WO2020242362A1

WO2020242362A1 - Portable electronic camera device

Info

Publication number: WO2020242362A1
Application number: PCT/SE2020/050485
Authority: WO
Inventors: Anton Falk; Anni LEHMUSKERO
Original assignee: Profoto Aktiebolag
Priority date: 2019-05-27
Filing date: 2020-05-12
Publication date: 2020-12-03

Abstract

A portable electronic camera device (1) is described, which comprises an imaging sensor (22) to capture an image of a scene (3); and illumination means configured to emit a first light flash in a first beam (8) and a second light flash in a second beam (10) to illuminate the scene (3) for capture by the imaging sensor (2). The portable electronic camera device (1) is characterised in that the second beam (10) is more narrow than the first beam (8) and in that the optical direction (11) of the peak intensity of the first beam (8) and the optical direction (12) of the peak intensity of the second beam (10) are essentially the same.

Description

PORTABLE ELECTRONIC CAMERA DEVICE

TECHNICAL FIELD

The present invention relates to a portable electronic camera device comprising an imaging sensor to capture an image of a scene and a first illumination device configured to emit a first light flash in a first beam to illuminate the scene for capture by the imaging sensor.

BACKGROUND ART

Portable electronic camera devices are commonly used for imaging. The electronic camera devices may be a dedicated camera device or, as is increasingly common, a handheld computing device with an integrated camera. The handheld computing device may be, e.g., a tablet or a smartphone.

Portable electronic camera devices may have a number of different modes for capturing images. One such mode may be a portrait mode, which is configured to capture a portrait image, i.e., an image of the face of a person. According to general belief within the

photographic community, a good portrait image is characterized in that the face of the person to be portrayed should be clearly distinguished from the surroundings. There are different techniques to achieve this. One technique is to take advantage of the focal depth of the imaging system. With a short focal depth of the imaging system everything out of focus will be blurred and the face will be distinguished from the surroundings in case the surroundings are at a different focal depth. Another possibility to distinguish the face is to use a spotlight which illuminates only the face. This is usual in studio photography where the size of the equipment is not an issue. However, for a portable electronic camera device it is desirable to avoid the need of having a spotlight.

Thus, there exist a need for an alternative portable electronic camera device with which it is possible to capture enhanced portrait images. SUMMARY OF THE INVENTION

An object of the present invention is to provide a portable electronic camera device with which the capability of portrait photography is enhanced.

Another object of the present invention is to provide a portable electronic camera device with which the illumination of the object may be adapted to capture portrait images.

At least one of these objects is provided with a portable electronic camera device according to the independent claim.

Further advantages are provided with the features of the dependent claims.

According to a first aspect of the present invention, a portable electronic camera device is provided. The portable electronic camera device comprises an imaging sensor to capture an image of a scene, and illumination means configured to emit a first light flash in a first beam and a second light flash in a second beam to illuminate the scene for capture by the imaging sensor. The portable electronic camera device is characterised in that the second beam is narrower than the first beam and in that the optical direction of the peak intensity of the first beam and the optical direction of the peak intensity of the second beam are essentially the same.

By the portable electronic camera device having the capability of emitting two light flashes of different widths the portable electronic camera device may illuminate a face in a scene such that the illumination is suitable for portrait photography.

By the second beam being narrowerthan the first beam is meant that the intensity of the second beam decreases more rapidly with an increasing angle to the direction of peak intensity for the second beam compared to the first beam.

The portable electronic camera device may be configured to emit the second light flash simultaneously with the first light flash. This is advantageous in that the combined intensity then may be better adapted to be optimal for the scene. Alternatively, the portable electronic camera device is not configured to emit the second light flash simultaneously with the first light flash. In this case the second illumination device is used for capturing portraits in a portrait mode.

The optical direction of the peak intensity of the first beam and the optical direction of the peak intensity of the second beam are essentially the same. This is advantageous in that the face of a person to be portrayed is often placed in the middle of the scene and that the first light flash preferably should also be configured to illuminate the scene with the peak intensity centred. Both beams may of course have the same optical directions without being centred on the scene to be captured by the imaging sensor, i.e., both beams may be directed to a point in the scene, which point is off centre.

The first beam may have a beam angle such that the light intensity varies with less than a factor of 2 over the scene captured by the imaging sensor. This means that the illumination from the first light source is essentially even over the scene. This corresponds to the limitations on flash lights in portable electronic camera devices according to the prior art. The second beam may have a beam angle such that the light intensity varies with at least a factor of 2 over the scene captured by the imaging sensor. This is the lower limit for the second beam. Preferably, the second beam is more narrow and has a variation in intensity of more than a factor of 2 over the scene.

The intensity of the second beam is at least half of the peak intensity of the second beam within a high intensity region, wherein the high intensity region is incident on 20-50 %, preferably 35- 45 % of the scene captured by the imaging sensor. Such a size on the high intensity region gives good portrait illumination for a majority of portrait photos captured.

The ratio between the peak intensity of the second beam from the second illumination device and the peak intensity of the first beam from the first illumination device is fixed and is in the interval 3-20, preferably in the interval 5-15, and most preferred in the interval 8-10. This ratio has proven to be suitable for portrait photography.

The illumination means may comprise a first illumination device configured to emit the first light flash in the first beam and a second illumination device configured to emit the second light flash in the second beam. It is most practical to have the illumination means divided into two illumination devices even if it is possible to achieve two different beams from the same illumination device.

The first illumination device and the second illumination device may be configured to be controlled independently such that the intensity of the first light flash can be controlled independently of the intensity of the second light flash. Such a configuration of the first illumination device and the second illumination device increases the possibility to achieve an optimal illumination.

The portable electronic camera device may comprise a display, which is configured as the first illumination device. An example of such a device is a smartphone. The display of the smartphone may be used as the first illumination device while the second illumination device is a separate illumination device. This combination of illumination devices is used when taking so-called selfies.

The first illumination device may comprise a first LED flash. In addition, the second illumination device may comprise a LED flash. LED flashes are suitable for portable electronic camera devices as they are small and efficient.

The first illumination device and the second illumination device may be arranged side-by-side. This is the most straightforward solution.

According to an alternative solution, the second illumination device may be arranged surrounding the first illumination device. This enables a decrease of the total area used for the first and second illumination devices and also makes it possible to use a single lens element for both illumination devices.

The first illumination device may comprise at least a first lens arranged to collimate the light from the first LED flash, and the second illumination device may comprise at least a second lens arranged to collimate the light from the second LED flash.

The portable electronic camera device may comprise a third illumination device configured to emit, simultaneously with the first light flash, a third light flash in a third beam to illuminate at least a part of the scene, wherein the second beam is more narrow than the third beam, and wherein the third beam is more narrow than the first beam. With such a third illumination device it is possible to better adapt the combined light from the illumination devices to the actual scene. When capturing a portrait image the light from the illumination devices should be adapted to the size of the face in the scene. Thus, for a small face at a large distance only the second illumination device and possibly the first illumination device may be used to produce a narrow beam. For a large face at a small distance, only the third illumination device and possibly the first illumination device may be used to produce a wider beam. The first illumination device and the third illumination device may be combined to produce beams of intermediate width.

The third illumination device may also comprise a LED flash and possibly also a lens.

The portable electronic camera device may comprise a processing unit connected to the imaging sensor and configured to control the illumination devices, wherein the processing unit, prior to capturing the image, is configured to receive, from the imaging sensor, image data, identify, in the image data, face data related to a face of a person, determining from the face data an optimal distribution of light from the illumination devices, and controlling, during capture of the image with the imaging sensor, the illumination devices based on the determined optimal distribution of light from the illumination devices. By configuring the portable electronic camera device in this way, it may automatically adjust the illumination to the face to be portrayed.

The portable electronic camera device may be a handheld computer device, such as, e.g., a tablet or a smartphone. The portable electronic camera device may alternatively be a digital camera. In the following preferred embodiments of the invention will be described with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows schematically a portable electronic camera device according to a first

embodiment of the present invention. Fig. 2 shows the portable electronic camera device according to a second embodiment of the present invention.

Fig. 3 illustrates schematically a portable electronic camera device when it is used for capturing an image of a scene

Fig. 4 shows schematically in cross section the first illumination device and the second illumination device.

Fig. 5a shows, in cross section, the first illumination device and the second illumination device according to another embodiment. Fig. 5b shows, in a view from above, the first illumination device and the second illumination device in Fig 5a.

Fig. 6 shows schematically the light intensity from the first illumination device and the second illumination device at the scene. Fig. 7 shows schematically the combined light intensity from the first illumination device and the second illumination device.

Fig. 8 shows schematically illumination devices according to other embodiments.

Fig. 9 shows the light intensity from the first illumination device, the second illumination device, and the third illumination device in Fig. 8, for a first setting of the intensities of the illumination devices.

Fig 10 the light intensity from the first illumination device, the second illumination device and the third illumination device in Fig 8 for a second setting of the intensities of the illumination devices.

Fig 11 the light intensity from the first illumination device, the second illumination device and the third illumination device in Fig 8 for a second setting of the intensities of the illumination devices.

DETAILED DESCRIPTION

In the drawings, similar features in different drawings are denoted by the same reference numerals. The drawings are not drawn to scale.

Fig. 1 shows schematically a portable electronic camera device 1 according to a first embodiment of the present invention. Fig. 2 shows the portable electronic camera device 1 according to a second embodiment of the present invention. Fig. 3 illustrates schematically a portable electronic camera device 1 when it is used for capturing an image of a scene 3. The portable electronic camera device 1 in Fig. 1 is a smartphone 1. The smartphone 1 comprises an imaging sensor 2 to capture an image of a scene 3 (Fig. 3). The smartphone 1 also comprises optics in the form of lenses 4 in front of the imaging sensor 2. The configuration of the lenses 4 and the imaging sensor 2 determines the size of the scene 3 captured by the imaging sensor 2.The imaging sensor may be of the CMOS type or the CCD type. The smartphone also comprises a processing unit 33 and drive electronics 31 configured to drive the illumination devices 6, 9, controlled by the processing unit. The processing unit is also connected to the imaging sensor 2. The size of the scene 3 is indicated by the broken lines in Fig. 3. The smartphone 1 comprises a first illumination device 6 in the form of a first LED flash 6. The first LED flash 6 is configured to emit a first light flash in a first beam 8 to illuminate the scene 3 (Fig. 3) for capture by the imaging sensor 2. The smartphone 1 also comprises a second illumination device 9 in the form of a second LED flash 9 configured to emit, simultaneously with the first light flash, a second light flash in a second beam 10 to illuminate at least a part of the scene 3, wherein the second beam 10 is more narrow than the first beam. The width of the first beam 8 and the second beam 10 may be defined as the width at which the intensity of the beam has decreased to half of the maximum intensity in the beam. The optical direction of the peak intensity of the first beam 8 and the optical direction of the peak intensity of the second beam 10 are essentially the same and are at the centre of the scene 3. The intensity of the second beam 10 decreases outwards from a peak intensity at the centre of the second beam 10. The intensity has decreased to half of the peak intensity at the dashed line 11. The intensity of the first beam 8 does not decrease below half of the peak intensity of the first beam 8 in the centre of the scene 3. The edges 18 of the scene 3 are straight lines.

The portable electronic camera device 1 in Fig. 2 is a smartphone 1. The first illumination device 6 is in this second embodiment the screen 6 of the smartphone 1. The imaging sensor 2 and the lenses 4 in front of the imaging sensor 2 constitutes the so called selfie camera of the smartphone 1. In selfie mode, the user may watch herself on the screen when arranging the scene 3. When the photo is taken the screen lights up to function as the first illumination device 6. The second illumination 9 device is a LED flash and corresponds to the second illumination device 9 in Fig. 1. Thus, the intensity of the first beam 8 from the screen 6 does not decrease below half of the top intensity of the first beam 8 within the scene 3.

Common for both of the first embodiment shown in Fig. 1 and the second embodiment shown in Fig. 2 is that they produce the same illumination of the scene, i.e., that the centre of the scene 3 is illuminated with a more intense light. This is indicated with the dashed line 11 in Fig. 3.

Fig. 4 shows schematically in cross section the first illumination device 6 and the second illumination device 9. The first illumination device 6 comprises a first LED 12. A first lens 13 is arranged to focus the light from the first LED 12. The second illumination device 9 comprises a second LED 14. A second lens 15 is arranged to focus the light from the second LED 14. The first LED 12 and the second LED 14 are both arranged on a common substrate 16 in which wiring for powering the first LED 12 and the second LED 14 are provided. The first lens 13 has a longer focal length than the second lens 15. Thus, the light from the second LED 14 will be focussed to a more narrow second beam 10 than the light from the first LED which will be focussed to a first beam 8. In Fig. 4, in order to clearly explain the concept, the lenses are shown as ordinary lenses. However, according to a preferred embodiment, the lenses 13, 15, should be Fresnel lenses to minimize the thickness of the lenses.

Fig. 5a shows, in cross section, the first illumination device 6 and the second illumination device 9 according to another embodiment. Fig. 5b shows, in a view from above, the first illumination device 6 and the second illumination device 9 shown in Fig. 5a. The first illumination device 6 comprises a first LED 12. A first lens 13 is arranged to focus the light from the first LED 12 to a first beam 8. The second illumination device 9 comprises a plurality of second LEDs 14 arranged around the first LED 12. The first LED 12 and the plurality of second LEDs 14 are arranged on a common substrate 16 in which wiring for powering the first LED 12 and the number of second LEDs 14 are provided. A second lens 15 is arranged over each one of the plurality of second LEDs 14. The focal length of the first lens is longer than the focal length of each one of the second lenses 15. Thus, the light from each one of the second LEDs 14 will be focussed to a second beam 10 which is more narrow first beam 8 to which the light from the first LED 12 is focussed. Also, in this case it is preferred that the lenses 13, 15, are configured as Fresnel lenses to minimize the thickness of the lenses. By having a large number (eight in Fig. 5) of second LEDs it is possible to achieve a high intensity of the second beam 10.

Fig. 6 shows schematically the light intensity from the first illumination device 6 and the second illumination device 9 at the scene 3 along the centre line 17 (Fig. 3) of the scene 3. The vertical dashed lines 18 in Fig. 6 are the edges of the scene 3. The intensity of the first beam 8 from the first illumination device 6 is shown with the solid line 8 and has a small variation in intensity between the edges 18 and the centre 19. The intensity of the second beam 10 from the second illumination device 9 is shown with the dashed line 10. The top intensity of the second beam 10 is considerably higher than the top intensity of the first beam 8. The intensity variation in the vertical direction in Fig. 3 is similar to the intensity distribution shown in Fig. 6, which is the intensity variation in the horizontal direction in Fig. 3.

Fig. 7 shows schematically the combined light intensity 20 from the first illumination device 6 and the second illumination device 9. The combined light intensity 20 drops below half of the top intensity at the border 11 of the region indicated by the dashed line 11.

Fig. 8 shows schematically illumination devices according to another embodiment. A first illumination device 6 comprising a first LED 12 and a first lens 13, a second illumination device 9 comprising a second LED 14 and a second lens 15 and a third illumination device 22 comprising a third LED 24 and a third lens 27. The first LED 12, the second LED 14 and the third LED 24 are arranged on a common substrate 25. The third illumination device 22 is configured to emit, simultaneously with the first light flash, a third light flash in a third beam 23 to illuminate at least a part of the scene 3, wherein the second beam 10 is more narrow than the third beam 23, and wherein the third beam 23 is more narrow than the first beam 8. This is achieved by having the focal length of the third lens 27 shorter than the focal length of the first lens 13 and longer than the focal length of the second lens 15.

Fig 9 shows schematically the light intensity from the first illumination device 6, the second illumination device 9, and the third illumination device 22 at the scene 3 along the centre line 17 (Fig. 3) of the scene 3. The vertical dashed lines 18 are the edges of the scene 3. The intensity of the first beam 8 from the first illumination device 6 is shown with the line 8 and has a small variation in intensity between the edges 18. The intensity of the second beam 10 from the second illumination device 9 is shown with the line 10 and has a more narrow peak than the first beam 8. The intensity of the third beam 23 from the third illumination device 22 is intermediate between the first beam 8 and the second beam 10 with respect to the width. The top intensity of the second beam 10 and the third beam 23 are considerably higher than the top intensity of the first beam 8. The combined intensity 30 of the first beam 8, the second beam 10, and the third beam 23 is shown with the solid line 30. In Fig. 9 the intensity of the second illumination device 9 is set to the maximum setting and the intensity of the third illumination device 22 is set to the maximum setting. The intensity variation in the vertical direction in Fig. 3 is similar to the intensity distribution shown in Fig. 9 which is the intensity variation in the horizontal direction in Fig. 3.

Fig 10 shows the light intensity from the first illumination device 6, the second illumination device 9 and the third illumination device 22 in Fig 8 for a second setting of the intensities of the illumination devices. In Fig. 10 the intensity of the third illumination device 22 is set to zero and the intensity of the second illumination device 9 is set to the maximum setting.

Fig 11 shows the light intensity from the first illumination device, the second illumination device and the third illumination device in Fig 8 for a second setting of the intensities of the illumination devices. In Fig. 11 the intensity of the third illumination device 22 is set to the maximum setting and the intensity of the second illumination device 9 is set to zero.

The width W of the combined intensity 30 at half of the peak intensity is shown in Figs. 9, 10 and 11. It is clearly evident that the width W is smallest in Fig. 10 when mainly the second illumination device 9 contributes to the combined intensity 30. The width is largest in Fig. 11 when mainly the third illumination device 22 contributes to the combined intensity. The width W for the combined intensity 30 at half of the peak intensity in Fig 9 is between the widths W in Fig. 10 and Fig. 11. This possibility to change the width of the combined intensity can be used to adjust the beam width to the size of the face to be portrayed. The size of the region 11 (Fig. 3) in which the intensity is above 50% of the peak intensity should be adapted to the size of the face in the scene. The optimal size is dependent on the actual size of the head and also on the distance between the portable electronic camera device 1 and the face. The processing unit 33 can from data from the imaging sensor 2 identify a face in the scene and determine the size of the face. The processing unit can control the drive electronics 31 based on the determined size of the face to optimize the width of the combined beam 30. Thus, the portable electronic camera device may automatically adjust the illumination of the face in a scene depending on the relative size of the face in the scene 3. The above described embodiments of the invention may be amended in many ways without departing from the scope of the invention which is limited only by the appended claims.

Claims

1. A portable electronic camera device (1) comprising:

an imaging sensor (2) to capture an image of a scene (3); and

illumination means configured to emit a first light flash in a first beam (8) and a second light flash in a second beam (10) to illuminate the scene (3) for capture by the imaging sensor (2); characterised in that the second beam (10) is more narrow than the first beam (8) and in that the optical direction (11) of the peak intensity of the first beam (8) and the optical direction (12) of the peak intensity of the second beam (10) are essentially the same.

2. The portable electronic camera device (1) according to claim 1, configured to emit the second light flash simultaneously with the first light flash.

3. The portable electronic camera device (1) according to any one of the preceding claims, wherein the first beam (8) has a beam angle (a) such that the light intensity varies with less than a factor of 2 over the scene (3) captured by the imaging sensor (2).

4. The portable electronic camera device (1) according to any one of the preceding claims, wherein the second beam (10) has a beam angle (b) such that the light intensity varies with at least a factor of 2 over the scene (3) captured by the imaging sensor (2).

5. The portable electronic camera device (1) according to claim 4, wherein the intensity of the second beam (10) is at least half of the peak intensity of the second beam (10) within a high intensity region (HI), wherein the high intensity region (HI) is incident on 20-50 %, preferably 35-45 % of the scene (3) captured by the imaging sensor (2).

6. The portable electronic camera device (1) according to claim 5, wherein the ratio between the peak intensity of the second beam (10) from the second illumination device (9) and the peak intensity of the first beam (8) from the first illumination device (6) is fixed and is in the interval 3-20, preferably in the interval 5-15, and most preferred in the interval 8-10.

7. The portable electronic camera device (1) according to any one of the preceding claims, wherein the illumination means comprises:

a first illumination device (6) configured to emit the first light flash in the first beam (8); and a second illumination device (9) configured to emit the second light flash in the second beam

(10).

8. The portable electronic camera device (1) according to claim 7, wherein the first illumination device (6) and the second illumination device (9) are configured to be controlled independently such that the intensity of the first light flash can be controlled independently of the intensity of the second light flash.

9. The portable electronic camera device (1) according to any one of the claims 7 or 8, comprising a display (6), which is configured as the first illumination device (6).

10. The portable electronic camera device (1) according to claim 7 or 8, wherein the first illumination device (6) comprises a first LED flash.

11. The portable electronic camera device (1) according to any one of claims 7, 8 or 10, wherein the second illumination device (6) comprises a LED flash.

12. The portable electronic camera device (1) according to any one of claims 7, 8, 10 or 11, wherein the first illumination device (6) and the second illumination device (9) are arranged side-by-side.

13. The portable electronic camera device (1) according to any one of claims 7, 8 or 10-12, wherein the second illumination device (6) is arranged surrounding the first illumination device (9).

14. The portable electronic camera device (1) according to any one of claims 7, 8 or 10-13, wherein the first illumination device (6) comprises at least a first lens (13) arranged to collimate the light from the first LED flash (12), and

the second illumination device (9) comprises at least a second lens (15) arranged to collimate the light from the second LED flash (14).

15. The portable electronic camera device (1) according to any one of claims 7-14, comprising a third illumination device (22) configured to emit, simultaneously with the first light flash, a third light flash in a third beam (23) to illuminate at least a part of the scene (3), wherein the second beam (10) is more narrow than the third beam (23), and wherein the third beam (23) is more narrow than the first beam (8).

16. The portable electronic camera device (1) according to any one of claims 7-15, comprising a processing unit (33) connected to the imaging sensor (2) and configured to control the illumination devices (6, 9, 22), wherein the processing unit (33), prior to capturing the image, is configured to:

receive, from the imaging sensor (2), image data,

identify, in the image data, face data related to a face of a person,

determining from the face data an optimal distribution of light from the illumination devices (6, 9, 22), and

controlling, during capture of the image with the imaging sensor (2), the illumination devices (6, 9, 22) based on the determined optimal distribution of light from the illumination devices (6, 9,

22).

17. The portable electronic camera device (1) according to any one of the preceding claims, wherein the portable electronic camera device (1) is a handheld computer device.