Abstract:
A solid state imaging camera having an imaging element to image light from a subject using pixel groups. The pixel groups are arrayed two-dimensionally to obtain a pixel signal group by transmitting serially to a first horizontal transmission register, and from the first horizontal transmission register to a second horizontal transmission register. The first and second horizontal transmission registers each have a respective output terminal positioned in parallel relative to each other to output two fields of picture signals that are then added by an adding circuit. A signal processing unit outputs predetermined signal processing of the added picture signals. In addition, a second signal processing unit can be disposed which effects predetermined signal processing on the signals from one of the two picture output terminals of the imaging element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation of U.S. patent application Ser. No. 08/982,705, filed Dec. 1, 1997, now abandoned. This application is based upon and claims priority to Japanese patent application No.  08-334617 , filed Nov. 29, 1996 and U.S. patent application Ser. No. 08/982,705, filed Dec. 1, 1997, the contents of which are incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to solid state imaging cameras. More particularly, the present invention relates to solid state imaging cameras for simultaneously performing separated picture readout in two field times and readout of all the pixel data in one field time.  
           [0003]    [0003]FIGS. 5A (prior art) and  5 B (prior art) illustrate a first conventional solid state imaging element having a transmission operation which outputs a plurality of pixel image signals  102  by way of a corresponding plurality of photosensors FS 1  and FS 2 . In FIG. 5A, a first pixel signal field  104  is formed from a horizontal row of pixel image signals  102 . Likewise, in FIG. 5B, a second pixel signal field  105  is formed from a horizontal row of pixel image signals  102 . Each pixel signal field  104  and  105  is simultaneously output until all image signals  102  have been output.  
           [0004]    All imaged pixel signals from a conventional solid state imaging element are transmitted by fields, separated in time, from a single transmission output terminal (not shown). For example, in FIG. 5A, pixel signal field  104  imaged by photosensors FS 1  correspond to a first field and are sequentially transmitted. Likewise, in FIG. 5B, pixel signal field  105  imaged by photosensors FS 2  correspond to a second field and are sequentially transmitted. Since first pixel signal field  104  is transmitted in a first field time, and the second pixel signal field  105  is transmitted in a second field time, two fields are required in order to transmit all pixel signals  102 .  
           [0005]    [0005]FIGS. 4A (prior art) and  4 B (prior art) illustrate a second conventional solid state imaging element having a transmission operation which reads out fields of imaged pixel signals  102  in one field time. Pixel image signals  102  are imaged by photosensors FS 1  and FS 2  and then added by transmission units within a charge coupled device (“CCD”). Imaged pixel image signals  102  are added to become pixel signals  103 , which are then transmitted and output. The solid state imaging element illustrated in FIGS. 4A and 4B are similar to the solid state imaging elements illustrated in FIG. 5A (prior art) and FIG. 5B (prior art). Output from photosensors FS 1  are grouped as a first field  104  and output from photosensors FS 2  are grouped as a second field  105 . As illustrated in FIG. 4A, in a first field time, the imaging element adds the pixel signals from photosensors FS 1  corresponding to the first field  104  and pixel signals from photosensors FS 2  corresponding to the second field  105  in a vertical transmission CCD  41 . The added two-line pixel signals  103  are transmitted horizontally and output by a horizontal transmission CCD (not shown). Similarly, in a second field time, illustrated in FIG. 4B, the imaging element adds the pixel signals from photosensors FS 1 , corresponding to a first field  104 , and the pixel signals from the photosensors FS 2  corresponding to a second field  105 , in the vertical transmission CCD  41 . The added two-line pixel signals  103  are horizontally transmitted and output by a horizontal transmission CCD (not shown). As a result, in both the first field time and the second field time, all of the pixel signals which were imaged by the solid state imaging element can be transmitted and output in one field time. But despite being able to be transmitted and output in one field time, a problem arises in that the imaging element can only read out the photosensors corresponding to either the first field  104  or the second field  105 , rather than the combined pixel signals formed by the photosensors from both the first and second field.  
           [0006]    Since the structure of a conventional solid state imaging element that separately reads out pixel signals in two field times differs from the structure of a conventional solid state imaging element that reads out pixel signals in one field time, such solid state imaging elements cannot be interchanged. This lack of interchangeability requires the use of more than one solid state imaging element and makes the imaging element inefficient.  
         SUMMARY OF THE INVENTION  
         [0007]    It is therefore an object of the present invention to provide a single solid state imaging element unit which can be interchangeably used to read out pixels in either two field times, or to read out pixel signals in one field time.  
           [0008]    It is a further object of the present invention to provide a single solid state imaging element camera which can output signals of pixel data separately in two field times at the same time that it outputs signals of data of pixel signals in one field time.  
           [0009]    It is a further object of the present invention to provide a single solid state imaging element camera in which a control state can be monitored while performing high speed position control.  
           [0010]    It is still a further object of the present invention to provide a single solid state imaging element camera in which picture signals are simultaneously obtained at high speed with high resolution picture data.  
           [0011]    Objects of the invention are achieved by a solid state imaging element camera equipped with an imaging element that images imaging light from a subject by pixel groups arrayed two-dimensionally in rows and columns. The imaging element obtains a pixel signal group from rows sequentially transmitted to a first horizontal transmission register, and from the first horizontal transmission register to a second register. An adding circuit adds two fields of picture signals that are output by the first and second horizontal transmission registers along respective parallel picture output terminals. A signal processing circuit performs predetermined signal processing on the added picture signals and outputs the processed added signals.  
           [0012]    Further objects and advantages of the invention are achieved by a solid state imaging unit having an imaging element that images imaging light from a subject using pixel groups arrayed two-dimensionally in rows and columns. A picture signal group is obtained by the imaging element from rows that are sequentially transmitted to a first horizontal transmission register, and then transmitted from the first horizontal transmission register to a second transmission register. The first horizontal transmission register has a first picture output terminal that outputs a first field of picture signals, and the second horizontal transmission register has a second picture output terminal, positioned in a parallel relation to the first output terminal, that outputs a second field of picture signals. An adding circuit adds the first and second field of picture signals, and a first signal processing circuit performs predetermined signal processing on the added picture signals. A second signal processing circuit performs predetermined signal processing either exclusively on the first field of picture signals that were output at the first picture output terminal, or exclusively on the second field of picture signals output at the second picture output terminal. In this way, picture signals output from the first signal processing circuit can be used in position detection of an article to be controlled, while picture signals output from the second signal processing circuit can be used in the display of photographic pictures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:  
         [0014]    [0014]FIG. 1 is a schematic view of a solid state imaging element camera according a preferred embodiment of the present invention.  
         [0015]    [0015]FIGS. 2A and 2B are schematic views of the transmission of electric charge in the solid state imaging element camera of FIG. 1.  
         [0016]    [0016]FIGS. 3A, 3B and  3 C are graphs illustrating the timing of an output state of picture signals in the solid state imaging element camera of FIG. 1.  
         [0017]    [0017]FIGS. 4A (prior art) and  4 B (prior art) are schematic views of a transmission operation of a conventional solid state imaging element which transmits and outputs all pixel signals in one field time.  
         [0018]    [0018]FIGS. 5A (prior art) and  5 B (prior art) are schematic views of a transmission operation of a conventional solid state imaging element which transmits and outputs pixel signals in two field times. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.  
         [0020]    A preferred embodiment of a solid state imaging element camera according to the present invention is illustrated in FIG. 1. A processing device  11  uses a CCD imaging element  1  to process an image. CCD imaging element  1  images a neighborhood of a mark “m” on a treatment subject, such as a wafer  12  or the like, located on a movable two-dimensional table  14 . Imaged picture signals are output from a first output terminal  2  and a second output terminal  3  of CCD imaging element  1 . Picture signals are output from first output terminal  2 , amplified by a buffer amplifier  4  and input to a first signal processing unit  7  as a first picture signal S 1 . First picture signal S 1  is input to a connection point T 1  by a buffer amplifier  10 , and the signal amplified by the buffer amplifier  10  is input to an adder  6 . The picture signal output from second output terminal  3  is amplified by a buffer amplifier  5  and input to the adder  6  as a second picture signal S 2 .  
         [0021]    Adder  6  adds first picture signal S 1  input from buffer amplifiers  4 ,  10  and the second picture signal S 2  input from buffer amplifier  5 , and the added signal S 3  is input to a second signal processing unit  8 .  
         [0022]    First signal processing unit  7  has an A/D converter  7 A, a monitor signal forming unit  7 B, and a D/A converter  7 C. A/D converter  7 A inputs the first picture signal S 1  from connection point T 1  and converts it from an analog to a digital signal. Monitor signal forming unit  7 B, based on the converted digital signal, forms a digital monitor signal suitable for an analog monitor  9 . D/A converter  7 C converts the digital monitor signal to an analog monitor signal S 4 , and outputs the signal S 4  at a predetermined timing to an analog monitor  9 .  
         [0023]    Second signal processing unit  8  has an A/D converter  8 A, an image processing unit  8 B, a difference detection unit  8 C, and a drive signal output unit  8 D. A/D converter  8 A converts added signal S 3  from an analog to a digital pixel signal on which the image processing unit  8 B then performs predetermined image processing. Difference detection unit  8 C performs match processing on the processed image signal using a predetermined pattern, for example, the image signal of a “+” pattern, and detects as differences the positional displacements of CCD imaging element  1  and a mark “m” on the process subject  12 . Drive signal output unit  8 D outputs to a drive system  13 , as a control signal, a feedback drive signal S 5  which makes the detected difference zero. Drive system  13 , based on input drive signal S 5 , then performs two-dimensional movement of the table  14 .  
         [0024]    The transmission process of the CCD imaging element  1  corresponding to odd numbered lines is shown in FIG. 2A. A plurality of photosensors, including the photosensors  21 ,  22  shown by squares, after receiving imaging light over a predetermined time, simultaneously output resulting corresponding stored electrical charge to vertical transmission CCDs  23 A- 23 D. The odd numbered photosensors include a row of photosensors  21  having spaced hash marks, as shown in FIG. 2A, while the even numbered photosensors include a row of photosensors  22  having closely spaced hash marks, as shown in FIG. 2A. A pixel signal El is the stored charge of an odd numbered field output from photosensor  21  and a pixel signal E 2  is the stored charge of an even numbered field output from photosensor  22 . Accordingly, photosensors  21 ,  22  and pixel signals E 1 , E 2  output from the photosensors  21 ,  22  are alternately present as lines of odd numbered fields and lines of even numbered fields.  
         [0025]    Pixel signals output to vertical transmission CCDs  23 A- 23 D are transmitted vertically and output to horizontal transmission CCDs  24 A,  24 B. In the transmission state in an odd numbered field time, shown in FIG. 2A, a pixel signal corresponding to an odd numbered field is vertically transmitted and input to horizontal transmission CCD  24 A where it is horizontally transmitted and output at high speed. A pixel signal corresponding to an even numbered field is vertically transmitted from horizontal CCD  24 A and input to horizontal CCD  24 B where it is horizontally transmitted and output at high speed.  
         [0026]    Horizontal transmission CCD  24 A and  24 B perform horizontal transmission when the vertical transmission of two line portions has been performed. For example, during the initial vertical transmission, one line of pixel group E 11 -E 14  is simultaneously vertically transmitted and input to horizontal transmission CCD  24 A. At the same time, pixel signal group E 21 -E 24  is transmitted to the line of previously vertically transmitted pixel signal group E 11 -E 14 . No horizontal transmission is performed at this initial state. Pixel signal group E 11 -E 14  is vertically transmitted to a further line, from horizontal transmission CCD  24 A to horizontal transmission CCD  24 B simultaneously with the next vertical transmission. At the same time, pixel signal group E 21 -E 24  is also vertically transmitted to horizontal transmission CCD  24 A. Then, pixel signal group E 21 -E 24 , which is within horizontal transmission CCD  24 A, and pixel signal group E 21 -E 24  which is within horizontal transmission CCD  24 B, are simultaneously transmitted horizontally. After this horizontal transmission, the pixel signal group of the third line vertical transmission sequence is transmitted to horizontal transmission CCD  24 B, and the pixel signal group of the fourth line vertical transmission sequence is transmitted to horizontal transmission CCD  24 A. Proceeding in this manner, two line horizontal transmission is performed at about the end of the vertical transmission of two line portions. Then, at the point in time when horizontal transmission of all pixel signals has ended, transmission processing corresponding to odd numbered field(s) ends.  
         [0027]    Pixel signals output from horizontal transmission CCD  24 A are amplified by buffer amplifier  4  and output as first picture signal S 1 . Pixel signals output from horizontal transmission CCD  24 B are amplified by buffer amplifier  5  and output as second picture signal S 2 .  
         [0028]    In the transmission processing corresponding to even numbered lines, which is performed after the transmission processing corresponding to odd numbered fields shown in FIG. 2A, pixel signals of even numbered fields are transmitted and output from horizontal transmission CCD  24 A, and pixel signals of odd numbered fields are transmitted and output from horizontal transmission CCD  24 B. Accordingly, in FIG. 2B, pixel groups transmitted by horizontal transmission CCDs  24 A and  24 B, shown in FIG. 2A, become replaced.  
         [0029]    In the vertical transmission sequence for pixel signal group E 11 -E 14 , shown in FIG. 2B, one line is vertically transmitted and input to horizontal transmission CCD  24 A simultaneously with the initial vertical transmission. After this vertical transmission, pixel signal group E 11 -E 14  is horizontally transmitted. In the vertical transmission sequence for the second line, pixel signal group E 21 -E 24 , and the third line, pixel signal group E 31 -E 34 , the two lines are serially vertically transmitted to respective horizontal transmission CCDs  24 B and  24 A, simultaneously with vertical transmission of the next two line portions. Transmitted pixel signal group E 21 - 24  and E 31 - 34  is then horizontally transmitted. The transmission processes shown in FIG. 2A and 2B thereafter become alternately repeated for the transmission of all pixel signals.  
         [0030]    An output time chart of first picture signal S 1 , second picture signal S 2 , and additive signal S 3 , output from CCD imaging element  1 , is shown in FIGS.  3 A- 3 C. First picture signal S 1  includes odd numbered fields and even numbered fields alternately output from horizontal transmission CCD  24 A, as shown in FIG. 3A. Second picture signal S 2  includes even numbered fields and odd numbered fields which are alternately output from horizontal transmission CCD  24 B, as shown in FIG. 3B. When first picture signal S 1  is a pixel signal of an odd numbered field, second picture signal S 2  is a pixel signal of an even numbered field, and when first picture signal S 1  is a pixel signal of an even numbered field, second picture signal S 2  is a pixel signal of an odd numbered field.  
         [0031]    Additive signal S 3  is obtained with every field time by adding the first picture signal and the second picture signal, as shown in FIG. 3C, by adder  6 .  
         [0032]    Processing a first picture signal S 1  using first signal processing unit  7  and generating a signal processed monitor signal using analog monitor  9 , in addition to having one frame time as 1/30 second and each field time as 1/60 second of odd numbered and even numbered fields which constitute one frame, results in an interlaced method of image output. The pixels of analog monitor  9  correspond to each photosensor of the CCD imaging element(s), and normal resolving power is obtained with each pixel of each photosensor made independent.  
         [0033]    Since signal processing is possible in one field time, and second picture signal S 2  input in second signal processing unit  8  is a signal which corresponds to the data of all the pixel signals in each field, high speed processing becomes possible.  
         [0034]    Although first signal processing unit  7  and second signal processing unit  8  are both used in order to generate the drive signal S 5 , first signal processing unit  7  and analog monitor  9  could be eliminated without affecting the performance of the position control.  
         [0035]    By having two picture output terminals available prior to the processing of the signals, picture signals that include the data of all pixels can be output at high speed, without changing the solid state imaging element itself, so that the imaging element can easily be used to perform high speed position control. In addition, by being able to process the signal from the output of one of the two picture output terminals of the imaging element, high resolution picture signals can be obtained, making it possible to obtain picture signals output at high speed simultaneously with picture signals having high resolution so that the control state of the subject can be monitored at high resolution. Using only one CCD imaging element  1 , position matching of the processing subject  12  on table  14  can be performed at high speed, with respect to the absolute position of the processing device  11  containing the imaging element  1 , and the picture which CCD imaging element  1  has imaged can be monitored at high resolution.  
         [0036]    Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. For example, although a preferred embodiment of the invention has been described in the context of a camera, the invention is not so limited and a solid state imaging unit can be used in other applications.