JPH07114087A - Interchangeable lens camera - Google Patents

Abstract

PURPOSE:To prevent malfunction caused by leaking and to prevent current consumption on pull-up resistance from increasing at the time of lens mounting, and to prevent power supply to a power supply terminal caused by leaking influence in the case of lens mounting. CONSTITUTION:When a lens mount condition detecting means 1 does not detect that the lens is mounted, the resistance values of the pull-up resistances 32 and 33 are lowered; when the means 1 detects that the lens is mounted, resistance value varying means 1 and 34 making the resistance value of the pull-up resistance high only in the case a communicating means normally communicates with an interchangeable lens are provided. When the lens is not detected to be mounted, the resistance value of the pull-up resistance is lowered so as to make impedance lowered; on the other hand, when the lens is detected to be mounted the interchangeable lens is discriminated to be correctly attached only in the case communication with the interchangeable lens in normally performed so as to make the resistance value of the pull-up resistance high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved lens interchangeable camera which supplies power to the interchangeable lens when the interchangeable lens is mounted.

[0002]

2. Description of the Related Art Conventionally, in a lens-replaceable camera that uses a photographing lens having an electric circuit in the lens, power is supplied to the electric circuit of the lens by detecting that the interchangeable lens is mounted in the camera body. The camera of the method that does is devised and commercialized. This type of camera determines the state of a mechanical switch that detects the mounting of an interchangeable lens to turn the power on / off, or electrically detects it using a semiconductor switch to turn the power on. / OF
The method of performing F is adopted.

FIG. 6 shows a conventional lens-replaceable camera having a structure in which the semiconductor switch is used to electrically detect whether or not an interchangeable lens is attached and the power is turned on / off. It demonstrates using.

In FIG. 6, reference numeral 51 is a battery which is a power source for the entire camera (including the interchangeable lens), and 52 is a power source for stabilizing the output of the battery 51 and supplying power to various circuits in the camera body and the interchangeable lens. DC / DC converter, 53 is a circuit in the camera for performing various controls of the camera body, 54
Is a Pch MOSFET as a semiconductor switch for supplying power to the interchangeable lens, and 55 is a Pch MOSFET
A pull-up resistor for pulling up the gate of 54,
Reference numeral 56 is a power supply terminal for supplying power to the interchangeable lens. Reference numeral 57 is a lens detection terminal for detecting that an interchangeable lens is attached, and is the circuit 53 in the camera and the PchM.
It is connected to the gate of the OSFET 54, and the PchMOSF
Turns ET54 on and off. Reference numeral 58 is a power supply and a circuit ground terminal.

Reference numeral 59 is an in-lens circuit for performing various controls in the interchangeable lens. Reference numeral 60 denotes a power supply terminal that is connected to the power supply terminal 56 of the camera body when the interchangeable lens is correctly attached to the camera body and receives power supply from the camera body. Reference numeral 61 denotes a lens attachment detection terminal that is connected to the lens attachment detection terminal 57 of the camera body and that allows the camera body to detect lens attachment. Reference numeral 62 is a power supply and a circuit ground terminal.

The circuit 53 in the camera and the circuit 5 in the lens
9 communicates via a communication line (not shown), and the in-lens circuit 59 operates under the control of the camera body.

In the above structure, when the interchangeable lens is attached to the camera body, the lens attachment detection terminal 57 is connected to the lens attachment detection terminal 61 in the interchangeable lens, and the ground terminal 62 is connected to the ground terminal 58 in the camera body. Then, the lens mounting detection terminal 57 is pulled down to the ground level (“L” level). As a result, Pch
The gate of the MOSFET 54 is pulled down so that the PchMO
The SFET is turned on, and power is supplied from the power supply terminal 56 to the interchangeable lens. In addition, the circuit 53 in the camera
Detects that the interchangeable lens is mounted by setting the lens mounting detection terminal 57 to the “L” level.

Next, when the interchangeable lens is not attached, since nothing is connected to the lens attachment detection terminal 57, the gate of the Pch MOSFET 54 is pulled up by the pull-up resistor 55, so "H". It becomes the level, and the Pch MOSFET 54 is OFF. Therefore, no power is supplied to the power supply terminal 56. In addition, the circuit 53 in the camera includes the lens attachment detection terminal 5
It is detected that the interchangeable lens is not attached by the fact that 7 is at "H" level.

[0009]

However, in the above-mentioned conventional example, the pull-up resistor 55 is connected to the ground when the interchangeable lens is mounted, and therefore the resistance value of the pull-up resistor 55 must be increased. Current consumption increases when wearing.

Further, if the resistance value of the pull-up resistor 55 is increased as a measure against the current consumption as described above, when dust or water drops adhere between the lens mounting detection terminal 57 and the ground terminal 58, a leak occurs and the lens The attachment detection terminal 57 is pulled down to the “L” level, the interchangeable lens is attached, and an output is output to the power supply terminal 56. The same is true even if a leak occurs in the circuit connected to the lens mounting detection terminal in the camera body.

(Object of the Invention) An object of the present invention is to prevent malfunction due to leakage when a lens is mounted and increase in current consumption due to a pull-up resistor, and to supply power due to leakage when a lens is not mounted. An object of the present invention is to provide a camera with interchangeable lenses that can prevent power supply to terminals.

[0012]

According to the present invention, the resistance value of the pull-up resistor is lowered when the lens mounting state detecting means does not detect the lens mounting, and the communication is performed when the lens mounting is detected. The resistance value changing means for increasing the resistance value of the pull-up resistance is provided only when the communication with the interchangeable lens is normally performed by the means, and the resistance value of the pull-up resistance is lowered when the lens attachment is not detected. If the lens attachment is detected, it is determined that the interchangeable lens is properly attached only when communication with the interchangeable lens is normally performed, and the resistance value of the pull-up resistor is set. I try to raise it.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a diagram showing an example of a specific configuration of an electric control block of a camera with interchangeable lenses according to an embodiment of the present invention. First, the configuration of each part will be described.

In FIG. 1, reference numeral 1 is a microcomputer for controlling each of the following circuits.
Built-in OM, EEPROM, etc. 2 is a strobe light emission control circuit for controlling strobe light emission and dimming, which is a circuit portion for storing electric charge for light emission, a xenon tube as a light emitting portion, a trigger circuit, a circuit portion for stopping light emission, and film surface reflection. It consists of existing circuits such as an optical metering circuit and an integrating circuit, and when the X contact that is turned on by the front curtain running of the shutter unit is turned on, the flash light of the strobe is started. Reference numeral 3 denotes a liquid crystal display circuit for displaying various photographing information of the camera body such as a shutter speed and an aperture control value. The liquid crystal display circuit 3 receives a DBCOM (data bus) while receiving a DPCOM signal from the microcomputer 1. Serial communication is performed via the, and liquid crystal display is performed based on the communication content.

A feeding circuit 4 controls the film feeding motor in accordance with a control signal from the microcomputer 1 to wind and rewind the film. A shutter control circuit 5 controls a shutter unit (not shown) according to a control signal from the microcomputer 1. Reference numeral 6 denotes a photometry circuit, which divides the screen into a plurality of areas, performs the TTL photometry of the brightness of the subject in each area, and sends the TTL photometry to the microcomputer 1.

Reference numeral 7 denotes a switch detection circuit, which is always supplied with power together with the liquid crystal display circuit 3 described above, and in a normal camera body, it is interlocked with the first stroke for starting the preparation for photographing of the release button of the camera body. Switch SW
It is possible to always read the statuses of the switch 1 and other switches (not shown) that determine the exposure mode and the switch that determines the auto focus (AF) mode of the camera body. When the switch is switched, the switch detection circuit 7 outputs DB
Serial communication is performed via the US to communicate each switch information to the microcomputer 1.

Reference numeral 8 denotes a focus detection unit, which detects from the image signal of the subject obtained through the photographic lens which position the subject is in focus by the photographic lens by calculation using the existing phase difference detection method. . A battery 9 serves as a power source for each part of the camera body and each part of the interchangeable lens.
A DC / DC converter 10 stabilizes the output voltage of the battery 9 which changes depending on the load condition and supplies the stabilized output voltage to each part of the camera body and the interchangeable lens. Reference numeral 11 denotes a lens detection circuit, which together with the microcomputer 1 controls lens attachment detection and power supply to the interchangeable lens.

Reference numeral 12 is a terminal for supplying power from the camera body to the interchangeable lens, and power is supplied from the lens detection circuit 11 when the lens is mounted. Reference numeral 13 denotes a lens mounting detection terminal on the camera body side, which is connected to a terminal on the interchangeable lens side when the lens is mounted. Reference numeral 14 is a ground terminal of the camera body. Reference numeral 15 denotes a lens communication terminal on the camera body side, which performs serial communication with the interchangeable lens through the terminals 15a, 15b, and 15c.

Reference numeral 16 denotes a microcomputer in the lens, which communicates with the microcomputer 1 of the camera body to drive focus, aperture, and zoom in accordance with instructions from the camera body, and communicates lens-specific information to the camera body side. To do. A focus driving circuit 17 drives the focus lens according to an instruction from the microcomputer 16 in the interchangeable lens. A focus position detector 18 detects the position and movement amount of the focus lens driven by the focus drive circuit 17. A diaphragm driving circuit 19 drives the diaphragm according to an instruction from the microcomputer 16 in the interchangeable lens. A diaphragm position detector 20 detects the position and movement amount of the diaphragm driven by the diaphragm drive circuit 19. Reference numeral 21 denotes a zoom drive circuit, which drives the zoom interchangeable lens according to an instruction from the microcomputer 16 in the interchangeable lens. A zoom position detector 22 detects the position and movement amount of the zoom lens driven by the zoom drive circuit 21.

Reference numeral 23 denotes a power supply terminal on the interchangeable lens side, which receives power supply from the power supply terminal 12 on the camera body side. Reference numeral 24 is a lens mounting detection terminal on the interchangeable lens side for the camera body to detect lens mounting by being normally connected to the lens mounting detection terminal 13 on the camera body side. Reference numeral 25 denotes a ground terminal on the interchangeable lens side, which is connected to the ground terminal 14 on the camera body side and also connected to the lens mounting detection terminal 24 on the interchangeable lens side. 26
Is a lens communication terminal on the side of the interchangeable lens,
The terminals b, 26c and 15a, 15b, 15c are respectively connected, and serial communication is performed between the interchangeable lens side and the microcomputers 1 and 16 on the camera body side.

Further, the microcomputer 1 has a switch SW2 for operating a shutter for photographing.
Are connected, and when the switch SW2 is turned on in a state where a predetermined condition is satisfied, the shutter is controlled and the exposure is started.

FIG. 2 is a front view of the camera body having the above structure.

Communication terminals 15a, 15b with the interchangeable lens,
15c, lens mounting detection terminal 13 and power supply terminals 12, 1
4 are arranged in the circumferential direction of the lens mount portion of the camera body.

FIG. 3 is a view of the interchangeable lens mounted on the camera body of FIG. 2 as viewed from the mount portion.

Communication terminals 26a, 26b with the camera body,
26c, a lens mounting detection terminal 24 and a power supply terminal 23,
25 are respectively arranged in the circumferential direction of the mount, and are mounted on the lens mount portion of the camera body of FIG. 2 to receive power supply and perform communication through each terminal.

FIG. 4 shows details of the lens mount and lens mounting detection according to the present invention, and is a block diagram showing a part of the configuration shown in FIG. 1 and details of the lens detection circuit 11.

First, the internal structure of the lens detection circuit 11 will be described.

Reference numeral 31 indicates ON / OFF of power supply to the interchangeable lens
Pch MOSFET, 32 is the PchMOSFE
It is a resistor connected between the gate and source of T31 and to the power source / lens mounting detection terminal 13 and has a high resistance of about 1 MΩ. 33 is a low resistance of about 10 KΩ which is arranged in parallel with the high resistance 32 and is connected / opened in parallel by the switch means.
Gate of hMOSFET 31 and lens mounting detection terminal 1
3 is connected / opened. 34 is an Nch MOSFET, the drain has a low resistance 33, and the source has a PchMOSF.
The gate is connected to the ET 31 and the lens mounting detection terminal 13, respectively, and the gate is turned on / off according to a signal from the microcomputer 1.
To do.

The Nch MOSFET 34 is turned off when communication with the microcomputer 16 of the interchangeable lens is established through the lens communication terminal 15, and is turned on when communication with the interchangeable lens is not possible.
It is controlled so that

The lens mounting detection terminal 13 is connected to the microcomputer 1, and the microcomputer 1 detects the signal level and state change of the lens mounting detection terminal 13.

In the above structure, first, the case where the interchangeable lens is not attached to the camera body will be described.

When the interchangeable lens is not attached,
Nothing is connected to each terminal of the mount of the camera body. Therefore, since the microcomputer 1 cannot communicate with the interchangeable lens, the NchMOSFET 34 is turned on.
Then, the low resistance 33 is connected between the gate and source of the Pch MOSFET 31. This enables PchMOS
A high resistance 32 and a low resistance 33 are connected in parallel between the gate and source of the FET 34, and the gate of the Pch MOSFET 31 is pulled up by a resistance having a low resistance value.

Further, since nothing is connected to the lens mounting detection terminal 13, since the gate-source voltage of the Pch MOSFET 31 connected to the lens mounting detection terminal 13 is equal, this Pch MOSFET is turned off, Since no current flows between the source and drain, no power is output to the power terminal 12 of the camera body,
The power to the interchangeable lens is turned off.

Next, the case where the interchangeable lens is attached to the camera body will be described.

When the interchangeable lens is attached to the camera body,
Corresponding terminals are respectively connected on the camera body side and the interchangeable lens side, and electrical continuity is established between the camera body and the interchangeable lens at each terminal. As a result, the lens mounting detection terminal 24 on the interchangeable lens side, which is connected to the ground terminal 25 on the interchangeable lens side, is connected to the lens mounting detection terminal 13 on the camera body, so that the lens mounting detection terminal 13 on the camera body is connected to the ground. It was done. Therefore, the gate voltage of the Pch MOSFET 31 becomes lower than the source voltage, and the Pch MOSFET 31
The FET is turned on, power is supplied from the power supply terminal 12 to the interchangeable lens to the interchangeable lens side, and the microcomputer 16 starts operating.

Further, the microcomputer 1 detects that the interchangeable lens is mounted on the camera body when the lens mounting terminal 13 is at "L" level, and the microcomputer 16 through the lens communication terminals 15 and 26.
To start communication with.

At this time, the microcomputer 1 initially sets the Nch MOSFET 34 to the ON state, but since the communication with the microcomputer 16 in the interchangeable lens can be performed, the interchangeable lens is provided in the camera body. It is judged that it is properly attached, and Nch
Turn off the MOSFET 34 and set the low resistance 33 to Pch.
The MOSFET 31 is cut off between the gate and the source, and the P
Only the high resistance 32 is used as the resistance connected between the gate and the source of the chMOSFET 31.

FIG. 5 is a flowchart relating to the lens mounting detection of the microcomputer 1, and the operation relating to the lens mounting detection of the microcomputer 1 will be described with reference to this flowchart.

When the power is turned on, the microcomputer 1 starts its operation, and after resetting, starts the operation from step 101. [Step 101] The gate of the Nch MOSFET 34 is turned to "H" level to be turned on, the low resistance 33 is connected to the lens mounting detection terminal 13, and the resistance value of the pull-up resistor of the lens mounting detection terminal 13 is lowered to set Step 1
Go to 02. [Step 102] The lens mounting detection terminal 13 is "L"
If the lens mounting detection terminal 13 is at "H" level, it is determined whether or not it is at the level, and this step remains until the "L" level. After that, when the lens attachment detection terminal 13 becomes the “L” level, the process proceeds to step 103. [Step 103] Communication is performed with the microcomputer 16 in the interchangeable lens through the lens communication terminal 15, and the process proceeds to step 104. [Step 104] It is determined whether the communication with the microcomputer 16 in the interchangeable lens performed in the above step 103 is normally performed, and if the lens communication is normally performed, it is determined that the interchangeable lens is properly mounted. Then, the process proceeds to step 105, and if not normally performed, the process returns to step 102. [Step 105] The gate of the Nch MOSFET 34 is set to "L" level to turn it off, the low resistance 33 is cut off from the lens mounting detection terminal 13, and the lens mounting detection terminal 1 is cut off.
As described above, the pull-up resistance of 3 is set to only the high resistance 32, and the lens mounting confirmation is completed.

Here, when the interchangeable lens is attached, the current flowing through the pull-up resistor only flows through the high resistance 32 of 1 MΩ. Therefore, if the power supply voltage is 5 V, 5 μA is sufficient, and the interchangeable lens is attached. When it is not present, it is pulled up by the high resistance 32 of 1 MΩ and the low resistance 33 of 10 KΩ, so if the power supply voltage is 5 V, the cutoff voltage of the Pch MOSFET 31 and the input threshold voltage of the lens mounting detection terminal 13 of the microcomputer 1 are 2.5 V. Even if the lens attachment detection terminal 13 or the like leaks at an impedance of 10 KΩ or more, it is not erroneously recognized that the interchangeable lens is attached, and the power is not output to the power supply terminal 12.

Although the FET is used as the switching element in the present embodiment, other switching elements such as a transistor may be used.

According to the present embodiment, the PchMO for turning the power on / off when the lens attachment is not detected.
Since the pull-up resistance of the SFET 31 is set to a low resistance value to lower the impedance, the influence of leakage disappears, and when lens attachment is detected, communication is performed with the interchangeable lens, and communication is normally performed. Only when the lens is connected, it is determined that the interchangeable lens has been installed correctly, and the resistance value of the pull-up resistor is set to a high value. You can do it.

In other words, it is possible to prevent malfunction due to leakage and reduce the current flowing through the pull-up resistor when the lens is attached. In addition, it is possible to prevent the power supply from being accidentally output to the power supply terminal due to the influence of leakage when the interchangeable lens is not attached.

[0045]

As described above, according to the present invention,
When the lens mounting state detecting means does not detect the lens mounting, the resistance value of the pull-up resistor is lowered, and when the lens mounting state is detected, the communication means normally communicates with the interchangeable lens. Only when the pull-up resistance is increased, a resistance value changing means is provided, and when the lens attachment is not detected, the pull-up resistance is lowered to lower the impedance, while the lens attachment is detected. If so, it is determined that the interchangeable lens is properly mounted only when communication with the interchangeable lens is normally performed, and the resistance value of the pull-up resistor is increased.

Therefore, it is possible to prevent the malfunction caused by the leak and the increase in the current consumption due to the pull-up resistor, which have occurred when the lens is attached, and the power is supplied by the influence of the leak which occurs when the lens is not attached. It is possible to prevent power from being output to the terminals.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a camera with interchangeable lenses according to an embodiment of the present invention.

FIG. 2 is a front view of the camera body side of FIG.

3 is a view of the interchangeable lens of FIG. 1 viewed from the lens mount side.

FIG. 4 is a block diagram showing a schematic configuration of a portion of the camera of FIG. 1 according to the present invention.

5 is a flowchart showing an operation of a main part of the microcomputer on the camera body side of FIGS.

FIG. 6 is a block diagram showing a schematic configuration of a main part of a conventional camera with interchangeable lenses.

[Explanation of symbols]

 1 Microcomputer in camera body 9 Battery 11 Lens detection circuit 12 Power supply terminal 13, 24 Lens attachment detection terminal 14, 25 Ground terminal 16 Microcomputer in interchangeable lens 23 Power supply terminal 31 PchMOSFET 32 High resistance 33 Low resistance 34 NchMOSFET

Claims (1)

[Claims] 1. Communication is performed between a resistor for pulling up a lens mounting detection terminal, a lens mounting state detecting means for detecting whether or not a lens is mounted from the state of the lens mounting detection terminal, and an interchangeable lens. In a lens-replaceable camera equipped with a communication means for performing, if lens attachment is not detected by the lens attachment state detection means,
A resistor that lowers the resistance value of the pull-up resistor and increases the resistance value of the pull-up resistor only when the communication with the interchangeable lens is normally performed by the communication unit when the lens attachment is detected. A lens-replaceable camera characterized by having a value varying means.