JPH0795859B2 - Image signal switching circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image signal switching for switching the display priority of these images when two types of images are displayed on one screen by using two systems of image signals or video signals. Regarding the circuit.

[0002]

2. Description of the Related Art A video system has been realized in which an image processed by a computer and an image processed by another video device are simultaneously output on one screen. For example, a video signal output from a video device such as a video camera, a video tape recorder or a laser disk is supplied to a computer system, and a processed image of a computer and an image output from a video device such as a video camera are displayed on a display screen. Is a method of performing. Also in the video conference apparatus exemplified in Japanese Patent Laid-Open No. 63-193682, an image captured and transmitted by a video camera or an image transmitted and a computer processed image are divided into areas on the same display screen or overlapped. Can be displayed in the area.

FIG. 4 shows a state in which two types of images are separately displayed on the display screen. An image 12 of a pull-down menu as an example of an image processed by a computer and an image (external image) 13 processed by a video camera, for example, are displayed on the display screen 11 of the CRT so as not to overlap each other. A square figure arranged as an example at the top of the display screen represents, for example, an icon. That is, by clicking a predetermined one of these icons by operating a mouse as a pointing device (not shown), an operation such as displaying a pull-down menu can be performed.

FIG. 5 shows an example in which an image processed by a video camera is displayed so as to overlap with an image processed by a computer as another display mode. When the display screen is relatively small and the image 12 processed by the computer does not need to be particularly noted, it is convenient because the external image 13 processed by the video camera can be displayed in a larger size.

FIG. 6 shows a display form opposite to that of FIG. For example, when the computer processing result appears while displaying in the display form of FIG. 5, it is possible to watch the image 12 processed by the computer by switching to the display form as shown in FIG. You can Further, the contents of the image 13 processed by the video camera can be grasped to some extent.

In this way, an image processed by a computer (hereinafter referred to as a computer processed image) and an image input from outside such as a video camera (hereinafter referred to as an external input image) are simultaneously displayed on a display screen such as a CRT. Will take either of the following first or second techniques.
The external input image processing technique is described in, for example, Japanese Patent Application Laid-Open No. 62-242488.

In the first method, an external input image is subjected to analog-digital conversion processing, once taken into a computer, and this is combined with the original computer-processed image and outputted. For example, JP-A-62-81887
In the publication, image data captured by a plurality of high quality cameras is divided into memories by using a switch and stored, and this is displayed on a display screen.

In the second method, the computer-processed image and the external input image are switched by hardware so that the two images are apparently combined.

In the first method, images are mainly composed by software. For this reason, it is relatively easy to perform display in various display forms as shown in FIGS. 4 to 6 and to control switching between these display forms. Also, 2
Since the two images are combined, it is easy to store these image data. Further, since both the computer processed image and the external input image are treated as digital signals, image processing such as processing of these is relatively easy.

However, the first method requires a large capacity memory for accommodating the video image. Moreover, since the display process is performed by software, it requires an execution time for this display process. Therefore, when the amount of image data is large, processing such as slow motion or thinning of the screen is required, and there are problems that real-time display is impossible and the motion of the subject or the like becomes rough. Further, since the images are combined by software, there is a problem that dedicated software for this combination is required.

[0011]

On the other hand, the second technique does not require dedicated software. That is, the external input image can be displayed regardless of the application software of the computer. Further, since it is not necessary to process with software, it is possible to always display in real time even if the amount of image data is large.

However, according to the second method, if one of the images is preferentially displayed as shown in FIG. 5 or 6, the image switching control becomes complicated and the realization thereof is not easy. Further, since the externally input image is an analog signal as it is, there is a problem that the image data cannot be stored or processed as it is.

Therefore, an object of the present invention is to provide an image signal switching circuit which can easily control the priority of an externally input image processed by a video camera or the like and an image processed by a computer without using special software. To provide.

[0014]

According to a first aspect of the invention, there is provided a first image signal input means for inputting a first image signal for forming a first image and a second image signal for forming a second image. The second image signal inputting means for inputting the image signal of, the determining means for determining whether or not the first image signal represents a chromatic color for each area of the first image, and the first image signal The image signal switching circuit is provided with image signal selection means for selecting and outputting the first image signal when the first image and the second image overlap in the image area representing the chromatic color.

That is, according to the first aspect of the present invention, by making the first image signal chromatic or achromatic, the image signal in the area where the first image and the second image are displayed in an overlapping manner is displayed. I am trying to switch the priority. Therefore, the first image can be preferentially displayed by a simple operation such as setting a chromatic color in a necessary window without using special software.

According to the second aspect of the invention, the first image signal input means for inputting the first image signal for forming the first image and the second image signal for forming the second image are input. Second image signal input means, saturation determining means for determining whether or not the first image signal represents a chromatic color having a predetermined saturation or higher for each area of the first image, and the first image Image signal switching means for selecting and outputting the first image signal when the first image and the second image overlap in the image area where the signal represents a chromatic color having a predetermined saturation or more. Prepare for the circuit.

That is, according to the second aspect of the present invention, in consideration of the case where it is difficult to express the first image signal as completely achromatic color, the first image signal has a chromatic color with a predetermined saturation or more. It is determined whether it is represented, and if so, the first
Image is displayed with priority over the second image.

According to the third aspect of the invention, the first image signal inputting means for inputting the first image signal for forming the first image and the second image signal for forming the second image are input. A difference (a positive value as a quantity representing the degree of the difference) between the amplitudes of the second image signal input means and the respective color components forming the first image signal for each area of the first image is obtained. A difference calculation circuit, an addition circuit that adds the differences obtained by the difference calculation circuit, and a comparison circuit that compares whether the addition value obtained by the addition circuit is greater than a predetermined positive value. , When the first image and the second image overlap in the image area where the added value is larger,
And an image signal selecting means for selecting and outputting the image signal of 1. in the image signal switching circuit.

That is, according to the third aspect of the invention, the difference between the amplitudes of the respective color components forming the first image signal is obtained for each area of the first image, and the result of adding these differences is predetermined. Greater than a positive value,
Since the first image signal has a chromatic color having a predetermined saturation or higher, the first image is displayed with priority over the second image.

According to the fourth aspect of the invention, the first image signal inputting means for inputting the first image signal processed by the computer and the second image generated by the image generating means other than this are formed. Second image signal inputting means for inputting a second image signal, a difference calculation circuit for obtaining a difference in amplitude between respective color components forming the first image signal for each area of the first image, and The absolute value circuit that finds the absolute value of the amplitude difference between the color components obtained by the difference calculation circuit, the addition circuit that adds the respective outputs of the absolute value circuit, and the addition value that is obtained by this addition circuit A comparison circuit that compares whether or not the value is larger than a predetermined positive value, and the first in the image area where the added value is larger
The image signal switching circuit is provided with image signal selecting means for selecting and outputting the first image signal when the image of 1 and the second image overlap.

That is, in the fourth aspect of the invention, for each area of the first image, the difference between the amplitudes of the respective color components forming the first image signal is obtained, and the absolute values of these are added together. Then, if the added value is larger than a predetermined positive value, the first image signal has a chromatic color having a predetermined saturation or higher, and therefore the first image is I decided to display it in priority to the second image. Other than this, a method of taking the square of the obtained difference and adding it is also effective.

[0022]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows the configuration of an image signal switching circuit according to an embodiment of the present invention. The image signal switching circuit 21 includes image signal input terminals 22 _R , 22 _G and 22 for three primary colors of R (red), G (green) and B (blue).
_{B signal} is provided, and an R signal 23 _R , a G signal 23 _G and a B signal 23 _B are input from a personal computer (not shown) in association with these signals.

The R signal 23 _R has its DC component superimposed on the R signal 23 _R removed by the coupling capacitor 24 _R , and is input to the DC regeneration circuit 25 _R. The DC regeneration circuit 25 _R is adapted to give a DC potential to this signal after the DC component is removed. DC regeneration circuit 25
The output of _R is the (-) terminal of the _first subtraction circuit 26 ₁ and the third
Is input to the (+) terminal of the subtraction circuit 26 ₃ .

On the other hand, the G signal 23 _G input to the image signal input terminal 22 _G has a DC component superimposed on the G signal 23 _G removed by the coupling capacitor 24 _G ,
It is input to the DC regeneration circuit 25 _G. DC regeneration circuit 25 _G
Is designed to give a DC potential to this signal after the DC component has been removed. The output of the DC regeneration circuit 25 _G is input to the (+) terminal of the _first subtraction circuit 26 _{1 and} the (−) terminal of the second subtraction circuit 26 ₂ .

Similarly, the B signal 23 _B input to the image signal input terminal 22 _B has the DC component superimposed on the B signal 23 _B removed by the coupling capacitor 24 _B , and is input to the DC reproduction circuit 25 _B. To be done. DC regeneration circuit 2
5 _B is adapted to give a DC potential to this signal after the DC component has been removed. The output of the DC regenerating circuit 25 _B is input to the (−) terminal of the _third subtraction circuit 26 ₃ and the (+) terminal of the second subtraction circuit 26 ₂ .

First subtraction circuit 26₁Is the DC regeneration circuit 2
5_GDC output circuit 25 from other output level_ROutput of
This is the circuit that subtracts the bell. Similarly, the second subtraction circuit
26 ₂Is the DC regeneration circuit 25_BOutput level from other direct
Flow regeneration circuit 25_GIs a circuit that subtracts the output level of
The third subtraction circuit 26₃Is the DC regeneration circuit 25_ROut of
Other DC regeneration circuit from power level 25_BThe output level of
It is a circuit that calculates. These first to third subtraction circuits 26
₁~ 26₃Are the corresponding first to third absolute value circuits 27.₁
~ 27₃Is supplied to and the absolute value is taken.

That is, the first absolute value circuit 27 ₁ is
Absolute value of the subtracted value (GR) of the subtraction circuit 26 ₁ of
R-G | is calculated. Here, “G” is the signal level of the G signal, and “R” is the signal level of the R signal. The second absolute value circuit 27 ₂ calculates the absolute value | GB | of the value (B−G) subtracted by the _second subtraction circuit 26 ₂ . However, "B" is the signal level of the B signal here. The third absolute value circuit 27 ₃ calculates the absolute value | BR | of the value (RB) subtracted by the _third subtraction circuit 26 ₃ . The output of absolute value circuit 27 ₁ to 27 ₃ are added by the adding circuit 28, the result is input to one input terminal of the comparator circuit 29.

A DC reference voltage is supplied from the variable voltage setting unit 30 to the other input terminal of the comparison circuit 29.
The comparator circuit 29 outputs a signal "1" when the output voltage of the adder circuit 28 is higher than the reference voltage, and outputs a signal "0" in other cases. However,
The priority display inhibition signal 32 is input from the external video read control circuit 31 to the comparison circuit 29, and the signal "0" is forcibly output from the comparison circuit 29 in the input state. It has become.

The output of the comparison circuit 29 is a 2-input OR gate 3
3 is supplied to one of the input terminals. This OR gate 33
An image switching signal 34 is input from the external video read control circuit 31 to the other input terminal of the. The output 35 of the OR gate 33 becomes the input of the selection circuit 36.

On the other hand, each DC regeneration circuit 25 _R , 25 _G , 2
The output of 5 _B is input to delay circuits 37, 38 and 39 for delaying the R signal, G signal and B signal, respectively. These delay circuits 37, 38 and 39 are provided for the DC recovery circuits 25 _R ,
The outputs of 25 _G and 25 _B are the first to third subtraction circuits 26 ₁ to
The propagation delay time of the path that reaches the selection circuit 36 from 26 ₃ through the first to third absolute value circuits 27 _{1 to} 27 ₃ , the addition circuit 28, the comparison circuit 29 and the OR gate 33 is the delay circuits 37, 38, 39. It is provided to delay the R, G, and B signals so that they are equal to the signal that has just passed through. The selection circuit 36 will be described in detail later.

On the other hand, the horizontal signal of the image signal switching circuit 21 is the same.
Period signal input terminal 41_HIs a personal computer not shown
Computer to horizontal synchronization signal (HSYNC) 42_HSupplied by
Has been done. Horizontal sync signal 42_HIs the external video read control time
In addition to being supplied to the path 31, it is also supplied to the PLL circuit 43.
It is like this. In addition, the vertical sync signal input terminal 41 _V
Is also the vertical sync signal from the personal computer.
(VSYNC) 42_VIs being supplied. Vertical sync signal
42_VIs supplied to the external video read control circuit 31.
Has become.

The PLL circuit 43 is a personal computer.
Horizontal synchronization signal 42 supplied from _HFrequency synchronized with
21.50MHz dot clock 44 is output.
Growling. The external video read control circuit 31 is a control program.
Receives the command set by the sessa 46 and synchronizes horizontally.
Signal 42_H, Vertical sync signal 42_VAnd dot clock
Based on 44, three types of signals are created. These are
The personal computer image explained in (
Called a statue. ) Priority display prohibition signal 32 for
Memory read signal for switching signal 34 and memory 48
No. 49. However, the memory 48 is an external video circuit.
It is a memory circuit that I remember.

Although not shown, the writing circuit for writing data in the memory 48 is, for example, a circuit for writing a color image taken by a television camera (not shown) as a digital signal. In order to enable this writing and reading from the memory 48 in parallel, the memory 48 of this embodiment is composed of two image storage areas, and one area is writing. Then, the other area can read out the image.

The external image read from the memory 48
R, G, B three color data 51_R, 51 _G, 51_BIs that
D / A converter 52 respectively_R, 52_G, 52_BBy
Analog signal 53_R, 53_G, 53_BWill be converted to
Growling. These analog signals 53_R5,
Three_G, 53_BAre respectively the coupling capacitors 54_R, 54
_G, 54_BThe DC component is removed by. Combine these
Capacitor 54_R, 54_G, 54_BDC on the output side of
Reproduction circuit 56_R, 56_G, 56_BIs provided. This
These are the DC regenerating circuit 25 described above._R, 25_G, 25
_BIt is designed to give the same DC potential as.

The DC restoration circuit 56 _R, 56 _G, 56 each output 57 _R, 57 _G, 57 _B of _B is the delay circuits 37,3
The outputs 58 _R , 58 _G and 58 _{B of} 8 and 39 are input to the selection circuit 36. The selection circuit 36 is
Output 57 _R , 5 according to the output 35 of the OR gate 33
7 _G , 57 _B or any set of outputs 58 _R , 58 _G , 58 _B is selected, and output signals 59 _R , 59 _G , 59 _B are output to respective output terminals 61 _R , 61 _G , 61 _B. It is like this.

The circuit operation of the image signal switching circuit 21 having such a configuration will be described below.

(1) When displaying only PC images on the CRT
Combined

When only the PC image 12 is displayed on the CRT, the external video read control circuit 3 is controlled by the control processor 46.
The command for not displaying the external image is output to 1. Upon receiving this command, the external video read control circuit 31 sets the image switching signal 34 to the signal "1" state. When the image switching signal 34 becomes the signal "1",
The output 35 of the OR gate 33 also becomes the signal "1". The selection circuit 36 selects outputs 58 _R , 58 _G , and 58 _B based on the R signal 23 _R , G signal 23 _G, and B signal 23 _B input from the personal computer, and outputs these as output signal 5
9 _R , 59 _G and 59 _B are output terminals 61 _R and 61 _G ,
Output to 61 _B.

(2) When displaying an external image on the CRT

In this embodiment, a computer output image such as the above-mentioned pull-down menu or image data read by a scanner is displayed on the display screen.
An external image is displayed on a part of the screen if necessary. Therefore, when displaying an external image on the CRT, it is necessary to specify the range to be displayed. In this embodiment, a rectangular area is designated and an external image is displayed in that area.

FIG. 2 is for explaining how to provide a display area for displaying an external image. On the display screen 11 of the CRT, two diagonal points (X ₁ , Y ₁ ), (X ₂ ,
A rectangular display area 71 designated by Y ₂ ) is designated. In order to specify such a display area 71, a command indicating these two points (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ) is output from the control processor 46 to the external video read control circuit 31. Done by. Upon receiving the command, the external video read control circuit 31 outputs an image switching signal 34 corresponding to the command.

FIG. 3 shows two points (X ₁ , Y ₁ ), (X ₂ , Y ₁ ).
_This is for explaining the display principle of the external image when the data of ₂ ) is given. 2 points starting from the rise of the horizontal synchronizing signal _{42 H (X 1, Y 1} ), (X 2,
Positioning of (Y ₂ ) in the scanning line direction is performed, and positioning is performed in the direction orthogonal to the scanning line starting from the rising edge of the vertical synchronizing signal 42 _V. When the image switching signal 34 in front of the rectangular display area 71 determined by these is the signal "0", the memory read signal memory read signal 49 for reading the external video data from the memory 48 is output. Based on this, the memory 48 sequentially outputs the R, G, and B data of the external image to the D / A converters 52 _R , 52 _G , and 52 _B.

These D / A converters 52_R5,
Two_G, 52_BCorresponds to the input digital signal
It is designed to output analog signals. These a
Analog signal 53_R, 53_G, 53_BAre respectively
Capacitor 54_R, 54_G, 54_BDC component is removed by
DC recovery circuit 56_R, 56_G, 56_BBy
Same as R, G, B signals from personal computer
The same DC potential is applied and input to the selection circuit 36. Election
The selection circuit 36 responds to the output of the OR gate 33 with a personal computer.
N, R, G, B of either external computer or external video
Output (58_R, 58 _G, 58_B), (57_R, 57_G,
57_B), Select the output signal 59_R, 59_G, 59_BWhen
Output terminal 61_R, 61_G, 61_BOutput to. this
As a result, the composite image as shown in FIG. 4 is output.
Become.

Two cases will be described as modes for displaying such two kinds of images on the display screen 11.

(2-1) Display Mode Prioritizing External Video

This is a case where the external image 13 is preferentially displayed when the PC image 12 and the external image 13 processed by the video camera or the like overlap as shown in FIG. In this case, the control processor 46 outputs to the external video read control circuit 31 a command for prohibiting the priority display of the PC image. When the external video read control circuit 31 receives this command, the comparison circuit 2 receives the priority display inhibition signal 32.
The output of 9 is fixed to the signal "0". Other than this,
This is the same as the above description. As a result, the external image 13 is preferentially displayed. In the case of a video conference, the image of the person can be
When it is desired to give priority to the C image, such a display mode is executed.

(2-2) Display Mode Prioritizing PC Image

As shown in FIG. 6, when the PC image 12 and the external image 13 processed by the video camera overlap, P
This is a case where the C image 12 is preferentially displayed. In this case, the levels of the R, G, and B signals in the PC image 12 are different. When the levels of these R, G, and B signals are the same, that is, when the PC image is represented by an achromatic color, the external image 13 is preferentially displayed as shown in FIG.

In order to realize such switching of the display mode, the adder circuit 28 is adapted to perform the operation represented by the following expression (1).

[0051]

## EQU1 ## | R-G | + | GB-++ BR -... (1)

The result of this addition is compared by the comparison circuit 29 with the reference voltage of the variable voltage setting unit 30. Then, when the output voltage of the adding circuit 28 is higher than the reference voltage, that is, when the levels of the R, G, and B signals are different, the comparison circuit 29 outputs the signal "1". As shown in FIG. 6, the PC image 12 is preferentially displayed. In other cases, that is, in the case where the R, G, and B signals have the same level of achromatic color, the signal "0" is output,
As shown in FIG. 5, the display of the PC image 12 is not prioritized.

Therefore, in the application software on the personal computer side, a color such as blue is added to the display area of the icons and pull-down menus necessary for the operation. As a result, even if the PC image 12 such as the icon, the pull-down menu, the icon, or the cursor operated by the mouse is present in the same area as the external image 13 processed by the video camera or the like, the PC image 12 is not included in the external image 13. Will be displayed with priority over, and it will not hinder the operation.

In the above-described embodiments, the case where the external image is a color image has been described as an example, but it goes without saying that the present invention can be applied even if the external image is a monochrome image. Further, although the external image is converted into a digital signal and written in the memory 48 and is converted into an analog signal and supplied to the selection circuit 36, it may be supplied as an analog signal to the selection circuit 36 as it is in some cases. It is possible.

[0055]

As described above, according to the first aspect of the invention, the priority of the first image and the second image is changed by switching the chromatic color or the achromatic color of the first image. Since the area is switched, the area to be preferentially displayed in the image processed by the computer may be processed in the chromatic color, and the priority can be switched by a simple process. Moreover, since the first image that is preferentially displayed is a chromatic color unlike the other first images, there is little risk that these will be buried in other images. Moreover, as long as it is a chromatic color, various colors can be selected, and the visual display effect is great.

According to the second aspect of the invention, not only the same effect as that of the first aspect of the invention is obtained, but the levels of the image signals of the three colors of R, G, and B appear to be slightly different. Even in such a case, there is an effect that the area to be preferentially displayed can be stably displayed.

Further, according to the third aspect of the invention, the difference between the amplitudes of the respective color components forming the first image signal for each area of the first image is obtained, and the result of adding these differences is First if greater than a predetermined positive value
Decided to give priority to the display of images. Therefore, there is an effect that the priority of an image can be switched simply by preparing a circuit or means for performing a simple arithmetic operation.

According to the present invention, the difference in amplitude between the respective color components forming the first image signal for each region of the first image processed by the computer is obtained, and their absolute values are obtained. If the added value is larger than a predetermined positive value, the second image generated by other image generating means is given priority and the first image is displayed. To do. Therefore, there is an effect that the priority of the first image can be easily switched by computer processing and no special software is required.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an image signal switching circuit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing how to provide a display area for displaying an external image.

FIG. 3 is an explanatory diagram showing a display principle of an external image when data of two points (X ₁ , Y ₁ ) and (X ₂ , Y ₂ ) is given.

FIG. 4 is a plan view showing how two types of images are displayed separately on a display screen.

FIG. 5 is a plan view showing a state in which an external image is preferentially displayed over a PC image on a display screen.

FIG. 6 is a plan view showing a state in which a PC image is preferentially displayed on an external image on a display screen.

[Explanation of symbols]

11 display screen 12 PC image 13 external video 22 _R, 22 _G, 22 _B image signal input terminal 23 _R R signal 23 _G G signal 23 _B B signals 26 ₁ to 26 ₃ first to third subtraction circuit 27 ₁ - 27 ₃ 1st-3rd absolute value circuit 28 Addition circuit 29 Comparison circuit 30 Variable voltage setting device 33 OR gate 36 Selection circuit 48 Memory 57, 58 Output 59 Output signal

Claims (4)

[Claims] 1. A first image signal input means for inputting a first image signal for forming a first image, and a second image signal input for inputting a second image signal for forming a second image. Means, determining means for determining whether or not the first image signal represents a chromatic color for each area of the first image, and the image area in which the first image signal represents a chromatic color, An image signal switching circuit, comprising: an image signal selection unit that selects and outputs a first image signal when the first image and the second image overlap. 2. A first image signal input means for inputting a first image signal for forming a first image, and a second image signal input for inputting a second image signal for forming a second image. Means for determining whether or not the first image signal represents a chromatic color having a predetermined saturation or higher for each area of the first image, and the first image signal determines whether the first image signal has the predetermined color. An image signal selecting means for selecting and outputting a first image signal when the first image and the second image overlap each other is provided in an image region representing a chromatic color of saturation or higher. Image signal switching circuit. 3. A first image signal input means for inputting a first image signal for forming a first image, and a second image signal input for inputting a second image signal for forming a second image. Means, a difference calculation circuit for obtaining a difference between the amplitudes of the respective color components forming the first image signal for each area of the first image, and an addition for adding the respective differences obtained by the difference calculation circuit. A circuit, a comparison circuit for comparing whether or not the addition value obtained by the addition circuit is larger than a predetermined positive value, and the first image and the second image in the image area where the addition value is larger. Image signal switching circuit for selecting and outputting the first image signal when the two images overlap each other. 4. A first image signal inputting means for inputting a first image signal processed by a computer, and a second image signal forming a second image generated by other image generating means. Second image signal inputting means for inputting, a difference calculation circuit for obtaining a difference in amplitude between respective color components forming the first image signal for each area of the first image, and this difference calculation circuit. An absolute value circuit for obtaining the absolute value of the amplitude difference between the respective color components, an addition circuit for adding the respective outputs of the absolute value circuit, and the addition value obtained by this addition circuit A comparison circuit for comparing whether or not the value is larger than a value, and an image for selecting and outputting the first image signal when the first image and the second image overlap in the image area where the addition value is larger Signal selection An image signal switching circuit comprising: a selecting unit.