JPS63120216A - Image sensor - Google Patents

Abstract

PURPOSE:To obtain an image sensor responding to the abrupt change in quantity of light, by providing a light receiving sensor and a reference charge control part detecting the change in the electric output of said sensor to regulate the charge accumulation time of the sensor. CONSTITUTION:When an image sensor advances along a light and shade boundary part in the state mounted to a moving vehicle, the lights from the light and dark places collimated by an optical system 1 pass through the optical system 1 to be received by the sensor (CCD row) 2 to accumulate charge. The accumulated voltage is converted to an electric signal to be sent to a reference charge control part 3. The control part 3 detects the output change of the electric signal and shortens the light receiving time of the sensor when the output is higher than a reference value and extends the same when the output is lower than the reference value to keep said output in the vicinity of reference output. By this constitution, light receiving quantity can be regulated at a high speed hard to respond by the regulation of an iris only by the program control of the control part 3 and a structure is simplified.

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an image sensor that is used for mobile work outdoors. Tractor equipped with a machine, combine harvester, and seedling transplanter 2
It can be used as a sensor for automatic control of the direction of travel, etc.

Conventional technology and problems to be solved by the invention Conventional image sensors are mainly for indoor use and do not require adjustment of the amount of light received, and for image detection, the period of electrical screen scanning is fixed. was.

For example, when using an image sensor in a mobile agricultural machine for outdoor work, the brightness of natural light often changes rapidly, and moreover, when a camera equipped with an image sensor is freely rotated and rotated, the brightness of natural light often changes rapidly. Changes in the amount of light are generally responded to using an aperture mechanism within the optical system, but structures that perform mechanical aperture adjustment at high speed are bulky and inconvenient to use.
In addition to being expensive, the response speed to rapid changes in the amount of light was slow.This invention is a first step to solving the problems.This invention detects the received light transmitted through the optical system (1) and converts it into an electrical signal. The light receiving sensor (2) is changed and the charge accumulation time (2) of the light receiving sensor (2) is determined by detecting the change in the output of this electric signal.
The image sensor has a configuration including a reference charge control unit (3) for increasing and decreasing TA.

Functions and Effects of the Invention When an image sensor is installed on a mobile agricultural machine, for example, and travels along the boundary between bright and dark areas, the light rays from the bright and dark areas that are referenced by the optical system (1) are reflected by the optical system (1). 1) and is received by the light receiving sensor (2), charge is accumulated in the light receiving sensor (2), and this accumulated voltage is converted into an electric signal and transmitted to the reference charge control section (3). The reference charge control unit (3) detects the change in the output of the electric signal from the light receiving sensor (2), and if the output is higher than the reference charge, it adjusts the charge accumulation time (a) of the light receiving sensor (2) to be shorter. If the method is changed and the output of the electrical signal is low, ′:! Adjust the one charge accumulation time (a) to be longer to maintain it near the output of the reference charge. The charge accumulation time corresponds to the exposure time in a camera using general film, and the light receiving sensor (
2), and the reference charge control unit (3) binarizes and judges the positions of the bright and dark areas in the outside world as determined by the optical system (1). In case,
This is good because the binarization level does not change too much.

In this way, the amount of light received can be adjusted simply by program control of the reference charge control section (3) at a high response speed that is difficult to respond to by adjusting the aperture in the optical system (1), which is generally performed to adjust the amount of light received by the image sensor. This is good because the structure is simple and inexpensive.

Embodiment In the illustrated example, the optical system (1) includes a telephoto lens system housed in a lens barrel (4).

The light-receiving sensor (2) is a linear image sensor in which a charge-coupled device (CCD), for example, 512 bits, is arranged in the - column. They are arranged in rows in the same direction. This light-receiving sensor (2) is capable of accumulating a charge in each bit of the light beam received for a time corresponding to a set count number of the start pulse transmitted from the reference charge control section (3).
The output of the accumulated charge is transmitted to the reference charge control section (3). The cylindrical part (4) of the optical system (1) and the camera case (5) housing the light receiving sensor (2) are connected, and the camera case (5) includes an internal camera circuit (6). This in-camera circuit (6) is provided with a noise filter (7) and a data holder (8) of a transmission circuit from the light receiving sensor (2) to the reference charge control section (3). Camera case (
5) is provided with a vertical hollow rotation shaft (9) on its lower side.

The reference charge 1tIII control section (3) is connected to the camera case (5).
) is installed at the bottom of a fixed case (11) that rotatably supports the rotating wheel (9) of the camera with a bearing (lO), and the hollow rotating shaft (9) A wiring (12) passing through the inside is connected.

This reference charge control section (3) is mainly constituted by an EPU (13), and controls the level (voltage) of data held by the data holder (8) and a reference value setting section that communicates with the inside of the CPU (13). CPU (13) via a comparator (15) that compares the level set in (14) and a register (1O) that stores and holds the comparison data of this comparator (15).
It is input internally.

Based on this input, the charge accumulation time (
The output when it is decided to change the CPU (13
) from the start counter (17) directly to the light receiving sensor (
It is input to S in 2). In addition, the clock pulse (Φ) from the clock pulse transmitter (18) is transmitted to the light receiving sensor (
2).

In addition, from the CPU (13), the camera case (5)
In addition to providing an input/output circuit to a camera direction control section (20) that controls a motor (19) that rotates the section and other controls,
Based on the information of these CPUs (13), the work vehicle body (21
) is equipped with an input/output circuit to control the control equipment, etc.

The fixed case (11) includes the reference charge control section (3).
In addition, a rotating pulse motor (
18) and its transmission gear mechanism (22).

The pulse motor (18) and the transmission gear machine i (22) are configured so that they can be used with the camera case (5) fixed without rotating.

The light-receiving sensor (2) consisting of a linear image sensor has a light λ width (c) of outdoor light such as a clear day, a cloudy day, morning, noon, and evening, expressed as a number from O to 10, as shown in Figure 3. As shown in , the sensitivity It @ (d) is narrow, and in order to detect the bright and dark dead areas from this sensitivity width (d), the broad frame is adjusted with the aperture of the optical system (1) depending on the circumstances of the day and time. Then, in order to adjust the high-speed response within that range, the sensitivity range (d) of the light receiving sensor (2) is shifted to the bright/dark side. - Generally, in a charge-coupled device, under a constant brightness condition, the charge (voltage) accumulated in each device bit increases or decreases in proportion to the decay of the light reception time. To this end, as shown in Fig. 4, for example, each bit of 512 bits is charged for a time (usually 2 to 3 milliseconds) whose charge accumulation time (A) can be expressed by the number of pulses of the clock pulse (φ). , this (a) is automatically terminated, and the reference charge control unit (3
), and when this output ends, the charge accumulation time (a) returns to the start of time 0 and is repeated. As shown in Figure 2, the output signal of each bit is filtered with noise by a noise filter (7), and outputted to a comparator (15) with -1ν data held in a data holder (8). (15) compares it with the set voltage level value from the reference value setting unit (10), converts it into a binary value, and reads it into the register (16).This data is read into the register (16).
3) determines the charge accumulation time (a) of the light receiving sensor (2).
To change the charge accumulation time (17) from the start counter (17) in eP11 (13),
b) It is only necessary to change the count number of the corresponding Glock pulse (φ) to the light receiving sensor (2).

An image sensor (23) with such an action is attached to the front part of the control section (20) on the right side in the direction of travel (E) of the combine harvester, which is the work vehicle body (21), and is attached to the front part of the control section (20) on the right side in the direction of travel (E) of the combine harvester, which is the work vehicle body (21). In an example in which the work vehicle body (21) is moved forward along the boundary (H) to proceed with reaping while referring to the dark part of the soil surface at the boundary (H) with the image sensor (23
) is fixed to the work vehicle body (21) in its traveling direction (E), and has a horizontal field of view (N) along a line in the left and right direction at a certain distance (S) from the image sensor (23). Then, the bright and dark areas within this field of view (N) are received by all the 512-bit elements of the light receiving sensor (2), and a voltage graph showing the brightness and darkness at the reference level of the output of each bit at this time is shown. If the reference level curve (R) in FIG. 6(b) is used, if the reference charge control of each bit of the light receiving sensor (2) is not performed, the bright level curve (O) or the dark level curve (R) in the same figure will be used. It fluctuates up and down like w). The maximum level (power) indicates the brightest place on the reference level curve (L), the minimum level (Y) indicates the 9 parts of lcla, and the average level (RI) indicates the average brightness. When the dark part (l/) of the widest width (number of bits) of the graph shown in (C) after binarizing into the graph does not reach a predetermined value (number of bits) that can be determined as the boundary part (ch), this binary value is When the binarization is started by moving the binarization level little by little in a short period of time and binarization is performed at the discovery level (n), the boundary part (c) can be cut off using the binarization graph shown in (d). It is determined that the dark area has a predetermined width (number of bits), and if the position of this dark area is located at the center of all 512 bits, it can be determined that the process is progressing correctly. If it is shifted to the left or right, the combine harvester of the work vehicle body (21) is shifted to the left or right from the boundary (H), and the control device of the work vehicle body (21) is not connected to the CPU (13). It is controlled to correct its advancing position and align it with the boundary (h).

Therefore, if reference charge control is not performed, if the voltage level at the binary level fluctuates greatly due to changes in the weather, such as the bright level curve (O) or the dark level curve (W), the voltage level will be binarized and the voltage level will be changed within a predetermined width. It takes a lot of calculation time to find the dark area (T), which causes a delay in the control of the work vehicle body (21), but with the configuration shown in the example, it can be concentrated near the reference level curve (L). Because it can be done quickly, the work vehicle body (2
1) can be used for control.

The rotation of the image sensor (23) is determined by measuring the direction and distance of the balls (2B) provided at the three corners of the rectangular field (25) shown in FIG. In the field, such as a tractor working machine (27) equipped with
25) and detects the position of the tractor working machine (27).
This is used when controlling the direction of travel (e), etc.

Furthermore, what is shown in FIG. 8 is another embodiment, in which a start counter section (17) is provided in the camera internal circuit (6), and the epu
(13) changes the designation of the clock pulse, receives this changed pulse from the clock pulse transmitter (1st) to the start counter part (17), and sends the clock pulse (φ) to the light receiving sensor (2). Also, the charge accumulation time (
It also performs pulse counting (b), and may be provided in this form.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, in which Fig. 1 is a side sectional view, Fig. 2 is a control block diagram, Figs. 3, 4, and 5.
6 is a partial operational diagram, FIG. 7 is an operational diagram, and FIG. 8 is a control block diagram of another embodiment. In the figure, code (1) is the optical system, (2) is the light receiving sensor, and (3) is the optical system.
) indicates the reference charge control section.

Claims (1)

[Claims] A light receiving sensor (2) that detects the received light transmitted through the optical system (1) and converts it into an electrical signal, and a light receiving sensor (2) that detects changes in the output of this electrical signal and adjusts the charge accumulation time (a) of the light receiving sensor (2). An image sensor comprising: a reference charge control section (3) for controlling a reference charge;