Power Supply Device for Camera

1. Field of the Invention

This invention relates to a power supply device for a camera of the kind using an interchangeable lens or the like and more particularly to a power supply device to be used for a power supply to an accessory such as an interchangeable lens as well as for a power supply to a camera body.

2. Description of the Related Art

As a result of the recent advancement of camera automation, cameras are equipped with an automatic exposure control device, automatic focusing device, an automatic light amount control device, etc. For these devices, various electronic circuits, a motor and a battery are arranged within the camera. In the case of lens interchangeable type cameras which are provided with these devices, they have motors and electronic circuits arranged not only on the side of their camera bodies but also on the side of their lenses. Therefore, the camera of this kind is provided with a connector which is disposed at mount parts for coupling the camera body and the lens with each other and has electric contacts or connection terminals arranged to electrically connect various devices disposed within the camera body to those disposed within he lens.

These connection terminals include terminals for receiving a power supply and terminals for signal exchange. The power supply terminals includes terminals of two different kinds, one for receiving a positive power supply and the other for receiving a negative power supply. With respect to the power supply on the negative side, some electric connection part that is other than an electronic contact, such as the mount, can be employed. As for the power supply on the positive side, two power supply channels are generally arranged, one for operating an actuator such as the motor and the other for operating electronic circuits for control and information exchanges. Terminals are discretely arranged for these two channels. However, in the event of inadequate contact between contact points or during the process of mounting the lens on the camera body, the power supply is either not received or only intermittently received by the control circuits while the actuators are receiving the power supply. Under such a condition, a faulty action might be performed with the motor driven by the power supply. In other words, while the motor is rendered operative by the power supply, the control circuits are not receiving any power supply. Then, a normal operation of the motor is hardly expectable because of the unreliability of control signals.

Further, in cases where the motor power supply is alone effected while the communication lines of the electronic circuit on the side of the camera body is not completely in touch with the communication lines on the side of the lens due to inadequate contact between contact points or during the lens mounting process, the electronic control circuit on the side of the lens fails to correctly receive information from the camera body. As a result, an instruction for forward rotation of the motor might be mistaken for reverse rotation; or an instruction for a halt might be unreceived. A normal operation is not assurable also under such a condition. A conductive foreign matter such as conductive dust or water sticking to a communication line causes a short-circuit state between the communication line and the mount part or between adjacent connection terminals. In that case, the electronic control circuit on the side of the lens also fails to correctly receive information from the camera body. Then, a normal operation is likewise not assurable.

In the conventional lens interchangeable type camera, the number of connection terminals is reduced by using a ground line and its connection terminal for the motor on the side of the lens in common with a ground line and its connection terminal for the electronic control circuit which is also on the lens side. The common use of the ground line and the connection terminal, however, tends to break both the electronic circuits disposed on the sides of the camera body and the lens due to a difference in ground potential between the lens and the camera body. For example, assuming that the ground potential of the electronic circuit on the side of the camera body is at zero volt, that of the electronic circuit on the side of the lens is one volt (with 1 A of ground current flowing at contact resistance 1 .noteq. of the terminal), when a signal of a high level of 5 V and a low level of 0 V is applied from the electronic circuit on the camera body side to the electronic circuit on the lens side, the electronic circuit on the lens side is receiving a voltage which is lower than the ground potential by 1 V. This would cause either a faulty action or thermal breakage of the electronic circuit on the lens side. To solve this problem, an improved interchangeable lens has been proposed as disclosed in U.S. Pat. application Ser. No. 012,862, filed Feb. 10, 1987, assigned to the assignee of the present invention. The interchangeable lens disclosed in the previous application, however, has been found to have the probability of making some erroneous connection during the process of mounting the interchangeable lens on a camera body, because. The connection terminals on the sides of both the camera body and the lens have flat contact faces and are arranged to protrude to the same extent and to have the same pitch between them.

It is an object of this invention to provide a power supply device for a camera which is arranged to prevent a faulty action by effecting a power supply from a camera body to an accessory after confirmation of perfect connection of communication lines.

It is another object of the invention to provide a power supply device which is capable of preventing electronic circuits from breaking during a process of mounting an accessory on a camera body in a camera system, wherein a connector is arranged to interconnect an electronic circuit of the camera body and that of the accessory by bringing their connection terminals into contact with each other for continuity when the camera body and the accessory are coupled with each other by turning the latter round relative to the former.

These and further objects and features of the invention will become apparent from the following detailed description of embodiments thereof taken in connection with the accompanying drawings.

FIG. 1 is a diagram showing in outline an electric connection arrangement made between a camera body and an interchangeable lens according to this invention as a first embodiment thereof.

FIG. 2 is a flow chart showing the operation of the first embodiment.

FIGS. 3 and 4 are timing charts.

FIG. 5(a) is a diagram showing in outline an electric connection arrangement made between a camera body and an interchangeable lens according this invention as a second embodiment thereof.

FIG. 5(b) is a schematic illustration of the process of mounting the lens on the camera body by turning the former round relative to the latter.

FIG. 6 is a sectional view showing a connector as in a state obtained during the above stated mounting process.

FIG. 7 is a sectional view showing the same connector as in a state obtained after completion of the mounting process.

A first embodiment of this invention is described with reference to the accompanying drawings as follows: In FIG. 1, an electronic circuit 1 is disposed within a camera body. A power source 2 which is a battery or the like is removably disposed within the camera body. A constant voltage producing circuit 3 is arranged to have a power supply from the power source 2 and is arranged to serve as a power source for the electronic circuit 1 and another electronic circuit 10 which is disposed on the side of a lens. A motor 9 is disposed on the side of the lens. An analog switch 4 is arranged to turn on and off a power supply to the motor 9. A lens mounting mount 5 is provided on the camera body. A lens mounting detection switch 6 is provided on an input signal line of the electronic circuit 1 and is disposed near the lens mounting mount 5. A lens mounting-dismounting responsive member 7 is arranged to operate the lens mounting detection switch 6. The member 7 is a swingable member pivotally attached to the reverse side of the lens mounting mount 5 and is provided with two arm parts which are located on two sides of a pivotal point. One of the arm parts engages a part of the mount 5 and is arranged to be driven thereby. The other arm part is arranged to push one of two switch pieces of the lens mounting detection switch 6.

The two switch pieces of the lens mounting detection switch 6 are in a parted state when the lens is not mounted on the camera body. When the lens is mounted on the camera body, the two switch pieces come into contact with each other to connect the input terminal of the electronic circuit 1 to the output terminal of the constant voltage producing circuit 3.

A terminal block 8 for wiring connection is disposed in a lower inner circumferential area of the lens mounting mount 5. Many connection terminals or contact pins P1 to P7 are arranged on the connection terminal block 8 to abut on connection terminals or electric contacts which are disposed on the side of the lens. Each of these connection terminals P1 to P7 is urged by a spring to protrude forward from the front face of the terminal block 8. Further, wiring lines L1 to L7 which are arranged on a printed circuit board attached to the camera body are discretely connected to these connection terminals P1 to P7.

The line L1 which is connected to the connection terminal P1 serves as a motor power line for a power supply from the power source 2 disposed within the camera body to the motor 9 disposed within the lens. The above stated analog switch 4 is disposed on this line L1. The line L2 which is connected to the connection terminal P2 is a lens IC power line and connects the lens mounting detection switch 6 to the input terminal of the electronic circuit 1. The line L3 which is connected to the connection terminal P3 is a power ground line and is connected to the negative plate of the power source 2. The line L4 which is connected to the connection terminal P4 is arranged to be connected to the ground line of the electronic circuit 10 on the lens side and is connected to the ground terminal of the electronic circuit 1 on the camera body side and to the negative plate of the power source 2. The lines L5 to L7 which are connected to the terminals P5 to P7 are signal lines arranged to permit an exchange of signals between the electronic circuit 1 on the camera body side and the electronic circuit 10 on the lens side. These lines L5 to L7 are connected to the signal terminals of the electronic circuit 1.

The interchangeable lens is detachably mountable on the camera body which is arranged as described in the foregoing. The lens is provided with the focusing drive motor 9; a static switch device which is arranged to switch the direction of the power supply to the motor 9 from one direction over to another; the electronic circuit 10 which is arranged to control the motor 9 and to exchange signals with the electronic circuit 1 on the camera body side; a mount which is not shown but is arranged on the lens side to be detachably attached to the lens mounting mount 5 disposed on the camera body side; and a connection terminal block 11 which is disposed in a lower inner circumferential area of the mount on the lens side and is arranged to be opposed to the connection terminal block 8 which is disposed on the side of the camera body.

Seven connection terminals or contact pins P8 to P14 are arranged on the connection terminal block 11 on the lens side to come into contact with the connection terminals P1 to P7 which are disposed on the camera body side as shown in the drawing. Wiring lines L8 to L14 are discretely connected to these connection terminals P8 to P14 respectively.

The lines L8 and L10 are connected to the motor 9 via a static switch which will be described later and are arranged as power lines to permit larger current flows than other lines L9 and L11 to L14. The line L8 is a motor power line. The line 10 is a power ground line for grounding one of the poles of the motor 9. The line L9 which is connected to the connection terminal P9 is a power line for supplying a current to the electronic circuit 10 on the side of the lens. The line L9 is connected to the power supply terminal of the circuit 10 and is arranged to be connected to the line L2 on the camera body side via the connection terminals P9 and P2.

The line L11 is connected to the ground terminal of the electronic circuit 10 and is also arranged to be connected to the line L4 of the camera body via the connection terminals P11 and P4. The line L11 thus serves as a signal ground line for the circuit 10 on the lens side. The lines L12 to L14 are connected to the signal terminals of the electronic circuit 10 and to the connection terminals P12 to P14 respectively. These lines L12 to L14 are also arranged to be connected respectively to the lines L5 to L7 of the camera body via the connection terminals P12 to P14 on the side of the lens and the connection terminals P5 to P7 on the camera body side. The lines L12 to L14 thus serve as signal lines.

Data transmitted from the electronic circuit 1 is received by the electronic circuit 10 via the line L5, connection terminals P5 and P12 and the line L12. Data from the electronic circuit 10 is received by the circuit 1 via the line L13, the connection terminals P13 and P6 and the line L6. Further, clock pulses which are produced for synchronizing serial signal transmission are sent from the electronic circuit 1 to the circuit 10 via the line L7, the connection terminals P7 and P14 and the line L14.

The static switch device which is arranged to change the direction of a current supply to the motor 9 is composed of a total of four transistors T1 to T4. These transistors are arranged in two pairs, each pair consisting of one NPN transistor and one PNP transistor. One pair of transistors is connected to one pole of the motor 9 and the other pair to the other pole. The emitters of the PNP transistors T1 and T2 of these pairs are connected to the line L8 disposed on the side of the lens. The line L8 is arranged to be connected to the line L1 of the camera body via the connection terminal P8 on the connection terminal block 11. In other words, the line L8 forms a power line for supplying electric energy to the motor in conjunction with the line L1.

One pole of the motor 9 is connected to the collectors of the paired PNP and NPN transistors T1 and T4. The other pole of the motor 9 is connected to the collectors of another pair of the PNP and NPN transistors T2 and T3. Meanwhile, the emitters of the NPN transistors T3 and T4 which belong to different pairs are connected to the line L10. The line L10 serves as a power ground line on the side of the lens. The line L10 is arranged to connect the negative pole of the motor 9 to the connection terminal P3 on the camera body side via the connection terminal P10 and also to be connected to the negative plate of the power source 2 via the line L3 on the side of the camera body.

The electronic circuit 10 is provided with control terminals for controlling the transistors T1 to T4 of the static switch device. Signal lines Ml to M4 are arranged to connect the bases of the transistors T1 to T4 to these control terminals of the circuit 10. Reference symbols R1 to R4 denote resistors.

A switch 21 is arranged, for example, to be turned on by the first step of stroke of a shutter button which is not shown. The camera performs a light measuring action when the shutter button is pushed to the first step of stroke. Then a shutter time value and an aperture value are displayed on an external display device which is not shown. While FIG. 1 shows the switch 21 alone, the switch may be replaced with a plurality of switches in the case of the camera of the recently proposed kind displaying the shutter time and aperture values with a liquid crystal display device. In the case of the camera of that kind, to better the operability of the camera, the liquid crystal display device is arranged to be displayed when an operation member is operated to turn on a switch instead of pushing the shutter button to the first step of stroke. A reference symbol R5 denotes a pull-up resistor which is connected to the switch 21.

The following paragraphs briefly describe the operations of various components shown in the drawing

(1) When the lens is not mounted on the camera body

The connection terminal block 11 which is disposed on the side of the lens is away from the connection terminal block 8 which is disposed on the side of the camera body. Therefore, the connection terminals P1 to P7 of one block are not contacting with the terminals P8 to P14 of the other block. Further, the lens mounting detection switch 6 which is disposed on the lens mounting mount 5 of the camera body has its two switch pieces in a parted state as shown in FIG. 1. Therefore, the input terminal of the electronic circuit 1 is connected to the negative plate of the power source 2 via a reducing resistor RPD. The input terminal is under a voltage of a low level close to the ground voltage. This state causes a high level voltage which turns off (or opens) the analog switch 4 to be produced from the output terminal of the circuit 10. The analog switch 4 is, therefore, in an open (off) state to disconnect the connection terminal P1 from the power source 2.

(2) When the lens is mounted on the camera body

In mounting the lens on the camera body, the mount on the side of the lens is turned round clockwise as viewed on the drawing against the lens mounting mount 5 of the camera body. Then, the mount on the side of the lens causes the lens mounting-dismounting responsive member 7 to turn round counterclockwise on its pivot point. One of the arm parts of the member 7 pushes one of the switch pieces of the lens mounting detection switch 6 to the left as viewed on the drawing. The two switch pieces of the switch 6 come into contact with each other to turn on the switch 6. Therefore, the 5-V output terminal of the constant voltage producing circuit 3 is thus connected to the input terminal of the electronic circuit 1 via the switch 6. As a result, a high level (5 V) voltage is applied to the input terminal of the circuit 1. This causes the output voltage level of the circuit 1 to change from a high level over to a low level.

When the lens is completely mounted on the camera body via the lens mounting mount 5 thereof, the connection terminals P1 to P7 on the camera body side come into contact with the connection terminals PB to P14 on the lens side as shown in the drawing. Therefore, the wiring lines L1 to L7 on the side of the camera body are connected to the lines L8 to L14 via the connection terminals P1 to P14 to complete the wiring connection as shown in FIG. 1. In FIG. 1, the lens mounting detection switch 6 is shown as in an open state having its two switch pieces away from each other. However, the switch 6 is kept in a closed state after the lens is completely mounted.

The communication between the lens and the camera body is conducted as follows. For example, with each data composed of 8 bits, data is arranged to be serially transmitted. Command data is transmitted from the electronic circuit 1 on the side of the camera body to the electronic circuit 10 on the side of the lens. In response to this, the lens side sends data to the camera body side in accordance with the command data. After completion of lens mounting, the electronic circuit 1 on the camera body side sends to the circuit 10 of the lens command data "0A" which is composed of 8 bits and is expressed by hexadecimal notion. At the same time, the camera body side receives invalidity data "00" from the lens side. FIG. 3 shows this state of communication in a timing chart. Concurrently with sending the data "0A", the circuit 1 on the camera body side produces clock pulses to a DCLK signal line for the purpose of synchronizing the communication.

On the side of the lens, the electronic circuit 10 discriminates the meaning of the data "0A" and produces data "AA" when the synchronizing clock pulses are produced for a next step of communication. Then, the camera body side sends the invalid data "00" to the lens side. FIG. 4 shows that state of communication in a timing chart.

Upon receipt of the data "AA", the camera body side assumes that normal communication has become possible and causes the electronic circuit 1 on the camera body side to produce a low level voltage from its output terminal. The low level output voltage turns the analog switch 4 on to electrically connect the connection terminal P1 to the positive terminal of the power source 2.

In case that the electronic circuit 1 on the side of the camera body fails to correctly receive the data "AA" because of faulty communication, a high level voltage is produced from the output terminal of the circuit 1 of the camera body to turn the analog switch 4 on. With the analog switch 4 turned on, the connection terminal P1 is disconnected from the power source 2. While the communication is described above to be conducted on the basis of 8 bits data the number of bits of the data is not limited to 8 bits. The communication between the camera body and the lens is further described as follows:

After completion of lens mounting, the circuit 1 on the side of the camera body sends control signals relative to camera actions (mainly a focusing action) to the circuit 10 on the side of the lens via the lines L5 to L7 and the lines L12 to L14. At the same time, the circuit 10 on the lens side sends to the circuit 1 on the camera body side some signal relative to the motor 9 via the same lines. The timing of this signal exchange is the same as the timing mentioned above. Assuming that the circuit 10 makes the signal level of the line M1 high and that of the line M3 high in response to a control signal from the circuit 1, for example, the transistors T1 and T3 become conductive to allow a current flow in the direction of arrow b to the motor 9 via the line L8 and the transistor T1. This current causes the motor 9 to make forward rotation. The current is then circulated to the negative plate of the power source 2 via the transistor T3, the line L10, the connection terminals P10 and P8 and the line L3.

When a signal for reverse rotation of the motor 9 is sent from the circuit 10 to the circuit 1 via the lines L5 to L7, the circuit 10 produces a low level signal to the line M2 and, at the same time, a high level signal to the line M4. Meanwhile the signal level of the line M1 is high and that of the line M3 is low. The transistors T2 and 14 are then rendered conductive. As a result, the motor 9 is caused to reversely rotate by a current flowing in the direction reverse to the direction of arrow b shown in the drawing.

Referring to FIG. 2 which is a flow chart, the circuit operation of the embodiment is as follows. First, at a step #1, a check is made to see if the position of the above stated switch 21 has changed. If not, the operation comes back to a start position. If the switch position is found changed, the operation proceeds to a step #2. At the step #2, a check is made to see if the lens has been completely mounted. This discrimination is made by seeing if the lens mounting detection switch 6 is turned on by the lens mounting-dismounting responsive member 7. If so, the operation proceeds to a step #3. If not, no power supply is made from the power source 2 to the connection terminal P1. At the step #3, while a command signal "0A" which is expressed by hexadecimal monitor is sent via the connection terminals P5 and P12 while producing the synchronizing clock pulses. At the same time, invalid data "00" is received. At a next step #4, therefore, the camera body side continues to receive data from the lens side via the connection terminals P13 and P6 while producing the clock pulses for synchronization and, at the same time, sends the invalid data to the lens side. At a step #5, a check is made to see if the data received is the hexadecimal notation data "AA". If not, no power supply is effected from the power source 2 to the connection terminal P1 (at a step #7). If so, the operation proceeds to a step #6. At the step #6, a current is supplied to the motor 9 on the lens side from the power source 2 on the camera body side via the connection terminals P1 and P8.

As described above, in accordance with this embodiment, the analog switch which is provided for a power supply to the motor on the lens side is not turned on unless communication comes to be correctly performed between the lens and the camera body. Therefore, the motor can be prevented from doing any faulty action even in case that an erroneous control signal is produced from the motor control circuit as a result of inadequate contact of the communication lines or the power lines of the circuit.

A second embodiment of this invention is arranged as follows: The second embodiment is arranged to be capable of preventing a problem presented by the connector arrangement of the first embodiment. In the case of the connector arrangement of the first embodiment, the current flowing out of the motor 9 is arranged to flow back to the negative plate of the power source 2 via the line L10 and the connection terminal P10 on the lens side and the connection terminal P3 and the line L3 on the side of the camera body in both cases of forward and reverse rotation of the motor 9. The power supply to the motor which is arranged in this manner has some contact resistance between the connection terminals P10 and P3 and there takes place a voltage drop. As a result, there arises a potential difference between the potential of the line L10 on the lens side and that of the line L3 on the camera body side (i.e. the grounding potential of the power source 2). Therefore, the actual grounding potential of the motor 9 becomes considerably higher than that of the power source 2. For example, if the contact resistance between the connection terminals P3 and P10 is one ohm with the current flowing to the motor 9 assumed to be at one ampere, the grounding potential of the motor is one volt instead of zero volt. Meanwhile, in the connector arrangement, the connection terminals on the camera body side and the lens side have flat contact faces. The protruding extent and the spacing pitch of the group of the terminals P1 to P7 and those of the group of terminals P8 to P14 are arranged to be equal to each other. This arrangement tends to have some erroneous contact during the process of mounting the interchangeable lens on the camera body by turning the former round relative to the latter. More specifically, immediately before completion of the mounting process, the connection terminal P2 on the side of the camera body comes into contact with the connection terminal P8 on the side of the lens; and likewise the terminal P3 comes into contact with the terminal P9, the terminal P4 with the terminal P10, the terminal P5 with the terminal P11, the terminal P6 with the terminal P12 and the terminal P7 with the terminal P13 respectively. Then, under this condition, the voltage of 5 V from the constant voltage producing circuit 3 comes via the connection terminal P2 to be applied to the emitters of the PNP transistors T1 and T2. Further, the ground line of the power source 2 is connected to the emitters of the NPN transistors T3 and T4 via the line L4, the terminals P4 and the line L10.

Further, the power terminal of the electronic circuit 10 on the side of the lens is on a power ground line as the terminal P3 is connected to the terminal P9. The ground terminal of the circuit 10 is connected to the signal terminal of the electronic circuit 1 via the terminals P11 and P5. Under this condition, therefore, the circuit 1 is unable to operate in a normal manner and its operation becomes unstable. Although the transistors T1 to T4 of the static switch device are under the control of the lines M1 to M4, the unstable operation of the electronic circuit 1 causes a large current to flow to the PNP transistor T2 and the NPN transistor T3 when the PNP transistor T2 and the NPN transistor T3 are rendered conductive by a low level of the line M2 and the high level of the line M3. The PNP transistor T2 and the NPN transistor T3 tend to be broken by the large current. Then, the PNP transistor T1 and the NPN transistor T4 also might be broken.

FIGS. 5(a) to 7 show the second embodiment. The components and parts similar to those of the first embodiment are indicated by the same reference numerals and symbols in these drawings and the details of them are omitted from description. Referring to FIGS. 6 and 7, a connection terminal block 8' on the side of the camera body is provided with a stepped surface consisting of a first face 8a' and a second face 8b'. Meanwhile a connection terminal block 11' on the side of the lens has also a stepped surface consisting of a first face 11a' and a second face 11b'. The recessed degree of the second face 8b' in reference to the first face 8a' of the terminal block 8' and the protruding degree of the second face terminal block 11' are about equal to each other.

Three connection terminals P1, P3 and P3' are arranged on the first face 8a' of the terminal block 8' which is disposed on the side of the camera body. Six connection terminals P2, P5, P6, P7, P4 and P4' are arranged on the second face 8b'. Meanwhile, three connection terminals P8, P10 and P10' which correspond to the above stated terminals P1, P3 and P3' are arranged on the first face 11a' on the side of the lens. On the second face 11b' are arranged connection terminals P9, P12, P13, P14, P11 and P11' which correspond to the above stated terminals P2, P5, P6, P7, P4 and P4' The connection terminals on the side of the camera body are urged by springs to be normally in protrudent positions (upward as viewed on FIG. 6) in the direction of an optical axis and are retractable by pushing them. The normal protruding degree of these terminals is arranged to be in such a manner that the tips of the terminals P2, P5, P6, P7, P4 and P4' disposed on the second face 8b' of the connection terminal block 8' are not contacting with the terminals P8, P10 and P10' disposed on the first face 11a' of the connection terminal block 11' on the side of the lens when the lens is turned round for mounting it on the camera body as shown in FIG. 6.

As shown in FIG. 5(a), on the side of the camera body, the connection terminal P1 is connected to the line L1, the terminal P3 to the line L3, the terminal P3' to the line L3' which is connected in parallel to the line L3, the terminal P2 to the line L2, the terminal P5 to the line L5, the terminal P6 to the line L6, the terminal P7 to the line L7, the terminal P4 to the line L4 and the terminal P4' to the line L4' which is connected in parallel to the line L4. Meanwhile, on the side of the lens, the connection terminal P8 is connected to the line L8, the terminal P10 to the line L10, the terminal P10' to the line L10' which is connected in parallel to the line L10, the terminal P9 to the line L9, the terminal P12 to the line L12, the terminal P13 to the line L13, the terminal P14 to the line L14, the terminal P11 to the line L11 and the terminal P11' to the line L11' which is connected in parallel to the line L11.

Further, the connection terminal P3' is arranged to have a cleaning function, though the cleaning function P3+ is not directly related to this invention. The terminal terminals P1 and P3 and is in a position to first come into sliding contact with the connection terminal P8 on the lens side when the lens is turned round for mounting it on the camera body. During the process of mounting the lens, the terminal P3' thus acts to remove any foreign matter such as dust from the contact faces of the terminals P8 and P10 by sliding over them. The connection terminal P4' is in the same diametral position as other terminals P2, P6, P7 and P4 and is arranged to likewise perform a cleaning function by first coming into sliding contact with the terminal P9 on the lens side when the lens is turned round for mounting it on the camera body. The terminal P4' is thus arranged also to remove any foreign matter such as dust from the contact faces of the terminals P9, P12, P13 and P11 during the lens mounting process.

The second embodiment which is arranged as described above operates as follows: FIG. 5(b) is a schematic illustration showing the relative positions of the connection terminals which vary as the connection terminal block 11' on the lens side is turned round against the lens mounting process as shown in FIG. 6. As shown at a part (I) in FIG. 5(b), The connection terminal P4' on the camera body side and the terminal P9 on the lens side first come into contact with each other. Following that, the group of the connection terminals on the lens side shift to the left as shown at parts (II) and (III) in FIG. 5(b). During this period, however, the terminals P8, P10 and P10' never come into sliding contact with any of the terminals on the lens side. The terminal P8 on the lens side comes into sliding contact first with the terminal P3' on the camera body side at a point as shown at a part (IV) in FIG. 5(b). The positional relation obtained at this point of time is identical with what is shown in FIG. 6. Then, through a state as shown at a part (V) in FIG. 5(b), the positional relation eventually comes to a state as shown at a part (VI) in FIG. 5(b) and also as shown in FIG. 7 when the lens is completely mounted on the camera body. Upon completion of lens mounting, the connection terminals P1, P3, P3', P2, P5, P6, P7, P4 and P4' on the side of the camera body are respectively in touch with the connection terminals P8, P10, P10', P9, P12, P13, P14, P11 and P11' on the side of the lens to obtain required continuity.

In the arrangement described, the connection terminal P1 connected to the line L1 which is a motor power line is arranged to be at a different height from the terminal P2 connected to the line L2 which is a power line for the electronic circuit on the lens side. Meanwhile, the terminal P3 connected to the line L3 which is a power ground line is arranged to be at the same height as the terminal P1. The terminal P4 connected to the line L4 which serves as a signal ground line is arranged to be at the same height as the terminal P2. Therefore, the terminal P2 does not contact with any of the connection terminals on the lens side even in the state as shown at the part (V) in FIG. 5(b). This arrangement prevents the electronic circuit from being broken by the reason as described in the foregoing.

While the connection terminals on the side of the camera body are arranged to be movable in the case of the embodiment described, the same advantageous effect of the invention is attainable by arranging to be movable the connection terminals on the side of the lens to be movable, instead of the terminals on the side of the camera body.

In the second embodiment which relates to a connector arrangement for connecting the electronic circuit of the necessary to the body of an optical apparatus with continuity attained by bringing the connecting terminals of the two into contact with each other, the confronting faces of the connection terminal blocks carrying these terminals are formed in stepped shapes in such a manner as to prevent accidental contact between connection terminals. The embodiment thus effectively prevents the electronic circuit from breaking during the process of turning round the accessory for mounting it on the body of the optical apparatus.