JPH11194386A - Light adjusting device and image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and always appropriately adjust the light quantity of an everchanging scene, and also, to prevent malfunction and hunting, etc. SOLUTION: The adjusting device is provided with light quantity adjusting members 12 and 13 which are driven in order to adjust a variable diaphragm aperture for transmitting light to be made incident on an image pickup means 22, and control means 23, 24, 25, 27, 34, 35, 36, 37, 30 and 31 for controlling the drive of each light quantity adjusting member 12 and 13 based on the driving information set in accordance with a difference between a real incident light quantity and a target incident light quantity on the image pickup means 22. In the particular case that the light quantity difference is beyond the extent of a prescribed light quantity difference, the light quantity adjusting members 12 and 13 are driven by the control means so as to adjust the diaphragm aperture.

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 driving 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. 5 are proposed. Have been.

[0005] The reciprocating drive means of the light quantity adjusting device shown in FIG. 5 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.

There is also a disadvantage that a large-scale and complicated configuration is required for automatically setting the number of steps.

Further, since the rate of change of the light quantity in one step of the stepping motor is small on the open aperture side and large on the small aperture side, the target light quantity on the small aperture side can be obtained only by converting the light quantity error into the number of steps in the continuous operation. The hunting is caused by repeating the opening and closing (light and dark) operations without reaching. Also,
When the stepping motor operates to adjust the excessive or excessive light amount beyond the light amount adjustment range, not only does the light amount adjustment uselessly operate, but also the gear which is the driving force transmission member rides over the movable range. It also has drawbacks such as poor damage to

In view of the above, the present invention provides a light amount adjusting device and an image input device capable of easily and always adjusting the light amount of an imaging scene that changes every moment, and preventing malfunction and hunting. The purpose is to do.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, a light amount adjusting member driven to adjust a variable aperture opening for passing incident light to an image pickup means, and an image pickup means Control means for controlling the driving of the light amount adjusting member based on driving information set according to the difference between the actual incident light amount and the target incident light amount,
Only when the light amount difference is outside the predetermined light amount difference range, the control means drives the light amount adjusting member to adjust the aperture.

That is, when the light amount difference is out of the predetermined light amount difference range, the aperture opening is adjusted in accordance with the light amount difference, so that the light amount can be appropriately adjusted for an imaging scene that changes every moment. On the other hand, when the light amount difference is within the predetermined light amount difference range, the light amount adjusting member is stopped so that malfunction or hunting can be prevented.

The predetermined light amount difference range is set in accordance with the size of the aperture opening formed by the light amount adjusting member, so that the amount of light per unit drive amount of the driving source that differs for each size of the aperture opening. It is desirable to perform control that matches the rate of change.

Further, even when the light amount difference is outside the predetermined light amount difference range, the drive of the light amount adjusting member is controlled so that the aperture opening is outside the predetermined stop opening range corresponding to the range from the maximum to the minimum. It is desirable to prevent the driving force transmitting member from being damaged. Further, in the second invention of the present application, the light amount adjusting member driven to adjust the variable aperture opening for transmitting the incident light to the image pickup means, and the actual aperture information and the target aperture information corresponding to the size of the aperture aperture. Control means for controlling the driving of the light amount adjusting member based on the driving information set in accordance with the difference. As far as possible, the light amount adjusting member is driven to adjust the aperture.

That is, when the difference in the aperture information is out of the predetermined aperture difference range, the aperture opening is adjusted in accordance with the difference in the aperture information, so as to perform appropriate light amount adjustment for an ever-changing imaging scene. On the other hand, when the aperture information difference is within the predetermined aperture difference range, the light amount adjusting member is stopped so that malfunction or hunting can be prevented.

It is desirable that the target aperture information is set according to the amount of light incident on the image pickup means. Further, the predetermined aperture difference range is set in accordance with the size of the aperture opening formed by the light amount adjusting member, so that the rate of change in the amount of light per unit drive amount of the drive source varies depending on the size of the aperture opening. It is desirable to perform matched control.

In the third invention of the present application, the control means includes a first operation mode in which the light amount adjusting member is driven to adjust the aperture opening only when the light amount difference is outside the predetermined light amount difference range; A second operation mode is provided in which the light amount adjusting member is driven to adjust the aperture opening only when the information difference is outside the predetermined aperture difference range.

Thus, in the image input apparatus provided with the light amount adjusting device, the control means can be operated in the first operation mode in the shutter priority mode, and the control means can be operated in the second operation mode in the aperture priority mode. Thus, it is possible to realize an image input device capable of making a picture according to a situation.

In the fourth aspect of the present invention, when the light amount adjusting member is not driven, the power supply to the motor which is a driving source for driving the light amount adjusting member is turned off, so that the power saving type device is provided. Has been realized.

Further, in the fifth invention of the present application, when the power is turned off, the light amount adjusting member is moved to a position where the aperture opening is closed, so that unnecessary light is prevented from entering the image pickup element when not in use, and the power is turned on. It enables fast startup at the time.

In each of the above-mentioned inventions, a case is provided in which a stepping motor for driving the light amount adjusting member is provided, and the control means supplies a continuous driving pulse train formed in accordance with the driving information to the stepping motor. Set the frequency of the continuous drive pulse train higher than the resonance frequency of the stepping motor and lower than the self-starting frequency to operate the stepping motor smoothly and at high speed, or set the frequency lower than the resonance frequency of the stepping motor to smooth the stepping motor. It may be operated at a low speed.

According to a sixth aspect of the present invention, in the image input device provided with the light amount adjusting device according to the first or third aspect, the shutter speed is set by adjusting the charge accumulation time of the image sensor. A shutter speed setting means is provided. In a shutter priority mode (first operation mode of the control means), the shutter speed is fixed to a predetermined value when the light amount adjusting member is driven, and is set when the light amount adjusting member is stopped. It is desirable that the setting be made in accordance with the difference between the actual incident light amount on the imaging means and the target incident light amount, thereby enabling a fine adjustment of the light amount which cannot be adjusted by the aperture opening.

According to a seventh aspect of the present invention, in the image input device provided with the light amount adjusting device according to the second or third aspect, the shutter speed is set by controlling the charge accumulation time of the imaging means. A shutter speed setting means is provided, and in the aperture priority mode (second operation mode of the control means), the shutter speed is set according to the difference between the actual incident light quantity on the image pickup means and the target incident light quantity. It is desirable to enable fine light amount adjustment which cannot be adjusted by the above.

[0026]

(First Embodiment) FIG. 4 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 32) 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 which has a detection gap 7a and detects 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 adjust 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 for forming an image of the incident light on the image sensor 22. Reference numeral 22 denotes an image of the incident light adjusted by the light amount adjustment members 12 and 13 at a shutter speed according to the output of the electronic shutter control circuit 29.
An image sensor that outputs an output to the light amount comparison circuit 24 and the image processing circuit 28.

Numeral 23 designates a target quantity of incident light which is an appropriate quantity of incident light incident on the image pickup device 22, and a light quantity comparing circuit 2
4 is a light quantity setting circuit for outputting to 4.

The light quantity comparing circuit 24 compares the actual incident light quantity with the target incident light quantity based on the output of the image sensor 22 in proportion to the incident light quantity, and generates a light quantity error signal Ey corresponding to the difference. And electronic shutter control circuit 2
9 and the aperture value setting circuit 36.

Reference numeral 25 designates a threshold value for defining an appropriate light amount range (a predetermined light amount difference range in the claims) based on the aperture value information of the aperture value detection circuit 33 in accordance with the mode information of the mode setting circuit 26. In the mode 2, a threshold value setting circuit which sets a threshold value defining an appropriate aperture value range (a predetermined aperture difference range referred to in the claims) and outputs the threshold value to the operation setting circuit 27.

A mode setting circuit 26 selectively sets a mode 1 for optimally setting the light amount and a mode 2 for optimally setting the aperture for the light amount, and operates the mode information with the threshold value setting circuit 25. This is a mode setting circuit that outputs to the setting circuit 27 and the electronic shutter control circuit 29.

When the mode 1 is set, the operation setting circuit 27 compares the light amount error signal Ey with a threshold value, and further calculates the stepping motor by taking into consideration the maximum / minimum aperture value information of the aperture value range detection circuit 35. The first drive information (stop or operation, and in the case of operation, the operation direction) is set. When the mode 2 is set, the operation setting circuit 27 compares the aperture value error signal Ef of the aperture value comparison circuit 37 with a threshold value to calculate the drive information of the stepping motor 1 (stop or operation, and Set the operation direction). The drive information Di is output to the electronic shutter control circuit 29, the drive circuit 31, and the aperture value detection circuit 33.

The image processing circuit 28 processes the output of the imaging element 22 into image information.

The electronic shutter control circuit 29 operates in mode 1
Is set, the drive information Di and the light amount error signal Ey
The charge accumulation time of the image sensor 22 is controlled according to the signal from the shutter speed setting circuit 38 and the shutter speed is set. The electronic shutter control circuit 29
When the mode 2 is set, the shutter speed is set by controlling the charge accumulation time of the image sensor 22 according to the light amount error signal Ey. Then, the electronic shutter control circuit 29 outputs the shutter speed information to the aperture value setting circuit 36.

Numeral 30 denotes a pulse train generating circuit for continuously supplying a continuous drive pulse of the optimum drive frequency of the stepping motor 1 to the drive circuit 31. The drive circuit 31 includes drive information Di
, The drive frequency of the continuous drive pulse is converted into an excitation pulse for driving the stepping motor 1 to drive and control the stepping motor 1.

As described above, the transmission member 32 is the gears 2, 3, the feed screw 4 and the rack gear 10 shown in FIG. 4 for transmitting the driving force of the stepping motor 1 to the light amount adjusting members 12, 13.

The aperture value detection circuit 33 forms aperture value information by adding or subtracting continuous drive pulses based on the drive information Di, and outputs the information to the threshold value setting circuit 25. The aperture value detection circuit 33 determines the position of the rack gear 10 when the light amount adjusting members 12 and 13 are at the closed position.
, And is detected as initial position information, and aperture value information is initialized. In this way, the accuracy is maintained by correcting the absolute position of the aperture value information.

Numeral 34 designates an effective maximum aperture value and a minimum aperture value range which is a small aperture limit at which diffraction is not remarkably pictorial, and sets maximum / minimum aperture value setting information to an aperture value range detection circuit 35.
Is a circuit for setting an aperture value range to be output.

The aperture value range detection circuit 35 detects the aperture value range from the aperture value information and the maximum / minimum aperture value setting information, and outputs it to the operation setting circuit 27. The aperture value setting circuit 36 sets an optimal aperture value from the light amount error signal Ey, the aperture value information, and the shutter speed information, and outputs the optimal aperture value to the aperture value comparison circuit 37.

The aperture value comparison circuit 37 compares the aperture value information with the optimal aperture value and outputs the difference to the operation setting circuit 27 as an aperture value error signal Ef. The shutter speed setting circuit 38 sets the shutter speed and outputs it to the electronic shutter control circuit 29.

The light amount setting circuit 23 and the light amount comparison circuit 2
4, threshold setting circuit 25, operation setting circuit 27, aperture value detection circuit 33, aperture range setting circuit 34, aperture value range detection circuit 35, aperture value setting circuit 36, aperture value comparison circuit 37,
The pulse train generation circuit 30, the drive circuit 31, and the stepping motor 1 correspond to the control means in the claims. FIG. 2 is an operation flowchart of mode 1 in which the light amount is optimally set in the image input apparatus of the present embodiment. 5
1 is a step of setting the aperture value of the minimum aperture aperture and the maximum aperture aperture that can be adjusted by the stepping motor 1, 52 is a step of setting a target light quantity which is an optimal incident light quantity, 53 is a step of setting an initial shutter speed, 54 is a step of measuring the amount of incident light from the image sensor 22, 55 is a step of calculating a light amount error signal Ey which is a difference between the amount of incident light and the target amount of light, and 56 is a step of measuring an aperture value from the aperture value detection circuit 33.

Reference numeral 57 denotes a threshold ULD (Upper Level Discriminator) and an LLD (Lower L) which define an appropriate light amount range.
evel Discriminator) is set based on the aperture value information. Step 58 compares the light amount error signal Ey with the threshold value ULD.
If <ULD, the process branches to step 62.

Reference numeral 59 denotes a step which branches to step 66 if the aperture value is smaller than the minimum aperture, and branches to step 60 if the aperture value is larger than the minimum aperture. 60 is set so that the stepping motor 1 is driven in the closing direction in which the aperture opening becomes smaller. Step 61 is a step in which the stepping motor 1 is driven in the closing direction with a pulse train having an optimum driving frequency, and the process proceeds to step 54.

Reference numeral 62 denotes a light amount error signal Ey and a threshold value LLD.
And if Ey <LLD, then go to step 63,
When y> LLD, the process branches to step 66.

Reference numeral 63 denotes a step for branching to step 66 if the aperture value is equal to or larger than the maximum aperture, and branch to step 64 if the aperture value is smaller than the maximum aperture. 64 is set so that the stepping motor 1 is driven in the opening direction in which the aperture opening becomes large. Step 65, a step of driving the stepping motor 1 in the opening direction with a pulse train having an optimal driving frequency to shift to step 54, 66, a step of setting the stepping motor 1 to stop, and 67, a step of adjusting the shutter speed And 68 are steps for stopping the stepping motor 1 and proceeding to step 54.

FIG. 3 is a flowchart showing the operation of the image input apparatus according to the present embodiment in mode 2 in which the aperture is optimally set with respect to the amount of light. 71 is a step of setting a target light amount which is an optimal incident light amount, 72 is a step of measuring the incident light amount from the image sensor 22, 73 is a step of calculating a light amount error signal Ey which is a difference between the incident light amount and the target light amount, 74 is a step of A step of adjusting the shutter speed so as to obtain an appropriate light amount based on the light amount error signal Ey, and a step 75 of measuring the aperture value information from the aperture value detection circuit 33.

Reference numeral 76 denotes a step for setting a target aperture value, which is an optimal aperture for the amount of incident light, and reference numeral 77 denotes a step for calculating an aperture value error signal Ef which is a difference between the aperture value information and the target aperture value.

Numeral 78 denotes thresholds ULD (Upper Level Discriminator) and LLD (Lower Lower) which define an appropriate aperture value range.
Level Discriminator) is set based on the aperture value information.

Reference numeral 79 denotes an aperture value error signal Ef and a threshold value UL.
D, and if Ef> ULD, go to step 80;
If Ef <ULD, the process branches to step 82.

Reference numeral 80 denotes a step for setting the stepping motor 1 to be driven in the closing direction in which the aperture is reduced, and reference numeral 81 denotes a step for driving the stepping motor 1 in the closing direction with a pulse train having an optimum driving frequency and proceeds to step 72. It is.

Reference numeral 82 denotes an aperture value error signal Ef and a threshold value LL.
D, and if Ef <LLD, go to step 83;
When Ef> LLD, the process branches to step 85.

Reference numeral 83 denotes a step for setting the stepping motor 1 to be driven in the opening direction in which the aperture is increased, and reference numeral 84 denotes a step for driving the stepping motor 1 in the opening direction with a pulse train having an optimum driving frequency, and proceeds to step 72. , 85 are steps for setting the stepping motor 1 to stop, and 86 are steps for stopping the stepping motor 1 and proceeding to step 72.

As described above, in the light amount adjusting device configured in the image input device, when the mode 1 for optimally setting the light amount is set by the mode setting circuit 26, the aperture value range setting circuit 34 controls the stepping motor 1 Set the aperture values of the adjustable minimum aperture aperture and the maximum aperture aperture (step 5).
1) The light quantity setting circuit 23 sets the target light quantity which is the optimum incident light quantity (step 52), and the shutter speed setting circuit 38 sets the optimum shutter speed (step 53), and repeats the following loop.

The incident light passing through the image pickup lens 21 is adjusted by the light amount adjusting members 12 and 13 and forms an image 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 (step 54), and the light amount comparison circuit 2
4 outputs a light amount error signal Ey by comparing and calculating the difference from the target light amount set in step 52 (step 5).
5). Also, the aperture value detection circuit 33 detects the aperture value of the aperture and outputs the aperture value information (step 56).

Further, the threshold value setting circuit 25 sets threshold values ULD and LLD for defining an appropriate light amount range adjustable by the stepping motor 1 based on the aperture value information, and outputs the threshold values to the operation setting circuit 27. (Step 57). On the other hand, the aperture value range setting circuit 35 compares the aperture value information with the maximum / minimum aperture value set by the aperture value range setting circuit 34, and outputs an aperture value range detection signal to the operation setting circuit 27. Further, the operation setting circuit 27 determines the operable range from the aperture value range detection signal, and determines the direction in which the aperture value cannot be adjusted (opening direction when the aperture value information indicates the maximum operable range, closing when the minimum indicates the operable range). Direction).

The operation setting circuit 27 compares the light quantity error signal Ey with the threshold values ULD and LLD (steps 58 and 62). Here, when the light amount error signal Ey is within the range between the threshold value ULD and the threshold value LLD, the stop of the stepping motor 1 is set (step 6).
6).

On the other hand, the light quantity error signal Ey is
If the aperture value information is not the maximum value of the operable range, the closing direction operation is performed (step 59,
60) If it is smaller than the threshold value LLD and the aperture value information is not the minimum of the operable range, the opening direction operation is set (steps 63 and 64). However, even when the light amount error signal Ey is larger than the threshold value ULD, the aperture value information is operable even when the aperture value information is the maximum of the operable range and when the aperture value information is smaller than the threshold value LLD. If the range is the minimum, the stop operation is set so that the operation direction does not exceed the operable range (step 66). Then, in steps 60, 64, and 66, information to be set in these steps is output as drive information Di.

The pulse train generating circuit 30 constantly outputs a continuous drive pulse of the optimum drive frequency of the stepping motor 1 to the drive circuit 31 and the aperture value detection circuit 33, and the drive circuit 31 performs continuous drive based on the drive information Di. The pulse is converted into an excitation pulse of the stepping motor 1, and the stepping motor 1 is driven by the driving information Di at the driving frequency of the continuous driving pulse.
(Steps 61, 65, 68).

When stopping the stepping motor 1, the electronic shutter control circuit 29 adjusts the shutter speed by changing the charge accumulation time of the image sensor 22 according to the drive information Di (step 67). Specifically, the light amount error signal Ey is corrected based on the light amount error signal Ey so as to obtain an optimal incident light amount, and the shutter speed is finely adjusted to control the image sensor 22.

On the other hand, when the drive of the stepping motor 1 is controlled (when the drive information Di is a setting corresponding to the closing or opening direction operation), it is fixedly adjusted to the optimum shutter speed set by the shutter speed setting circuit 38 (step 53). ).

When the drive of the stepping motor 1 is controlled, the stepping motor 1 drives the light amount adjusting members 12 and 13 according to the excitation pulse of the drive circuit 31 and
The operation is performed by adjusting the incident light amount of No. 2 so as to be in an appropriate light amount range.

The driving force of the stepping motor 1 is transmitted to the light amount adjusting members 12 and 13 via the transmitting member 32 to move the same, and accordingly, the main plate 11 and the holding plate 1 are moved.
The amount of incident light passing through the four openings 11f and 14f is adjusted by the openings 12f and 13f.

As described above, in the mode 1, the image pickup device 2
The operation of appropriately adjusting the incident light amount of No. 2 is repeated, and the image processing circuit 28 can form an image with the optimum light amount.

When the mode setting circuit 26 sets the mode 2 for optimally setting the aperture for the light quantity, the light quantity setting circuit 23 sets the target light quantity which is the optimum incident light quantity (step 71). Repeat the following loop.

The incident light passing through the image pickup lens 21 is adjusted by the light amount adjusting members 12 and 13 and forms an image 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 (step 72), and the light amount comparison circuit 2
4 compares and calculates the difference between the incident light amount and the target light amount set in step 71, and outputs a light amount error signal Ey (step 73).

The electronic shutter control circuit 29 changes the charge accumulation time of the image pickup device 22 based on the light amount error signal Ey, corrects the light amount error signal Ey so as to obtain an optimum incident light amount, and adjusts the shutter speed. In addition to controlling the image sensor 22, it outputs shutter speed information to the aperture value setting circuit 36 (step 74).

Next, as in the case of setting the mode 1, the aperture value detection circuit 33 detects the aperture value of the aperture and outputs the aperture value information. The aperture value setting circuit 36 sets an optimal aperture value for the incident light amount as a target aperture value from the light amount error signal Ey, the aperture value information, and the shutter speed information, and outputs the target aperture value to the aperture value comparison circuit 37 (step 76).

The aperture value comparison circuit 37 compares the aperture value information with the target aperture value and outputs an aperture value error signal Ef corresponding to the difference to the operation setting circuit 27 (step 77).

The threshold value setting circuit 25 sets threshold values ULD and LLD for defining an appropriate aperture value range that can be adjusted by the stepping motor 1 based on the aperture value information, and outputs it to the operation setting circuit 27 ( Step 78).

The operation setting circuit 27 compares the aperture value error signal Ef with the threshold values ULD and LLD (steps 79 and 82). Here, the aperture value error signal Ef
Is within the range between the threshold values ULD and LLD, the stop of the stepping motor 1 is set (step 85).

On the other hand, when the aperture value error signal Ef is equal to the threshold value UL
If it is larger than D, the closing direction operation is performed (step 8).
0), if it is smaller than the threshold value LLD, the opening direction operation is set (step 83). And step 80,
In steps 83 and 85, information to be set in these steps is output as drive information Di.

The pulse train generating circuit 30 constantly outputs a continuous drive pulse of the optimum drive frequency of the stepping motor 1 to the drive circuit 31 and the aperture value detection circuit 33, and the drive circuit 31 performs continuous drive based on the drive information Di. The pulse is converted into an excitation pulse of the stepping motor 1, and the stepping motor 1 is driven by the driving information Di at the driving frequency of the continuous driving pulse.
(Steps 81, 84, 86).

When controlling the driving of the stepping motor 1, the stepping motor 1 drives the light amount adjusting members 12 and 13 according to the excitation pulse of the driving circuit 31, and
The operation is performed by adjusting the incident light amount of No. 2 so as to be in an appropriate light amount range.

The driving force of the stepping motor 1 is transmitted to the light amount adjusting members 12 and 13 via the transmitting member 32 to move the same, and accordingly the base plate 11 and the holding plate 1 are moved.
The amount of incident light passing through the four openings 11f and 14f is adjusted by the openings 12f and 13f.

As described above, in the mode 2, the image pickup device 2
The operation of appropriately adjusting the incident light amount of No. 2 is repeated, and the image processing circuit 28 can form an image with the optimum 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.

In this embodiment, the light amount adjusting member 1 is used.
Although the photo interrupter 7 is arranged so that the output signal changes when the openings 2 and 13 are completely closed, the photo interrupter 7 is changed so that the output signal changes when the light amount adjusting members 12 and 13 are fully opened. The photointerrupter 7 may be arranged such that the output signal changes between a fully closed state and a fully opened state, or between a maximum aperture value state and a minimum aperture value state.

Further, a photo interrupter may be used as the aperture range detection circuit 35.

Further, in the image input apparatus provided with the light amount adjusting device of the present embodiment, the mode 1 for setting the light amount optimally is set (fixed) so that the shutter speed of the shutter speed setting circuit 38 is optimal for the incident light amount. Mode 2 in which the aperture opening is optimally set for the light amount may be set as the aperture value priority mode.

The shutter speed set by the shutter speed setting circuit 38 may be synchronized with the image capturing time or may be synchronized with the power supply frequency. This is effective in preventing the image from flickering.

The drive frequency of the pulse train generating circuit 30 is preferably set higher than the resonance frequency of the stepping motor and lower than the self-starting frequency, or may be set lower than the resonance frequency.

When the stepping motor 1 is stopped, it is preferable to turn off the power supply to the stepping motor 1.

When the power is turned off, it is preferable to stop the stepping motor 1 by moving the stepping motor 1 to a closed position where the initial position information of the photo interrupter 7 is detected.

Further, an external sensor other than the image sensor may be used for measuring the amount of incident light.

[0090]

As described above, according to the first and third aspects of the present invention, when the difference between the amount of incident light to the image pickup means and the target amount of incident light is out of the range of the predetermined amount of light difference, the aperture opening of the diaphragm opening is changed. Therefore, appropriate light amount adjustment can be performed for an imaging scene that changes every moment. on the other hand,
When the light amount difference is within the predetermined light amount difference range, the light amount adjusting member is stopped, so that hunting or the like can be prevented. In addition, when a stepping motor is used as a driving source, it is not necessary to calculate the number of steps of the motor, so that a simple system can be configured.

If the predetermined light amount difference range is set according to the size of the aperture opening formed by the light amount adjusting member, the light amount change rate per unit drive amount of the driving source, which differs for each size of the aperture opening. And hunting can be prevented more effectively.

Further, even when the light amount difference is outside the predetermined light amount difference range, the drive of the light amount adjusting member is controlled so that the aperture opening is outside the predetermined stop opening range corresponding to the range from the maximum to the minimum. In addition to being able to perform efficient light amount adjustment by omitting operations that do not change the aperture,
It is possible to prevent a malfunction in which an excessive force is applied to the transmission member. Further, by setting the predetermined aperture range according to the maximum aperture value of the lens, it is possible to cope with lenses having different maximum aperture values. In addition, if the predetermined aperture range is set to be larger than the small aperture larger than the fully closed position, it is possible to prevent a large hunting when an excessive amount of light is emitted. Is set, high image quality can be maintained.

According to the second and third aspects of the present invention, when the difference between the actual aperture information and the target aperture information is out of the predetermined aperture difference range, the aperture is adjusted according to the difference between the aperture information. Therefore, appropriate light amount adjustment can be performed for an imaging scene that changes every moment. On the other hand, when the aperture information difference is within the predetermined aperture difference range, the light amount adjusting member is stopped, so that hunting or the like can be prevented. In particular, when the time delay from the light incidence to the signal output in the image sensor is large, the determination is made based on the aperture information having the fast response speed, so that the optimum amount of incident light can always be obtained at high speed.

If the predetermined aperture difference range is set according to the size of the aperture opening formed by the light amount adjusting member, the rate of change in the amount of light per unit drive amount of the driving source, which differs for each size of the aperture opening. And hunting can be prevented more effectively.

Further, as in the third invention of the present application, the control means controls the light amount adjusting member to drive the light amount adjusting member to adjust the aperture opening only when the light amount difference is outside the predetermined light amount difference range. Priority mode) and a second operation mode (aperture priority mode) in which the light amount adjustment member is driven to adjust the aperture opening only when the difference between the two pieces of aperture information is outside the predetermined aperture difference range.
Is provided, it is possible to create a picture according to the situation by using one light amount adjusting device and one image input device.

According to the fourth aspect of the present invention, when the light amount adjusting member is not driven, the power supply to the motor which is a driving source for driving the light amount adjusting member is turned off. A type of device can be realized.

Further, according to the fifth aspect of the present invention, when the power is turned off, the light amount adjusting member is moved to the position where the aperture is closed, so that unnecessary light is prevented from entering the image sensor when not in use, and the power is turned on. High-speed startup at the time can be made possible.

In each of the above-mentioned inventions, by setting the frequency of the continuous drive pulse train supplied to the stepping motor as the driving source to be higher than the resonance frequency of the stepping motor and lower than the self-starting frequency, it is possible to prevent the stepping motor from being tuned or misstepped. Thus, the stepping motor can be operated smoothly and at high speed. Further, if the frequency of the continuous drive pulse train is set lower than the resonance frequency of the stepping motor, the stepping motor can be operated smoothly and at low speed by preventing the stepping motor from being tuned or misstepped.

According to the sixth aspect of the present invention, in the shutter priority mode (first operation mode), the shutter speed is fixed to a predetermined value when the light amount adjusting member is driven,
Since the shutter speed is set according to the difference between the actual incident light amount on the imaging means and the target incident light amount when the light amount adjusting member is stopped, it is necessary to perform fine light amount adjustment that cannot be adjusted by the aperture opening. Can be.

According to the seventh aspect of the present invention, in the aperture priority mode (second operation mode), the shutter speed is set according to the difference between the actual incident light amount on the image pickup means and the target incident light amount. Therefore, it is possible to perform fine light amount adjustment that cannot be performed by the aperture.

[Brief description of the drawings]

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

FIG. 2 is an operation flowchart of a mode 1 of the light quantity adjusting device.

FIG. 3 is an operation flowchart of a mode 2 of the light quantity adjusting device.

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

FIG. 5 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 adjusting member 22 image sensor 23 light quantity setting circuit 24 light quantity comparison circuit 25 threshold value setting circuit 27 operation setting circuit 30 pulse train generation circuit 31 drive circuit 32 transmission member 33 aperture value detection circuit 34 aperture value range setting Circuit 35 Aperture value range detection circuit 36 Aperture value setting circuit 37 Aperture value comparison circuit

Claims (21)

[Claims] 1. A light amount adjusting member which is driven to adjust a variable aperture opening for transmitting light incident on an image pickup means, and which is set according to a difference between an actual light amount incident on the image pickup means and a target incident light amount. A light amount adjusting device having control means for driving and controlling the light amount adjusting member based on the driving information, wherein the control means drives the light amount adjusting member only when the light amount difference is outside a predetermined light amount difference range. A light amount adjusting device for adjusting the aperture of the diaphragm. 2. The light amount adjusting device according to claim 1, wherein the predetermined light amount difference range is set in accordance with a size of an aperture formed by the light amount adjusting member. 3. The method according to claim 2, wherein the controller controls the driving of the light amount adjusting member when the light amount difference is outside the predetermined light amount difference range when the light amount difference is outside the predetermined light amount difference range. The light amount adjusting device according to claim 1. 4. A light amount adjusting member driven to adjust a variable aperture opening for passing incident light to an image pickup means, and according to a difference between actual aperture information corresponding to the size of the aperture opening and target aperture information. Control means for controlling the light amount adjusting member based on the driving information set in the light amount adjusting device, wherein the control means only controls when a difference between the two pieces of aperture information is outside a predetermined aperture difference range. A light amount adjusting device, wherein the light amount adjusting member is driven to adjust the aperture. 5. The apparatus according to claim 4, wherein the target aperture information is set according to the amount of light incident on the image pickup means.
The light amount adjusting device according to 1. 6. The light amount adjusting device according to claim 4, wherein the predetermined aperture difference range is set in accordance with a size of an aperture opening formed by the light amount adjusting member. 7. A light amount adjusting member driven to adjust a variable aperture opening for passing incident light to an imaging unit, a difference between an actual incident light amount and a target incident light amount to the imaging unit, or a size of the aperture opening. Control means for controlling the driving of the light amount adjusting member based on driving information set according to the difference between the actual aperture information corresponding to the target aperture information and the target aperture information, the control means comprising: The first operation mode in which the light amount adjusting member is driven to adjust the aperture opening only when the light amount difference is outside the predetermined light amount difference range, and only when the difference between the two pieces of aperture information is outside the predetermined aperture difference range. A second operation mode in which the light amount adjusting member is driven to adjust the aperture opening. 8. The apparatus according to claim 7, wherein in the first operation mode, the predetermined light amount difference range is set according to a size of an aperture formed by the light amount adjusting member. Light intensity control device. 9. In the first operation mode, when the light amount difference is outside the predetermined light amount difference range, the control means drives the light amount adjustment member such that the diaphragm opening is outside the predetermined stop opening range. The light amount adjusting device according to claim 7, wherein the light amount is regulated. 10. The light amount adjusting device according to claim 7, wherein, in the second operation mode, the target aperture information is set in accordance with the amount of light incident on the imaging unit. . 11. The apparatus according to claim 7, wherein in the second operation mode, the predetermined aperture difference range is set according to a size of an aperture opening formed by the light amount adjustment member. The light amount adjusting device according to any one of the above. 12. The apparatus according to claim 1, further comprising: a motor for driving the light amount adjusting member, wherein the power supply to the motor is turned off when the light amount adjusting member is not driven.
2. The light amount adjusting device according to claim 1. 13. The light amount adjusting device according to claim 1, wherein the control unit moves the light amount adjusting member to a position where an aperture opening closes when a power supply is turned off. 14. A stepping motor for driving the light amount adjusting member, wherein the control means supplies a continuous driving pulse train formed in accordance with the driving information to the stepping motor. 14. The light amount adjusting device according to claim 1, wherein a frequency of the driving pulse train is higher than a resonance frequency of the stepping motor and lower than a self-starting frequency. 15. A stepping motor for driving the light amount adjusting member, wherein the control means supplies a continuous driving pulse train formed in accordance with the driving information to the stepping motor. 15. The light amount adjusting device according to claim 1, wherein a frequency of the driving pulse train is lower than a resonance frequency of the stepping motor. 16. An image input device comprising the light amount adjusting device according to claim 1. Description: 17. An image input device comprising the light amount adjusting device according to claim 1, further comprising a shutter speed setting unit for controlling a charge accumulation time of the imaging unit to set a shutter speed. The shutter speed setting means fixes the shutter speed to a predetermined value when the light amount adjusting member is driven, and sets the shutter speed to the actual incidence to the image pickup means when the light amount adjusting member is stopped. An image input device, wherein the setting is made in accordance with a difference between a light amount and a target incident light amount. 18. An image input apparatus comprising the light amount adjusting device according to claim 7, further comprising: a shutter speed setting unit that controls a charge accumulation time of the imaging unit to set a shutter speed. The shutter speed setting means, when the control means is operating in the first operation mode, fixes the shutter speed to a predetermined value when the light amount adjusting member is driven, and controls the light amount adjustment. An image input device, wherein when a member is stopped, a shutter speed is set according to a difference between an actual incident light amount on the image pickup means and a target incident light amount. 19. An image input apparatus comprising the light amount adjusting device according to claim 4, further comprising: a shutter speed setting unit that controls a charge accumulation time of the imaging unit to set a shutter speed. The shutter speed setting means sets a shutter speed in accordance with a difference between an actual light quantity incident on the imaging means and a target light quantity. 20. An image input device provided with the light amount adjusting device according to claim 7, further comprising a shutter speed setting unit that controls a charge accumulation time of the imaging unit to set a shutter speed. The shutter speed setting means sets a shutter speed in accordance with a difference between an actual light quantity incident on the imaging means and a target light quantity when the control means is operating in the second operation mode. An image input device, comprising: 21. A shutter priority mode in which the control means is operated in the first operation mode and an aperture priority mode in which the control means is operated in the second operation mode can be selectively set. Item 21. The image input device according to Item 18 or 20.