JPS6113565B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a focusing device of the type that photoelectrically compares two images using the principle of a rangefinder with a baseline length, and more particularly to an optical scanning system in such a device. The present invention relates to a focus adjustment device that enables display of a distance detection position during overtravel.

FIG. 1 is a schematic diagram of the optical scanning system and electronic module. In the above optical system, the scanning mirror M ₁ not only covers the photographable range of the camera, but also extends from a point even closer than close range to infinity (mirror angle 45
It is designed to move further to infinity than ゜). This is to maintain the scanning speed of the mirror at the closest point and the infinity point, and to ensure the accuracy of focus detection in these areas.

FIG. 2 is a schematic diagram for explaining the relationship between optical scanning and module output. In the process of moving from close range to infinity, a signal peak occurs at the focal point position as shown in the lower row. When the contrast of the subject is insufficient, a correlation output as shown by curve b is obtained, and when the contrast is sufficient, a correlation output as shown by curve a is obtained, and at the peak point, a signal as shown by A is output. When the rising signal A continues to an infinite position or a position exceeding it, this is used as a focus signal and the focus position is known at the time of its rise. In the present invention, the signals as shown in FIG. 2 cannot be obtained, and in the figure B ₁ and B ₂
This was done by focusing on the problem when a peak detection signal or a signal confusing thereto occurs in the region indicated by .

The objective lens is movable between positions corresponding to close range and infinite distance, and cannot be moved beyond that range. However, as mentioned above, the area nearer than the closest area shown in Figure 2
There is a possibility that a focal signal is generated even in the region of infinity B ₂ rather than B ₁ and infinity.

The objective lens is constantly moved in the direction of the focal point by the signal from the module, but for example, when the objective lens is stopped at a close position, it is difficult to check whether the object corresponds to the close position or whether the object is being photographed. It is impossible to determine whether the object is physically stopped at a close position.

A similar problem exists for infinite positions. There is a subject in the actual photographable range, but because the contrast of the subject is insufficient, a focus position determination signal is not generated between them, and the object moves in the direction of infinity due to noise signals in an area that corresponds to infinity. It is impossible to determine whether the motor is stopped indefinitely, or whether it is stopped indefinitely due to the generation of a signal at the infinite position.

In both of the above cases, if the lens position is determined by the signal from the area where photography is not possible, the erroneous photography will continue unless the user takes measures such as stopping photography. Become,
This is extremely inconvenient.

As mentioned above, the object of the present invention is to provide a focus adjustment device that can generate a signal that can indicate when the lens has stopped at the limit and has not stopped by a correct signal. Our goal is to provide the following.

In order to achieve the above object, the focusing device according to the present invention uses the principle of a rangefinder with a baseline length,
A signal indicating that the objective lens is at the extreme position in a focus adjustment device that scans the object from the closest point of the objective lens to a position beyond infinity, and adjusts the focus using the focus detection signal generated during that time. A circuit that generates a lens position signal, a circuit that generates a lens position signal that indicates the current position of the lens, and the output of each of the above circuits and a focus detection signal are input. It is configured to include a discrimination circuit that generates a signal for display.

According to the above configuration, the user can recognize that the objective lens is not at the correct focal position, so the problem of continuing to shoot at the wrong distance is solved.
The objectives of the invention are fully achieved.

The present invention will be explained in more detail below with reference to the drawings. FIG. 3 is a circuit diagram showing an embodiment of the display circuit when a photographing signal is obtained in a very close range (B ₁ in FIG. 2), which is even closer than the closest point.
FIG. 4 is a waveform diagram for explaining the operating state.

The synchronization signal S is a signal generated corresponding to the forward path of optical scanning. In conjunction with the movement of the optical scanning system, a signal W is generated to indicate the position of the objective lens. The relationship between this signal W and the focus signal A that rises at the peak of the correlation signal determines which side the objective lens should be driven to, and the objective lens position is adjusted so that the rise of the focus signal A and the fall of W coincide. Corrections are being made. In the case shown in Figure 4, the focus signal A is generated in the super close range, but the objective lens itself cannot move to the super close range, so it remains stationary at the close range. .

The focus signal A is supplied to the base of a transistor 3 via an inverter 1 and a resistor 2. When the focus signal occurs, the transistor is turned off and the capacitor 5
is charged via resistor 4. The terminal of capacitor 5 is connected to the input terminal of operational amplifier 7,
When this terminal voltage reaches the voltage determined by variable resistor 6, operational amplifier 7 sends out an output.
This output is the delayed focus signal A. Let this output be A′. The switch 20 is a switch that is linked to an objective lens (not shown), and is closed when the objective lens is in a close position, and sends out a signal NSW (=0V). This signal is input to an AND gate 8 forming a discrimination circuit via an inverter. The AND gate 8 further receives a synchronizing signal S and a signal W indicating the position of the objective lens. AND gate 8 generates a signal when the following logic is satisfied.

ε=W・・A′・S On the other hand, the synchronization signal S is inverter 15, resistor 1
6. A circuit including a capacitor 17, a NAND gate 18, and an inverter 19 forms a pulse S corresponding to the rising edge of the signal S. This pulse S is used as a set pulse for flip-flop 9. The output end of the flip-flop has a resistor of 10,1
2 to the inverter 14. A diode 11 and a capacitor 13 are provided to stabilize the display output.

Next, further explanation will be given with reference to FIG.

When the focus signal A is generated, charging of the capacitor 5 is started, and after a certain period of time determined by the resistor 4 and the capacitor 5 has elapsed, a signal A' is generated.

At this point, = 1 (lens is in close position), synchronization signal S = 1, lens position signal W
= 1, so ε=W・A′S=1,
An output appears at gate 8. The output of flip-flop 9, which had already been set by S', is reset to the L level, and the input of inverter 14
_V2 is also at the L level, and the output _VD is at the H level, generating an output indicating that it should be displayed.

Note that the resistance value of the resistor 10 is made sufficiently larger than the resistance value of the resistor 12.

Even if the output of the flip-flop 9 becomes H level by the next reset pulse S', _V2 does not suddenly change, so the output _VD does not change immediately.

FIG. 5 shows an embodiment of a circuit portion that generates a signal for display when a focus signal occurs at a position further than infinity. FIG. 6 is a waveform diagram for explaining the operation.

The lens position signal W is applied to a NAND gate 34 together with the output of the inverter 30 via inverters 30 and 31 and further via an integrating circuit consisting of a resistor 32 and a capacitor 33. nand gate 34
output ('), a signal obtained by inverting the focus signal by the inverter 35, a synchronization signal S, and
A signal ∞ which is obtained by inverting a signal (V=0) indicating that the objective lens is at the ∞ position by an inverter 37 is input to the AND gate 36 . This gate 36 outputs when the following logic is satisfied.

ε=(')S・(∞)・On the other hand, the flip-flop 39, which was in the set state due to the signal (') that continues for a certain period of time after the falling edge of the lens position signal W, is reset by the output of the gate 36, and the output becomes The signal becomes L level, and the output of the inverter 44 becomes H level, generating a signal. Note that the resistance value of the resistor 40 is made sufficiently larger than the resistance value of the resistor 42. Focusing only on the logic of the circuit with the above configuration, this circuit can be used to generate a signal if the objective lens exists at an infinite position and the focus signal A does not exist after the time specified by (') has elapsed from infinity. will occur. Since this does not match the logic that a signal is generated when a signal is generated at a position beyond infinity, a supplementary explanation will be provided. Generally speaking, the fact that a focus signal is not generated until beyond infinity is manifested as a state in which A does not persist to a position of ∞ or beyond because the contrast of the subject is low.
As shown in FIG. 7, the correlation signal appears as a train of many pulses that are generated in response to a low peak, disappear before the next peak occurs, and then occur again.

Therefore, very short pulses are often generated even when the infinite position is exceeded, and it is rare that no pulses are generated at all.
Of course, a signal output is generated even when no pulse is generated at all, but even in that case, there is no problem even if a signal is generated because the focal signal was not obtained at infinity or until a certain time elapsed from infinity. Not. The fact that a very large number of pulses are occurring means that there is always an L level between them, and the presence of an L level means that there is a pulse that rises at the end (focus signal pulse), so this is not a problem. This means that the display may be performed by detecting the presence of the L level in the area.

The output of each circuit described above is used as a drive signal for a light source for display.

This display allows the user to know that focus adjustment is not being performed properly.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the optical scanning system and module, Figure 2 is a graph showing the relationship between scanning and module output, and Figure 3 is a graph showing the relationship between scanning and module output. Fig. 4 is a graph for explaining the operation of the circuit shown in Fig. 3. Fig. 5 is a circuit diagram showing an example of a circuit that generates 6 is a graph for explaining the operation of the circuit shown in FIG. 5, and FIG. 7 is a module for when the contrast of the subject is relatively low. It is a graph showing the output. M ₁ ... Fixed mirror, M ₂ ... Scanning mirror, 1,
14, 15, 19, 30, 31, 38, 44...
Inverter, 3... Transistor, 4, 32...
Resistor, 5, 33... Capacitor, 8, 36... AND gate, 9, 39... Flip-flop, 1
1,41...diode, 20,46...switch.

Claims (1)

[Claims] 1. Using the principle of a rangefinder with a baseline length, the object is scanned from the closest point of the objective lens to a position beyond infinity, and the focus is adjusted using the focus detection signal generated during that time. This type of focus adjustment device includes a circuit that generates a signal indicating that the objective lens is at its extreme position, a lens position signal generation circuit that indicates the current position of the lens, and an objective that receives the outputs of each of the circuits and a focus detection signal as input. A focus adjustment device including a discrimination circuit that generates a signal for display when a focus signal is generated at a portion where the lens is at an extreme position and exceeds the extreme limit. 2. In a focus adjustment device that uses the principle of a rangefinder with a baseline length to scan the object further from the closest point of the objective lens in the direction of infinity, and adjusts the focus using the focus detection signal generated during the scanning, a close position signal generation circuit that indicates that the objective lens is at a close position; a lens position signal generation circuit that indicates the current position of the objective lens; a focus detection signal delay circuit that generates a focus detection signal with a certain period of delay; A focus adjustment device including a discrimination circuit that receives a circuit output as an input and generates a signal for display when a focus detection signal is generated a certain distance before the closest point. 3 In a focus adjustment device that uses the principle of a rangefinder with a baseline length to scan the object to a position beyond the infinity position of the objective lens, and adjusts the focus using the focus detection signal generated during that time, when the objective lens is at the infinity position, a lens position signal generating circuit that indicates the current position of the objective lens; a delay circuit that delays the output of the lens position signal generating circuit for a certain period of time; and the infinite position signal generating circuit and the lens position. A focus adjustment device including a signal generation circuit, a delay circuit output, and a focus detection signal as input, and a discrimination circuit that generates a signal for display when a focus signal is generated at a position more than a certain distance away from an infinity position.