JPS6155099B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an autofocus camera, and more particularly to an autofocus camera having a protection mechanism that prevents failure of the autofocus mechanism from spreading.

In the case of a movable lens camera, before shooting,
It is necessary to move the lens along the optical axis to a position where the subject is in focus, and the lens position on the optical axis is a function of the distance from the camera lens to the subject (hereinafter referred to as the lens/subject function).

For proper axial positioning of the lens, the output arm of the optical rangefinder is mechanically coupled to the lens mount via a cam system that incorporates the lens/subject function, allowing operation of the rangefinder to Conventionally, a method has been adopted in which an appropriate displacement is applied to the lens. Furthermore, by using another method that employs electric drive of the lens mount, it is possible to electrically create the lens object function.
An example of this electrical method is described in US Pat. No. 3,522,764. The arrangement disclosed in the above-referenced US patent uses a sonic range finder in connection with lens positioning, and the duration of the range pulse generated by the range finder is directly related to the distance between the lens objects. This distance pulse is then used to control an electric focusing mechanism for moving the lens in the axial direction to a lens position where the subject is brought into focus.

When the motorized focusing mechanism moves the lens mount to the focal position, the motorized drive of the lens mount is deenergized (i.e., disconnected from power).
The shutter mechanism is operated and exposure is performed.

One of the problems with such autofocus cameras
First, the lens/subject function is highly nonlinear, with the slope of the function being maximum for nearby objects and progressively decreasing to zero slope as the object position moves away from the camera. That's true. Another problem is that the motorized drive that moves the lens mount for focusing may not move even when energized, potentially causing electrical and mechanical damage to the camera. That's true.

The solution of the first problem is the subject of the invention of the divisional application of the present application [Japanese Patent Application No. 57-224825 (see Japanese Patent Application Laid-open No. 58-193528)], and the present invention is the subject of the invention of the divisional application of the present application
aims to solve the problem. That is, in an autofocus camera, activation is energized to begin a photographic cycle that includes autofocus and exposure steps. In other words, the electric drive device is first energized to move the lens mount to a focal position corresponding to the subject distance for focusing, and then the shutter mechanism is operated to perform the exposure process and the electric drive device is deenergized. be done. If the lens mount does not move even if the electric drive device is energized, this is detected, the exposure process is executed, and the electric drive device is deenergized.

Preferred embodiments of the invention will now be described in conjunction with the accompanying drawings. In FIG. 1, an automatic focusing snapshot camera according to the present invention is designated by the reference numeral 10. The camera 10 includes a housing 11 in which a film 12 is held at a focal plane opposite a hub 13.
Within the hub 13, a lens assembly or lens mount 14 is located at both end positions of a distance M,
It is designed to be able to move axially between the
Between the lens mount 14 and the film 12,
A shutter 15 for controlling exposure of the film 12 is provided. It is preferable that the shutter mechanism 15 has a function of determining the exposure time and the aperture diameter according to the intensity of field light. The distance N from the position of the lens mount 14 focused on the subject 16 located at a distance R from the camera to the end position is a predetermined function of the distance R,
This function is highly non-linear and is called the lens/object function.

The distance meter means 17 coupled to the camera outputs a distance parameter, ie a distance signal, which has a characteristic directly proportional to the distance R, when activated by a key operation. This distance signal is fed to a pulse generating means 18 where it is converted into lens parameters by generating a pulse train, the number of pulses representing the lens mount position for focusing on an object at distance R. . When pulses from the pulse generating means are applied to a drive means 19 operatively coupled to the lens mount, the drive means 19 axially moves the lens mount in response to the total number of pulses applied. 1/
k is the displacement rate or specific displacement of the lens mount,
(specific displacement), that is, the amount of displacement of the lens mount per pulse supplied to the drive means 19, the lens mount will move from its position when kN pulses are supplied to the drive means. , is displaced to a position a distance N away from the position. If the lens mount is in position, the lens mount will be displaced to its proper position when k(M-N) pulses are applied to the drive means.

When the lens mount 14 reaches its final position, i.e., the proper position for imaging the subject on the film 12, a signal is generated from the proper focus sensor 20, which is supplied to the shutter actuator 21, which controls the shutter actuator 21. operates the shutter mechanism 15 in response to this signal. In this manner, the proper exposure of the film 12 with the subject 16 properly focused can be performed simply by manually initializing the keys of the rangefinder means.

The hub 13 and lens mount 14 are mechanically coupled in exactly the same manner as in the prior art, as shown in FIG. Referring to FIG. 4, the lens mount 14 may include an internally threaded sleeve 22 for carrying an objective lens 23 of the camera. The internally threaded sleeve 22 is attached to an externally threaded sleeve 24 fixed to the camera housing 11, and is adapted to be displaced axially in response to rotation of the sleeve. A rotatable camera is mounted on the cylindrical outer surface of the sleeve 22.
Teeth 25 are provided which mesh with spur gears 26 mounted on the housing 11. Gear 26 meshes with a corresponding gear 27 rotatably mounted to housing 11 . The gear 27 has a driving gear 28
and a disk 29 having a slot on its circumference are fixed so that they rotate together with the gear 27. The gear 28 is connected to a pinion 3 connected to an output shaft 31 of a stepping motor 32.
It meshes with 0. When the motor 32 is energized,
The rotation of the pinion 30 is transmitted to the sleeve 22 via the gears 28, 27, and 26, and simultaneously with the rotation, the sleeve 22 is axially displaced in either direction determined according to the rotational direction of the motor.
In order to mesh the spur gear 26 that does not undergo axial displacement with the sleeve 22 that causes axial displacement,
The teeth 25 of the sleeve 22 are cut over the entire axial length of the sleeve.

Stops are provided to limit axial displacement of lens mount 14 in both directions, and a slip clutch (not shown) is used between motor 32 and gear 26. The lens mount 14 moves axially from a position for focusing on a subject that is 9 meters or more away from the camera until it reaches a position for focusing on a subject that is 25 cm from the camera. The rotation angle of the lens mount is typically within 360 degrees. If you select the appropriate gear ratio, drive gear 2
8 can have the same angular displacement as the sleeve 22, in which case a stop can be associated with this gear 28. For example, a slot 33 is provided on the axial surface of the gear 28, and a camera/
The stop pin 34, which is fixed to the housing, may cooperate with the slot 33. In this manner, pin 34 engages the closed end of slot 33, thereby limiting the displacement of the lens mount between the positions shown in FIG.

The detailed description will be given later, but the slotted disk 2
9 forms part of an auxiliary pulse generator 35 (see Figure 2A) and is coupled to the lens mount 14 to provide the necessary feedback information for proper positioning of the lens mount. . Means for detecting the position of the lens mount 14, and more specifically, means for indicating the displacement of the lens mount 14 from its initial position, is obtained from the auxiliary pulse generator 35 described above. In addition,
In this embodiment, the initial position is set to an infinity point position or a position slightly exceeding it. The auxiliary pulse generator 35 (see FIG. 2A) is connected to the fixed source 3
6 (see FIG. 4) and a fixed photovoltaic cell 37, and the fixed light source may be a light emitting diode. The light source 36 and the photovoltaic cell 37 are placed facing each other with the slotted disk 29 in between, and the light entering the photovoltaic cell from the light source is periodically interrupted by the rotation of the disk 29. There is. And the screwing relationship between the sleeves 22 and 24,
The meshing relationship between the teeth of the sleeve 22 and the gears 26 and 27,
Furthermore, the relationship between the number of slots and the parameters described above defines a relative displacement of the lens mount, which represents the axial displacement of the lens mount per pulse generated by the auxiliary pulse generator. As mentioned above, this specific displacement is expressed as 1/k.
It should be noted that as the lens position detection device, a configuration different from that described above, for example, a magnetic system or a mechanical switch, etc. can also be used.

A block diagram of a preferred embodiment of the motorized focusing mechanism is shown in FIG.
It is represented by 8. In this embodiment, a pulse is used as the distance signal, and the pulse width τ is proportional to the object distance obtained by the distance meter means 17. It is possible to use optical means as the rangefinder means, in which case a linear potentiometer is driven by the output of the movable arm, and the resistance value of the potentiometer at that time is proportional to the object distance. The width of the distance pulse is determined. Preferably, the range finding means is a sonic transponder as described in US Pat. No. 3,522,764. In both of the above fields, τ is a function of the subject distance R.

The pulse generating means 18 of the focus adjustment mechanism 38 includes:
A pulse generator 39 with a programmed temporally variable pulse repetition frequency and a gate 40 for introducing the output of the pulse generator 39 via an OR gate 42 into a counter 41 depending on the duration of the distance pulse. include. The counter 41, together with the decoder 43, is connected to the driving means 19 of the focus adjustment mechanism.
forms part of. The drive means 19 further includes a motor 32 and an auxiliary pulse generator 35 (lens pulse generator) serving as a lens position indicator.
and a power supply 44, from which power is supplied to the motor 32 through the gate 45 when the gate 45 is activated by a latch 46.

The electric focus adjustment mechanism 38 maintains the following state until a distance pulse is applied to the input end. That is, the pulse generator 39 is in a rest state, the counter 41 is in a cleared state, the gate 45 is in an inactive state (off), and the lens mount 14 is in an initial position (corresponding to a state in which the focus is adjusted to an object at infinity). i.e., placed at a position). And since the lens mount is stationary, auxiliary pulse generator 35 produces no output.

At the start of operation, the leading edge of the distance pulse is detected by the leading edge detector 47, which triggers the pulse generator 39 and activates the gate 40. During the time period τ, the pulse generator 39
The repetition frequency is programmed to generate kN pulses, and the generated pulses are accumulated in the counter 41. That is, at the time of the trailing edge of the distance pulse, the counter 41 has accumulated a number of pulses representing the lens mount position for focusing on the subject.

Latch 46 is set by detection of the trailing edge of the distance pulse, thereby actuating or opening gate 45, rotating motor 32, and rotating lens.
Mount 14 moves in the axial direction. At the same time as the lens mount starts moving, the auxiliary pulse generator 35
is activated and starts sending pulses to the counter 41 via the OR gate 42.

The lens mount 1 is rotated by the rotation of the motor 32.
4 is moving from position to position, the pulses generated by the auxiliary pulse generator 35 are accumulated in the counter 41. Then, the number of generated pulses is k
When the number of pulses accumulated is (M-N), the number of accumulated pulses of the counter 41 becomes kM, and an output pulse 48 is generated from the decoder. This pulse 48 resets the latch 46 and closes or disables the gate 45 so that the motor 32
is emasculated. No further pulses are generated from the auxiliary pulse generator and the lens mount 14
Since the auxiliary pulse generator has generated k(M-N) pulses during the period _τ1 during which the latch 46 was set, at this point, the pulse generator is located at a distance N from the position. It turns out. Reset/
When the pulse 48 is generated, the object which is at the object distance R and which has generated the distance pulse is correctly focused. This reset pulse is also supplied to the shutter mechanism 15 to start exposure. Shutter of shutter mechanism 15 (not shown)
An exposure end detector 49 is connected to the detector 4.
The output of 9 is used to return the mechanism 38 to the initial position. In order to generate the correct number of pulses from the pulse generator 39 during the duration of the distance pulse, the pulse repetition frequency of the pulse generator varies at least according to the derivative with respect to time of an approximation of the lens/object function. There is a need to. However, since this problem is not related to the present invention, detailed explanation will be omitted.

Next, the configuration of a preferred embodiment of an autofocus camera to which the present invention is applied will be explained with reference to FIG. 3A. Although this embodiment has a novel configuration for obtaining the nonlinearity of the lens/subject function described above, the present invention is not limited to such a configuration. The automatic focus adjustment camera 10 includes an acoustic distance meter means 17 with a manual operation key and an electric focus adjustment mechanism 3.
8A, and the mechanism 38A is provided with a pulse generator 18A and a driving means 19A.
At the beginning of operation, a manual operation, such as pressing a push button, provides a start signal to the leading edge detector 47, which sends a key operation transmit signal to the clock oscillator 58. The clock oscillator remains active until a stop signal is then applied on line 59. The acoustic distance meter 17 is also activated by the key operation transmission signal, and the output wave 6
Send 1. This output wave is reflected by the subject,
It returns to the device 17 when time τ has elapsed since it was sent. Note that the value of τ depends on the subject distance. The output of oscillator 58 is sent to counter 60;
The contents of the counter 60 are input to the decoder 62 according to each bending point of the tangent that approximates the non-linearity of the lens/object function.
The program divider 63 changes the divisor for dividing the output of the oscillator 58.

The pulse repetition frequency of the output signal of the divider 63 decreases over time. Divider 63
The output of
gate 40 and OR gate 4
2 to the counter 41. Latch 6
4 is set by the transmitted signal of the detector 47 and then reset by a pulse 48 (see FIG. 3B) generated by the range finder 17 when the time .tau. has elapsed. Gate 40 is then held open or conductive for the duration of the distance pulse by the above described operation of latch 64.
Therefore, for a subject that can be brought into focus by placing the lens mount 14 at a distance N from the position (see FIG. 1), the latch 64
kN pulses are applied to the counter 41 during the duration of the distance signal defined by the elapsed time from set to reset. In this way,
A distance parameter is obtained by the distance pulse.
Oscillator 58, counter 60, divider 63 and their associated gate controls thus provide a means for converting object distance parameters into lens parameters according to a lens/object distance function.

The received pulse 48 generated when the rangefinder 17 detects a reflected wave activates the latch 64, which in addition to stopping the operation of the oscillator 58, also activates the trailing edge detection latch 6.
(latch 65 remains on until decoder 43 detects the number of km in counter 41). The time period during which the latch 65 is in operation τ ₁
During this period, the gates 66 and 68 are opened (operated) by the latch 65, and power is supplied from the power supply 44 to the motor forward rotation control device 67 through these gates. Power supply 44 to motor forward rotation control device 67
is applied in a rotational direction that drives the lens mount from the infinity focus position to the close-up focus position shown in FIGS. 2A and 2B;
Motor 32 rotates. Rotation of motor 32, and hence rotation of lens mount 14, generates an output from auxiliary pulse generator 35, which is supplied to counter 41 via gate 68 and OR gate 42.

k from the auxiliary pulse generator 35 to the counter 41
(M-N) pulses are supplied and the counter 41
When the total number of pulses reaches kM, a command signal is issued to start the exposure process, which via decoder 43 resets latch 65, so that gates 66 and 68 are deactivated.

The command signal is also supplied to the shutter operating device 69 via the decoder 43, whereby the shutter mechanism 15 is operated and exposure is performed. To detect the end of exposure, a detector 49, for example a switch arrangement, is used, the output of which is fed to a one-shot multivibrator 70,
By supplying a return pulse with a predetermined pulse width from the multivibrator 70 to the gate 71, the gate 71 is opened or conductive.
A power source 44 is connected to the motor reverse rotation control device 72 . The duration of the pulses generated by multivibrator 70 is long enough for motor 32 to drive the lens mount from position to position. In normal operation, the lens mount reaches its end of travel position before the energization of the motor 32 is stopped by the return pulse, so that there is a gap between the motor and the lens mount.
A slip clutch arrangement (not shown) is provided.

If a system malfunction occurs after a manual start operation, the exposure end detector 49 may not output an output. To prevent such a malfunction, the multivibrator 70 is triggered after an appropriate delay time. If no malfunction occurs, the system operation will be completed within the above delay time. Additionally, if a malfunction occurs between the motor connection and the lens mount, no rotation or displacement will be transmitted from the motor to the lens mount, even if the motor is energized. In order to solve this problem, an OR gate 73 is provided, and the Morch forward rotation control device 6 is connected to this OR gate.
7 and a motor reverse rotation control device 72 are supplied. The output of this gate 73 and the output of the auxiliary pulse generator 35 are supplied to a jam sensor 74, and the jam sensor 74 is configured to:
Regardless of whether either the motor control device 67 or 72 is energized and an output is given to the OR gate 73 (at this time, the motor rotates and the lens mount moves, so if it is normal, an auxiliary pulse will be generated. When the auxiliary pulse generator 35 does not generate a series of pulses, it generates a jam signal.

The jam signal generated by jam sensor 74 is provided as a stop signal to motor reverse rotation controller 72 (its purpose will be explained later) and also activates pulse generator 75 to generate a series of pulses. Since no pulses are generated from the correction pulse generator 35, no pulses are applied to the counter 41 through the gates 68 and 40; instead, a series of pulses generated from the pulse generator 75 is applied to the counter 41 through the OR gate 42. 41. The counter 41 counts this, and when the cumulative value reaches a predetermined value (kM in this embodiment), a command signal is generated in the same manner as in the above case, and the command signal is sent to the trailing edge detection latch 65 and the shutter actuator 69 via the decoder 43. given to. This resets latch 65 and disables gates 66 and 68. This de-energizes the motor forward rotation controller and therefore stops generating the jam signal. On the other hand, the shutter actuating device 69 operates the shutter mechanism 15 to execute the exposure process. When the exposure process ends as in the normal case, a return pulse generated by the one-shot multivibrator 70 opens the gate 71 in response to a signal from the exposure end detector 49, energizes the motor reverse rotation controller 72, and starts the motor 32. is rotated in the opposite direction to return the lens mount to its final position. At this time as well, the jam sensor 74 does not generate a jam signal due to the series of pulses generated by the auxiliary pulse generator 35. However, if the motor is not driven or the lens does not move due to a failure, the auxiliary pulse generator 35 will not generate a series of pulses, so the jam sensor 74 generates a jam signal and de-energizes the motor reversal controller 72, causing the camera to move. prevent further mechanical or electrical damage.

The jam sensor 74 can be configured as a timing device using a clock type counter, and is activated upon receiving the output from the gate 73, starts counting clock pulses from a built-in clock oscillator, and the counted value reaches a predetermined value. When it reaches
Generate a signal. Under normal conditions, the auxiliary pulse generator 35 generates a series of pulses to repeatedly reset the counter before it reaches a predetermined value, thus preventing the occurrence of a jam signal.

Although the outputs of the decoder 43 and the jam sensor 74 are shown as being given as stop signals to the motor controllers 67 and 72, they may also be given as inactivation signals to the gates 66 and 71, respectively. .

In this way, in the present invention, even though the lens mount driving device is energized in the automatic focusing mechanism, if the lens mount does not move, the shutter mechanism is operated by the jam signal and the camera is The cycle continues and the lens mount drive is deenergized, so the lens mount may not necessarily be in the correct focus position, but it not only allows the exposure to be made and captures the desired subject, but also allows the camera to Mechanical and electrical damage can be prevented.

Although the present invention has been described above using an example of a camera having a specific automatic focusing mechanism, the present invention is not limited to a camera having such a specific automatic focusing mechanism, and the scope of the claims Various modifications can be made without departing from the description.

[Brief explanation of the drawing]

1 is a partial block diagram of an autofocus camera according to the present invention, FIG. 2A is a block diagram of an electric focusing mechanism with a lens mount implemented in the camera of FIG. 1, and FIG. 2B is a partial block diagram of an autofocus camera according to the invention. 3A is a detailed block diagram of a preferred embodiment of the autofocus camera of FIG. 1; FIG. 3B is a waveform diagram showing the pulse configuration in the circuit of FIG. 3A; FIG. The figure is a perspective view of one embodiment of the lens mount driving means. (Explanation of reference symbols), 10...camera, 11...
...Housing, 12...Film placed in the focal plane, 13...Hub, 14...Lens mount,
15...Shutter mechanism, 16...Subject, 17...
... Distance meter means, 18, 18A... Pulse generating means, 19, 19A... Drive means, 20... Proper focus sensor, 21... Shutter actuating device, 38, 3
8A, 38B, 38C...Electric focus adjustment mechanism.

Claims (1)

Claims: 1. Upon being energized for activation, it initiates a photographic cycle including autofocus and exposure steps, and is deactivated after the completion of the photographic cycle. The automatic focus camera includes a rangefinder that measures the distance from the camera to a subject and generates a distance signal representing the subject distance; and a rangefinder that is energized in response to the generation of the distance signal to move the lens toward the focal position. a series of pulses (a first series of pulses) that are set to a value according to the object distance by the distance signal and then generated in response to movement of the lens;
a first counter device that generates a command signal for counting the number of seconds and, when the value thereof reaches a predetermined value, deenergizing the lens driving device to stop the movement of the lens and to start an exposure step of the photographic cycle; a jam sensor that generates a jam signal when the first series of pulses is not generated regardless of whether the lens drive device is energized; and a jam sensor that generates a jam signal when the first series of pulses is not generated; a device for generating and supplying the pulses to the first counter device in place of the first series of pulses, whereby the first counter device counts the second series of pulses so that the content thereof is determined as described above. The autofocus camera is configured to also generate the command signal to deenergize the lens drive and start the exposure process when a predetermined value is reached. 2. In claim 1, the jam sensor is set when the lens driving device is energized and starts counting a predetermined clock pulse, and when the content reaches a predetermined value, the jam sensor generates the jam signal. a second counter device and means for resetting the second counter device by the first series of pulses, thereby preventing generation of the jam signal when the first series of pulses is occurring; An autofocus camera designed to 3. In claim 1, the first counter device is set to a value related to the focal position of the lens determined by the distance signal, and the set value and the count value of the first series of pulses are The autofocus camera is configured to generate the command signal when the sum of the values reaches a predetermined value.