the object speed data organizing circuit 7. 
     The object speed data organizing circuit 7 is supplied with that data that is required for creating data for the control of the shutter control IC and for focusing by exposure times TV1 . . . , stop values AV1 . . . , and a mode signal MOD for objects having a higher speed rank order that are input from the above-mentioned object speed rank order decision circuit 6. 
     A mode selection button 8 is composed of pushbuttons, and a reference potential point is not usually connected to terminals 8a, 8b and 8c. With the first pushbutton operation, the terminal 8a is connected to a reference potential point, the terminal 8b is connected during the second pushbutton operation and the terminal 8c is connected during the third pushbutton operation to the reference potential point. Since data that shows which effective object has been sent to the CPU at the time forecast in the range forecasting circuit 15, the CPU sends out a mode signal MOD 0 to the shutter control IC 9 when the mode selection button 8 is not operated. In the case of mode signal MOD 0, an average mode is obtained, and all the operations are performed on the central object. When the terminal 8a is the reference potential point, the left object has priority. The central object has priority at the terminal 8b and the right side object has priority at the terminal 8c. However, a stop value AVn allowed from the focal point depth is determined from mode signals MOD1˜MOD3 with respect to the object which is forecast to exist in a scene at the time of opening and closing the shutter aperture, exposure times TV1 . . . and stop values AV1 . . . for objects having higher speed rank order are determined, and shutter blades 12a and 12b of the shutter 12 are opened and closed through a motor drive circuit 10. 
     Further, a focus drive circuit 13 performs extension of a lens 13a by a focus signal FOU from the CPU. This focus signal FOU is created in focus decision circuit 16. 
     In operation, electrical signals TD1 . . . TD6 formed in the range-finding means 1 are input to the range and element position data arithmetic circuit 2. Since the scanning period is 60 nS, the scanning is completed in 360 nS in the case of electrical signals TD1 and TD6. However, time for conversion is required after the scanning because of the A/D conversion operation. The range and element position data arithmetic circuit 2&#39; being of digital processing, time for A/D conversion is not required, but the period of ΔT0 becomes 36 times 60 nS, viz., 2,160 nS. Accordingly, when it is assumed that the period of ΔT0 is 2,160 nS for both, there is an allowance of approximately 1 mS for the A/D conversion operation for electrical signals TD1˜TD6. 
     When electrical signals TD1˜TD36 from the range-finding circuit 1&#39; are sent to the range and element position data arithmetic circuit 2&#39; and the object S1 is located in the zone 3, 17 bits of word 0 of the memory area ΔT0 are activated. When the object S1 moves to the position of the object S2 so it is located in the zone 3 after 2,160 nS, 17 bits at the 0th word of the memory area ΔT1, that is, at the 7th word of the range and element position data storage circuit 3 are activated. Furthermore, since all of subareas XD1˜XD6 at the 0th word of the memory area ΔT3 corresponding to the object S1 are at &#34;0&#34;, the object S1 does not exist after the next 2,160 nS, it means that the object S1 moves to the location of the object S2 in 2,160 nS. The speed of the object Sn may be computed from the numeric values of YDn and XDn of the memory areas ΔT0˜ΔT127. 
     Also, when the object S1 retreats along a remote direction, the 18th bit of the 0th word of the memory area T1 after 2,160 nS and after 17 bits of the 0th word of the memory area TD, is activated. Furthermore, if the object S1 continues to retreat even after 2,160 nS, the 19th bit of the 0th word of the memory area ΔT3 is activated. Therefore, the speed at which the object S1 retreats may be computed. 
     Since the period of ΔT0 is 2,160 nS, the time required up to ΔT127 is 274 mS. When the time required to open and close the shutter aperture in advance after the shutter button is pushed down is set at 350 mS, the timewise process for forming the storage operation is sufficient. 
     When it is forecast that the object on the right side appears from the scene on the right side 350 mS after the shutter button is pushed down in the case when the terminal 8c is connected to the reference potential point by operating the mode selection button 8, the mode signal MOD3 of the object on the right side is not sent out. As a result, mode signals MOD1 and MOD2 only are sent to the shutter control IC 9. The shutter control IC 9 controls the motor drive circuit with high speed object exposure times TV1 and TV2 and stop values AV1 and AV2 such as the exposure time TV1 and stop values AV1˜AV2 (intermediate values sometimes) allowed by the exposure time TV1. 
     In the above embodiment, the reflected light of the light projected onto an object from luminous elements Q1˜Q6 is received by the position detection light-receiving element Ph, but the light may be projected onto the object at first through sixth angles with the position detection light-receiving element Ph as a luminous element. 
     Also, the present invention may be executed in an equivalent manner by using a system in which a signal passing through a photographing lens is detected and an automatic focusing detection signal is output. 
     The automatic focusing camera according to the present invention is composed of an automatic focusing camera provided with a range-finding means in which the distance to an object is measured with first, second, . . . and nth elements which are disposed in parallel and is output as an electrical signal on a time base, comprising: range and element position data arithmetic means which outputs range data to the object and element position data of the first, second, . . . and nth elements under active state from an electrical signal on the time base; and object speed arithmetic means that outputs speed data obtained by computing the speed of the object from the range data and element position data on the time base. Accordingly, the speed of an object may be computed from range data and element position data on the time base. 
     Also, an automatic focusing camera according to the present invention is provided with a range-finding means in which the distance to an object is measured with first, second, . . . and nth elements which are disposed in parallel and is output as an electrical signal on a time base, comprising: range and element position data arithmetic means which outputs range data to the object and element position data of first, second, . . . and nth elements under active state from an electrical signal on the time base; object speed arithmetic means that outputs speed data obtained by computing the speed of the object from the range data and element position data on the time base; and object speed rank order decision means which compares a plurality of speed data related to a plurality of objects that are output from the object speed arithmetic means with one another, thereby to judge the speed rank order of the plurality of objects. Accordingly, it is possible to compute respective speeds of a plurality of objects and to judge which is the fastest object among respective objects. 
     Furthermore, since there is provided a shutter control means which controls a shutter in accordance with the speed rank order of the plurality of objects and which is capable of image pickup at the time of opening and closing the shutter aperture, it is possible to open and close the shutter aperture at the maximum speed and stop value from the speeds of the plurality of objects. 
     Although the present invention has been described through specific terms, it should be noted here that the described embodiment is not necessarily exclusive and that various changes and modifications may be imparted thereto without departing from the scope of the invention which is limited solely by the appended claims.