JPH02145072A - Charge transfer device - Google Patents

Abstract

PURPOSE:To reduce the capacity of a memory means by allowing a line sensor to apply photoelectric conversion of an incident light in itself, employing a charge transfer means transferring a stored charge unidirectionally mainly and forming the charge transfer means in parallel closely on a chip. CONSTITUTION:Line sensors 12, 14, 16 are arranged on one and same chip in parallel without any interval. Then CCD light shielding sections 24, 26, 28 are provided and the initial charge stored in CCD light receiving sections 18, 20, 22 is stored once in the CCD light shielding sections 24, 26, 28 and then read out. Thus, the readout has only to be implemented till the next charge from the CCD light receiving sections 18, 20, 22 exists to the CCD light shielding sections 24, 26, 28. Thus, even when the operating frequency of the devices after the readout circuit is low and the operation is slow, the stored charge is read without being affected.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to charge transfer devices such as CCDs and BHDs, and particularly relates to charge transfer devices suitable as input means for color image reading devices. be.

[Prior Art] As a charge transfer device for color image reading, for example, there is a device using a three-color integrated line sensor disclosed in Proceedings of the Information Systems Division of the Institute of Electronics and Communication Engineers, 1985 National Convention, Proceedings 1-232. There is a reading device.

The charge transfer device in this reading device has an effective pixel count of 34.
Line sensors with 56 pixels are formed in three rows at the wafer stage, and each line has R (red) and G (green).
, B (blue) color filters are stacked.

FIG. 3 shows a conventional arrangement of such a charge transfer device on a semiconductor chip. In the figure, line sensors 50, 52, 54 include photodiode arrays 56, 58, 60, charge-coupled devices or CCDs 62.
．． 64, 66, and readout circuits 68, 70, and 72, respectively.

Among these, the photodiode array 56.degree. 58.60 is constituted by a large number of photodiodes of, for example, a PN junction type or a MOS ribbon. Each photodiode row 56.degree. 58.60 is provided with R, G, and H color filters, so that color images can be read.

Such line sensors 50, 52, and 54 are formed in parallel on the same chip at a predetermined interval ΔSt.

Next, we will discuss the operation of the charge transfer device as described above in the fourth section.
This will be explained with reference to the figures. Line sensor 50.52.
54 is, for example, a dashed-double line in FIG. indicates the lines read by the line sensors 50, 52, and 54, and the interval between them corresponds to the movement pitch.

In the line sensor 50, 52, 54, each of the R2O and B lights incident on the photodiode arrays 56, 58, 60 is converted into an electrical signal, and from each element as shown by the arrow F2 in FIG. The charge is manually applied to .66.

The charge input to CCD 62, 64, 66 is shown by arrow F3.
As shown in , the signals are sequentially transferred and outputted to successive circuits 68, 70, 72, and further temporarily stored in a memory means (not shown). Thereafter, the R, G, and B signal outputs of the respective line sensors 50, 52, and 54 on the same reading line are combined, thereby obtaining the color 7 output.

[Problem to be solved by the invention] However, in the conventional charge transfer device as described above,
Distance ΔSl on the chip of line sensors 50, 52, 54
cannot be made very narrow, which causes the following disadvantages.

In detail, the photodiode of the line sensor 50.52.54, the ode array 56.58.60 and the CCD 62.64.6
6 are arranged alternately as shown in FIG.

That is, since one C0D62.64, etc. are each formed in the interval Δsi, it is necessary to secure these spaces, and therefore the interval ΔS1 cannot be made less than a predetermined value.

Here, 1/6 of the interval ΔS1 is the line sensor 50.
Assume a reading pitch of 52.54. Assuming that the reading line L is read by the first line sensor 50 as shown in FIG. It is necessary to move the sensor in the F1 direction.Then, until the reading line L is read by the last line sensor 54, it is necessary to move the sensor in the F1 direction.
It is necessary to move the sensor in the direction of arrow F1 by the pitch.

That is, in order to obtain the read signals R2O and H for the read line L, as shown in FIG. It is necessary to move.

On the other hand, the color signal output on the reading line L cannot be obtained without the signal output of the reading line L of each line sensor 50.degree. 52.54, as described above.

Therefore, in order to obtain a color signal output, the output of the line sensor 50 needs to be held for 12 pitches, and the output of the line sensor 52 needs to be held for 6 pitches. In other words, the conventional device requires memory means for storing 12 lines of signal output from the line sensor 50 and memory means for storing 6 lines of signal output from the line sensor 52.

In order to reduce the capacity of such a memory means, the interval ΔS1 between the line sensor 50, 52, 54 or photodiode array 56, 58, 60 described above should be narrowed. .64 exists, such an interval cannot be narrowed.

The present invention has been made in view of the above, and an object of the present invention is to provide a charge transfer device capable of reducing the capacity of a memory means for temporarily storing read signals for obtaining color signals. This is the purpose.

[Means for Solving the Problems] The present invention provides a line sensor for obtaining a photoelectric conversion signal that is synthesized for each reading line in order to obtain a desired reading signal. In the transfer device: The line sensor performs photoelectric conversion of incident light by itself, and has a charge transfer means that transfers accumulated charges in one direction; and a readout means that independently reads charges. Features: The charge transfer means of each cell sensor are closely arranged in parallel on the chip.

[Function] According to the present invention, the licensor is configured around a charge transfer means that performs photoelectric conversion of incident light by itself and transfers accumulated charges in one direction. The charge transfer means are formed in parallel and closely spaced on the chip. As a result, the spacing between the line sensors becomes smaller, and the reading line spacing in each line sensor also becomes narrower.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a charge transfer device 10 according to an embodiment of the present invention.

In the figure, the charge transfer device 10 has R, G.

It has line sensors 12, 14, and 16 for B, respectively. These line sensors 12.14゜16 include CCD light receiving sections 1B, 20.22 (charge transfer means), and CCD light receiving sections 1B, 20.22 (charge transfer means),
D light shielding part top 46.28 and readout circuit 30.32.3
4 (reading means). The CCD light receiving section 18.20.degree. 22 is provided with R, G, and B filters (not shown), respectively. Since each of the line sensors 12, 14, and 16 has the same configuration, the line sensor 12 will be described below as a representative.

First, the CCD light receiving section 18 has a function of directly receiving light incident from the outside and converting it into a considerable amount of charge, and a light shielding film is provided continuously on the charge transfer output side of the CCD light receiving section 18. A COD light shielding section 24 is arranged. CCD light receiving section 1
8 and CCDCD light-shielding portion 4, each having the same number of stages of elements so that charge transfer for the same number of pixels can be performed. The transferred charges are serially output to the outside from a readout circuit 30 connected to the No. 4 output end side of the upper CCDCD light shielding section.

In other words, a line sensor such as 0 or more in which a long COD is divided into a light receiving part and a light shielding part, and an independent signal readout circuit is connected to the charge transfer output side of this CCD. 12, 14, and 16 are arranged and formed in parallel on the same chip without any separation.

Next, the operation of the above embodiment will be explained. First, the line sensors], 2, 14, and 16 move in a predetermined direction at a predetermined pitch over a document to be read as shown in FIG. The R, G, and B optical images are then read by the CCD light receiving sections 18, 20.22, and charges corresponding to the amount of incident light are accumulated for each pixel in each element.

Next, the charges accumulated in each element of the CCD light receiving section 18, 20, 22 are serially transferred at high speed to the COD light shielding section 24, 26, 28, as shown by the arrow FA in the figure.
They are accumulated once. Thereafter, the readout circuits 30, 32, and 34 sequentially read out the accumulated charges as shown by arrows FB in the same figure.
.

Photoelectric conversion signals corresponding to the B optical images are serially output.

In this case, in this embodiment, the upper 4
6.28 are provided respectively, and the CCD light receiving section 18.2
The initial charge accumulated at 0.22 is -dan CCD
The light is stored in the light shielding portion 24.26°28 and then read out. Therefore, such reading is performed by the COD light shielding section 24.
It is only necessary to carry out this operation before the next charge transfer from the CCD light receiving section 18, 20, 22 to 26°28.

Therefore, the operating frequency of the device after the readout circuit is low,
Even if the operation is slow, the accumulated charges can be read without being affected by it.

As described above, if the operation of the device after the readout circuit is fast, it may be configured as shown in FIG. 2, that is, the line sensor 40.42.4
4, CCD light receiving section 18, 20° 22 and readout circuit 30.32.3 excluding CCD light shielding section 24.26.28
4 respectively.

The read photoelectric conversion signals are temporarily stored in a memory means (not shown) as required, and furthermore, the R, G, and H signals are combined for each read line, and the color is converted as described above. I get a signal.

In this case, in this embodiment, R, G.

Since the arrangement interval of each line sensor B on the chip can be narrowed, it is possible to reduce the capacity of the memory means for storing photoelectric conversion signals.

For example, if the interval ΔS2 between the CCD light receiving sections 1B and 20.22 is the same as the reading pitch, the output of the CCD light receiving section 18 is for two lines.

For the output of the CCD light receiving section 20, a memory means for one line is sufficient.

Furthermore, in the manufacturing process, the patterns of each part are made even finer, and the line sensor or CCD light receiving part 18.20.2
If the two reading circuits are integrated at an interval ΔS2 that is narrower than the reading pitch, a color signal can be obtained by directly combining the outputs from each reading circuit. Therefore, in this case, a memory means for temporarily storing the photoelectric conversion signal is not required.

As described above, according to this embodiment, since the line sensors are closely arranged on the same chip, temporary storage of signals,
It is possible to reduce the capacity of the memory means that performs this, and in some cases, it becomes unnecessary. Furthermore, since the manufacturing conditions of the line sensor during the manufacturing process are made uniform, variations in their characteristics are reduced and the area of the chip is also reduced. Furthermore, since the structure is simpler than conventional devices, the manufacturing yield is improved, and since only the charges accumulated in the CCD are transferred, there is no afterimage.

Note that the present invention is not limited to the above embodiments (for example, in the above embodiments, CC is used as the charge transfer means).
I used D, but you can use other ones such as BBD.
Further, in the above embodiment, line sensors were provided for each of R, G, and B, but the number of line sensors may be increased or decreased as necessary.

[Effects of the Invention] As explained above, according to the present invention, it is possible to reduce the capacity of the memory means for temporarily storing read signals, and in some cases, there is an effect that the memory means is not required. be.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a block diagram showing another embodiment of the present invention, Fig. 3 is a block diagram showing an example of a conventional device, and Fig. 4 is a block diagram showing a conventional device. It is an explanatory diagram showing the effect of. 10... Charge transfer device, 12.14.16°40.4
2.44...Line sensor, 18.20°22...
CCD light receiving section, 24.26.28... COD light shielding section,
30.32.34...Readout circuit, ΔSt, ΔS2
···interval. Patent applicant Kunio Kakiki, Representative of Victor Japan Co., Ltd.

Claims (1)

[Scope of Claims] A charge transfer device in which at least two sets of line sensors are formed on the same chip to obtain photoelectric conversion signals that are combined for each read line to obtain a desired read signal, the line sensor The sensor performs photoelectric conversion of incident light by itself, and is equipped with a charge transfer means that transfers the accumulated charge in one direction, and a readout means that independently reads out the charge. A charge transfer device, wherein the transfer means are closely arranged in parallel on the chip.