JPH11194388A - Light quantity adjusting device and image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately and finely adjust the quantity of light made incident on an image pickup means in accordance with an ever-changing scene. SOLUTION: The adjusting device is provided with light quantity adjusting members 12 and 13 which are driven in order to adjust the quantity of light made incident on the image pickup means 22, information setting means 23 to 26 for setting drive information on the light quantity adjusting members 12 and 13 in accordance with a difference between a real incident light quantity and a target incident light quantity on the image pickup means 22, and driving means 21 and 28 for driving the light quantity adjusting means 12 and 13 based on the drive information. In this case, the device is provided with a signal outputting means 31 for outputting a signal for instructing the information setting means to set the drive information, and in the case the signal is given from the signal outputting means 3 to the information setting means, no matter whether the drive of the light quantity adjusting means in accordance with the drive information is finished, that is, in the case the signal is given from the signal outputting means 31 to the information setting means before the drive of the light quantity adjusting means is finished, prior to the finish of the drive, new drive information is set by the information setting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount adjusting device for adjusting the amount of light incident on an image pickup device and an image input device such as a camera equipped with the same.

[0002]

2. Description of the Related Art For example, a light amount adjusting device mounted on a video camera performs a smooth reciprocating drive of a light amount adjusting member in order to perform automatic exposure control in response to a photographing condition and brightness that change every moment, and to open an aperture. As the reciprocating drive means for reciprocatingly driving the light amount adjusting member, the aperture is changed, and a method of driving only by an electromagnetic action and a method of using a spring action in combination with the electromagnetic action shown in FIG. 4 are proposed. Have been.

The reciprocating drive means of the light amount adjusting device shown in FIG. 4 includes a ground slope 136 having an aperture 135 and a cap 13.
7, a magnet net rotor 131 having an output shaft rotatably supported by each bearing portion, a yoke 132 fixed to a ground plate 136 which is provided with an air gap on the outer periphery, and a magnet rotor 131 and the yoke 132 A driving unit is constituted by the driving coil 133 and the braking coil 134 which are arranged, and the driving lever 13 is connected to the output shaft of the magnet rotor 131.
8 is fixed.

A pair of light amount adjusting members 13 is provided between the base plate 136 and the case 141 having the aperture 141a.
9 and 140 are provided.
9, 140 are guide holes 139c, 139d, 140c, which engage with guide pins (not shown) provided on the main plate 136.
The moving direction is guided by 140d. The engagement holes 139a and 140a formed in the end groups are provided with drive levers 138.
The engagement pins 138a and 138b at both ends of the first member are engaged with each other to transmit the rotational force from the drive unit.

[0005] A return spring 142 is incorporated to bias the drive lever 138 in the closing direction. And ND
The filter 143 is fixed to the light amount adjusting member 139, and increases or decreases the amount of light passing through a part or the whole of the opening formed by the light amount adjusting members 139 and 140.

In such a configuration, the driving coil 13
By energizing 3, the magnet rotor 131 and the drive lever 138 rotate against the return spring 142 to move the pair of light amount adjusting members 139 and 140 so that the light flux passing through the aperture 135 is increased. . On the other hand, when the amount of current supplied to the drive coil 133 is reduced, the remagnet rotor 131 and the drive lever 13
8 rotates to move the pair of light amount adjusting members 139 and 140 such that the light flux passing through the aperture 135 is reduced.

Japanese Patent Application Laid-Open No. 2-114246 proposes a device using a stepping motor as a drive source of a light amount adjusting device. In the light amount adjustment device proposed in this publication, the stepping motor is pulse-driven and stopped until the drive is completed by the number of steps (target number of steps) obtained by converting the difference (light amount error) between the amount of light incident on the imaging means and the target amount of light. It is configured to repeat a series of operations.

[0008]

However, in the apparatus proposed in the above publication, the target number of steps is not changed unless the above series of operations is completed. There is a disadvantage that even if the light amount changes, it cannot follow the change.

Further, in order to finely adjust the light amount, it is necessary to increase the resolution (the number of steps) of the stepping motor. However, when the resolution is increased, the time required for completing the above-described series of operations becomes longer. Therefore, when the above-described series of operations is completed, there is a possibility that the target appropriate light amount has already changed, and in this case, the captured image does not become a picture. In particular, there is a concern about the practicality of an apparatus for capturing high-speed continuous images.

If the resolution of the stepping motor capable of completing the above series of operations in a short time is limited, only coarse adjustment of the light amount can be performed.

In view of the above, the present invention provides a light amount adjusting device capable of appropriately and finely adjusting the amount of incident light to an image pickup means in accordance with an ever-changing image pickup scene, and an image input device provided with the same. With the goal.

[0012]

In order to achieve the above object, according to a first aspect of the present invention, a light amount adjusting member driven to adjust the amount of light incident on an image pickup means, and an actual light incident on the image pickup means are provided. In the light amount adjusting device having information setting means for setting driving information of the light amount adjusting member in accordance with the difference between the light amount and the target incident light amount, and driving means for driving the light amount adjusting member based on the driving information, A signal output means for outputting a signal for causing the means to perform setting of drive information, wherein the information setting means receives a signal from the signal output means regardless of whether or not the drive according to the drive information of the light amount adjusting member is completed. When a signal is received, that is, when a signal is received from the signal output means before the drive according to the drive information of the light amount adjusting member is completed, the drive information is newly set without waiting for the completion of the drive. I have to.

More specifically, the signal output means outputs a signal synchronized with the image capturing cycle of the image pickup means.

Thus, when the synchronization signal is output before the drive according to the drive information is completed, the light amount adjusting member is driven according to the newly set drive information without waiting for the drive to be completed. Therefore, it is possible to always and appropriately adjust the amount of light incident on the imaging unit for an imaging scene that changes every moment.

[0015]

(First Embodiment) FIG. 3 shows an exploded state of a light amount adjusting device according to a first embodiment of the present invention. In this figure, 1 is a base plate 11 by a cover 8.
Is a stepping motor which is a driving source fixed to the motor.

2, 3, 4 and 10 are stepping motors 1
(Hereinafter, also collectively referred to as a transmitting member 29) for transmitting the driving force of the above to the light amount adjusting members 12 and 13. The gear 2 is press-fitted into the output shaft of the stepping motor 1 and transmits the driving force of the stepping motor 1 to the gear 3. The gear 3 is fixed to the feed screw 4 and transmits the driving force of the gear 2 to the feed screw 4. The feed screw 4 is rotatably supported by the cover 8 and the bearing 9, is fixed to the gear 3, rotates integrally, and transmits a driving force to the rack gear 10. Reference numeral 5 denotes a screw for fixing the holding spring 6 to the cover 8. The pressing spring 6 presses one end of the feed screw 4 against the bearing 9 to suppress thrust play.

Reference numeral 7 denotes a photo interrupter having a detection gap 7a and detecting a position where the light shielding portion 10a of the rack gear 10 shields the detection gap 7a. The photo interrupter 7 constitutes an aperture value detection circuit 30 described later. The cover 8 includes the stepping motor 1
And the transmission members 2, 3, 4, 10, the photo interrupter 7 and the like are supported and fixed to the main plate 11.

The rack gear 10 has a guide hole 11 of a ground slope 11.
a and the light amount adjusting members 12, 13 are engaged with the elongated holes 12 b, 13 b, and the driving force of the feed screw 4 is reduced by the light amount adjusting members 12, 13.
To communicate. The rack gear 10 shields the detection gap 7 a of the photo interrupter 7 from light at the closed positions of the light amount adjusting members 12 and 13.

The base plate 11 has an opening 11f and a guide hole 11a.
And movably supports the light amount adjusting members 12 and 13 and supports each member. Light intensity adjustment members 12, 13
Has openings 12f, 13f and elongated holes 12a, 13a, and has openings 12f, 13f as the rack gear 10 moves.
Move so as to change the amount of light passing through f.

The holding plate 14 has an opening 14f, is engaged with the base plate 11, and movably supports the light amount adjusting members 12, 13. Reference numeral 15 denotes an optical axis of incident light.

FIG. 1 is a block diagram of an image input device provided with the light amount adjusting device of the present embodiment. Reference numeral 21 denotes an imaging lens that forms incident light on the imaging element 22. Reference numeral 22 denotes an image formed by the incident light determined by the light amount adjustment members 12 and 13 in accordance with the imaging element control circuit 27, and outputs a light amount comparison circuit. 24 and an image sensor for outputting to the image processing circuit 32.

Reference numeral 23 denotes a light amount setting circuit for setting a target incident light amount, which is an appropriate amount of light incident on the image pickup element 22, and outputting the target light amount to a light amount comparison circuit 24.

The light quantity comparison circuit 24 compares the actual incident light quantity with the target incident light quantity based on the output of the image pickup device 22 in proportion to the actual incident light quantity, and converts the light quantity error signal Ey corresponding to the difference into a step number. Output to the circuit 26.

Reference numeral 25 denotes a light amount error signal E which is synchronized with the output of the synchronization circuit 31 and is based on the aperture value information of the aperture value detection circuit 30.
y is step number information including the driving direction of the stepping motor 1 and the number of driving steps (driving information referred to in the claims).
And a step number conversion circuit that outputs the converted number to the step number correction circuit 26.

When the step number correcting circuit 26 receives the step number information from the step number converting circuit 25, the step number correcting circuit 26 replaces the step number information with the previously received step number information to obtain new step number information. The motor 1 is converted into drive pulse train information including a drive frequency, a drive direction, and the number of steps, and is output to the aperture control circuit 28 and the aperture value detection circuit 30.

The image sensor control circuit 27 controls the driving of the image sensor 22 in synchronization with the output of the synchronization circuit 31. The aperture control circuit 28 controls the drive of the stepping motor 1 by converting the drive pulse train information of the step number correction circuit 26 into an excitation pulse for driving the stepping motor 1.

As described above, the transmission member 29 is the gear 2, 3, the feed screw 4 and the rack gear 10 shown in FIG. 3 for transmitting the driving force of the stepping motor 1 to the light amount adjusting members 12, 13.

The aperture value detection circuit 30 forms aperture value information by adding or subtracting the drive pulse train information, and outputs the information to the step number conversion circuit 25. The aperture value detection circuit 30 detects the position of the rack gear 10 as initial position information through the photo interrupter 7 when the light amount adjusting members 12 and 13 are at the closed position, and initializes the aperture value information. In this way, the accuracy is maintained by correcting the absolute position of the aperture value information.

A synchronizing circuit (signal output means in claims) 31 sets and measures an image capturing cycle and outputs a synchronizing signal to the step number conversion circuit 25, the image sensor control circuit 27, and the image processing circuit 32. .

The image processing circuit 32 processes the output of the image sensor 22 into image information in synchronization with the output of the synchronization circuit 31.

The light amount setting circuit 2 according to the present embodiment
3. The light quantity comparison circuit 24, the step number conversion circuit 25, and the step number correction circuit 26 correspond to "information setting means" in the claims.

FIG. 2 shows an image pickup device 2 according to this embodiment.
2 shows a control flowchart for optimally setting the amount of light incident on the light source 2. 41 is a step of setting a target light amount which is an optimal incident light amount, 42 is a step of measuring the incident light amount based on a signal from the image sensor 22, and 43 is a light amount error signal Ey which is a difference between the incident light amount and the target light amount. Step 44 is a step of measuring the aperture value information from the aperture value detection circuit 30, and 45 is a step of converting the light amount error signal Ey into an appropriate number of steps of the stepping motor 1 based on the aperture value information.

Reference numeral 46 denotes a step for driving the stepping motor 1 in an appropriate driving direction and a pulse rate; 47, a step for measuring the number of steps in which the stepping motor 1 is driven from a driving pulse train; This is a step of measuring the time required for the element 22 to accumulate the electric charge necessary to form one screen.

The process branches to step 53 when the image capture time has elapsed, and to step 5 when the image capture time has not elapsed.
Step 50 branches to 0. Step 50 branches to step 51 when the stepping motor 1 has been driven by an appropriate number of steps, and shifts to step 46 if the stepping motor 1 has not been driven yet. Step 1 of stopping the step operation, 5
2 is a step for branching to step 53 when the image capturing time has elapsed, and to step 52 when the time has not elapsed, and 53 is a step for capturing the image and shifting to step 42. In the light amount adjusting device configured in the image input device as described above, the light amount setting circuit 23 sets a target light amount which is an optimum incident light amount (step 42), and repeats the following loop for capturing a continuous image. .

First, the amount of incident light passing through the image pickup lens 21 is determined by the aperture formed by the light amount adjusting members 12 and 13, and an image is formed on the image pickup device 22. An output proportional to the amount of incident light of the image sensor 22 is output to the light amount comparison circuit 24. The light amount comparison circuit 24 compares the difference with the target light amount set in step 42, and converts the light amount error signal Ey into a step number conversion circuit 25. (Step 43).

Next, the aperture value detection circuit 30 detects the aperture value and outputs the aperture value information to the step number conversion circuit 25 (step 44). Next, the step number conversion circuit 25 converts the light amount error signal Ey into positive / negative step number information including the driving direction of the stepping motor 1 and the number of steps based on the aperture value information, and outputs the information to the step number correction circuit 26.

The step number correction circuit 26 converts the step number information into a drive pulse train including the drive frequency, the drive direction, and the number of steps of the stepping motor 1, and outputs the drive pulse train to the aperture control circuit 28 and the aperture value detection circuit 30. (Step 45).

The aperture control circuit 28 converts the driving pulse train into an excitation pulse for driving the stepping motor 1, and controls the driving of the stepping motor 1 (step 46).

When the stepping motor 1 is driven, the light amount adjusting members 12 and 13 are driven via the transmission member 29,
The aperture openings formed by the openings 12f and 13f change, and the openings 11f and 14f of the base plate 11 and the holding plate 14 are changed.
Is adjusted. At this time, the number of driven steps of the stepping motor 1 is measured (step 47).

The synchronization means 31 measures the image capture time (step 48). If the synchronization signal has not yet been output from the synchronization circuit 31 (step 49), the number of driven steps of the stepping motor 1 is reduced to step 45.
It is determined whether or not the number of drive steps in the step number information set in step (5) has been reached (step 50).

Then, the number of driven steps is equal to step 4.
When the number of drive steps set in step 5 has been reached, the drive of the stepping motor 1 is stopped. Subsequently, it is determined again whether or not the image capturing time has elapsed (step 52).
When the image capture time has elapsed, the next image capture is started (step 53).

On the other hand, when the synchronization signal is output in step 49 (that is, when the number of driven steps of the stepping motor 1 has not reached the number of drive steps set in step 45, but the synchronization signal is output) ) Starts the next image capture as it is (step 53).
As a result, steps 42 to 45 are executed again, and new step number information is set in the step number correction circuit 26, and the stepping motor 1 is driven according to the new step number information (step 46).

Thereafter, steps 47 to 4
9 is executed, and if the number of driven steps of the stepping motor 1 does not reach the newly set number of drive steps (step number information) in step 45 in step 49, but the synchronization signal is output, Further, the next image is captured (step 53).

As described above, in this embodiment, the step number conversion circuit 25 sets new step number information according to the latest aperture value information and the latest light amount error signal Ey for each image capture cycle. Then, the step number correction circuit 26 discards the previous drive pulse train and generates a new drive pulse train based on the new step number information. Therefore, it is possible to always appropriately and finely set the amount of incident light to the image sensor 22 even for an imaging scene that changes every moment.
2 can cause the image input device provided with the image capturing apparatus 2 to capture a continuous image having an optimal light amount.

In this embodiment, the light amount adjusting device using a stepping motor as the driving source has been described. However, the present invention can be applied to a light amount adjusting device having a driving source other than the stepping motor.

[0046]

As described above, according to the present invention,
Since the drive information can be newly set before the drive according to the drive information of the light amount adjustment member is completed, it is possible to always appropriately and finely adjust the amount of light incident on the image pickup means for the image scene that changes every moment. This makes it possible to cause the imaging unit to capture a continuous image with an appropriate amount of light.

[Brief description of the drawings]

FIG. 1 is a block diagram of a light amount adjusting device and an image input device according to a first embodiment of the present invention.

FIG. 2 is a system flowchart of the light amount adjusting device.

FIG. 3 is an exploded perspective view of the light amount adjusting device.

FIG. 4 is an exploded perspective view of a conventional light amount adjusting device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 stepping motor 12, 13 light quantity adjustment member 23 light quantity setting circuit 25 step number conversion circuit 30 aperture value detection circuit 29 transmission member 22 image sensor 24 light quantity comparison circuit 26 step number correction circuit 28 aperture control circuit

Claims (7)

[Claims] 1. A light amount adjusting member driven to adjust the amount of light incident on an imaging unit, and driving information of the light amount adjusting member according to a difference between an actual amount of incident light on the imaging unit and a target amount of incident light. And a driving unit for driving the light amount adjusting member based on the driving information. A signal for causing the information setting unit to set the driving information is output. A signal output unit, wherein when the information setting unit receives a signal from the signal output unit before the drive of the light amount adjustment member according to the drive information is completed, the information setting unit does not wait for the completion of the drive. A light amount adjusting device for newly setting drive information. 2. A light amount adjusting member driven to adjust an amount of light incident on an imaging unit, and driving information of the light amount adjusting member according to a difference between an actual amount of incident light on the imaging unit and a target amount of incident light. And a driving unit for driving the light amount adjusting member based on the driving information. A signal for causing the information setting unit to set the driving information is output. A signal output unit, wherein the information setting unit newly receives a signal from the signal output unit regardless of whether or not the drive of the light amount adjustment member according to the drive information has been completed. Light amount adjusting device, wherein driving information is set in the light amount adjusting device. 3. When the information setting means newly sets drive information without waiting for the drive completion, the information setting means responds to the drive information newly set without waiting for the drive completion. The light amount adjusting device according to claim 1, wherein the light amount adjusting member is driven by driving the light amount adjusting member. 4. The light amount adjusting device according to claim 1, wherein the signal output from the signal output unit is a signal synchronized with an image capturing cycle of the imaging unit. 5. The light amount adjusting device according to claim 1, wherein the driving information includes a target driving amount from a position before the light amount changing unit is driven. 6. The light amount adjusting device according to claim 5, wherein the driving unit uses a stepping motor as a driving source, and the target driving amount is the number of driving steps of the stepping motor. 7. An image input device comprising the light amount adjusting device according to claim 1. Description: