JPS59135448A - Indicating circuit for auto-focusing device - Google Patents

Abstract

PURPOSE:To make a display device simple and easy to see and determine easily the composition of a picture, by providing two driving signal generating circuits, which generate a driving signal of an indicating circuit, for servo mode and one shot and driving the circuit with different driving signal generating circuits. CONSTITUTION:Since an oscillating circuit consisting of means 51-54 and an oscillating circuit consisting of means 45-48 are different in oscillation frequency, the photographer finds clearly the in-focus display due to servo mode, the in-focus display due to one shot, or the AF lock display in accordance with flickering or lighting of an LED 58. When a camera is in focus in the one shot mode, the photographer can find it easily by the display that the in-focus state due to the one shot mode is held, and a fear that another object is photographed erroneously in this state to take an out-of-focus picture is eliminated. The same is true of the case where the camera is in-focus in the servo mode. Since only one display device is used, the constitution of the display device is simple and the display device is easy to see, and the photographer fixes his attention to only one point of the display device to concentrate upon determination of the composition of a picture.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an indicating circuit for a camera chamber having an automatic focus adjustment device.

Traditionally, automatic focusing devices for cameras have been divided into two types: one that continuously follows the movement of the subject and performs sequential focusing operations (hereinafter referred to as servo mode), and the other that performs focusing only once (hereinafter referred to as servo mode). ) exists.

Both the servo and one-shot modes have different characteristics, and it is desirable to use them properly depending on the purpose of photography, and it is conceivable to be able to select between the servo and one-shot modes with the same camera.

On the other hand, when performing focus display with a camera that can select from each of the above modes, if the instruction format is the same in the servo mode and the one-shot mode, the following problem will occur.

As mentioned above, in servo mode, focusing is always performed by following the movement of the subject, so when a focus instruction is given, the photographing lens is always at the in-focus position for the subject, but in one-shot mode, , - Once in focus mode, even if the subject moves from then on, focusing will not be executed to follow it. Therefore, when the focus state is reached in one-shot mode, focusing will be performed in the same manner as in the servo mode described above. When a focus instruction is given, the instruction is given even though the subject is not actually in focus, and there is a risk that the photographer may mistakenly think that the subject is in focus. or,
Even when a camera having the above-mentioned servo mode is provided with a so-called AF lock mode, which is a function of stopping focusing after the operation member is operated, the same inconvenience as the above-mentioned one-shot mode occurs.

To solve the above problem, it may be possible to provide separate focus instruction means for servo and one-shot mode, or for servo and AF lock, but this method requires a large number of instruction means, which is costly. Not only problems with
The indicating circuit becomes large and is not suitable as an indicating circuit for a small device such as a camera, where the installation space for the indicating circuit becomes a problem.

The present invention has been made in view of the above-mentioned matters, and includes two drive signal forming circuits, one for servo mode and one for one shot, which form drive signals for driving the instruction circuit, and the characteristics of the drive signals from each circuit. By driving the instruction circuit with drive signals from different drive signal forming circuits when the servo mode is selected and when the one-shot mode is selected, the servo mode can be set using the same instruction means. Alternatively, the above-mentioned problem can be solved by changing the focus instruction mode in the one-shot mode.

Further, the present invention similarly drives the instruction means with drive signals having different characteristics from different drive signal forming circuits in the servo mode and the AF lock mode, thereby solving the problems in the AP lock mode and the problems in the servo and one shot modes. This was solved in the same way.

The instruction circuit of the automatic focus adjustment device according to the present invention will be explained below.

FIG. 1 is a sectional view showing the structure of a known light receiving optical unit for focus detection in a focus adjustment device applied to the present invention, where 2 is a relay lens for focus detection, and 1 is a focus detection unit. The unit includes a beam splitter 1a1 substrate 1C and two light receiving elements 1b and Ib' provided on the substrate 1C.
It consists of The light receiving elements 1 b and 1 b'
For example, in the case of TTL distance measurement, the elements are arranged at so-called front focus and rear focus positions, and in a focused state, the sharpness of the image formed on each element is almost the same.

FIG. 2 is a circuit diagram showing an embodiment of a focus adjusting device to which a display device according to the present invention is applied;
Since a photoconductive element such as OaS is used as b, 11)', the resistance value of 0(is corresponds to the image clarity. 3 and 8 are constant current sources, and 4 to 7 and 9 to 12 are A sensor circuit is formed by a resistor and an operational amplifier that constitute a non-inverting amplification circuit. 13 to 18 are resistors and an operational amplifier that constitute a differential amplifier, and 21 to 26 are window comparators. A detection circuit is formed by a differential amplifier and a window comparator by the comparators and resistors that constitute it. Reference numerals 29 to 32 are transistors that constitute a forward/reverse control bridge for the motor 33, and when the comparator 23 is at a high level (hereinafter referred to as H level), ), transistors 29 and 32 are on, and when comparator 24 is at H level, transistors 30 and 31 are off.
N. 27 and 28 are protection resistors that control the current to these transistors. A drive control circuit is composed of these transistors.

34.35 is A as a resistor and AF knob operating member
The F-lock switch 36 and 37 are resistors and a mode changeover switch as means for selecting between the one-shot mode and the servo mode. 38.39.45, 45.

46.49.51 and 52 are NOT game 1- of the logic circuit.
, 40°42. 44 and 50 are AND gates, and 41 and 55 are OR gates. AND gate 400 Å force is supplied from NOT gate) 38, 39 and 49, and A
The input of the ND gate 42 is the NOTOR gate 419 and the AF
Supplied from the lock switch and mode changeover switch. Further, 45 to 48 and 51 to 54 are the NOT gate and the resistance capacitor, respectively, which constitute an oscillation circuit.
The values of each capacitor and resistor are set so that the oscillation frequency is different from that of the oscillation circuit configured with. AND
The input to the gate 44 is supplied from an oscillator circuit composed of NOT gates 43 and 45 to 48, and an AND gate) 50
The input voltage is supplied from an oscillation circuit composed of NOTOR gates 4139, 49, an AP lock switch, and 51-54. 19.20 is a transistor and a protection resistor, the base of the transistor 190 is the resistor 2o, and the collector is the positive input of the comparator 23 and the comparator 24.
is connected to the negative input of , and its emitter is grounded. The OR gate 41 receives inputs from the AND gate 40 and the NOT gate 43, and supplies its output to the base of the transistor 9 via the resistor 2o. Also, OR gate 5
The input of 5 is supplied from AND game) 42.44 and 5o. Reference numerals 56 and 57 denote a transistor and a resistor for driving the light emitting element (LED) 58. The base of the transistor 56 is connected to the OR gate 55, the collector is connected to the power supply, and the emitter is connected to the LED 58 via the resistor 57.

The AND gate 42 is connected to a first drive signal forming a first drive signal.
The oscillation circuit formed by 51 to 54 forms a second drive signal formation circuit for forming a second drive signal, and the oscillation circuit formed by 45 to 48 forms a second drive signal formation circuit. A sixth drive signal forming circuit for forming the third drive signal is configured. Moreover, the AND gates 42 and 44
, 50, NOT game) 49, 43, 38, and 39 form an instruction operation control circuit.

Now, in the above configuration, the outputs of CdS ib and 1b' are input to the differential amplifier 17 via non-inverting amplifiers, and the sharpness difference between the images on each C(Is is input to the window comparator. The window comparator is resistor 2
It has threshold values set by 1 and 22, and if the sharpness difference is within the range of these two threshold values, it is considered to be in focus.

That is, since the sharpness of the images at 0 dSib and 1 b' are almost the same in the focused state as described above, the output of the differential amplifier 17 is almost at zero level. A value within the threshold is taken and the comparator 23
, 24 both output low level (hereinafter referred to as L level).

Assume that the mode changeover switch 37 is currently set to the servo mode side (b). In this state, the differential amplifier 17 is Cd51b as described above.

The comparator 23 generates an output (positive, negative or zero) according to the sharpness difference of 1b', and when the in-focus state is not present, the amplifier output shows a positive or negative value outside the above threshold. An H level is sent out from one of the comparators of 24. Therefore, the motor forward/reverse control circuit rotates the motor forward or backward based on the comparator output, drives the photographing lens linked to the motor in the focusing direction, and executes focusing. When the photographing lens is driven in this way and reaches a focused state, the difference in sharpness of the images at Ca511) and 1b' are almost the same, so the output of the amplifier 17 becomes a value within the threshold value. , the outputs of the comparators 26 and 24 both go to L level, and the motor forward/reverse control circuit that drives the motor 36 becomes inactive, keeping the lens at the in-focus position. Further, the L level signals from the comparators 23 and 24 become H level through the NOTOR gate 4169 and are input to the AND gate 42. The AND gate 42 is also supplied with an H level signal from the power supply via the resistor 34 when the AF lock switch 65 is OFF, and an H level signal from the power supply via the resistor 36 since the mode selector switch is in servo mode. There is. Therefore, AND
The output of the gate 42 is H as the first drive signal during focusing.
level is input to the OR gate 55, and the output of the OR gate 55 becomes H level, so the transistor 56
is turned on and the LED 58 lights up to display the in-focus state.

Furthermore, even if the subject changes position after reaching the in-focus state, the motor 33 will again turn forward or backward as described above to move the photographic lens to the in-focus position by following the movement of the subject. When the focus is reached, the LED 58 lights up. In this way, in the servo and -do, LED 5
8 always indicates the in-focus state, and the photographer can accurately know the in-focus state.

Also, in servo mode, after the focus display is displayed, A
When the P lock switch 65 is turned on, the L level signal from the switch 35 passes through the NOTOR gate 41 and becomes H level, and is applied to the OR gate 41 and the AND gate 44. Therefore, OR gate 4
1 becomes H level, the transistor 19 is turned on, and the input signal to the window comparator is thereafter locked to almost zero level regardless of the sharpness of the image received by the a4s. Therefore, the outputs of the comparators 23 and 24 are locked to the L level, and the forward/reverse rotation control circuit is held in an inactive state. In addition, the output of the oscillation circuit composed of 45 to 48 is input to the OR gate 55 via the heD gate 44, so the LED 58 blinks based on the oscillation pulse from the oscillation circuit composed of 45 to 48. to notify the photographer that the AF is locked.

Next, set the mode selector switch 67 to one-shot mode (
a side), an L level signal is input to the NOT gate 49, and the output becomes an H level, which is input to the AND gates 40 and 50. The AND gate 40 operates when the output signals of the comparators 23 and 24 both become L level.
That is, when the focus is achieved, an H level signal is supplied via the NOT gates 68 and 39, so the AND
The output of the gate 40 becomes H level and is input to the OR gate 41, whose output is H level and turns the transistor 19 off.
Therefore, in the one-shot mode, focusing is carried out in the same manner as in the servo mode, and when the focusing state is reached, the driving of the forward/reverse control circuit is stopped. Also,
When the IJD gate 50 is in focus, an H level signal is sent from the NOT gates 68 and 69, and the AF lock switch is turned OFF.
Since it is an FF, an H level signal is supplied from the power supply and an H level signal is further supplied from the NOT gate 49, so the output pulse of the oscillation circuit composed of 51 to 54 is outputted as a second drive signal via the AND gate 50. and the pulse is OR
It is transmitted to the transistor 56 through the gate 55, and the LED
5B blinks based on the output pulse of the oscillation circuit constituted by 51 to 54, indicating that the camera is in focus in the one-shot mode. As mentioned above, the oscillation circuit composed of 51 to 54 and the oscillation circuit composed of 45 to 48 have different oscillation frequencies, so the LED
By blinking and lighting 5B, the photographer can clearly know whether the focus display is based on servo mode, one shot mode, or AF lock display.

As explained above, according to K and the present invention, it is possible to clearly distinguish between the focus states of different modes, and when focusing in one-shot mode, the photographer can maintain the focus state in one-shot mode. Since the information can be easily notified through the display, there is no risk of accidentally photographing another subject in the same state and resulting in an out-of-focus photograph. Furthermore, even when the AP is locked, the user is clearly informed that the AP is locked, so there is no need to take unsuccessful photos due to misidentification, and the user does not forget to release the AF lock.

In addition, since only one display device is required to indicate the focus status and AP lock status of each mode, the configuration of the display device is simple and easy to see, and the photographer only needs to pay attention to one point on the display device and then decide on the composition. It is very advantageous from a cost perspective.

In the above embodiment, a focus display device in the viewfinder was used as a means to clearly distinguish between the focus state and AF lock state of different modes, but a sounding device may also be used to achieve the same effect. is possible. In other words, by changing the period of the sound, the focus state and AF lock state of different modes are clearly distinguished, but the sounding device like this can be used alone, and the above practical example If used together with the display device inside, even greater effects can be obtained. In addition, the first drive signal may be an H level signal for continuously lighting the LED, or an oscillation circuit that outputs a frequency different from the output pulses of the above-mentioned oscillation circuits is provided, and the output pulses from the oscillation circuits are - It may be used as the first drive signal.

Furthermore, as the output characteristic of the oscillation path, it is also possible to use a structure in which the duty ratio differs from each other in place of the frequency.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a focus detection light receiving unit applied to an automatic focus adjustment device having an instruction circuit according to the present invention, and FIG. 2 is a block diagram of a focus adjustment device including an instruction circuit according to the present invention. FIG. 2 is a circuit diagram showing an example. 1... Focus detection light receiving unit 21-26... Window comparator 29-32.
・Forward/reverse control circuit 35 for motor 63 ・AF lock switch 37 ・Mode changeover switch Patent applicant Canon Co., Ltd.

Claims (2)

[Claims] (1) A detection circuit that detects the degree of matching based on the output of a sensor circuit that receives light flux from the subject and outputs a degree of matching signal such as a focus signal or a drive signal, and a detection circuit that detects the movement of the subject based on the output of the detection circuit. a drive control circuit having a servo mode in which the photographic lens is moved to the in-focus position in a continuous manner following the detection circuit; and a shot mode in which the photographic lens is moved to the in-focus position only once based on the output of the detection circuit; and the servo mode. or a selection means for selecting a one-shot mode, in an automatic focus adjustment device, an instruction circuit for instructing a focus state, and a first drive signal for forming a first drive signal for driving the instruction circuit; a second drive signal for forming a second drive signal having different characteristics than the first drive signal;
a drive signal forming circuit connected to the selection means to supply the first drive signal to the instruction circuit in response to the focus signal when the servo mode is selected and the one shot mode is selected; An instruction circuit for an automatic focus adjustment device, characterized in that an instruction operation control circuit is provided for supplying the second drive signal to the instruction circuit in response to the focusing signal when the focusing signal is being focused. (2) The drive control circuit has an AF lock mode 2 in which subsequent lens drive is stopped by operating an operating member, and also forms a third drive signal having different characteristics from the first and second drive signals. A sixth drive signal forming circuit is provided, and the instruction operation control circuit is configured to generate a third drive signal by operating the operating member.
An instruction circuit for an automatic focus adjustment device according to claim 1, wherein the instruction circuit supplies a drive signal of 1 to the instruction circuit.