JPH0245396B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging system that combines a linear array sensor and a scanning mirror to obtain visible high-resolution images.
More specifically, a linear array sensor in which light-receiving elements are arranged in a line, and a charge transfer unit that outputs a time-series signal by driving and transferring the charge from each light-receiving element of the linear array sensor in a main scan; The present invention relates to a new driving method for a solid-state imaging device equipped with a sub-scanning mirror.

Generally, in fields that require high-resolution visible images, for example, a combination of CCD and linear array sensor is used.
Using a long sensor such as a CCD linear sensor,
Mechanical scanning is performed in a direction perpendicular to the arrangement direction of the linear array sensors. This mechanical scanning becomes the sub-scanning of the imaging device. A case will be described below in which a vibrating mirror is used for sub-scanning and its motion is at a constant angular velocity.

FIG. 1 is a conceptual diagram of main parts showing an example of the configuration of a visible long sensor consisting of a linear array sensor and a charge transfer section, in which 1' is a light receiving element, and each light receiving element 1' is arranged in a line shape. They are arranged to form a linear array sensor 1. Charge transfer section 2 shown adjacent to linear array sensor 1 and largely surrounded by a dashed line
The charges photoelectrically converted by the light receiving element 1' are transferred directly under the charge transfer electrode 4 or 5 through each charge storage region 3', and the transferred charges are driven by main scanning and transferred. It is designed to be output from the output terminal OUT as a series signal.

FIG. 2 is a conceptual diagram of main parts showing the configuration of a solid-state imaging device consisting of a combination of a visible long sensor and a sub-scanning vibrating mirror as described above, and the incident light P from the object to be imaged is used for sub-scanning. It is reflected by the vibrating mirror 6 and passes through the lens 7 to form an image on the linear array sensor of the elongated sensor 8 . At this time, the sub-scanning vibrating mirror 6 repeatedly rotates around the fulcrum 9 and moves at a constant angular velocity to perform sub-scanning.

As described above, the signal light imaged on the linear array sensor is photoelectrically converted and transferred directly below the charge transfer electrodes 4 and 5 of the CCD through the charge storage region 3'.
The transfer clock voltages φ ₁ and φ ₂ applied to the CCD are output from the output terminal OUT, and this output signal passes through the video signal processing section 10 and becomes a luminance signal Z of an appropriate level, which is then displayed on the monitor display 11. Given. On the other hand, according to the movement of the scanning mirror 6, a synchronization signal synchronized with the repetitive movement of the scanning mirror 6 is generated by intermittent incident light incident on a phototransistor (not shown) for detecting the rotational position of the scanning mirror 6. Then, the synchronization signal is generated by the synchronization signal generating section 12. Further, the drive signal generating section 13 receives the synchronization signal and generates sweep signals in the X and Y directions, blanking signals, etc. necessary for sweeping the monitor display 11. A conventional imaging method using such an imaging system will be explained using a time chart shown in FIG.

First, the movement of the scanning mirror 3 is shown in time chart a. This movement is a repetition of reciprocation, and the movement is temporally reciprocated within the range of deflection angle θ from the equilibrium position. The scanning angular velocity θ of the scanning mirror 3 obtained by differentiating this θ with respect to time t is shown in b. The upper and lower portions of the waveform shown in b indicate the direction of movement from the equilibrium position of the reciprocating motion, respectively. In this figure, there is a period in which the scanning angular velocity θ is constant, and this period is the effective scanning range of the sub-scanning mirror 3.

On the other hand, an ideal main scanning waveform of a solid-state functional sensor having a main scanning function of an imaging device is shown in c. This waveform corresponds to the case where an integral multiple of one period _t1 of the main scanning matches one period of vibration of the scanning mirror 3 that performs the sub-scanning, that is, the scanning period of one frame. The main scanning is synchronized, but since conventional methods did not have a means of synchronizing the main scanning and sub-scanning, the main scanning waveform was as shown in c' of the time chart, and each frame caused the sub-scanning mirror to On the imaging plane, the effective scanning start time and the scanning timing of the main scanning are shifted by Δt.
That is, this method has the drawback that fluctuations (jitter) in the scanning position occur on the screen of the monitor display, resulting in an unclear image. Note that in FIG. 3, diagram d shows the effective scanning period of the sub-scanning mirror.

The present invention eliminates the above-mentioned drawbacks by suppressing fluctuations in the scanning position on the monitor display surface to within at most one clock of the drive pulse for driving the solid-state functional sensor that is the main scanning device. The aim is to minimize the fluctuation of the linear array sensor, which has a linear array sensor with a main scanning function and a scanning mirror with a sub-scanning function. In an imaging method that completes one main scan of the scanning mirror and completes one frame scanning of the entire screen in one scanning period of the sub-scanning mirror, a detection means is provided for detecting the initial position of the scanning of the scanning mirror, The detection signal from the detection means is taken in as a synchronization signal that provides the initial scanning timing of a linear array sensor having a main scanning function. That is, the synchronizing signal from the synchronizing signal generating section 12 shown in FIG. Control is performed so that effective main scanning starts at the timing when scanning ends and the next frame scan begins. Note that 15 is a driving power source for the solid-state functional sensor.

FIG. 3e is a synchronization signal according to the present invention, which is generated at the initial position of each frame scan. Also, Figure 3 f
is the main scanning waveform of the present invention, where the solid line portion indicates the main scanning period in which the output of the solid-state functional sensor contributes as a repetitive scanning signal to create one frame of the screen of the monitor display 11, and the broken line portion indicates the period of one frame. During the blanking period on the monitor display, during which the solid-state functional sensor is transferred from the solid-state functional sensor and the remaining charges of the transfer section CCD of the solid-state functional sensor are discharged to the outside, the screen scan is completed. Indicates the period during which no contribution is made. In the present invention, the timing generation circuit 14 is configured to operate so as to end the transfer period at the falling timing _t0 of the synchronization signal and at the same time provide the initial timing of main scanning that contributes to screen scanning. With this configuration, the initial timing of the main scan is set for each frame scan, so that a high-quality screen can be obtained without fluctuations in the scanning lines on the screen as in the conventional case.

Next, FIG. 5 shows a block diagram of a timing generation circuit that obtains the screen scanning timing, and FIG. 4 shows an operation timing diagram of the solid-state functional sensor.
The scanning method of the present invention will be explained using FIGS. 4 and 5.

FIG. 4 is a timing chart showing the drive signals applied to each bus bar of the charge transfer section of the elongated sensor, that is, the solid-state functional sensor shown in FIG. 1, and the output signal from the output terminal, with corresponding symbols. One main scanning period is shown, and since C is provided within one main scanning period, it is a period in which the output signal (OUT) corresponding to the transfer time is not output. The charges photoelectrically converted by each light receiving element 1' shown in FIG.
A voltage is applied to the transfer gate TG, and the charge is transferred directly under the charge transfer electrode 5 connected to the bus φ _1. A voltage is further applied to the bus φ ₂ , and a voltage is applied alternately to φ ₁ and φ ₂ . Charges are transferred sequentially and output as a time-series signal from the output terminal OUT. Here, RS is a reset pulse for reading. Note that BG is an accumulation gate, and in order to keep the charge accumulation time constant, it is necessary to keep the voltage cycle applied to this accumulation gate BG constant.

Next, the timing generation circuit will be explained using the block diagram of FIG. The counter 17 is connected to a P-ROM 20 and a P-ROM 21 in which the timing of the solid-state functional sensor explained in FIG. 4 is written.
The counter 23 is a counter that scans the third
This is a counter for counting the number of main scans shown in FIG. First, the switching timing generator 19 changes the timing logic to "1" when the synchronization signal shown in FIG. A binary signal FRM is generated which is inverted to logic "0" at the time when scanning is started, that is, at point P in FIG. The FRM signal is input to the counter control section 18, and based on this signal, a counter preset signal LD is generated for the counter 17 and counter 23, and each starts counting. The counter 17 outputs a completion signal RC to the counter control unit at the time when main scanning B shown in FIG.
Upon receiving the signal, it generates an LD signal for the counter 17. Further, a count up signal EN is generated for the counter 23. In this way, the counter 23 is a counter that increments the contents one by one for each main scan, and is a counter for the number of main scan lines scanned. Furthermore, counter 2
3 is for the switching timing generator 19, FRM
A signal SFRM is provided which inverts the signal to a logic "0". As described above, the counter 17 and the counter 23 repeat the main scanning necessary for frame scanning. At this time, the P-ROM 20 has the main scanning timing shown by B in FIG. 4, and the P-ROM 21 has the C
Since the transfer timing is written as shown in , the data selector 22 indicates that the FRM signal is logic "1".
When the logic value becomes "0", the output from the P-ROM 20 is selected, and when the logic becomes "0", the output from the P-ROM 21 is selected. That is, when the required number of main scans are completed, the FRM signal is inverted to logic "0", and then the transfer operation begins. When the transfer operation starts, the counter control section stops the LD signal in response to the RC signal of the counter 17 using the FRM signal.
The counter 17 free runs and repeats the binary number counted by the counter 17 from 0 to the maximum. Further, when an up counter is used as the counter 17, it is necessary to configure the structure so that transfer continues even when the counter number changes from the maximum to 0. To obtain such an arrangement, _the P-ROM has a number of addresses, usually expressed as 2 ^N , while _, for the timing of FIG. If the counter 17 is operated with the reset pulse RS width being 1/4 of A), exactly an integer multiple of section A can be written to the P-ROM. from 0
The timing of the transfer can be made continuous when changing from to .

However, regarding the signal applied to the storage gate BG during the last main scanning and transfer period of one frame,
During this time, it is undesirable for the solid state functional sensor to be in the accumulation state, so it is necessary to keep it at level 0. This means that if the SFRM signal is a signal that outputs logic "1" during the last main scan of one frame,
The original BG over the entirety of one frame is as shown in the following equation. BG・(FRM+SFRM)・SFRM However, BG in the above formula indicates the BG signal shown in FIG. Here, * indicates logical product, and + indicates logical sum.

As described above, transfer continues until a synchronization signal indicating the next frame scan is received.

Although the P-ROMs 20 and 21 surrounded by broken lines in FIG. 5 have been described as being separate, they can be replaced by one memory with a larger capacity, and in this case, the data selector 22 is not necessary.

As explained above, a high-resolution image can be obtained by controlling the scanning clock of the solid-state functional sensor that performs main scanning using the synchronization signal obtained from the sub-scanning mirror.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of main parts showing an example configuration of a solid-state functional sensor having a linear array sensor and a charge transfer section, Fig. 2 is a conceptual diagram of main parts showing the structure of a solid-state imaging device, and Fig. 3 is a conceptual diagram of main parts showing the structure of a solid-state imaging device. 4 is a timing chart showing the operation timing of the solid-state functional sensor shown in FIG. 1, and FIG. 5 is a timing chart of the drive signal applied to each bus bar of the solid-state functional sensor shown in FIG. 1: Linear array sensor, 2: Charge transfer section,
3': Charge storage region, 4, 5: Charge transfer electrode,
6: Sub-scanning vibrating mirror, 7: Lens, 8: Solid-state functional sensor, 9: Fulcrum, 10: Video signal processing section, 1
1: Monitor display, 12: Synchronization signal generation section, 13: Drive signal generation section, 14: Timing generation circuit, 15: Drive power supply, 17: Counter, 1
8: Counter control section, 19: Switching timing generation section, 20, 21: P-ROM, 22: Data selector, 23: Counter.

Claims (1)

[Claims] 1 It has a linear array sensor with a main scanning function and a scanning mirror with a sub-scanning function, and one main scan of the linear array sensor is completed within a minute scanning angle of the sub-scanning mirror, and one scanning period of the sub-scanning mirror full screen 1
In an imaging method that completes frame scanning, a detection means is provided for detecting the initial scanning position of the sub-scanning mirror, and a detection signal from the detection means is used to determine the initial scanning timing of a linear array sensor having a main scanning function. An imaging method characterized in that it is captured as a synchronization signal.