JP4311191B2 - Imaging device - Google Patents

Description

  The present invention relates to an image pickup apparatus with an optical zoom that detects a motion vector from a video signal and performs camera shake correction according to the motion vector.

  In recent years, imaging devices represented by video cameras and digital still cameras have become smaller and have higher magnification, and image stability due to camera shake has become an issue, and most have image stabilization functions. Yes.

  Further, in order to further reduce the size and cost, a method for obtaining motion information of a camera shake from a video signal has been commercialized.

  However, in the method of obtaining a motion vector from a video signal, unlike the method of obtaining blur information from a sensor typified by an angular velocity sensor, a motion vector is generated due to a change in the subject even when the optical zoom is in operation, resulting in malfunction. It becomes a factor of.

Therefore, in the conventional first image pickup apparatus, as described in Japanese Patent Laid-Open No. 11-177786, during the optical zoom operation, control is performed so as to ignore the output of the motion detection circuit, thereby preventing malfunction. ing.
Japanese Patent Laid-Open No. 11-177876

  However, the configuration of the conventional first imaging device has a problem that the camera shake correction does not work even when camera shake is a concern, such as when the optical zoom of the imaging device is operated at a low speed. Was.

  In order to solve the above problems, the present invention does not ignore motion vectors under all conditions during an optical zoom operation, but is a condition where image instability is most noticeable due to erroneous detection of motion vectors, i.e., imaging. It is an object of the present invention to provide an imaging apparatus capable of obtaining a stable image by automatically determining whether or not the apparatus is in a stationary state and performing control such that the motion vector is ignored only when the apparatus is determined in the stationary state.

In order to solve the above problems, an imaging apparatus of the present invention condenses an optical signal from a subject to form a subject image, and is included in the optical system, in the optical axis direction of the optical system. A zoom lens that is movable and capable of changing the size of the subject image, an imaging unit that converts an optical signal of the subject image to generate a video signal, and the imaging unit Based on the video signal, a motion vector detection means for detecting a motion vector, a stillness determination means for determining whether or not the apparatus is in a stationary state, and the zoom lens moves to change the size of the subject image. When the stationary determination means determines that the apparatus is in a stationary state, the stationary determination means does not output the motion vector detected by the motion vector detection means, while the stationary determination means is not in a stationary state. If you cross, and a motion vector processing means for outputting the motion vector detected by said motion vector detecting means.

With the above-described configuration of the present invention, during the optical zoom operation, the motion vector is not ignored under all conditions, but the condition in which the instability of the image is most noticeable due to erroneous detection of the motion vector, that is, the imaging device is in a stationary state It is possible to provide a stable image by controlling whether the motion vector is ignored only when it is automatically determined and whether it is determined in a stationary state.

According to the first aspect of the present invention, an optical system that collects an optical signal from a subject and forms a subject image, and the optical system are included in the optical system and are movable in the optical axis direction of the optical system. A zoom lens capable of changing a size of the subject image, an imaging unit that converts an optical signal of the subject image to generate a video signal, and a video signal generated by the imaging unit. Based on motion vector detection means for detecting a motion vector, stationary determination means for determining whether or not the apparatus is in a stationary state, and a state in which the size of the subject image is changed by moving the zoom lens When the stationary determination unit determines that the device is in a stationary state, the motion vector detected by the motion vector detection unit is not output, while the stationary determination unit determines that the device is not in a stationary state. And motion vector processing means for outputting the motion vector detected by the serial motion vector detection means is an imaging device comprising a.

According to a second aspect of the present invention, in the first aspect of the invention, the stationary determination unit determines whether or not the own apparatus is in a stationary state based on the motion vector detected by the motion vector detection unit. To do.

According to a third aspect of the present invention, in the second aspect of the present invention, the stationary determination means detects that the stationary determination unit is mounted or fixed on an external stabilizer, and the own apparatus is stationary according to the detection result. It is determined whether or not it is in a state.

In the invention according to claim 3 , the stationary determination means is provided in a bottom surface of the device itself or in a female screw provided on the bottom surface, and mechanically detects that it is placed on or fixed to an external stabilizer. To do.

(Embodiment 1)
The first embodiment of the present invention will be described with reference to FIGS. 1 to 20. First, the basic operation will be described with reference to FIGS.

  FIG. 1 shows an imaging device having the most basic configuration according to Embodiment 1 of the present invention (hereinafter, the configuration of the imaging device is referred to as a basic configuration). In FIG. 1, reference numeral 1 denotes a lens having an optical zoom function, 2 is a zoom switch for operating the lens 1 to the wide-angle side or the telephoto side in order to determine the field angle of the subject, 3 is a two-dimensional solid-state imaging device for converting an optical signal having information on the subject into an electrical signal, and An image pickup unit including a signal processing circuit that outputs an output signal of the two-dimensional solid-state image pickup device as a video signal, 4 is a zoom position detection circuit that is a zoom position detection unit that detects the magnification of the optical zoom from the lens 2, and 5 is an image pickup unit. 3 is a motion vector detection circuit which is a motion vector detection means for detecting motion included in the video signal from 3 as a motion vector, and 6 is a level of the motion vector from the motion vector detection circuit 5 A level detection circuit that is a level detection means for detecting, 7 is a counter control circuit that is a counter control means for controlling the counter based on level information from the level detection circuit 6, and 8 is a counter value output from the counter control circuit 7, and the device is controlled by the counter value. A first stillness determination circuit, which is a first stillness determination means for determining whether or not the vehicle is still, 9 is information indicating whether or not the first stillness determination circuit 8 is stationary, and the zoom switch 2 Motion that is an output signal of the motion vector detection circuit 5 from information on whether or not the zoom switch 2 is on and information on whether or not the zoom position is at the wide-angle end or telephoto end from the zoom position detection circuit 4 It is a motion vector processing circuit which is a motion vector processing means for controlling a vector.

  FIG. 2 is a flowchart showing a series of processing algorithms of the level detection circuit 6, the counter control circuit 7 and the stillness determination circuit 8 in FIG. In the figure, S21 to S27 indicate steps of each processing, step S21 is processing in the level detection circuit 6, steps S22 to S24 are processing in the counter control circuit 7, and steps S25 to S27 are processing in the first stillness determination circuit 8. It is.

  FIG. 3 is a flowchart showing the processing algorithm of the motion vector processing circuit 9 in FIG. In the figure, step S31 is a step processed based on information from the zoom switch 2, step S32 is a step processed based on information from the zoom position detection circuit 4, and step S33 is information from the first stillness determination circuit 8. Step S34, which is processed based on the above, is processing for the signal from the motion vector detection circuit 5.

  The operation principle of the most basic imaging apparatus of the present embodiment having the above-described configuration will be described with reference to FIGS.

  First, an optical signal having subject information obtained through the lens 1 is converted into a video signal by the imaging unit 2. Then, camera shake information of the imaging device included in the video signal is extracted as a motion vector by the motion vector detection circuit 5.

  Typical processing of the motion vector detection circuit 5 includes a video signal at the current time, a video signal before a unit time output from a two-dimensional solid-state imaging device (inside the imaging unit 3), such as one field before or one frame before. Thus, calculation is performed by performing correlation calculation. Since specific processing methods are described in detail in Japanese Patent Application Laid-Open Nos. 61-269475 and 2-241188, they are omitted here.

  Next, an algorithm for determining whether or not the imaging apparatus is stationary based on the motion vector will be described with reference to FIG. The algorithm uses a level detection circuit 6, a counter control circuit 7, and a first stillness determination circuit 8.

  First, the absolute level of the motion vector is detected by the level detection circuit 6 (step S21). Then, the absolute level of the motion vector is input to the counter control circuit 7, and it is determined whether it is larger or smaller than a preset threshold (Vector_Th_Level) (step S22). If it is smaller than “Vector_Th_Level”, a counter that can determine how long this state has continued is incremented (step S23). However, if it is larger than the threshold, the counter is cleared (step S24). Then, the counter value is input to the first stillness determination circuit 8, and it is determined whether it is also larger or smaller than a preset threshold value (Th_Count) (step S25). At this time, if the counter value is larger than “Th_Count”, it is determined that the imaging apparatus is in a stationary state (step S26). On the other hand, if it is smaller, it is determined that it is not yet stationary or moving (step S27). Based on the motion vector, it is determined whether or not the imaging apparatus is stationary.

  Next, the motion vector detection circuit 5 is based on the information from the first stillness determination circuit 8 and the information from the zoom switch 2 and the zoom position detection circuit 4 for determining whether or not the optical zoom is operating. The operation for controlling the motion vector, which is the output signal from, will be described. The operation is performed by the motion vector processing circuit 9, and the algorithm in the circuit is as shown in FIG.

  First, it is determined whether or not the zoom switch 2 has been pressed (step S31), and if it has been pressed, the process proceeds to condition determination based on the next zoom position information (step S32). If not pressed, the motion vector is passed through without any control.

  In the condition determination based on the next zoom position information, if the zoom position is at the wide-angle end or the telephoto end, the optical zoom operation is not performed no matter how much the zoom switch 2 is turned on. Pass through without any control. However, if the zoom position is not in the end state and the optical zoom is operating, a condition determination is made as to whether or not the next imaging device is in a stationary state (step S32).

  The determination as to whether or not the vehicle is stationary is made based on the information from the stationary circuit determination circuit A8 described above (step S33). If the motion vector is stationary, the input motion vector is ignored, that is, the motion vector is forcibly set to 0 (step S34). If the motion vector is not stationary, no control is performed on the input motion vector. Get out of it.

  With the above operation, in the conventional control method, during the optical zoom operation, the image pickup apparatus sets the motion vector to 0 in any situation to stop the effect of camera shake correction, whereas in the present invention, stillness determination is performed. By providing a control, it automatically determines when the imaging device stands out as a side effect in the optical zoom operation and when it is not, and stops the camera shake correction effect only in the former case, thereby correcting camera shake during the optical zoom operation. The effect can be improved.

  The above is the most basic operation principle in the first embodiment of the present invention.

  Next, three types of configurations for further improving the performance will be described with respect to the configuration for explaining the basic operation principle described above.

  The first embodiment will be described with reference to FIGS. 4 to 7, and FIG. 4 is a block diagram of the embodiment. In this figure, the difference from FIG. 1 showing the configuration of the basic configuration described above is that the control method in the counter control circuit 7 (the reference in the figure is also changed from “7” to “7A”) and the overall configuration. Among them, in addition to the output information from the level detection circuit 6, information from the zoom position detection circuit 4 is also input as an input to the counter control circuit 7A. Other blocks having the same figure number are omitted because they have the same functions as those in FIG.

  FIG. 5 is a flowchart showing an algorithm in the same configuration as that of FIG. 2 in the basic configuration. Steps S51 to S57 are the same as S21 to S27 in FIG. In the circuit 7A, the threshold for determining the absolute level of the motion vector is a fixed value in the basic configuration (FIG. 2), whereas in the first form (FIG. 5), the threshold (Vector_Th_Level) is set according to the zoom position. It is a point to change.

  FIG. 6 and FIG. 7 show specific characteristic examples of this zoom position and Vector_Th_Level. As is clear from FIGS. 6 and 7, the value of Vector_Th_Level increases as the telephoto end is reached. This is because when the amount of blur is the same, the motion vector detected by the zoom position is detected as large as the telephoto end. Therefore, if the threshold is also made variable to the zoom position, whether or not the camera is in a stationary state with higher accuracy. Can be judged.

  In FIG. 6, Vector_Th_Level is continuously changed between the wide-angle end and the telephoto end, whereas in FIG. 7, the Vector_Th_Level is changed stepwise by dividing the wide-angle end and the telephoto end into some parts. Which characteristic is to be selected may be determined by judging the performance and circuit scale of the system.

  6 shows the continuous change by a linear function and FIG. 7 shows three steps. However, there is no particular limitation on this, and there is a characteristic that Vector_Th_Level increases from the wide-angle end to the telephoto end. For example, characteristics may be determined based on performance and circuit scale.

  This is the second form, which further improves the accuracy of the stillness determination algorithm from the first form, and will be described with reference to FIGS.

  FIG. 8 is a block diagram of the form. The difference from the first form is that the control method in the first stationary determination circuit 8 (the sign in the figure is also changed from “8” to “8A”), In the overall configuration, in addition to the output information from the counter control circuit 7A, information from the zoom position detection circuit 4 is also input as an input to the first stillness determination circuit 8A. Descriptions of other identical figure numbers are omitted because they have the same functions as those in FIG. 4 or FIG.

  FIG. 9 is a diagram showing an algorithm of the same portion as FIG. 5 in the first form in a flowchart format. Steps S91 to S97 are the same as S51 to S57 in FIG. 5, but are different from FIG. In the first stillness determination circuit 8A, the threshold value (Th_Count) of the counter value for determining whether or not the vehicle is in a still state is changed from a fixed value according to the zoom position.

  Specific examples of the characteristics of the zoom position and Th_Count are shown in FIGS.

  As is clear from FIG. 10 and FIG. 11, there is a characteristic that the value of Th_Count decreases as the telephoto end is reached. This is because, according to the first mode, since the Vector_Th_Level is lowered as the angle is widened, there is a high possibility that it is determined to be still. Therefore, in the case of a good photographer, a situation where it is determined that the camera is in a still state can be considered even in hand-held shooting on the wide-angle side. Therefore, by increasing Th_Count, an effect of suppressing this is added. On the other hand, on the telephoto side, even if it is difficult to raise the Vector_Th_Level and make it difficult to determine that it is still, it is difficult to continue hand-held shooting with a blur below the Vector_Th_Level.

  In FIG. 10, Th_Count is continuously changed between the wide-angle end and the telephoto end, whereas in FIG. 11, Th_Count is changed stepwise by dividing the wide-angle end and the telephoto end into some parts. Which characteristic is to be selected may be determined by judging the performance and circuit scale of the system.

  Further, in FIG. 10, the continuous change is shown by a linear function and in FIG. 7 is shown by three steps. However, there is no particular limitation on this, and Th_Count can be reduced from the wide-angle end to the telephoto end. For example, characteristics may be determined based on performance and circuit scale.

  Although it is a 3rd form, a form is demonstrated using FIGS. 12-17 based on a basic structure. FIG. 12 is a block diagram of the embodiment, but there are two points different from FIG. 1. The first point is that a zoom speed setting circuit 10 is newly provided so that the zoom speed of the optical zoom can be changed. Is output from the motion vector detection circuit 5 according to the zoom speed (in order to change the circuit from the basic configuration, the sign in the figure is also changed from “10” to “10A”). This is a point where gain control is applied to a motion vector as information. In addition, about the same figure number as FIG. 1, since it has the same function, description is omitted.

  As a specific control example, in the embodiment, the zoom speed is made variable by the pressure applied to the zoom switch 2 in the zoom switch 2 for performing the optical zoom operation, as shown in FIGS. This control is performed by detecting the pressure with the zoom speed setting circuit 10A. The zoom speed as output information from the zoom speed setting circuit 10A is output to the lens 1 and also input to the motion vector processing circuit 10A.

  Here, in the motion vector processing circuit 10A, differences from the control in the basic configuration will be described. The algorithm of the motion vector processing circuit 10A in the form is as shown in the flowchart form in FIG. 15, but as compared with FIG. 3 showing the algorithm of the circuit in the basic configuration, it differs from the basic configuration. Is added during the optical zoom operation (step S515) and not in a stationary state (step S153), that is, when it is determined that it is in a hand-held state, gain control is applied according to the zoom speed (step S154). It is.

  As shown in FIGS. 16 and 17, the relationship between the zoom speed and the gain is such that the gain is set close to 1 when the zoom speed is slow and close to 0 when the zoom speed is fast. This is because when the zoom speed is fast, the angle of view by zooming changes quickly, so even if some blurring occurs, there are few cases where the blurring is visually concerned.

  In FIG. 16, the relationship between the zoom speed and the gain is changed continuously, whereas in FIG. 17, the zoom speed is divided into several parts and the gain is changed stepwise. Whether to select the characteristic is determined by judging the performance and circuit scale of the system.

  In FIG. 16, the continuous change is shown by a linear function and in FIG. 17 is shown by three steps. However, there is no particular limitation on this, and if the zoom speed increases, the gain becomes close to zero. The characteristics may be determined from the aspect and circuit scale.

  In addition, the form which combined the 3rd form and the 1st form, and the form which combined the 3rd form and the 2nd form can also be considered, and each block diagram is shown in FIG. 18, FIG. . By adopting such a configuration, if possible in terms of circuit scale as a system, it is possible to realize camera shake correction control in an optical zoom operation with further improved accuracy.

  As described above, the first embodiment of the present invention has been described. By introducing these controls into the conventional imaging apparatus, it is possible to enhance the camera shake correction effect during the optical zoom operation.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIGS. 20 and 21. FIG.

  FIG. 20 is a block diagram showing a first embodiment showing the second embodiment of the present invention. The embodiment will be described in comparison with the second embodiment of the first embodiment. In the figure, 11 is a touch sensor provided on the bottom surface of the imaging device or a screw thread used for fixing the imaging device such as a tripod, and 12 is whether the imaging device is in a stationary state by the output of the touch sensor 11. 2 is a second stillness determination circuit that is a second stillness determination means, and other blocks having the same reference numerals as those in FIG.

  Now, the specific operation of the first embodiment of the second embodiment will be described. As is clear compared with FIGS. 20 and 8, whether or not the first embodiment is in a stationary state from the motion vector. In the second embodiment, the touch sensor or the like is used to determine whether or not the imaging device is stationary, and the motion vector processing circuit 9 controls the motion vector based on the information. Is. The processing algorithm of the motion vector processing circuit 9 has the same function as the second embodiment of the first embodiment as described above.

  FIG. 21 is a block diagram showing a second embodiment showing the second embodiment of the present invention. The embodiment will be described in comparison with the third embodiment of the first embodiment. In the figure, the functions of the touch sensor 11 and the second stationary determination circuit 12 are the same as those described in the first embodiment of the second embodiment (see FIG. 20). The blocks with the same figure number have the same functions as those of the third embodiment of the first embodiment, and hence the description thereof is omitted.

  Now, the specific operation of the second embodiment of the second embodiment will be described. As is clear compared with FIGS. 21 and 12, in the first embodiment, it is determined whether or not the motion vector is in a stationary state. In contrast to this, in the second embodiment, a touch sensor or the like is used to determine whether or not the imaging device is stationary, and the motion vector processing circuit 9A controls the motion vector based on the information. It is. As described above, the processing algorithm of the motion vector processing circuit 9A has the same function as the third embodiment of the first embodiment.

  As described above, in the second embodiment of the present invention, in the case of an imaging device provided with the touch sensor 11 and the like, the circuit for determining the stillness based on the motion vector described in the first embodiment is not provided. An effect equivalent to that of Embodiment 1 can be obtained.

  As another effect, the first stationary determination circuit that determines whether or not the imaging apparatus is stationary from the motion vector described in the configuration of the present invention, the motion vector is forcibly determined when it is determined that the imaging apparatus is stationary. Introducing an algorithm for zeroing can also solve the problem of the screen moving with the movement of the subject.

FIG. 1 is a block diagram showing a basic configuration according to Embodiment 1 of the present invention. The flowchart which shows the stationary determination algorithm by the basic composition in Embodiment 1 of this invention The flowchart which shows the processing algorithm of the motion vector in the basic composition in Embodiment 1 of this invention The block diagram which shows the 1st form in Embodiment 1 of this invention The flowchart which shows the stationary determination algorithm in the 1st form in Embodiment 1 of this invention 1 is a first characteristic diagram showing a relationship between a zoom position and a motion vector threshold value in the stillness determination algorithm according to the first embodiment of the present invention. Second characteristic diagram showing the relationship between the zoom position and the motion vector threshold in the stillness determination algorithm according to the first embodiment of the first embodiment of the present invention The block diagram which shows the 2nd form in Embodiment 1 of this invention The flowchart which shows the stationary determination algorithm in the 2nd form in Embodiment 1 of this invention First characteristic diagram showing a relationship between a zoom position and a counter threshold value for determining stillness determination in the stillness determination algorithm according to the second embodiment of Embodiment 1 of the present invention Second characteristic diagram showing a relationship between a zoom position and a counter threshold value for judging stillness in the stillness judgment algorithm according to the second embodiment of the first embodiment of the present invention The block diagram which shows the 3rd form in Embodiment 1 of this invention First characteristic diagram showing the relationship between the pressure applied to the zoom switch and the zoom speed in the optical zoom speed control according to the third embodiment of the first embodiment of the present invention. Second characteristic diagram showing the relationship between the pressure applied to the zoom switch and the zoom speed in the speed control of the optical zoom in the third embodiment in the first embodiment of the present invention. The flowchart which shows the motion vector processing algorithm in the 3rd form in Embodiment 1 of this invention The 1st characteristic view which shows the relationship between the optical zoom speed in the 3rd form in Embodiment 1 of this invention, and the gain applied to a motion vector Second characteristic diagram showing the relationship between the optical zoom speed and the gain applied to the motion vector in the third embodiment of the first embodiment of the present invention The block diagram which combined the 1st form and the 3rd form in Embodiment 1 of this invention The block diagram which combined the 2nd form and the 3rd form in Embodiment 1 of this invention The block diagram which shows the 1st form in Embodiment 2 of this invention The block diagram which shows the 2nd form in Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens which has an optical zoom function 2 Zoom switch 3 Image pick-up part 4 Zoom position detection circuit 5 Motion vector detection circuit 6 Level detection circuit 7 Counter control circuit 8 First stationary determination circuit 9 Motion vector processing circuit

Claims (5)

An optical system that collects optical signals from the subject and forms a subject image;
A zoom lens included in the optical system, movable in the optical axis direction of the optical system, and capable of changing the size of the subject image;
An imaging unit that converts an optical signal of the subject image to generate a video signal;
Motion vector detection means for detecting a motion vector based on a video signal generated by the imaging unit;
Stationary determination means for determining whether the own apparatus is in a stationary state;
In a state where the zoom lens moves and changes the size of the subject image,
When the stationary determination unit determines that the device is in a stationary state, the motion vector detected by the motion vector detection unit is not output,
A motion vector processing means for outputting a motion vector detected by the motion vector detecting means when the stillness determining means determines that the apparatus is not in a static state;
An imaging apparatus comprising: The stillness determining means determines whether or not the own apparatus is in a stationary state based on the motion vector detected by the motion vector detecting means.
The imaging device according to claim 1 . The stationary determination means detects that it is placed or fixed on an external stabilizer, and determines whether or not its own device is in a stationary state according to the detection result.
The imaging device according to claim 1 . The stationary determination means is provided in a bottom surface of the own device or a female screw provided on the bottom surface, and mechanically detects that it is placed or fixed on an external stabilizer.
The imaging device according to claim 3 . The imaging apparatus according to claim 3, wherein the stillness determination unit includes a touch sensor .

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