JP2958653B2 - Accessory data retrieval method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a camera body and various accessories such as an interchangeable lens, an intermediate ring, a motor drive device, and an electronic flash device which are attached to or connected to the camera body. The present invention relates to a method for taking out types of accessories of a camera system that performs signal transmission and reception between them and performs photographing.

(Prior Art) A camera body is provided with a means for outputting address data including information designating an accessory, and in each accessory, whether or not the accessory is selected is determined by address data from the address data output means. As a data extraction method for discrimination, there is a method disclosed in Japanese Patent Application Laid-Open No. 58-105139, which is already known. Conventionally, in this type of system, the camera side sends address data of the accessory in advance, and then the accessory sends two steps: sending unique data to the camera side, or receiving data from the camera side. However, the transmission of data between the camera body and accessories in the current autofocus single-lens reflex camera requires the camera body to know data such as unique data and status of accessories as soon as possible in order to increase the focusing speed. Also,
The accessory must also know the status of the camera body and other data as soon as possible. Therefore, in the above-described retrieval method, there is a limit to the speed at which data is transmitted and received.

(Purpose) An object of the present invention is to improve the transmission speed by reducing the number of steps between the camera body and each accessory when transmitting and receiving signals between the camera body and each accessory.

(Means for Solving the Problems) The present invention relates to a camera system for transmitting and receiving a plurality of signals between a camera body and a plurality of types of accessories.
The camera body is provided with clock width conversion output means for converting a clock signal into a specific clock width designating an accessory. In each accessory, the accessory is provided based on the clock width of the clock signal from the clock width conversion output means. By providing a clock width determining means for determining whether or not the camera is selected, even if a plurality of accessories are simultaneously mounted on the camera body, data of only the designated accessory is input / output, and the camera body transmits data to each accessory. Added direct input / output.

Hereinafter, the present invention will be described with reference to examples.

FIG. 1 is a block diagram showing the entire camera system to which the present invention is applied, and (Bo) is a camera body. (St)
Is an accessory for flash photography, and the camera body (B
o) and signals, and strobe (St) control. (Lea) is a lens accessory such as a converter and an intermediate ring for increasing and decreasing the focal length and the like of the interchangeable lens, and exchanges signals with the camera body (Bo) and controls each lens accessory (Lea). (Le) is an interchangeable lens, which exchanges signals with the camera body (Bo) and controls the interchangeable lens (Le). (Md) is a motor drive, which exchanges signals with the camera body (Bo) and controls the motor drive (Md).

Camera body (Bo) and accessories (St), (Le),
Terminals (a), (Lea) and (Md)
Electrical connection is made by (b), (c), (d) and (e). A power source, a clock signal, and a reset signal are supplied from the camera body (Bo) to the respective accessories via the terminals (a), (b), and (c). In addition, camera body (Bo) from each accessory via terminal (d)
Is supplied with data unique to each accessory. Terminal (e) is a ground terminal.

In the camera body (Bo), (11) is a power supply, which supplies power to each accessory from the terminal (a). (SW ₁₎
Is a switch that is closed when the accessory is adhered to the camera body. (SW ₂ ) is a release switch for starting the exposure control operation, and (SW ₃ ) is a photometric switch for starting the photometric operation. (12) is a timing circuit, the switches (SW _1), (SW _2), on the basis of the closing signal (SW _3), the clock width converter output circuit (13), timing data input circuit (16) A signal is supplied to control the output of a clock signal having a specific clock width which can be designated as an accessory, the capture of data, the transmission timing of data, and the supply of a reset signal to a terminal (c). Further, the clock width conversion output circuit (13) receiving the timing by the timing circuit (12) supplies a clock signal to the terminal (b). The data input circuit (14) synchronizes with the clock signal of the terminal (b), reads various data of each accessory serially input bit by bit from the terminal (d), converts the data into parallel data, and converts the data into parallel data. ). The arithmetic circuit calculates various control data based on the read data and sends the data to various control devices (16) such as an aperture, a shutter, and a display.

In the interchangeable lens (Le), which is an accessory, a clock width discriminating circuit (21) inputs a clock signal converted to a specific clock width from a terminal (b) of the camera body (Bo) and outputs a clock having a specific clock width indicating the interchangeable lens. When the signal is confirmed, the fixed data (22) and the variable data (23) are output from the data output circuit (24) to the terminal (d) in synchronization with the subsequently input clock signal.

The same applies to other accessories (St) (Md) (Lea).

FIG. 2 shows a clock signal output from the clock width conversion output circuit of the camera body in the block diagram shown in FIG. Each accessory can be designated by expanding and contracting the time (t) of the leading clock to the length shown in Table 1.

(A) specifies the interchangeable lens, the time (t) is set to 30 μs, (B) specifies the lens accessory, the time (t) is 40 μs, and (C) specifies the strobe ( (D) designates a motor drive, and (D) designates a motor drive as 60 μsec.

FIG. 3 is a flowchart of the clock width conversion output circuit of the camera body (Bo).

In the figure, when the pre-process is completed and an interchangeable lens is specified as an accessory, High is output to the terminal (b) which is a clock terminal, and as shown in Table 1, Hi is output for 30 μs.
gh, and then output low and high clock signals to the terminal (b). The interchangeable lens is designated by the above operation. When the strobe is designated as the accessory, the terminal (b) may be set to output High for 50 μs, and then the low and high clock signals may be output to the terminal (b).

FIG. 4 is a flowchart of a clock width determining circuit for determining the clock width of the interchangeable lens.

In 8-bit serial communication, a signal is received from the terminal (b), which is a clock terminal, and watching is continued until the signal becomes a high level. Once the signal goes high, measure the time it takes for the signal output to go low. If the high level time of the clock signal is not 30 μs, the process returns to receiving the signal after counting 7 pulses. If the time of the high level of the clock signal is 30 μs, the interchangeable lens is designated, and the clock width determination circuit of the interchangeable lens is connected to the terminal (b).
, And outputs data serially from the terminal (d) for each bit from the terminal (d).

The same applies to other accessories (St) (Md) (Lea).

(Effect of the Invention) According to the present invention, a clock signal of a specific clock width transmitted from the camera main body to various accessories connected to the camera main body can determine whether the accessory is selected by the accessory determining means. Even if multiple accessories are attached to the camera body at the same time, data for only the specified accessories is input / output, and the camera body can directly input and output data to each accessory, so the camera body and each accessory By reducing the number of steps of the camera body and each accessory when transmitting and receiving signals between them, there is an effect of improving the transmission speed. In addition, since the accessory is specified using the clock terminal, there is no need for an address terminal for specifying the accessory, which has the effect of reducing the number of communication terminals.

[Brief description of the drawings]

1 is a block diagram showing the entire camera system to which the present invention is applied, FIG. 2 is a diagram showing a clock signal output from a clock width conversion output circuit of the camera body, and FIG. 3 is a clock width conversion of the camera body. FIG. 4 is a flowchart of an output circuit, and FIG. 4 is a flowchart of a clock width determining circuit for determining the clock width of the interchangeable lens. Bo… Camera body, Le… Interchangeable lens, Lea… Lens accessories, St… Strobe, Md…
Motor drive, 12 timing circuit, 13 clock width exchange output circuit, 14 data input circuit, 21 clock width discrimination circuit, 22 data output circuit.

Claims (1)

(57) [Claims] In a camera system for transmitting and receiving a plurality of signals between a camera body and a plurality of types of accessories, a clock width conversion output means for converting a clock signal into a specific clock width designating an accessory in the camera body. Provided in each accessory, based on the clock width of the clock signal from the clock width conversion output means, a clock width determining means for determining whether the accessory is selected or not is provided. Data retrieval method.