Patent Publication Number: US-2005122421-A1

Title: Photographing apparatus with lighting function

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a photographing apparatus with a lighting function and auto focusing (AF) function, such as digital cameras.  
      2. Description of the Related Art  
      Recently, a smaller amount of light than before is required for illuminating objects with a lighting apparatus, because of improvements of sensitivity of silver-halide films and charge coupled devices. Therefore, even though the amount of light output by LEDs is smaller than that output by conventional xenon tubes, usage of LEDs as lighting apparatus for photographing is proposed for improved lighting efficiency, reduced power consumption, and increased life.  
      On the other hand, in the active AF method, LEDs having high lighting efficiency are used as light sources.  
      In the case where an assisting light source independent of a strobe-flash is provided, the total photographing device becomes large, and has a complex structure. And generally, the assisting light source emits light only in a predetermined pattern, therefore, high-luminance areas formed on a subject, can not be changed according to the situation of the subject.  
     SUMMARY OF THE INVENTION  
      Therefore, an object of the present invention is to provide a photographing apparatus using a plurality of LEDs as light sources, having a simple structure, and having a lighting function for emitting illuminating light to illuminate an entire photographing area uniformly, and emitting assisting light used for AF in various patterns.  
      A lighting apparatus according to the present invention, includes a plurality of light sources, and a light-source controller that controls the plurality of light sources so that at least one light source in the plurality of light sources can emit assisting light to form contrasts of luminance on a photographic subject, and so that the light sources can simultaneously emit illuminating light to illuminate the photographic subject uniformly.  
      The light-source controller may control the plurality of light sources to form a high-luminance area on the photographic subject by emitting the assisting light, the high-luminance area having a higher luminance than the other areas on the subject, and being long and narrow.  
      A photographing apparatus, according to the present invention, includes the lighting apparatus mentioned above, a line sensor and a distance measurer. The line sensor forms image signals corresponding to an image of the photographic subject by receiving reflected light of the assisting light or the illuminating light reflected by the photographic subject. The distance measurer measures a distance to the subject based on the image signals formed by the line sensor. Here, the high-luminance area and the line sensor cross each other on a plane including the light receiving surface of the line sensor.  
      The line sensor may extend in a horizontal direction, that is a width direction of the photographing apparatus, and the light-source controller may control the plurality of light sources so that at least one of the high-luminance areas having a horizontal length equaling that of the illuminating area of one of the plurality of light sources, and extending in a perpendicular direction, is formed.  
      The plurality of light sources can be arranged in a matrix manner to form a shape which is a similar shape to the photographing area of the photographing apparatus.  
      The photographing apparatus can further include a distance judging device that judges whether the distance measured by the distance measurer can be used for focusing or not. In this case, the light-source controller may control the plurality of light sources so that the assisting light is emitted again by at least partially different light sources to the light sources that emitted the assisting light previously, when it is judged that the distance can not be used for focusing.  
      The photographing apparatus can further include a memory that stores light-source emission combinations for emitting the assisting light.  
      The plurality of light sources may include LEDs.  
      A photographing apparatus, according to another aspect of the present invention, includes the lighting apparatus mentioned above, an imaging device, a contrast detector, and a focusing system. The imaging device generates image signals corresponding to an image of the photographic subject by receiving reflected light of the assisting light and the illuminating light reflected by the photographic subject. The contrast detector detects contrast of the image signals generated by the imaging device. The focusing system focuses on the photographic subject based on the contrast.  
      In the photographing apparatus, at least one light source in the plurality of light sources may emit the assisting light.  
      The photographing apparatus can further include, a focus judging device that judges whether the photographic subject is in focus or not when the assisting light is emitted. In this case, the light-source controller may control the plurality of light sources so that a combination of light sources for emitting the assisting light and intensity of the assisting light, is different from combinations used in previous emissions of the assisting light, when it is judged that the subject is not in focus.  
      The photographing apparatus can further include a memory that stores combinations of light-source emission patterns and intensities for emitting the assisting light. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will be better understood from the description of the preferred embodiment of the invention set forth below together with the accompanying drawings, in which:  
       FIG. 1  is a front view of a digital camera of the first embodiment;  
       FIG. 2  is a block diagram of the digital camera of the first embodiment;  
       FIG. 3  is a conceptual view of the photographing area illuminated by the illuminating light;  
       FIG. 4  is a view representing an example of assisting light emission;  
       FIG. 5  is a view representing the photographing area in which the assisting light is emitted;  
       FIG. 6  is a conceptual view of the luminance distribution on the photographic subject when the assisting light is emitted;  
       FIG. 7  is a flowchart of a light emission control routine;  
       FIG. 8  is a block diagram of the digital camera of the second embodiment;  
       FIG. 9  is a conceptual view of the photographing area of the second embodiment illuminated by the illuminating light;  
       FIG. 10  is a view representing an example of the assisting light emission of the second embodiment;  
       FIG. 11  is a conceptual view of the luminance distribution in a horizontal direction, on the photographic subject when the assisting light is emitted;  
       FIG. 12  is a conceptual view of the luminance distribution in a perpendicular direction, on the photographic subject when the assisting light is emitted; and  
       FIG. 13  is a flowchart of a light emission control routine of the second embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Hereinafter, the preferred embodiments of the present invention are described with reference to the attached drawings.  
       FIG. 1  is a front view of a digital camera of the first embodiment of the present invention.  
      A digital camera  10  has a release button  12  on an upper surface  10 U, and has a photographing optical system  14 , a view finder  18 , a CCD line sensor  26 , and a lighting apparatus  16  on a front surface  10 F. The lighting apparatus  16  has a plurality of lighting units including LEDs emitting white light, as light sources. The lighting units are arranged in a matrix manner, 6 rows and 8 columns, corresponding to the shape of the photographing area of the digital camera  10 . Light emission intensities for all lighting units can be modulated respectively.  
       FIG. 2  is a block diagram of the digital camera  10  of the first embodiment.  
      A system control circuit  22  controls the whole digital camera  10 . A distance-measuring switch S 1  and a release switch SWR are connected to the system control circuit  22  respectively. The distance-measuring switch S 1  is turned on when the release button  12  is half depressed, and a distance to an object is measured for auto-focusing (AF). In an object distance measuring action, first, image signals according to the photographic subject are generated in a CCD line sensor  26  provided for the AF. The CCD line sensor  26  has a plurality of imaging devices, and is arranged along a horizontal direction, that is parallel to the upper surface  10 U. And then, the image signals are transmitted to the system control circuit  22 , via a CCD interface  24 . In the system control circuit  22 , the distance to the subject is measured by phase contrast method, based on the image signals generated in the CCD line sensor  26 .  
      When the luminance is too small, a subject image can not be detected under the natural light and the object distance can not be measured, therefore, the object distance measuring action is repeated. That is, control signals to make the lighting unit  16  emit assisting light, are transmitted from the system control circuit  22  to an LED driving circuit  30  via an LED interface  28 . The LED driving circuit  30  controls the lighting apparatus  16  so that some of the lighting units of the lighting apparatus  16 , arranged in columns, emit assisting light simultaneously with a predetermined intensity, based on the control signals. A high-luminance area having a higher luminance than the other areas, and being long and narrow, is formed by the assisting light, on the surface of the photographic subject.  
      When reflected light of the assisting light reflected by the high-luminance area, is received by the light-receiving surface of the CCD line sensor  26 , the reflected light and the light-receiving surface of the CCD line sensor  26  cross each other on a plane including light-receiving surface of the CCD line sensor  26 . Therefore, intensity of a part of the image signals generated in the CCD line sensor  26 , becomes higher, and a large contrast output is detected. Based on the large contrast output, the focusing position is calculated, and a lens in the photographing optical system  14 , is moved by a lens driving circuit (not shown) to the focused position.  
      Data indicating which lighting units emit assisting light, and the intensities of assisting light emitted by the lighting units, are stored temporally in the system control circuit  22 . When it is judged by the system control circuit  22 , that the distance to the subject is not measured although the assisting light has been emitted by the lighting apparatus  16 , assisting light will be emitted again. In this case, control signals for controlling the lighting apparatus  16  are transmitted from the system control circuit  22 , to the LED driving circuit  30 , so that lighting units at least partially different from the lighting units previously used to emit assisting light, emit assisting light. This is because changing the combination of lighting units that emit the assisting light, may make the distance measuring possible. Data indicating which lighting units emit assisting light, is memorized in the system control circuit  22 , every time the distance measuring fails, and is deleted when the distance measuring has succeeded. Assisting light emission by the lighting apparatus  16 , is repeated until the distance is measured by the system control circuit  22 .  
      When the release button  12  is fully pressed, the release switch SWR is turned on. When the release switch SWR is turned on, a shutter is opened to adjust exposure at a predetermined aperture for a predetermined time, based on the control signal from system control circuit  22 . And then a CCD (not shown) is exposed.  
      In this case, when the illuminating mode, that is the mode for illuminating a subject for any photographing time, is set, or when the luminance of the subject measured by a photometry-measuring sensor (not shown) is smaller than the predetermined amount, the amount of illuminating light necessary is calculated by the system control circuit  22  according to the distance to the photographic subject, and the lighting apparatus  16  illuminates the photographic subject. In this case, all lighting units of the lighting apparatus  16  emit illuminating light because the entire photographic subject should be illuminated. On the other hand, when the illuminating mode is not set, or the luminance of the subject is large enough, the lighting apparatus  16  does not emit illuminating light.  
      When the CCD (not shown) is exposed, electric charge according to the image, that is, image signals are produced. The image signals successively read from the CCD, are transmitted to the system control circuit  22  after amplifying processes, digitalizing processes, white balance adjustments, and gamma corrections.  
      Image signals transmitted to the system control circuit  22 , are further transmitted to the LCD driving circuit (not shown). An LCD (not shown) is driven based on the image signals, (not shown) and the subject image is displayed on the LCD. The image data of the photographed subject are memorized in the DRAM (not shown) or a memory card (not shown). Note that not only still pictures, but also moving pictures can be displayed on the LCD based on the image signals generated by the exposure of the CCD.  
       FIG. 3  is a conceptual view of the photographing area illuminated by the illuminating light.  
      Illuminating light emitted by each of the lighting units arranged in a matrix manner according to the aspect ratio 3:4 of the photographing area of the digital camera  10 , has a predetermined illuminating angle. Therefore, the lighting apparatus  16  can illuminate a subject in the photographing area uniformly, and when the light emission intensities for all the lighting units are the same, such as in strobe flashing, all of the subject is illuminated under the constant luminance.  
      A distance measuring area  34  extends in a horizontal direction and is located at the center of the photographing area  32 . When reflected light reflected by the photographic subject in the distance measuring area  34  corresponding to the CCD line sensor  26 , is received by the CCD line sensor  26 , the distance to the subject is measured. Note that the distance measuring area  34  has an extremely short length in the perpendicular direction, although it is exaggerated in  FIG. 3 .  
       FIG. 4  is a view representing an example of assisting light emission.  
      To distinguish each of the lighting units arranged in 6 rows parallel to the upper surface  10 U, and 8 columns parallel to a side surface  10 S of the digital camera  10 , all of the lighting units are expressed as A to F rows and 1 to 8 columns. For example, the lighting unit located at the upper left corner in  FIG. 4 , is A 1 , and the one neighboring it on the right, is A 2 , and the one located in the lower right corner is F 8 . The emission intensities of all the lighting units are controllable respectively, and here, all of the lighting units in the columns  2 , 5 , and  7 , that is the lighting units A 2 -F 2 , A 5 -F 5 , and A 7 -F 7 , emit assisting light with the same emission intensity.  
      As mentioned above, the lighting apparatus  16  can emit not only the illuminating light used for photographing, but also the assisting light used for measuring distance. Therefore, the structure of the digital camera  10  can be simplified because an assisting light source independent of the digital camera  10 , for AF, is unnecessary.  
       FIG. 5  is a view representing the photographing area  32  in which the assisting light shown in  FIG. 4  is emitted.  
      When the assisting light is emitted by the lighting units in the columns  2 , 5 , and  7  at the same intensity as mentioned above, high-luminance areas  36  orthographically crossing the distance measuring area  34 , are formed. Each of the high-luminance areas  36  is long and narrow, that is, each of the high-luminance areas  36  has a horizontal width equaling that of the illuminating area of one of the lighting units, and extends in a vertical direction. The reason that the assisting light is emitted to form such high-luminance areas  36  orthographically crossing the distance measuring area  34 , is to measure the distance to the photographic subject efficiently, by partially forming narrow higher luminance zones in the distance measuring area  34 .  
      When the high-luminance area  36  and the distance measuring area  34  are parallel, the high-luminance area  36  is not included in the distance measuring area  34  at all, or the entire high-luminance area  36  is included in the distance measuring area  34 . In the former case, there is no effect on measuring distance by emitting assisting light, and in the latter case, intensity of the image signals generated in the CCD line sensor  26  becomes higher uniformly, and no contrast output is detected. On the other hand, when the assisting light is emitted to form a high-luminance area  36  crossing the distance measuring area  34  at a slope, contrast can not be detected sufficiently because many neighboring imaging devices of the CCD line sensor  26  receive the reflected light from the high-luminance area  36 .  
      The distance measuring areas  34  can be formed to have a shape of a plurality of lines by using a plurality of the CCD line sensors  26 . For example, in addition to the distance measuring area  34  shown in  FIG. 5 , another distance measuring area  34  running through the center of the photographing area  32  and extending in a perpendicular direction, can be formed to create a cross shaped distance measuring area  34 . Further, an “H” shaped distance measuring area  34  can also be made, that is formed by adding two linear distance measuring areas  34  in a vertical direction at the edge of the distance measuring area  34  in the horizontal direction shown in  FIG. 4 . These distance measuring areas  34  are useful when changing the direction of the digital camera  10  for photographing, or when a photographic subject is in the peripheral area of the photographing area  32 . In any case, the assisting light is emitted so that the high-luminance areas  36  are orthographically crossing the distance measuring areas  34 .  
       FIG. 6  is a conceptual view of the luminance distribution on the photographic subject when the assisting light is emitted as shown in  FIG. 4 .  
      When the high-luminance areas  36  are formed by the assisting light emitted by the lighting units in the columns  2 , 5 , and  7  at the same intensity, the luminance distribution in the horizontal direction is as shown by the peaks  38  (a higher peak means a higher luminance). On the other hand, the luminance distribution in a vertical direction is constant over the entire photographing area  32  as shown by the peaks  40 . When the distance to the photographic subject can not be measured using only natural light and the lighting apparatus  16  emits the assisting light, the luminance of the subject is generally small. Even in such a situation, emitting assisting light to form the high-luminance area  36  on the surface of the photographic subject, crossing the distance measuring area  34  orthographically as shown in  FIG. 5  and  FIG. 6 , can make the distance measurement easier by making the intensity of the image signals partially higher and enhancing the contrast, when the reflected light reflected by the subject is received by the CCD line sensor  26 .  
       FIG. 7  is a flowchart representing a light emission control routine for the assisting light and the illuminating light, by the lighting apparatus  16 .  
      At step S 101 , it is judged whether the distance-measuring switch S 1  is turned on or not. The step S 101  is repeated until it is judged that the distance-measuring switch S 1  is turned on. At step S 102 , light reflected by the photographic subject is received by the CCD line sensor  26 , and then the process proceeds to step S 103 .  
      At step S 103 , it is judged whether the distance to the subject can be measured or not, that is, whether the image signals generated by the CCD line sensor  26  and the distance data calculated by the system control circuit  22  can be used for AF or not (i.e., whether reliable distance data is obtained or not). This judgment is carried out by comparing the contrast value obtained using the data output from the CCD line sensor  26 , and a predetermined contrast value. When it is judged that the distance is measured correctly, the control proceeds to step S 108 , and when it is judged that the distance is not measured correctly, the control proceeds to step S 104 .  
      At step S 104 , it is judged whether the assisting light has already been emitted to attempt the distance measurement and the distance measurement has failed or not, that is, it is judged whether the data regarding the lighting units having emitted the assisting light is memorized in the system control circuit  22  or not. When it is judged that the distance measurement has not yet been attempted, the control proceeds to step S 105 . And when it is judged that the distance measurement has already been attempted and failed, the control proceeds to step S 106 .  
      At step S 105 , the assisting light is emitted by the lighting units that are predetermined to emit the assisting light for the first distance measurement, and then the control proceeds to step S 107 . Here, the lighting units to emit the assisting light for the first time can be freely set, although the lighting units in the columns  2 , 5 , and  7  are set to emit the assisting light first, in this first embodiment.  
      At step S 106 , a different combination of lighting units from the combinations that were previously used, is selected to emit the assisting light, so as to avoid the failed combination, and to emit the assisting light efficiently. That is, data regarding the combinations of the lighting units already used to emit the assisting light are searched by the system control circuit  22 , and a new combination having a different light emission pattern from the patterns already used, is selected. In the selection, combinations having exactly the same arrangement of the lighting units as the combinations already used, and also combinations with a similar arrangement, such as those having the same distances between lighting units as the failed combinations, are not selected. For example, after the assisting light emitted by the lighting units in the columns  2 , 5 , and  7 , the combination of the lighting units in the columns  1 , 4 , and  6 , or the columns  3 , 6 , and  8  are not selected because these combinations have the same distances between lighting units and light emission patterns as the combination of the  2 , 5 , and  7  columns. In this example, a combination of the lighting units at  1 , 3 , and  7  columns can be selected as having a new light emission pattern. When the assisting light is emitted by the lighting units included in the newly selected combination, the control proceeds to step S 107 .  
      At step S 107 , light reflected by the photographic subject is received by the CCD line sensor  26 , and the control proceeds to step S 103 .  
      At step S 108 , the photographing lens in the photographing optical system  14  is driven and a photographic subject is focused. And step S 109 , it is judged whether the release switch SWR is turned on or not, and the judgment is repeated until it is judged that the release switch SWR is turned on. When it is judged the release switch SWR is on, the control proceeds to step S 110 .  
      At step S 110 , it is judged whether the illuminating light is emitted when photographing, or not. When the illuminating mode for emitting the illuminating light every photographing time is set, or when the luminance of the photographic subject measured by a photometry-measuring sensor (not shown) is smaller than the predetermined amount, it is judged that emitting illuminating light is required, and the control proceeds to step S 111 . On the other hand, when it is judged that emitting illuminating light is not required, the light emission control routine ends.  
      At step S 111 , the amount of the illuminating light is calculated by the system control circuit  22  according to the distance to the photographic subject, and the lighting apparatus  16  illuminates the photographic subject. In this case, all the lighting units A 1 -F 8  of the lighting apparatus  16  emit illuminating light with the same intensity, because the entire photographic subject should be illuminated uniformly. When the illuminating light is emitted, the light emission control routine ends.  
      When it is judged that the distance measurement has already been attempted and failed at step S 104 , the control may proceed to step S 105  to attempt the same combination of the lighting units again, although the control proceeds to step S 106  to change the combination of the lighting units in this embodiment. In this case, it is necessary to judge how many times the same combination failed at step S 104 , and when the number of failure times reaches the predetermined maximum number of failure times for the same combination, the control should proceed to step S 106  to change the failed combination.  
      In the first embodiment mentioned above, a photographing apparatus has a lighting function for emitting illuminating light to illuminate a photographic subject and emitting assisting light in various patterns for AF, and has a simple structure. The photographing apparatus can easily measure a distance to a photographic subject, differing from conventional cameras using assisting light sources, because the lighting apparatus  16  of the photographing apparatus can automatically change a combination of lighting units to emit assisting light when the previous distance measurement has failed due to unsuitable conditions. And the lighting apparatus  16  can be used for photographing apparatuses having different shapes of the distance measuring area  34  from that in the first embodiment, because the lighting units to emit the assisting light can be changed according to the shapes of the distance measuring area  34 .  
      Hereinafter, the second embodiment of the present invention is described with reference to the attached FIGS.  8  to  13  and the difference to the first embodiment is explained. In these following figures, the same components as those in the first embodiment, have the same reference numerals.  
       FIG. 8  is a block diagram of the digital camera  10  of the second embodiment.  
      In this second embodiment, a CCD sensor  29  having a plurality of imaging devices is provided. The CCD sensor  29  is used for both AF and generating image signals according to a photographic subject, although in the first embodiment, the CCD line sensor  26  is used for measuring distance for AF and another CCD is used for generating image signals according to a photographic subject.  
      An auto-focusing switch S 2  and a release switch SWR are connected to the system control circuit  22  respectively. When the release button  12  is half depressed the auto-focusing switch S 2  is turned on, and an auto-focusing (AF) action is carried out. In the AF action, first, image signals according to the photographic subject are generated by the CCD sensor  29 . And then, the image signals are transmitted to the system control circuit  22 , via a CCD interface  24 . In the system control circuit  22 , a contrast is detected based on luminance data of part of the image signals, and is memorized.  
      Further, driving signals for driving a motor  25  to slightly move a photographing lens  27 , are transmitted from the system control circuit  22  to a lens driving circuit  23 . After the photographing lens  27  has been slightly moved based on the driving signals, a contrast is detected again, and the contrast is memorized in the system control circuit  22 . Data of the slightly changing contrasts are memorized after repeating the detection of the contrast after changing the position of the photographing lens  27 . And the position of the photographing lens  27  in which the contrast is maximum in the memorized data, is set as a focused position.  
      When the contrast of luminance is too small, the AF action can not be carried out. Therefore, some of the lighting units of the lighting apparatus  16 , emit assisting light with a predetermined intensity based on the control signals transmitted from the system control circuit  22  to the LED driving circuit  30  via the LED interface  28 . The emission of the assisting light makes the contrast of the image signals generated by the CCD sensor  29  larger, and makes the AF action easy, because contrasts of luminance on a photographic subject are formed. Note that in this second embodiment, emission of the assisting light is not limited to the lighting units arranged on columns, although the lighting units arranged in columns emit assisting light in the first embodiment.  
      After data indicating which lighting units emit assisting light, and the intensities of the assisting light are memorized, and when it is judged by the system control circuit  22  that the AF action is not finished although the assisting light has been emitted by the lighting apparatus  16 , the assisting light will be emitted again. In this case, control signals for controlling the lighting apparatus  16  are transmitted from the system control circuit  22  to the LED driving circuit  30 , so that the combination of lighting units to emit the assisting light and the intensities of the assisting light, are changed from the combinations in previous emissions of the assisting light. This is because changing the combination of lighting units to emit the assisting light and intensities of the assisting light, may accomplish the AF action. Data indicating the combination of the lighting units emit assisting light and the intensities of the assisting light is memorized in the system control circuit  22 , every time the AF action fails, and is deleted when the AF action has succeeded. Assisting light emission by the lighting apparatus  16 , is repeated until the contrast of image signals is detected by the system control circuit  22  and the AF action is accomplished.  
      Note that in this second embodiment, the emission intensities of the assisting light are not always constant, although the emission intensity is constant in the first embodiment.  
       FIG. 9  is a conceptual view of the photographing area of the second embodiment illuminated by the illuminating light.  
      The distance measuring area  34  does not exist in this second embodiment, because the CCD line sensor  26  in the first embodiment is not provided. However, the lighting apparatus  16  of this second embodiment can illuminate a subject in the photographing area  32  uniformly, by emitting the illuminating light, totally the same as in the first embodiment.  
       FIG. 10  is a view representing an example of assisting light emission of the second embodiment.  
      The emission intensity of each lighting unit can be set in two steps. In the example shown in  FIG. 10 , the lighting units D 3 , D 5 , and D 6  emit assisting light, the intensity of the assisting light emitted by the lighting units D 3  and D 6  is low, and the intensity of the assisting light emitted by the lighting unit D 5  is high.  
       FIG. 11  is a conceptual view of the luminance distribution in a horizontal direction, on the photographic subject when the assisting light is emitted as shown in  FIG. 10 .  
      When the assisting light is emitted by the lighting units D 3 , D 5 , and D 6 , a partial photographic subject in the partial photographing area S 5  that is a part of the photographing area  32 , is illuminated brightly. On the other hand, each partial photographic subject in the partial photographing areas S 3  and S 6  is illuminated less brightly than the partial photographic subject in the partial photographing area S 5 . Therefore, the luminance distribution in the horizontal direction (of D row) is as shown by the peaks (a higher peak means a higher luminance). Thus, the contrast of the photographic subject in the photographing area  32  is enhanced.  
       FIG. 12  is a conceptual view of the luminance distribution in a perpendicular direction, on the photographic subject when the assisting light is emitted as shown in  FIG. 10 .  
      When the assisting light is emitted by the lighting units D 3 , D 5 , and D 6 , the luminance of the partial photographing areas S 3 , S 5 , and S 6  becomes higher than the other areas, and the luminance distribution in the perpendicular direction is as shown by the peaks (a higher peak means a higher luminance). When the AF action is not accomplished under natural light and the lighting apparatus  16  emits the assisting light, the contrast of luminance of the photographic subject is generally small. Even in such a situation, emitting assisting light having partially different brightness to form a pattern of luminance difference on subject as shown in  FIG. 11  and  FIG. 12 , can help the AF action.  
      Note that emission of the assisting light is not limited to the lighting units arranged in the same row, although the lighting units arranged in the same row emit assisting light in the second embodiment. Emission of the assisting light by the lighting units arranged on different rows and columns, can form contrast of luminance on subject in a wide area.  
       FIG. 13  is a flowchart representing a light emission control routine of the assisting light and the illuminating light, of the second embodiment.  
      At step S 201 , it is judged whether the auto-focusing switch S 2  is turned on or not. Step S 201  is repeated until it is judged that the auto-focusing switch S 2  is turned on. At step S 202 , the contrast of the image signals according to the photographic subject, generated by the CCD sensor  29 , is detected. Then the control proceeds to step S 203 .  
      At step S 203 , it is judged whether a contrast exists or not, that is, whether there is a contrast having higher value than the predetermined value, and reliable contrast data is obtained or not is judged. When it is judged that a useful contrast has been detected, the control proceeds to step S 208 , and when it is judged that a useful contrast has not been detected, the control proceeds to step S 204 .  
      At step S 204 , it is judged whether the assisting light has already been emitted to attempt the AF action and if the AF action has failed or not, that is, it is judged whether the data regarding the lighting units emitted the assisting light has been memorized in the system control circuit  22  or not. When it is judged that the AF action has not yet been attempted, that is the assisting light has not been emitted, the control proceeds to step S 205 . And when it is judged that the AF action has already been attempted and failed, the control proceeds to step S 206 .  
      At step S 205 , the assisting light is emitted by the lighting units that are predetermined to emit the assisting light for the first AF action, and then the control proceeds to step S 207 . Here, the emission intensity of the lighting units D 3  and D 6  is set low, and intensity of the lighting unit D 5  is set high. However, the combination of the lighting units to emit the assisting light and emission intensities can be set freely.  
      At step S 206 , a different combination of lighting units for emitting the assisting light and intensities of the assisting light, from the combinations that were previously used, is selected randomly by the system control circuit  22 , after detecting the memorized data representing previously used combinations. The assisting light is emitted in a newly selected combination, and the control proceeds to step S 207 .  
      At step S 207 , contrast of the image signals generated by the CCD sensor  29  is detected, and the control proceeds to step S 203 .  
      At step S 208 , the photographing lens  27  is driven based on the detected contrast. And at step S 209 , it is judged whether the release switch SWR is turned on or not, and the judgment is repeated until it is judged that the release switch SWR is turned on. When it is judged that the release switch SWR is on, the control proceeds to step S 210 .  
      At step S 210 , it is judged whether the illuminating light is emitted when photographing, or not. When the illuminating mode for emitting the illuminating light every photographing time is set, or when the luminance of the photographic subject measured by the photometry-measuring sensor is smaller than the predetermined amount, it is judged that emission of the illuminating light is required, and the control proceeds to step S 211 . On the other hand, when it is judged that emission of the illuminating light is not required, the light emission control routine ends.  
      At step S 211 , the amount of the illuminating light is calculated by the system control circuit  22  according to the distance to the photographic subject, and the lighting apparatus  16  illuminates the photographic subject. In this case, all lighting units A 1 -F 8  of the lighting apparatus  16  emit illuminating light at high intensity, because the entire photographic subject should be illuminated uniformly. When the illuminating light is emitted, the light emission control routine ends.  
      When it is judged that the AF action has already been attempted and failed at step S 204 , the control may proceed to step S 206  to attempt the same combination of lighting units and intensities of the assisting light again, although the control proceeds to step S 206  to change the combination of the lighting units and intensities in this embodiment. In this case, it is necessary to judge how many times the same combination has failed at step S 204 , and when the number of failure times reaches the predetermined number of failure times for the same combination, the control should proceed to step S 206  to change the failed combination.  
      In the second embodiment mentioned above, the photographing apparatus has a lighting function for emitting illuminating light to illuminate photographic subject and for emitting assisting light used for AF in various patterns, and also has a simple structure.  
      The selection of the lighting units to emit the assisting light is not limited to those in the both embodiments. For example, considering the first embodiment, any combinations of the lighting units to form the high-luminance areas  36  orthographically crossing, can be used. Further, not all of the lighting units on the column need to emit the assisting light as far as forming the high-luminance areas  36  crossing the distance measuring area  34 .  
      In terms of the second embodiment, lighting units in the same column, or lighting units on a diagonal line can emit the assisting light. In any cases, the distance between the lighting units that emit the assisting light can be set freely. Further, the lighting units for emitting the assisting light can be selected randomly, and only one lighting unit may emit the assisting light. In addition to this, lighting units for emitting the assisting light can be selected from ones located in a plurality of areas, for example in the multiple auto focus method, and selection of the lighting units may be according to the photographing modes. The emission intensities of the assisting light, are not limited to the two steps in the second embodiment, further steps can be set. On the other hand, only one step can be set, that is, luminance of the assisting light may be distinguished by only lighting or not lighting of the lighting units, although the emission intensity is preferably modulated.  
      Although each of the lighting units has the LED as a light source, other light sources in which the light emission intensity is adjustable, for example electric lamps and so on, can be used as light sources.  
      The arrangement of the lighting units in the lighting apparatus  16  is not limited to those in the embodiments. For example, lighting units arranged in a matrix manner of 3 rows in the horizontal direction and 4 columns in the vertical direction along the front surface  10 F, according to the aspect ratio 3:4 of the photographing area of the digital camera  10 , or 9 rows and 16 columns, can be used. In these cases, each of the lighting units emits light in a predetermined direction and at a predetermined illuminating angle to illuminate the entire photographing area. Further, the arrangement of the lighting units is not limited to a matrix structure, that is, the lighting units can be arranged on other polygons or a circle.  
      The lighting apparatus  16  can be used not only with a digital camera  10 , but also with cellular phones with photographing functions, and so on. And the lighting apparatus  16  can be detachably attached to the camera body and can be controlled by received control signals from the system control circuit  22 , differing from forming one body as shown in these embodiments.  
      Finally, it will be understood by those skilled in the art that the foregoing description is of a preferred embodiments of the apparatus, and that various changes and modifications may be made to the present invention without departing from the spirit and scope thereof.  
      The present disclosure relates to subject matters contained in Japanese Patent Application Nos. 2003-404251 (filed on Dec. 3, 2003) and 2003-404276 (filed on Dec. 3, 2003) which are expressly incorporated herein, by reference, in their entirety.