Patent Application
20090283665
The present invention relates to image sensors and, more particularly, to an optical assembly attached parallel or substantially parallel to an array of photosensitive sites of the image sensor to eliminate tilt of the optical assembly relative to the array of photosensitive sites.
Presently, image sensors include an array of photosensitive sites surrounded by an enclosing structure, typically made of plastic. Glass is mounted on the top of the enclosing structure, which in combination with the enclosing structure, totally encapsulates the array of photosensitive sites.
Typically, a lens and/or a filter is placed over the image sensor for either directing the incident light toward the array of photosensitive sites or filtering the light or a combination of both directing and filtering incident light. The lens or filter is mounted to the plastic enclosing structure by mounting extensions for rigidly mounting the lens and/or filter.
Although the presently known and utilized image sensor is satisfactory, it includes drawbacks. One drawback is that the mounting of the lens and/or filter to the plastic enclosing structure is not precise as desired and the lens and/or filter may tilt relative to the array of photosensitive sites. This causes the incident light to be directed inappropriately onto the array of photosensitive sites.
Consequently, a need exists for improving the mounting of the lens and/or filter to the plastic enclosing structure so that tilting is eliminated or substantially eliminated within desired tolerances.
It is therefore an object of the present invention to provide an image sensor in which the optical assembly is aligned in such a way as to eliminate or substantially eliminate tilt of the optical assembly relative to the array of photosensitive sites.
This object is achieved by an image sensor having a substrate; a photosensitive die having an array of photosensitive sites for receiving incident light; wherein at least a portion of the substrate extends beyond a boundary of the silicon die for forming a mounting surface; a support, which includes a receiving portion, mounted to the substrate and surrounds at least a portion of the array of photosensitive sites; a transparent layer mounted in the receiving portion of the support; an optical assembly through which the incident light passes and includes at least three mounting structures which are mounted respectively to one mounting location on the support and two mounting locations on the mounting surface of the substrate for aligning the assembly to the array of photosensitive sites.
The present invention provides the advantage of eliminating undesirable tilt of the optical assembly relative to the array of photosensitive sites.
Referring to
A support 50, preferably plastic, extends around the periphery of the photosensitive sites 40 and typically completely surrounds the photosensitive site 40. It is noted that a mating surface 59 of the plastic support 50 is placed and glued parallel to the substrate 20. The support 50 includes a receiving portion 55, preferably L-shaped, in which a transparent layer 60, preferably glass, is placed in the receiving portion 55. The transparent layer 60 is sealed to the receiving portion 55 by either glue, adhesive, epoxy or the like 58. The transparent layer 60 and the support 50 encloses the photosensitive die 30 on its top and side with the substrate 20 enclosing it from the bottom. A plurality of wire bonds 70 each extend from the periphery of the photosensitive die 30 to the substrate 20 and are each connected to a solderpad 80 via metal contacts 90, commonly referred to in the art as VIAs. The solderpads 80 permit the signal to be passed therefrom for further processing, as is well known in the art.
An optical assembly 100, which may be either a lens and/or a filter, is placed over the array of photosensitive sites 40 in the photosensitive die 30 and includes a mounting structure 120 having mounting extensions 110a and 110b (only two of which is visible in
Preferably, the location 115a on the plastic support 50 is substantially at a midpoint of the array of photosensitive sites 40 of the photosensitive die 30, and preferably the two mounting locations 115b on the mounting surface of the substrate 20 are each substantially at an edge of the array of photosensitive sites 40 of the photosensitive die 30. The placement of the optical assembly 100 to the array of photosensitive sites 40 is parallel or substantially parallel which alleviates tilting and the like. The two mounting locations 115b on the substrate 20 are aligned to the longer side of the image array.
Referring to
Digital camera phone 1202 is a portable, handheld, battery-operated device in an embodiment in accordance with the invention. Digital camera phone 1202 produces digital images that are stored in memory 1206, which can be, for example, an internal Flash EPROM memory or a removable memory card. Other types of digital image storage media, such as magnetic hard drives, magnetic tape, or optical disks, can alternatively be used to implement memory 1206.
Digital camera phone 1202 uses optical assembly 100 to focus light from a scene (not shown) onto the image sensor array 10 of pixel sensor 1212. Image sensor array 10 provides color image information using the Bayer color filter pattern in an embodiment in accordance with the invention. Image sensor array 10 is controlled by timing generator 1214, which also controls flash 1216 in order to illuminate the scene when the ambient illumination is low.
The analog output signals output from the image sensor array 10 are amplified and converted to digital data by analog-to-digital (A/D) converter circuit 1218. The digital data are stored in buffer memory 1220 and subsequently processed by digital processor 1222. Digital processor 1222 is controlled by the firmware stored in firmware memory 1224, which can be flash EPROM memory. Digital processor 1222 includes real-time clock 1226, which keeps the date and time even when digital camera phone 1202 and digital processor 1222 are in a low power state. The processed digital image files are stored in memory 1206. Memory 1206 can also store other types of data, such as, for example, music files (e.g. MP3 files), ring tones, phone numbers, calendars, and to-do lists.
In one embodiment in accordance with the invention, digital camera phone 1202 captures still images. Digital processor 1222 performs color interpolation followed by color and tone correction, in order to produce rendered sRGB image data. The rendered sRGB image data are then compressed and stored as an image file in memory 1206. By way of example only, the image data can be compressed pursuant to the JPEG format, which uses the known “Exif” image format. This format includes an Exif application segment that stores particular image metadata using various TIFF tags. Separate TIFF tags can be used, for example, to store the date and time the picture was captured, the lens f/number and other camera settings, and to store image captions.
Digital processor 1222 produces different image sizes that are selected by the user in an embodiment in accordance with the invention. One such size is the low-resolution “thumbnail” size image. Generating thumbnail-size images is described in commonly assigned U.S. Pat. No. 5,164,831, entitled “Electronic Still Camera Providing Multi-Format Storage Of Full And Reduced Resolution Images” to Kuchta, et al. The thumbnail image is stored in RAM memory 1228 and supplied to color display 1230, which can be, for example, an active matrix LCD or organic light emitting diode (OLED). Generating thumbnail size images allows the captured images to be reviewed quickly on color display 1230.
In another embodiment in accordance with the invention, digital camera phone 1202 also produces and stores video clips. A video clip is produced by summing multiple pixels of image sensor array 10 together (e.g. summing pixels of the same color within each 4 column×4 row area of the image sensor array 10 to create a lower resolution video image frame. The video image frames are read from image sensor array 1210 at regular intervals, for example, using a 15 frame per second readout rate.
Audio codec 1232 is connected to digital processor 1222 and receives an audio signal from microphone (Mic) 1234. Audio codec 1232 also provides an audio signal to speaker 1236. These components are used both for telephone conversations and to record and playback an audio track, along with a video sequence or still image.
Speaker 1236 is also used to inform the user of an incoming phone call in an embodiment in accordance with the invention. This can be done using a standard ring tone stored in firmware memory 1224, or by using a custom ring-tone downloaded from mobile phone network 1238 and stored in memory 1206. In addition, a vibration device (not shown) can be used to provide a silent (e.g. non-audible) notification of an incoming phone call.
Digital processor 1222 is connected to wireless modem 1240, which enables digital camera phone 1202 to transmit and receive information via radio frequency (RF) channel 1242. Wireless modem 1240 communicates with mobile phone network 1238 using another RF link (not shown), such as a 3GSM network. Mobile phone network 1238 communicates with photo service provider 1244, which stores digital images uploaded from digital camera phone 1202. Other devices, including computing device 1204, access these images via the Internet 1246. Mobile phone network 1238 also connects to a standard telephone network (not shown) in order to provide normal telephone service in an embodiment in accordance with the invention.
A graphical user interface (not shown) is displayed on color display 1230 and controlled by user controls 1248. User controls 1248 include dedicated push buttons (e.g. a telephone keypad) to dial a phone number, a control to set the mode (e.g. “phone” mode, “calendar” mode” “camera” mode), a joystick controller that includes 4-way control (up, down, left, right) and a push-button center “OK” or “select” switch, in embodiments in accordance with the invention.
Dock 1250 recharges the batteries (not shown) in digital camera phone 1202. Dock 1250 connects digital camera phone 1202 to computing device 1204 via dock interface 1252. Dock interface 1252 is implemented as wired interface, such as a USB interface, in an embodiment in accordance with the invention. Alternatively, in other embodiments in accordance with the invention, dock interface 1252 is implemented as a wireless interface, such as a Bluetooth or an IEEE 802.11b wireless interface. Dock interface 1252 is used to download images from memory 1206 to computing device 1204. Dock interface 1252 is also used to transfer calendar information from computing device 1204 to memory 1206 in digital camera phone 1202.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
