JPH04331Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to an active autofocus device, and in particular to a device that prevents erroneous distance measurement by determining whether the signal is from the camera itself or another camera. .

[Conventional technology]

Various autofocus devices have been proposed that emit infrared rays toward a subject, receive reflected signals, measure the distance to the subject using triangulation, and adjust focus. .

On the other hand, various autostroboscopic devices have been proposed that prevent malfunctions by distinguishing between self-emitted light and light emitted from other cameras (for example, Utility Model Publication No. 56-2455). [Problem that the invention aims to solve] However, in active autofocus cameras, there is no device that can distinguish between the camera's own transmission and transmission from other cameras to prevent erroneous distance measurement.

[Means for solving problems]

This invention consists of a transmitter that transmits infrared light, ultrasonic waves, etc. toward the subject for distance measurement to prevent erroneous distance measurement due to light or ultrasonic waves from other cameras; a transmission control unit that controls transmission timing and outputs a transmission notice signal; a reception unit that receives transmissions from the transmission unit and transmissions from other devices similar to the transmission unit by reflection from a subject, direct radiation, etc.; After inputting the transmission notice signal from the transmission control unit, the reception unit determines whether there is a similar reception signal from the other device for a certain period of time, and if there is a similar reception signal, the transmission unit transmits the signal. a transmission determining unit that sends a determination output to the transmission control unit to cause a normal transmission after a predetermined time delay immediately after receiving the similar received signal; a gate circuit that closes a circuit based on the determination output; When the gate circuit is closed by the discrimination output of the discrimination section, the received signal from the reception section is input through the gate circuit and a distance measurement section measures the distance to the subject, and the focus is determined according to the output from this distance measurement section. An active type autofocus device is provided, which includes a focus adjustment section that performs adjustment.

〔Example〕

The present invention will be explained in detail below using the drawings.

FIG. 1 is a block diagram of a device showing an embodiment of the present invention, and FIG. 2 shows time charts of various signals. In Fig. 1, 1 is a transmitter that transmits infrared light, ultrasonic waves, etc. toward the subject, and 2 is a transmitter controller that controls the transmitter 1 and the timing of the transmitter, and also outputs a transmission notice signal. 3 is a receiving section which receives reflected signals from a subject such as infrared light or ultrasonic waves transmitted from the transmitting section 1 and/or signals similar thereto, and 4 is a transmission discriminating section. , determines whether or not there is a received signal from the receiving unit 3 for a certain period of time after inputting a call notification signal from the transmission control unit, and when there is a received signal, causes the transmitting unit 1 to transmit after a specified time delay;
When there is no outgoing signal, a determination output is sent to the transmission control section 2 to cause the transmission to occur after a certain period of time, which is normal transmission. 5 is a gate circuit that outputs a determination output from the transmission determination section 4. 6 is a ranging section which inputs the received signal from the receiving section through the gate circuit when the gate circuit 5 is closed by the discrimination output, and when the signal from the transmitting section 1 is light, In the case of ultrasonic waves, the distance is measured by triangulation distance measurement, and in the case of ultrasonic waves, the distance is measured by the time required to reach the object and the result is output. 7 is a focus adjustment section that follows the output from the distance measurement section 6. to adjust the focus.

The operation in such a configuration will be explained next using FIG. 2. The horizontal axis in FIG. 2 is time. First, when the transmission control unit 2 sends a call notification signal as shown in (A) to the call discrimination unit 4, the call discrimination unit 4 receives a certain signal as shown in (B). The presence or absence of a signal from the receiving section 3 is determined during the determination period. If there is an input of another device's signal as shown in (C), the transmission control unit 2 ( A determination output I as shown in D) is sent to cause the transmitter 1 to make a call. On the other hand, if there is no other aircraft signal within the determination period of (B), (B) as shown in (E)'
A determination output as shown in (D)' is sent to the transmission control section 2 so that the self-transmission signal is input with a delay of a prescribed time d after the end of the determination period.

Although the above explanation has been made regarding an example of a one-shot transmission system, it is clear that the present invention can also be applied to a system that repeatedly transmits transmissions. In addition, when many devices of the same type operate simultaneously, the relationship between the repeated transmission period T, self-transmission signal width t, and delay time d is T≫
If t+d is set, malfunctions will be reduced. Further, in the case of repeated transmissions, the determination may be made only the first time as in this embodiment, or the determination may be made every time.

[Effect of idea]

As explained above, according to the present invention, even when a large number of AcDave-type autofocus devices are activated at the same time, it is possible to prevent malfunctions in which one's own camera is activated due to light emission or transmission from other cameras. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a time chart of various signals. DESCRIPTION OF SYMBOLS 1... Transmission section, 2... Transmission control section, 3... Receiving section, 4... Transmission determination section, 5... Gate circuit, 6...
... Distance measuring section, 7... Focus adjustment section.

Claims (1)

[Scope of utility model registration request] An active type autofocus device includes a transmitter that transmits infrared light, ultrasonic waves, etc. for distance measurement toward a subject, controls the transmitter's transmitter and transmit timing, and outputs a transmission warning signal. a transmission control unit; a reception unit that receives the transmission from the transmission unit and transmissions from other devices similar thereto by reflection from a subject, direct radiation, etc.; It is determined whether or not there is a similar received signal from the other device etc. from the receiving section for a certain period of time, and if there is a similar received signal, the transmission from the transmitting section is delayed for a specified period of time immediately after receiving the similar signal. a transmission discrimination section that sends a discrimination output to the transmission control section to cause normal transmission when there is no received signal; a gate circuit that closes a circuit based on the transmission discrimination output; and a discrimination output of the transmission discrimination section. a distance measuring section that inputs a received signal from the receiving section through the gate circuit when the gate circuit is closed and measures the distance to the subject; and a focus adjustment section that adjusts the focus according to the output from the distance measuring section. An autofocus device comprising: