JP2003116059A - Imaging device and image processing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the power consumption of an imaging device. SOLUTION: In a second field, a signal obtained by exposing in a first field is read from a photodiode 73 (T20), and an amplification factor of imaging data to be read in a third field is determined (T2).
9, T30) In the third field, image data obtained by exposure in the second field is read from the photodiode 73 (T28), and the image data is amplified at the amplification factor determined in the second field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus and an image processing system, and more particularly to an image pickup apparatus and an image processing system such as a digital camera, a subject collation apparatus, a code reader, a security device.

[0002]

2. Description of the Related Art Recently, an image pickup apparatus using a charge coupled device (CCD) or a CMOS type image pickup device has been used for various purposes. For example, it is a photographing device such as a video camera or a digital camera, and an image input device such as a scanner or a document camera.

Recently, there are products in which an image pickup device is incorporated in a mobile terminal such as a personal computer, a mobile phone, a PDA (personal data assistant), or a product in which the image pickup device is connected by an adapter.

Furthermore, in recent years, not only for industrial and special purposes, but also for general consumers, image pickup devices for recognizing characters, symbols, people, objects, etc. have begun to spread. Examples thereof include a pen-type digitizer, a face / fingerprint / iris collation device, various vehicle-mounted recognition devices, and an object recognition device mounted on an amusement robot or monitoring device.

An example of an image pickup apparatus using such an image pickup element is a bar code reader. Some bar code readers are so-called handy type and have a small size and are driven by a battery. In such an application, it is necessary to particularly reduce power consumption in order to extend the usable time with one charge.

Of the power consumption breakdown, the power consumption of the illumination light source and the imaging sensor circuit accounts for a large proportion. In order to reduce the power consumption in such products, the image sensor is not driven and the sensor is not output except when the image sensor is in a standby state, while the image sensor is exposed in synchronization with the illumination light such as an LED during the image sensor. Some have an imaging mode for output.

Exposure period of the image sensor (accumulation time of optical information)
While the illumination is turned on during the period, the illumination is turned off during the period in which the signal is read out from the image sensor after the accumulation, so that the lighting period of the illumination is shortened and power consumption is reduced.

In Japanese Patent Laid-Open No. 2000-196951, an imaging condition is set by reading out one part of image data for the AE function (automatic exposure amount adjusting function) and the AF function (autofocusing function). It shows how to save time and circuitry. In addition, Japanese Patent Laid-Open No. 2000-2249
Japanese Patent Publication No. 2 also discloses a configuration in which the electronic shutter time is continuously variable.

[0009]

However, even in such an image pickup mode, the exposure condition and the gain setting A are adjusted.
When the E function is realized by the output signal of the same image sensor, it is necessary to perform the imaging a plurality of times, such as the imaging for the AE function and the original imaging, which consumes a lot of power.

In another case, the power consumption also increases when the imaging is repeated a plurality of times due to factors such as camera shake and insufficient brightness. Further, performing the sensor operation a plurality of times as described above has another problem that it takes a long processing time.

Further, in recent years, due to low power consumption as compared with CCD sensors, demand for CMOS type sensors is increasing in mobile terminals and the like. Such a CMOS type sensor is
Unlike the T-type or FIT-type CCD, since it does not have a light-shielding buffer memory unit, it is exposed during the period for reading out the signal obtained from the pixel.

Therefore, it is necessary to make the exposure time uniform in the plane by, for example, idling the signal in the previous field or using a rolling shutter type electronic shutter, which will be described later. Since it also becomes the exposure period, it is necessary to make the illumination period longer than that of the CCD sensor.

For this reason, the light source for illumination, together with the image pickup circuit, is a major factor in the increase in power consumption.

The invention described in Japanese Unexamined Patent Publication No. 2000-196951 shows the effect of improving the processing speed by reducing the image reading time by using a random access circuit. In order to determine the exposure amount at the time of exposure, the illumination time of the LED, etc., it is necessary to read the image data for a plurality of fields.

Further, in the invention described in Japanese Patent Laid-Open No. 2000-22492, since the accumulation of the next field has already started at the time of reading the first field,
The electronic shutter time is controlled using the output of the first field from the third field onward, and the time taken to determine the amplification factor of the imaged data is long.

Unlike the case of moving images such as a video camera, the character / symbol recognition device and the object / person recognition device are required to process image data at high speed. In the case of a mobile device, it is required that the operation time is short, especially from the viewpoint of power consumption.

Therefore, an object of the present invention is to reduce the operating time of the image pickup device to reduce the power consumption.

[0018]

In order to solve the above-mentioned problems, the present invention reads sequential image data obtained by the exposure from the image elements which have been exposed while sequentially exposing the image elements arranged in two dimensions. An image pickup apparatus for amplifying the signal, comprising means for determining an amplification factor of the image pickup data based on the image pickup data read one field before.

Further, the present invention is an image pickup apparatus for sequentially reading image pickup data obtained by exposure from an image pickup device which has completed exposure while sequentially exposing image pickup devices arranged two-dimensionally. Is provided based on the imaging data read one field before.

Further, according to the present invention, while illuminating a subject by the illuminating means, the image pickup device sequentially exposes the reflected light from the subject by the image pickup device and reads out the sequential image pickup data obtained by the exposure from the image pickup device which has completed the exposure. A means for determining the illumination intensity or illumination time of the illumination means based on the imaging data read one field before.

Furthermore, the image processing system of the present invention comprises any one of the above-mentioned image pickup devices and a processing device for processing an image signal picked up by the image pickup device.

That is, the image pickup apparatus of the present invention performs the exposure of the (n + 1) th field while reading the exposure for the image pickup of the nth field or the signal obtained by the exposure, and reads the signal in the nth field. Based on the above, the exposure of the (n + 1) th field is performed, the illumination condition for the exposure is determined, or the signal obtained by the exposure of the (n + 1) th field is processed.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) "Description of Configuration" FIG. 1 is a block diagram showing a schematic configuration of a handy type barcode reader according to Embodiment 1 of the present invention. In FIG. 1, 1 is a bar code reader body, 2 and 3 are LEDs as a light source for illumination, and 4 is an LED.
Mirrors 5 that change the path of reflected light 20 of irradiation light 18 and 19 from 2 and 3 and 5 are reflected light 2 whose path is changed by mirror 4.
A lens for collecting 0, 6 is a sensor unit having an image sensor such as a CMOS type, CCD, 7 is a signal line for transmitting an image signal from the sensor unit 6, and 8 is a control for transmitting a signal for driving the sensor unit 6. A line, 9 is an image processing unit for processing the image signal from the sensor unit 6, 10 is a signal line for transmitting the image signal processed by the image processing unit 9, and 11 is a signal for controlling the image processing unit 9. A control line, 12 is a microcomputer unit that controls the operation of the barcode reader body 1, 13 is an operation switch, 14 is a signal line from the operation switch 13 to the microcomputer unit 12, and 15 is the amount of light emitted from the LEDs 2 and 3. A control line for sending a signal, 16 is a recorded matter to be read, 17 is a bar code marked on the recorded matter 16, and 18 and 19 are LEDs.
Illumination light from 2 and 3 is reflected light 20 which travels along the optical path of the barcode reader body 1.

FIG. 2 is a block diagram showing the internal structure of the image processing unit 9 of FIG. In FIG. 2, 21 is a signal line 7
A gain control amplifier (gain control amp: GCA) for adjusting the gain of an image signal input through
A front end processing unit including a clamp circuit for setting a DC level and an A / D converter (analog digital converter: ADC) for converting the output of the GCA from an analog signal to a digital signal, and 22 is processed by the front end processing unit 21. A signal line for transmitting the generated image signal, 23 performs digital image processing such as contrast and γ conversion of the image signal transmitted through the signal line 22 and determines the amplification factor of GCA of the front end processing unit 21 and controls the LED. A DSP (Digital Signal Processo) that generates a signal for controlling the operation of the unit 30 and sends a switching signal of a normal mode / standby mode (also called a low power consumption mode or a sleep mode) to the timing generation unit (TG) 26.
r) part, 32 is a signal line for transmitting a signal indicating the amplification factor of GCA determined by the DSP part 23, 33 is a signal line for sending a switching signal between the normal mode and the standby mode from the DSP part 23, 31 is a DSP part LED control unit 30 generated in 23
24 is a crystal oscillator (Xtal) that generates a clock, and 25 is a crystal oscillator 2
4 is a signal line for transmitting the clock from 4, DSP unit 2
An LED control unit 26 for switching ON / OFF of the LEDs 2 and 3 in accordance with a signal from the device 3, and a DSP unit 23 for outputting various timing signals generated based on the clock from the crystal oscillator 24 transmitted through the signal line 25. The timing generator outputs the signal to the signal lines 27 to 29 to the output destination according to the control signal.

FIG. 3 is a block diagram showing the internal structure of the sensor unit 6 of FIG. In FIG. 3, 41 is a sensor 1
A pixel portion forming a pixel, 42 is a read pulse (φS) input terminal in the pixel portion 41, 43 is a reset pulse (φR) input terminal in the pixel portion 41, and 44 is a transfer pulse (φT) input in the pixel portion 41 Terminals, 45 are signal read terminals (P0) in the pixel section 41, 46 is a signal line for sending a read pulse (φS) from the selector section 66 to each horizontal pixel, and 47 is reset from the selector section 66 to each horizontal pixel. A signal line that sends a pulse (φR),
48 is a signal line for transmitting a transfer pulse (φT) from the selector unit 66 to each pixel in the horizontal direction, 49 is a vertical signal line, 40 is a constant current source, 51 is a capacitor connected to the vertical signal line 49, and 52 is a capacitor.
Has a gate connected to the horizontal shift register 56 and a source −
The drain is a transfer switch connected to the vertical signal line 49 and the output signal line 53, 54 is an output amplifier connected to the output signal line 53, and 55 is an output terminal of the sensor unit 6.

Further, 56 is a horizontal shift register (HS
R) and 57 are start pulse (HST) input terminals, 5
8 is an input terminal of the transfer clock (HCLK1, 2), and 59
Is a vertical shift register (VSR), 60 is an input terminal of a start pulse (VST), 61 is a transfer clock (VCL)
K) input terminal, reference numeral 62 denotes an electronic shutter shift register (ES) of a system called rolling shutter described later.
R), 63 are input terminals for the start pulse (EST), 6
Reference numeral 4 is an output line of a vertical shift register (VSR), 65 is an output line of an electronic shutter shift register (ESR), and 66.
Is a selector section, 67 is an input terminal of a transfer pulse original signal TRS, 68 is an input terminal of a reset pulse original signal RES, and 69 is an input terminal of a read pulse original signal SEL.

FIG. 4 is a block diagram showing the structure of the pixel portion 41 shown in FIG. In FIG. 4, 71 is a power supply voltage (VC
C) and 72 are reset voltages (VR), 73 is a photodiode, 74 to 77 are switches formed by MOS transistors, 78 is a parasitic capacitance (FD), and 79 is a ground.

FIG. 5 is a block diagram showing a circuit configuration of the selector unit 66 of FIG. In FIG. 5, 81 is a vertical shift register 5 which is input through output lines 64 and 65.
9. An OR circuit for performing a logical sum operation of the respective outputs of the electronic shutter shift register 62, and an AN for performing a logical product operation of the output of the OR circuit 81 and the reset pulse original signal RES.
D circuit, 83 is the original signal TRS of the transfer pulse and the output line 64
AND circuit 84 for performing a logical AND operation with the output of the vertical shift register 59 input through the reference numeral 84, and a logical OR operation of the original signal RES of the reset pulse and the output of the electronic shutter shift register 62 input through the output line 65. An AND circuit for performing 85, an AND circuit for performing an AND operation of the original signal SEL of the selection pulse and the output of the vertical shift register 59 input through the output line 64, and 86 for the AND circuit 8
It is an OR circuit that performs a logical sum operation of each output of 3, 84.

Although FIG. 5 shows only the circuit configuration related to the first row of the pixel section 41, the second to nth rows have the same circuit configuration.

FIG. 6 is a block diagram showing the internal configuration of the DSP unit 23 and the front end processing unit 21 of FIG.
In FIG. 6, 23a is an integrating circuit that integrates the output from the front end processing unit 21, and 89 is a look-up table (LU that looks up the output of the integrating circuit 23a.
T), 90 is a D / A converter (DAC) for converting the data looked up by the look-up table 89 from a digital signal to an analog signal, and 91 is an integrating circuit 23.
a, look-up table 89 and D / A converter 9
0 is a control unit, 23b is an arithmetic circuit for performing image processing such as brightness / contrast adjustment, enhancement processing, smoothing, and averaging processing, and 92 and 93 are GCA and ADC that appeared in the description of FIG. Is.

Look-up table 89, D / A
Without the converter, the processing in these is performed by the microcomputer unit 1
It may be performed softly on the second side. However, as shown in FIG. 6, performing processing by hardware has an advantage that the time until the determination of the amplification factor can be shortened.

[0032]

[Table 1] Table 1 shows the data stored in the lookup table 89. The DATE-IN has an integrating circuit 23a.
It shows the 8-bit digital data integrated by.
LUT-OUT shows digital data obtained by inverting 3 bits from the left of the table of the digital data.

As shown in the second row of Table 1, the integration circuit 23
If, for example, "00111111" is input as the 8-bit digital data integrated in a, the LUT
At -OUT, digital data "110" which is the inverted 3 bits from the left of the table of the digital data is D /
The signal is output as a control signal for the A converter 90.

[Description of Operation] First, the operation of imaging the bar code 17 of the recorded matter 16 will be described.

The bar code reader 1 is set in the standby mode until the operation switch 13 is operated by the user to start image capturing. In this mode, for example, the operations of the sensor unit 6, the image processing unit 9, etc. are temporarily and partially stopped.

When the user operates the operation switch 13 to start image pickup, a signal to that effect is output from the operation switch 13 to the microcomputer section 12 through the signal line 14. The microcomputer section 12 detects that the operation switch 13 has been operated based on this signal.

Then, the microcomputer section 12 causes the image processing section 9
A control signal is output to the DSP unit 23 through the control line 11 so as to change the setting of the sensor unit 6 and the like from the standby mode to the imaging mode.

The DSP section 23 outputs a mode switching signal to the TG section 26 through the signal line 33 according to the control signal. The TG unit 26 outputs a clock to the sensor unit 6 and the like according to the switching signal from the DSP unit 23.

In the standby mode, the TG unit 26
The clock generated in FIG. 2 is only sent to the DSP unit 23 in FIG. 2, and in the normal mode, the front end processing unit 21, the LED control unit 30, the sensor unit 6 are used.
Will also be sent to.

Further, the microcomputer section 12 outputs a control signal to the LED control section 30 of the image processing section 9 so as to turn on the LEDs 2 and 3 in order to turn on the LEDs 2 and 3.

The LED control section 30 sends a light emission command to the LEDs 2 and 3 through the control line 15. Then the LED
2 and 3 emit light, and the recorded matter 16 is irradiated with illumination lights 18 and 19.

The reflected light 20 from the recorded matter 16 side has its optical path changed to the lens 5 side by the mirror 4, is condensed by the lens 5, and is imaged on the sensor section 6.

Next, an outline of the operation of the sensor section 6 will be described.

When the reflected light 20 is imaged on the sensor unit 6, the reset switch 74 of the sensor unit 6 and the switch 75 connected to the photodiode 73 are opened and the photodiode 73 is The charge is accumulated based on the reflected light 20.

Thereafter, with the switch 76 open, the switch 74 is closed to reset the parasitic capacitance 78. Next, by opening the switch 74 and closing the switch 76, the electric charge in the reset state is read to the signal read terminal 45.

Next, by closing the switch 75 with the switch 76 open, the photodiode 73 is closed.
The electric charge stored in is transferred to the parasitic capacitance 78. Next,
The switch 76 is closed with the switch 75 open, and the signal charge is read to the signal read terminal 45.

Driving pulse φS for each MOS transistor,
φR and φT are the vertical shift register 59 as described later.
Shift register 62 for electronic shutter and selector unit 66
And are supplied to the input terminals 42 to 44 of the pixels by the respective signal lines 46 to 48.

The signal read terminal 45 is connected to the constant current source 40 by the vertical signal line 49, and is also connected to the vertical signal line capacitor 51 and the transfer switch 52.
The charge signal is transmitted through the vertical signal line 49 to the vertical signal line capacitance 51.
After that, the transfer switch 52 is sequentially scanned according to the output of the horizontal shift register 56, the signal of the vertical signal line capacitance 51 is sequentially read to the output signal line 53, and the signal is output from the output terminal 55 via the output amplifier 54. Is output.

Here, the vertical shift register (VSR) 5
9 starts scanning by the start pulse (VST) input through the input terminal 60, and the transfer clock (VCL).
K) 61 is sequentially output to the output line 64 as VS1, VS2, ... VSn.

The electronic shutter vertical shift register (ESR) 62 starts scanning with the start pulse (EST) input from the input terminal 63, and the transfer clock (VCLK) input from the input terminal 61 is output to the output line 65. Then, ES1, ES2, ... ESn are sequentially output.

The signals output to the output lines 64 and 65 are
It is input to the selector unit 66. The selector unit 66 has a reset pulse source signal RES and a transfer pulse source signal TR.
The original signal SEL of S and the selection pulse is also input, and the high level / low level of the pulse output to the signal lines 46 to 48 is switched by the operation described later.

Regarding the reading order of each pixel section 41, first, the first row in the vertical direction is selected, and the pixel section 41 connected to each column is selected and output from left to right as the horizontal shift register 56 scans. When the output of the first row is completed, the second row is selected, and the pixel portions 41 connected to each column are selectively output from left to right in accordance with the scanning of the horizontal shift register 56.

Similarly, in accordance with the sequential scanning of the vertical shift register 59, the second, third, ...
Outputs one screen image.

Here, the CMOS type sensor is
terline transfer) type and FIT (frame-interline tran)
Unlike the sfer) type CCD element, since it does not have a light-shielding buffer memory section, the pixel section 41 that has not been read out is still exposed during the period in which the signals obtained from the pixel section 41 are sequentially read out. Therefore, the accumulation time is different on the screen.

For example, when all the pixel portions 41 are reset all at once and then read sequentially, the output from the first pixel portion 41 and the last pixel portion 41 is about one screen read time,
The last pixel portion 41 is exposed more.

In order to avoid this phenomenon, in the CMOS type sensor, as an electronic shutter (focal plane shutter), vertical scanning at the start and end of exposure is performed in parallel so that the exposure amount is constant in each vertical row. The driving method called rolling shutter is used.

The image of the bar code 17 thus read is sent to the image processing section 9 through the signal line 7.

In the image processing section 9, the gain of the image signal from the sensor section 6 is adjusted by the GCA 21. The amplification factor is generated by the control unit 91 based on the gain control signal fed back from the microcomputer unit 12 through the control line 11 and the previously read image signal.

The image signal, the gain of which is adjusted by the GCA 92, follows the ADC drive pulse created by the TG 26 based on the clock from the crystal oscillator 24, and the A / D signal is generated by the ADC 93.
After the conversion, the arithmetic circuit 23b of the DSP unit 23 performs image processing. The processed signal is output to the microcomputer unit 12 via the signal line 10.

The microcomputer section 12 receives the image signal from the image processing section 9 and recognizes the position of the bar code 17 in the recorded matter 16. Then, it is determined whether the brightness or contrast of the image of the barcode 17 is sufficient for decoding.

As a result of the discrimination, if the brightness or contrast of the image of the bar code 17 is not sufficient for decoding, a control signal for adjusting the gain is output to the image processing section 9 through the control line 11.

In place of the gain adjustment, the second embodiment
As described in Section 2, the illumination intensity of the LEDs 2 and 3 may be changed to send an image sufficient for decoding. L
When changing the illumination intensity of the EDs 2 and 3, the image processing unit 9
The LED drive clock for adjusting the illumination intensity is sent from the TG 26 to the LED control unit 30 via the control line 15 to adjust the irradiation light amount and the like.

On the other hand, the microcomputer section 12 determines whether or not the gain of the image signal is larger than the gain necessary for decoding the bar code 17.

When the gain is large, a control signal for reducing the gain stepwise is output to the GCA 21. Conversely, when the gain is small, a control signal for increasing the gain stepwise is output to the GCA 21.

When the brightness or contrast of the image of the bar code 17 is sufficient for decoding, or when the gain adjustment is completed, the image of the bar code 17 is read again to identify the system / type of the bar code 17. . Then, the character of the barcode 17 is identified by comparing the actually coded data with the data stored in the memory.

Then, a check digit is performed to check whether there is an error in the identification or the like, and if there is no error, it is converted into a character code such as an ASCII code. Finally, the converted data is displayed on a monitor or the like (not shown).

Next, the operation of the sensor section 6 will be described in detail.

FIG. 8 is a timing chart showing the operation of the sensor section 6 shown in FIG. In FIG. 8, the start pulse (HST) input to the input terminal 57, the start pulse (EST) input to the input terminal 63, the start pulse (VST) input to the input terminal 60, and the output pulse to the output line 64. Output of the vertical shift register 59 (VS1, VS
2, VSm) and the output of the electronic shutter shift register 62 (ES1, ES2, ES) output to the output line 65.
m) is shown.

Further, in FIG. 8, a period T10 for reading out signals from all the pixel portions 41 (one field), a period T11 for reading out signals from the pixel portions 41 for one row, and periods T13 to T29 described above. Is shown.

Here, the time from the start pulse (EST) of the electronic shutter shift register 62 switching to the high level until the start pulse (VST) of the vertical shift register 59 switching to the high level is about 1 It is in the field period.

The electronic shutter shift register 62
Of the vertical shift register 59 after the start pulse (EST) of the
ST) is the exposure time.

The time until the start pulse (VST) of the vertical shift register 59 switches to the high level is T
If it takes only 11 minutes, the exposure time is 1 / (30 ×
m) seconds. If m is 480, it is 1/1440 second.

In this embodiment, the electronic shutter shift register 62 sequentially outputs to each output line 65 (ES1, ES
2, ESm) (T21, T23, T2
5, T27), while sequentially exposing the photodiode 73, the amplification factor for amplifying the imaging data obtained by the exposure is sequentially output from the vertical shift register 59 to each output line 64 one field before ( VS1, VS2, V
Sm) (T14, T16, T18, T
20), based on the signal (T29) read out from each photodiode 73 (T30), the signals are sequentially output to the output line 64 connected to the already exposed photodiode 73 (VS1, VS2, VS2). VS
m), the imaging data is read out (T28), and amplified according to the determined amplification factor.

That is, in FIG. 8, in the second field, the signal obtained by the exposure in the first field is read out from the photodiode 73,
The amplification factor of the image data to be read is determined in the second field, the image data obtained by exposing in the second field is read out from the photodiode 73 in the third field, and the amplification data determined in the second field is amplified. Amplify at a rate.

In the first field, the exposure period of the pixel portion 41 in the first row is T13, and the readout period of signals from these pixel portions 41 is T14. Also,
The exposure period of the pixel unit 41 in the second row is T15, and the readout period of signals from these pixel units 41 is T16. The exposure period of the pixel unit 41 in the m-th row is T17, and the reading period of signals from these pixel units 41 is T18.

Therefore, in T19, the pixel portion 41 of which row is exposed, and in T20, the pixel portion 4 of which row is exposed.
The signal is read from 1.

Similarly, in the second field, the exposure period of the pixel portion 41 in the first row is T21, and the readout period of signals from these pixel portions 41 is T23. The exposure period of the pixel portion 41 in the second row is T23, and the reading period of signals from the pixel portion 41 is T24. The exposure period of the pixel portion 41 on the m-th row is T25,
The period during which the signals are read from these pixel portions 41 is T26.
Becomes

Therefore, in T27, the pixel portion 41 of which row is exposed, and in T28, the pixel portion 4 of which row is exposed.
The signal is read from 1.

In other words, the second field has an overlapping portion between the exposure periods T19 and T27 and the read period T20.

FIG. 9 is a timing chart showing a comparative example of FIG. In FIG. 9, the same parts as those shown in FIG. 8 are designated by the same reference numerals.

In the comparative example shown in FIG. 9, the exposure for determining the amplification factor for amplifying the image pickup data is performed in the first and second fields, and the signal obtained by the exposure in the second field is read from the photodiode 73. At the same time, the amplification factor is determined based on the signal.

Then, exposure for obtaining the image pickup data is performed in the third and fourth fields, and the image pickup data obtained by the exposure in the fourth field is transferred to the photodiode 7.
Read from 3. Then, the imaging data is amplified with the amplification factor determined in the second field.

In such a procedure, a period of 4 fields is required until the image data is finally read out, whereas in the procedure of the present embodiment, 3 fields are required before the image data is finally read out. The field period is sufficient, and the image can be displayed on the display unit and the like quickly, and power can be saved.

In particular, in the CMOS type image pickup device, even while the signal is being read out from the photodiode 73, the photodiode 73 which has not read out the signal continues to be exposed, so that the exposure period becomes longer than that of the CCD image pickup device.
Since the irradiation period of the LEDs 2 and 3 is long, it is effective in terms of power saving if the imaging data can be read in a period of a small number of fields.

The difference in current consumption due to this difference will be described. For the sake of simplicity, the exposure time of the electronic shutter is set to about 1 field period as shown in FIG. 9, and the power consumption of the sensor unit 6 when constantly driven is X (mW) and the current consumption of the LEDs 2 and 3 is Y (mA). ), The drive voltage of LED2,3 is E
Power consumption P1 of the image pickup apparatus of the comparative example, where (V) and T10 are T (s), and N is the number of times of image pickup of all pixel portions 41.
Is P1≈ {X × N × (2 × T)} + {Y × E × N × (2 × T)} = N × (2 × T) × (X + Y × E) (1) The power consumption P2 of the image pickup apparatus according to the embodiment is: P2≈ {X × (N + 1) × T} + {Y × E × (N + 1) × T} = T × (N + 1) × (X + Y × E) (2) Here, X = 60 mW, Y = 20 mA, T = 1/30,
If N = 2 and E = 3V, the average power consumption P1 is 16m.
W and power consumption P2 are 12 mW, and 25% power saving is possible.

Also, the driving period of the image pickup device is [2 × N ×
It becomes possible to reduce from T] (s) to [(N + 1) × T] (s).

Comparing equations (1) and (2), as the number of times N of imaging increases, the power saving effect and the shortening of the driving period are more excellent. Therefore, in general, a bar code reader, digitizer pen, which requires a large number of times N of imaging When applied to recognition devices for faces, fingerprints, irises, etc., various object recognition devices installed in cars, robots, image reading devices such as document cameras and various scanners, and mobile devices such as mobile phones and PDAs with imaging functions. It is suitable.

Further, it is also useful when the image is picked up by the outside light without using the illumination of the LEDs 2, 3, etc., because it has the effect of reducing the power consumption of the sensor section 6, and particularly, the image pick-up of a battery-driven portable terminal. It is effective for elements.

FIG. 7 is a timing chart showing the operation of three sensor units 6 of T11 including T18 of FIG.
FIG. 7 shows a timing chart for performing the rolling shutter type electronic shutter operation in the sensor unit 6.

In FIG. 7, a start pulse (HST) input to the input terminal 57, a transfer clock (HCLK) input to the input terminal 58, and m rows of the electronic shutter shift register 62 output to the output line 64. Eye output (ESm)
The output (VSm) of the m-th row of the vertical shift register 59 output to the output line 65, the original signal (SEL) of the read pulse input to the input terminal 69, and the source of the reset pulse input to the input terminal 68. The signal (RES), the original signal (TRS) of the transfer pulse input to the input terminal 67, the drive pulse (φSm) for the reading MOS transistor of the m-th row output to the signal line 46, and the output to the signal line 47. The waveforms of the drive pulse (φRm) for the reset MOS transistor of the m-th row and the drive pulse (φTm) of the transfer MOS transistor for the m-th row output to the signal line 48 are shown.

Further, FIG. 7 shows a vertical shift register 59.
A period T31 for scanning the side, a period T32 for scanning the transfer switch 52, a period T33 for accumulating electric charges based on incident light in the pixel unit 41, and a period T34 for reading out electric charges accumulated in the pixel unit 41. The period T35 mentioned above
T52 is shown.

Incidentally, the start pulse (HST), the transfer clock (HCLK), and the original signal (S
EL), the reset pulse source signal (RES), and the transfer pulse source signal (TRS) have the same waveform for each of T11 and T12. The output (ESn) of the n-th row of the electronic shutter shift register 62, which is output to the output line 64, and the output line 65.
The waveform is different from the output (VSn) of the nth row of the vertical shift register 59 which is output to the. Therefore, drive pulses (φSn, φRn, φTn) are generated as described below.

At T35, only the output pulse output to the output line 64 is switched to the high level.

Then, the OR circuit 81 and the AND circuit 84
A high level signal is input to one of the input terminals. O
Although the output terminal of the R circuit 81 is connected to one input terminal of the AND circuit 82, a low level signal is input to the other input terminal of the AND circuit 82, so the drive pulse φR remains at the low level. is there.

Further, since the original signal (RES) of the reset pulse input to the other input terminal of the AND circuit 84 remains at the low level, the AND circuit 84 outputs the signal at the low level and accordingly the drive pulse φT. Also remains low.

Since the output pulse output to the output line 65 remains at the low level until T46, AND
The drive pulse φS output from the output terminal of the circuit 85 is
The low level is maintained at least until T46.

Similarly, until T46, a low-level signal is input to one input terminal of the AND circuit 83, so that the OR circuit 86 depends exclusively on the output of the AND circuit 84 until then.

Since a high level signal is input to one input terminal of the OR circuit 81 until T40,
The output of the AND circuit 82 is the original signal of the reset pulse (RE
S) exclusively.

At T36, the high level / low level of the reset pulse original signal (RES) is switched while the high level of the output pulse output to the output line 64 is maintained.

Then, since a high level signal is input to each input terminal of the AND circuit 82, the drive pulse φR switches to a high level.

Since a high level signal is also input to each input terminal of the AND circuit 84, the drive pulse φR output from the output terminal of the OR circuit 86 is switched to a high level.

Therefore, the switches 74, 7 of the pixel section 41 are
5 is turned on, the storage capacitor 78 and the photodiode 73 are turned on.
Are reset to the reset potential VR.

At T37, the high level / low level of the original signal (SEL) of the read pulse is switched while the high level of the output pulse output to the output line 64 is maintained.

At this time, a high-level signal is input to one input terminal of the AND circuit 85.
Since the output pulse to the output line 64 is at the low level as described in the description of item 5, the drive pulse φ remains at the low level.

Since a low level signal is input to one input terminal of the AND circuit 82 and each input terminal of the OR circuit 86, the drive pulses φR and φT remain low level.

At T38, the high level / low level of the transfer pulse source signal (TRS) is switched while the high level of the output pulse output to the output line 64 is maintained.

At this time, a high-level signal is input to one input terminal of the AND circuit 83.
Since the output pulse to the output line 64 is at a low level as described in the description of item 5, a low level signal is output to one input terminal of the OR circuit 86. Further, since a low level signal is input to one input terminal of the AND circuit 84, a low level signal is also input to the other input terminal of the OR circuit 86, and the drive pulse φT remains low level. is there.

At T39, the same operation as at T37 is performed.

At T40, the transfer clock (HCLK) is switched between high level and low level.

Then, the transfer switch 52 is sequentially turned on / off. However, the drive pulse φS is generated between T35 and T39.
Remains at the low level, the switch 76 of the pixel unit 41 remains off, the signal is not read from the pixel unit 41, and the signal from the pixel unit 41 is accumulated in the vertical signal line capacitor 51. Therefore, no signal is transferred to the output amplifier 54 side.

In T41 to T46, since the output pulses to the output lines 64 and 65 are low level, the AND circuit 82
Since a low-level signal is input to each of the input terminals of each of the drive pulses ~ 85, the drive pulses φS, φR, and φT.
Remains low.

At T47, only the output pulse output to the output line 65 is switched to the high level.

Then, the OR circuit 81 and the AND circuit 85
A high level signal is input to one of the input terminals. O
Although the output terminal of the R circuit 81 is connected to one input terminal of the AND circuit 82, a low level signal is input to the other input terminal of the AND circuit 82, so the drive pulse φR remains at the low level. is there.

Further, since the original signal (RES) of the reset pulse input to the other input terminal of the AND circuit 82 remains low level, the AND circuit 82 outputs a low level signal, and accordingly the drive pulse φR. Also remains low.

Since the output pulse output to the output line 64 remains at the low level until T52, AND
The signal output from the output terminal of the circuit 84 is maintained at a low level at least until T52, and the output of the OR circuit 48 depends exclusively on the signal output from the AND circuit 83.

Similarly, since a high-level signal is input to one input terminal of the AND circuit 83 until T52, the output of the AND circuit 83 depends exclusively on the original signal (TRS) of the transfer pulse, Therefore, the output of the OR circuit 86 depends exclusively on the original signal (TRS) of the transfer pulse.

Since a high level signal is input to one input terminal of the OR circuit 81 until T52,
The output of the AND circuit 82 is the original signal of the reset pulse (RE
S) exclusively.

At T48, the high level / low level of the reset pulse source signal (RES) is switched while the high level of the output pulse being output to the output line 65 is maintained.

Then, since a high level signal is input to each input terminal of the AND circuit 82, the drive pulse φR switches to a high level. Therefore, the switch 74 of the pixel unit 41 is turned on and the storage capacitor 78 is reset.

At T49, the high level / low level of the original signal (SEL) of the read pulse is switched while maintaining the high level of the output pulse output to the output line 65.

Then, since a high level signal is input to each input terminal of the AND circuit 85, the drive pulse φS switches to a high level. Therefore, the switch 76 of the pixel unit 41 is turned on, and the amplified signal based on the noise component generated at the reset at T48 is read from the pixel unit 41 and accumulated in the vertical signal line capacitor 51.

The original signal of the reset pulse (RES)
Since both of the transfer pulse and the original signal (TRS) of the transfer pulse are at the low level, the drive pulses φR and φT remain at the low level.

At T50, the high level / low level of the transfer pulse source signal (TRS) is switched while the high level of the output pulse being output to the output line 65 is maintained.

Then, as described in T47, the AND circuit 83 outputs a high level signal,
The drive pulse φT switches to the high level. For this reason,
The switch 75 of the pixel portion 41 is turned on, and the charge accumulated in the photodiode 73 is transferred to the storage capacitor 78.

The original signal of the reset pulse (RES)
Since both the selection pulse and the original signal (SEL) of the selection pulse are at the low level, the drive pulses φR and φS remain at the low level.

At T51, the same operation as at T49 is performed.
Then, the switch 76 is turned on, and the amplified signal based on the charges of the storage capacitor 78 and the floating diffusion region is read from the pixel unit 41. This signal and the signal based on the noise component at the time of reset accumulated in the vertical signal line capacitance 51 are differentiated by a difference circuit (not shown), and the signal from which the noise component is removed is accumulated in the vertical signal line capacitance 51.

At T52, the transfer clock (HCLK) is switched between high level and low level.

Then, the transfer switch 52 is sequentially turned on / off, and the signals accumulated in the vertical signal line capacitance 51 are sequentially transferred to the output amplifier 54 side.

By performing the above operation by shifting the electronic shutter shift register 62 and the vertical shift register 59 by the same horizontal scanning period, the charge accumulation time of all the pixel portions 41 becomes the same, and in the short exposure. Imaging, that is, electronic shutter operation is realized.

In this way, in continuous two-field imaging, it is possible to change the image acquisition condition of the second field based on the read data of the imaging screen of the first field.

(Second Embodiment) FIG. 10 is a block diagram showing the internal structure of the DSP section 23 of the portable bar code reader according to the second embodiment of the present invention. FIG. 11 shows D shown in FIG.
6 is a flowchart showing an operation of a portable barcode reader including the SP unit 23.

In FIG. 10, the same parts as those shown in FIG. 6 are designated by the same reference numerals. Also, FIG.
In the case of 0, the processing may be performed by hardware as in the case of FIG. 6, but the operation described below can be shortened by performing by software as shown in FIG.

First, by the same method as in the first embodiment,
The microcomputer section 12 detects that the operation switch 13 has been operated based on this signal (step S1).

Then, the microcomputer section 12 turns on the LEDs 2 and 3 by the same method as in the first embodiment (step S2).

Further, the microcomputer section 12 switches the sensor section 6 to the image pickup mode by the same method as in the first embodiment (step S3).

Then, the exposure is performed for a predetermined length of electronic shutter time. The imaging data obtained by the exposure is processed by the front end processing unit 21, and the integration circuit 2
3a is output.

The integrating circuit 23 a integrates the image pickup data output from the front end processing section 21 and outputs the integrated value to the microcomputer section 12.

The microcomputer section 12 determines whether or not the electronic shutter time is an appropriate time based on the integrated value output from the integrating circuit 23a (step S4).

As a result of the determination, if the electronic shutter time is an appropriate time, the process proceeds to step S5, and if not, the process proceeds to step S9.

In step S9, it is determined whether the electronic shutter time is long and is not appropriate.

As a result of the determination, if the electronic shutter time is long, the process proceeds to step S10, and if not, the process proceeds to step S11.

In step S10, the electronic shutter time is shortened by one step, for example, and the process returns to step S5. Specifically, the TG unit 26 is instructed to shorten the electronic shutter time. By the way, in the present embodiment, when shortening by one step, it is shortened to, for example, 3/4.

In step S11, the electronic shutter time is increased by one step, for example, and the process returns to step S5. Specifically, the TG unit 26 is instructed to extend the electronic shutter time. By the way, in the present embodiment, when shortening by one step, it is shortened to, for example, 4/3.

If the electronic shutter time is an appropriate time,
The electronic shutter time is stored so that the actual image capturing can be performed with the electronic shutter time (step S5).

Then, in order to reduce the power consumption, the microcomputer section 12 changes the sensor section 6 from the image pickup mode to the standby mode through the TG section 26 (step S6).

Further, the microcomputer section 12 outputs a control signal to the LED control section 30 to turn off the LEDs 2 and 3. As a result, the LEDs 2 and 3 are turned off (step S
7).

Then, the user waits for the operation of the operation switch 13 (step S).
8).

FIG. 12 shows steps S10 and S1 of FIG.
FIG. 3 is an explanatory diagram of a method of adjusting the electronic shutter time in No. 1.
FIG. 12 shows a test chart of a gray scale pattern in which the density changes in four steps as an imaged subject.

In FIG. 12, 101 is the whole gray scale pattern, 102 is the whole gray scale pattern 1
01 is the reflectance, 103 is the axis indicating the reflectance 102, 104
˜107, the reflectance 102 is 25%, 50%, 7 respectively.
5%, 100% area, 108 in the horizontal scanning direction, 1
09 indicates the vertical scanning direction.

FIG. 13 shows steps S3, S4 and S9 of FIG. 11 when the test chart shown in FIG. 12 is used as a subject.
It is explanatory drawing of operation | movement of the sensor part 6 in S11. In addition,
In FIG. 13, the same periods as in FIG. 8 are designated by the same reference numerals. Here, the electronic shutter shift register 62
The electronic shutter time is from the rising edge of the start pulse (EST) input to the vertical shift register 59 to the rising edge of the start pulse (VST) input to the vertical shift register 59.

First, in the first field, exposure is performed for the electronic shutter time when the setting of the sensor section 6 is changed to the image pickup mode in step S3 (T13), and the image pickup data obtained by this exposure is read (T20). The output waveform (a) of the sensor unit is obtained.

A part of the center of the output waveform (a) of the sensor section is extracted (T29), and based on this signal, it is determined in step S4 whether the electronic shutter time is appropriate.
Here, since the output waveform (a) of the sensor unit is not the required waveform, it is determined in step S9 whether the electronic shutter time is long, and the electronic shutter time is shortened by one step in step S10 (T30).

Specifically, the electronic shutter time is changed by changing the pulse width of the start pulse (EST) input to the electronic shutter shift register 62.

Then, exposure is performed with the electronic shutter time changed in the second field (T21), the imaging data obtained by this exposure is read (T28), and the output waveform (b) of the sensor section is obtained.

A part of the center of the output waveform (b) of the sensor section is extracted (T29), and based on this signal, it is determined in step S4 whether the electronic shutter time is appropriate.
Here, since the output waveform (a) of the sensor unit is not the required waveform, it is determined in step S9 whether the electronic shutter time is long, and the electronic shutter time is shortened by one step in step S10 (T30).

By the same method, step S in FIG.
By forming the loop of 9 to S11, the output waveform (d) of the sensor unit, which is a required waveform, can be obtained.

Since the output waveforms (a) to (d) of the sensor section are obtained based on the image pickup data read one field before, the output waveform (a) is obtained based on the average of the image pickup data of several fields. ) To (d), the output waveform (d) can be obtained faster.

Third Embodiment In the first and second embodiments, the case where the sensor section 6 is provided with the electronic shutter shift register 62 has been described as an example, but the electronic shutter shift register 6 is described.
Even with a barcode reader that does not include the sensor unit 6 of the type that does not include the sensor 2, it is possible to achieve low power consumption by performing imaging using the method described below.

FIG. 14 is an explanatory view of the operation of the sensor section 6 according to the third embodiment of the present invention, which is similar to FIG. The configuration of the barcode reader of this embodiment is the same as the configuration shown in FIG. Further, the DSP unit 23
Although the operation as shown in FIG. 11 is performed, the control target is the light amount of the LEDs 2 and 3 instead of the electronic shutter time.

As shown in FIG. 14, the exposure is performed while the LEDs 2 and 3 are emitting light with a predetermined intensity and a predetermined amount of LED light amount (e). Imaging data obtained by exposure is
The signal is read when VCLK is applied, processed by the front end processing unit 21, and output to the integrating circuit 23a.

The integrating circuit 23a integrates the image pickup data output from the front end processing section 21 and outputs an integrated value indicating the output waveform (a) of the sensor section to the microcomputer section 12.

The microcomputer section 12 determines whether or not the LED light amount (e) is appropriate based on the integrated value output from the integrating circuit 23a.

If the light quantity of the LEDs 2 and 3 is not appropriate as a result of the judgment, it is judged whether or not the light quantity is large. As a result of the determination, if the light amount of the LEDs 2 and 3 is large, the light amount is decreased by, for example, one step, and if not, the light amount is increased by, for example, one step and the light amounts of the LEDs 2 and 3 are adjusted until appropriate.

Here, since the LED light amount (e) is large,
The light amount is reduced and adjusted until the light amount of the LEDs 2 and 3 becomes appropriate. Specifically, for example, LEDs 2 and 3
The drive voltage applied to the LED is reduced, the period for applying the drive voltage is shortened, or one of the LEDs 2 and 3 is not turned on.

If the light amounts of the LEDs 2 and 3 are appropriate, the light amounts are stored so that the actual image pickup can be performed with the light amounts.

[0166]

As described above, according to the present invention,
Since it is possible to reduce the power consumption of the imaging device,
For example, an image processing system such as a handy bar code reader can be used for a long time.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a handy type barcode reader according to a first embodiment of the present invention.

2 is a block diagram showing an internal configuration of an image processing unit 9 in FIG.

3 is a block diagram showing an internal configuration of a sensor unit 6 of FIG.

4 is a block diagram showing a configuration of a pixel portion 41 of FIG.

5 is a block diagram showing a circuit configuration of a selector section 66 in FIG.

6 is a block diagram showing an internal configuration of a DSP unit 23 and a front end processing unit 21 of FIG.

7 is a sensor unit 6 for three T11s including T18 of FIG. 8;
3 is a timing chart showing the operation of FIG.

FIG. 8 is a timing chart showing the operation of the sensor unit 6 of FIG.

9 is a timing chart showing a comparative example of FIG.

FIG. 10 is a block diagram showing an internal configuration of a DSP unit 23 of the portable barcode reader according to the second embodiment of the present invention.

11 is a flowchart showing the operation of the portable barcode reader including the DSP unit 23 shown in FIG.

FIG. 12 is an explanatory diagram of a method of adjusting the electronic shutter time in steps S10 and S11 of FIG.

13 is an explanatory diagram of the operation of the sensor unit 6 in steps S3, S4, S9 to S11 of FIG. 11 when the test chart shown in FIG. 12 is used as a subject.

FIG. 14 is an explanatory diagram of an operation of the sensor unit 6 according to the third embodiment of the present invention.

[Explanation of symbols]

1 Bar code reader body 2,3 LED 4 mirror 5 lenses 6 sensor 7, 10, 14 signal lines 8, 11, 15 control lines 9 Image processing section 12 Microcomputer section 13 Operation switch 16 Records 17 barcode 18,19 Illumination light 20 reflected light 21 Front-end processing section 23 DSP 24 Crystal oscillator 25 signal lines 26 Timing generator 40 constant current source 41 pixels 42 to 44 input terminals 45 signal readout terminal 46-48 signal line 49 Vertical signal line 51 capacity 52 Transfer switch 54 output amplifier 55 Output terminal 56 Horizontal shift register 57, 58, 60, 61, 63, 66 to 69 input terminals 59 Vertical shift register 62 Shift register for electronic shutter 64,65 output line 71 Power supply voltage 72 Reset voltage 73 Photodiode 74-77 switch 78 Parasitic capacitance 79 Ground 81,86 OR circuit 82-85 AND circuit 23a integrating circuit 89 Look-up table 90 D / A converter 91 control unit 92 GCA 93 ADC

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5B072 AA06 CC24 DD02 DD21 JJ11                       LL07 LL13 LL16 LL18                 5C022 AA00 AB15 AB17 AB20 AB31                       AB67 AC42                 5C024 AX02 CY42 EX00 GY31 HX18                       JX00

Claims (7)

[Claims] 1. An image pickup apparatus for sequentially reading image data obtained by exposure from an image pickup device that has completed exposure while sequentially exposing image pickup devices arranged two-dimensionally, and amplifying the signal. An imaging device comprising means for determining the rate based on the imaging data read out one field before. 2. An image pickup device for sequentially reading image data obtained by exposure from an image pickup device which has completed exposure while sequentially exposing image pickup devices arranged two-dimensionally, wherein the exposure amount at the time of the exposure is one field before. An image pickup apparatus comprising means for making a decision based on the image pickup data read out to. 3. An image pickup apparatus, which sequentially exposes an image of an object from the image pickup element while illuminating the object by an illuminating unit, and reads out sequential image pickup data obtained by the exposure from the image pickup element whose exposure has been completed. An imaging device comprising means for determining the illumination intensity or illumination time of the illumination means based on the imaging data read out one field before. 4. The image pickup apparatus according to claim 1, wherein the image pickup element is a MOS type image pickup element or a charge-coupled element. 5. The imaging device body is portable.
5. The image pickup device according to any one of items 4 to 4. 6. An image processing system comprising: the image pickup device according to claim 1; and a processing device which processes an image signal picked up by the image pickup device. 7. The image processing system according to claim 6, wherein the processing device is a subject matching device, a code reader, or a crime prevention device.