JPH0785570B2 - Data transfer device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention corresponds to an extracted video signal by extracting a 1-field video signal from a video signal corresponding to a video reproduced in a television receiver or the like. The present invention relates to a data transfer device that is preferably implemented in a thermal printer or the like configured to record an image on photographic paper by a thermal transfer method.

BACKGROUND ART From a video signal reproduced by a television receiver,
2. Description of the Related Art When a video signal of one field is extracted and a still image corresponding to the extracted video signal of one field is recorded on a recording sheet, a thermal printer has been conventionally used for recording by a thermal transfer method. The thermal printer is provided with a thermal head which faces the platen and includes a plurality of heating resistors linearly formed in the longitudinal direction of the platen. The recording paper is wound around a platen and conveyed, and an ink film coated with an ink containing a dispersible sublimation dye as a main component is interposed between the recording paper and the thermal head.

When a voltage is selectively applied to the heating resistor forming the thermal head, the ink of the ink film corresponding to the position of the heating resistor to which the voltage is applied sublimes and the sublimed ink adheres to the surface of the recording paper. . The amount of sublimation of the ink applied on the ink film corresponds to the amount of heat generated by the heating resistor. Therefore, when a constant voltage is applied to the heating resistor, one dot can be obtained by changing the voltage application time. Each gradation can be expressed. Since the video signal is basically a continuous brightness level of the subject, when a still image is to be recorded based on such a video signal, the gradation for each dot can be expressed. It must be. For example, depending on the device that expresses halftones by the density of black pixels,
It is not possible to record a still image based on the video signal.

In order to selectively apply a voltage to the plurality of heating resistors that form the thermal head, a digital signal having a bit number corresponding to the total number of the heating resistors is applied in parallel to the thermal head. That is, for example, data in which the bit corresponding to the heating resistor to which a voltage is applied is set to "1" and the bit corresponding to the heating resistor to which no voltage is applied is set to "0" is given to the thermal head. Since there are only two types of heating resistors to which a voltage is applied and heating resistors to which no voltage is applied, only two gradations can be expressed by one transfer of such data. However, for example, by performing 64 such data transfers,
The voltage application time to the heating resistor can be selected from 64 types, which enables representation of 64 gradations.

Problems to be Solved by the Invention In a thermal printer in which data transfer as described above is performed, for example, when expressing an image with 64 gradations, data transfer must be performed 64 times.
The data given to the thermal head by one transfer corresponds to, for example, one scanning line on the screen of a CRT (cathode ray tube), but the image of one scanning line to be printed is not always required.
It is not expressed using all 64 gradations. For example, when the dot having the maximum gradation is expressed by 10 times of data transfer, the data given to the thermal head after that. Is data in which all bits are "0". That is, even though all the information necessary for printing the image corresponding to one scanning line has been transferred by 10 times of data transfer, it is necessary to transfer the image information corresponding to one scanning line to the thermal head by 64 times. As a result of such meaningless data transfer, improvement in the printing speed of the thermal printer is hindered.

It is an object of the present invention to provide a data transfer rate that does not carry out meaningless data transfer and therefore the data transfer rate is significantly improved.

Means for Solving the Problems According to the present invention, a plurality of sets of data having a plurality of bit capacities are collected as one line data in a thermal printer in which a heating resistor is energized and heated according to a video signal to be recorded to record on a printing paper. In a data transfer device that transfers data to a heating resistor, a line memory 16 that stores one line of input data
A maximum value detection circuit 17 for sequentially comparing input data and holding a larger data value in the latch circuit, and a buffer 21. Output from 1
And a control circuit 14 for converting the line data into voltage application data, storing the data in the buffer, and transferring the data stored in the buffer to the heating resistor by the number of times of maximum value data held in the latch circuit. It is a data transfer device characterized by the above.

Operation In the present invention, in the data transfer device in which a plurality of sets of data having a plurality of bit capacities are used as one transfer unit, the maximum value of the number of bits corresponding to the level assigned to each set is detected by the maximum value detecting means. . Further, the storage means stores the specific data from one side of the plurality of bits by the number of bits corresponding to the level assigned to each set of the data having the plurality of bits capacity. The data transfer from the storage means is sequentially performed from one side of the plurality of bits for each set by the number of bits corresponding to the maximum value.

As a result, all the specific data are transferred without transferring all the data of one transfer unit, and it is possible to transfer only the necessary data. Therefore, for example, in a thermal transfer type thermal printer,
Since the image information is transferred a minimum number of times, the printing speed is improved.

According to the invention, the maximum value of the data for one line is detected in advance, and the maximum value sets the number of times the signal is sent to the heating resistor. This makes it possible to quickly stop the operation of sending to the heating resistor.

Second Embodiment FIG. 2 is a sectional view showing the configuration around the thermal head 1 of a thermal printer 11 which is an embodiment of the present invention. The thermal head 1 is disposed so as to face the platen 2 and has a plurality of heating resistors 3 formed along the longitudinal direction of the platen 2.
Is included. A photographic paper 4 is wound around the platen 2,
The photographic printing paper 4 is conveyed in the arrow R2 direction by the platen 2 being angularly displaced in the arrow R1 direction. An ink film 5 is interposed between the photographic printing paper 4 and the thermal head 1,
The ink film 5 has a structure in which an ink (hereinafter referred to as ink) 7 containing a dispersible sublimation dye as a main component is applied to the surface of the base film 6 facing the photographic paper 4. A heat radiating plate 8 is provided in association with the heating resistor 3 to prevent deterioration of printing quality due to residual heat when a voltage is applied to the heating resistor 3.

When a voltage is applied to the heating resistor 3 and the heating resistor 3 generates heat, the ink 7 formed on the base film 6 of the ink film 5 sublimes, and the sublimed ink 7a adheres to the surface of the printing paper 4. . The photographic printing paper 4 has a structure in which a base paper 4a is coated with a receiving layer 4b such as polyester terephthalate, and the sublimated ink 7a adheres to the receiving layer 4b.

The amount of the sublimated ink 7a corresponds to the heat generation amount of the heat generating resistor 3, and therefore, by controlling the heat generation amount of the heat generating resistor 3, the density of each dot printed on the printing paper 4 can be changed. . Since the amount of heat generated by the heating resistor 3 is proportional to the voltage application time, it is possible to display a dot having a desired density by appropriately selecting the voltage application time.

FIG. 1 is a block diagram showing the basic configuration of the thermal printer 11. The thermal printer 11 is provided, for example, in association with a television receiver or the like, and is used in the case where an image corresponding to a desired scene among the images reproduced by the television receiver is recorded as a still image on photographic paper. To be

When the operator gives an instruction to record a still surface corresponding to a desired scene, the video signal is given to the field memory 12, and the field memory 12 stores the video signal for one field. The output of the field memory 12 is given to an analog / digital (hereinafter referred to as A / D) conversion circuit 13. The A / D conversion circuit 13 has a line 1 from the control circuit 14
A sampling signal is given via 5, and the output of the field memory 12 is converted into digital signals of a plurality of levels determined according to the frequency of the sampling signal.

The digital signal output from the A / D conversion circuit 13 is given to a line memory 16 which stores video data corresponding to one scanning line represented by the digital signal, and a maximum value detection circuit 17 described later. The video data given to the line memory 16 is given to the control circuit 14 and is outputted to the thermal head 1 after being converted as will be described later. The output of the maximum value detection circuit 17 is also given to the control circuit 14.

The maximum value detection circuit 17 includes a latch circuit 18 and a comparison circuit 19. The latch circuit 18 receives an A / A signal every time a latch signal is given from the comparison circuit 19 through the line 20.
The digital signal output from the D conversion circuit 13 is latched, and the latched digital signal is supplied to the comparison circuit 19 and also to the control circuit 14 as the output of the maximum value detection circuit 17. The output of the A / D conversion circuit 13 given to the maximum value detection circuit 17 corresponds to the density of each dot when the thermal head 1 prints. For example, when the thermal printer 11 records a still image with dots having a density of 64 gradations, the digital signal output from the A / D conversion circuit 13 is a 6-bit digital signal.

When the video data D1 which is a digital signal corresponding to the dot at the head position of one scanning line among the digital signals output from the A / D conversion circuit 13 is given to the maximum value detection circuit 17, the comparison circuit 19 changes the line 20 to A latch signal is output to the latch circuit 18 via the. As a result, the latch circuit 18 stores the video data D1
Are latched and the output of the latch circuit 18 is given to the control circuit 14, so that the video data D1 is given as the maximum value to the control circuit 14 at this point.

When the image data D2 corresponding to the density of the second dot is given to the maximum value detection circuit 17, the comparison circuit 19 compares the image data D1 output from the latch circuit 18 with the given image data D2. . For example, when the video data D1 is larger than the video data D2, the comparison circuit 19 does not derive the latch signal on the line 20, and therefore the latch circuit
The image data D1 is still held in 18.

Next, the video data D3 corresponding to the third dot is given to the maximum value detection circuit 17. For example, when the video data D3 is larger than the video data D1, the comparison circuit 19 derives the latch signal on the line 20. This allows the latch circuit
The data held in 18 will change to the glory layer data D3. The same operation is performed over one scanning line,
After the video data corresponding to the last dot on one scanning line is input to the comparison circuit 19, the video data held by the latch circuit 18 is the maximum video data on one scanning line.

The control circuit 14 refers to the maximum image data held by the latch circuit 18 and transfers data to the thermal head 1 as described later. Data transfer from the control circuit 14 to the thermal head 1 is performed by the A / D converter in the line memory 16.
Since this is performed after the video data of one scanning line output from the conversion circuit 13 is input, the video data of that scanning line is transferred at the time when this video data of one scanning line is transferred from the control circuit 14 to the thermal head 1. The maximum value of is given to the control circuit 14.

The control circuit 14 includes a buffer 21 provided therein as a storage means, and the video data provided from the line memory 16 is subjected to conversion as described below to obtain the buffer 21.
Stored in. That is, the data transferred from the control circuit 14 to the thermal head 1 is the data stored in the buffer 21.

A motor control circuit 22 is connected to the control circuit 14, and a pulse motor 23 is connected to the motor control circuit 22. The pulse motor 23 is provided for rotationally driving the platen 2 described above, and the operation mode of the pulse motor 23 is changed by a control signal given from the control circuit 14 to the motor control circuit 22. . The above-mentioned control signal given from the control circuit 14 to the motor control circuit 22 corresponds to the maximum value of the image data given from the maximum value detection circuit 17, whereby the rotation angle side poison of the platen 2 is scanned by one scanning line. It changes in accordance with the image data of the dot having the maximum density within.

Table 1 shows the storage mode of the video data in the buffer 21 included in the control circuit 14. For example, one scan line is displayed by N dots, and the density of each dot is
In the case of changing to 64 gradations, a storage area of 64 × N bits in the storage area of the buffer 21 is assigned to one scanning line. It is stored in the 64 × N-bit storage area.
64 × N-bit data M (i, j) (where M (i, j) is “0” or “1”, i, j is an integer, and 1 ≦
i ≦ 64, 1 ≦ j ≦ N), the video data D1 corresponding to the first dot of one scanning line corresponds to the data M (i, 1), and the video data D2 corresponds to the data M (i , 2) is supported, ...
Data M (i, N) corresponds to the video data DN.

Although the video data provided to the line memory 16 is 6-bit binary data as described above, the decimal display will be used here for simplicity. For example, video data D1-DN , The data M corresponding to the video data D1
“1,” is assigned to (1,1), and the data M (i, 1) (2
“0” is assigned to ≦ i ≦ 64). Also video data
“1” is assigned to the data M (1,2), M (2,2) corresponding to D2, and “0” is assigned to the data M (i, 2) (3 ≦ i ≦ 64).
Are assigned. Similarly, for example, when the value of the video data Dk is m, data M (1, k) to data M
"1" is assigned to (m, k) and the data M (m + 1, k) ~
“0” is assigned to the data M (64, k). In this way, the image data of each dot is converted into the number of "1" corresponding to the value of the image data.

Table 2 shows a storage mode in the case where the video data D1 to DN shown in the above formulas 1 to 10 are stored in the buffer 21 as described above. The data corresponding to the first dot is data M (i, 1) (1 ≦ i ≦ 64), and one “1” is included in this data. The number of “1” s included in the data corresponding to each dot is proportional to the voltage application time to each heating resistor 3 in the thermal head 1, and for example, the heat generation corresponding to the first dot corresponding to the image data D1. If a voltage is applied to the resistor 3 for a unit time ΔT, for example, a voltage will be applied to the heating resistor 3 corresponding to the fifth dot for a time of 4 × ΔT. In this way, 64 types of voltage application time can be selected for the heating resistor 3, and the density of each dot can be selected in 64 gradations.

The data M (i,
j) is the data M (1, j) (1 ≦ 1) from the control circuit 14 to the thermal head 1 in the first data transfer.
j ≦ N) N-bit data is transferred, and data M (2, j) is transferred in the second data transfer.
The data M (64, j) is transferred in the 64th data transfer.

For example, when the decimal display of the video data Dk corresponding to the kth dot of one scanning line is m and the video data Dk is the video data having the maximum value in the scanning line, the data M (i, j) (m + 1 ≦ 64, 1 ≦ j ≦ N) are all “0”. In this case, the video data held in the latch circuit 18 of the maximum value detection circuit 17 is the video data Dk, and therefore its value m is given to the control circuit 14. The control circuit 14 performs the above-mentioned data transfer m times based on the given value m of the video data Dk. As a result, the N-bit data transferred at each time from the first data transfer to the m-th data transfer is data in which at least 1-bit data is "1". The (m +
1) The data corresponding to the transfer from the 64th time to the 64th time is all “0” as described above, so such data transfer is not performed in the present embodiment. For example, when the data shown in Table 2 is stored in the buffer 21 (when the maximum video data is the video data D6 (= 6))
In, the control circuit 14 only performs the first to sixth data transfers.

In the thermal head 1, 1 is the voltage application time to the heating resistor 3 corresponding to the image data Dk corresponding to the dot having the maximum density in the scanning line,
M / 64 times the maximum voltage application time. At such a time, the printing of one scanning line is completed, and the printing process corresponding to the next scanning line can be started.

With such shortening of the printing time, the control circuit 14 gives the motor control circuit 22 a control signal corresponding to the maximum image data given from the maximum value detection circuit 17, and based on the given control signal, Motor control circuit 22 is pulse motor 23
The angular velocity of rotation of the platen 2 is
It changes according to the output of the maximum value detection circuit 17. That is, the printing speed is increased by the amount of the reduced number of data transfers.

As described above, in the present embodiment, the density of one dot varies depending on the change in the voltage application time to the heating resistor 3, for example,
Thermal printer 11 configured to change to 64 gradations
When a video signal for one field is printed as a still image, the maximum value of the video data D1 to DN of one scanning line to be printed is detected by the maximum value detection circuit 17, and the detection result is detected by the control circuit. Given to 14. Control circuit
In 14, the data transfer is performed from the buffer 21 to the thermal head 1 as many times as the maximum value data given from the maximum value detection circuit 17, and at the same time, the platen 2 is rotationally driven corresponding to the maximum value data. Pulse motor
A control signal is supplied to the motor control circuit 22 that controls 23. As a result, the number of times of data transfer from the buffer 21 to the thermal head 1 does not necessarily have to be 64 times, and the printing speed of the thermal printer 11 is significantly improved.

As described above, according to the present invention, in a data transfer device in which a plurality of sets of data having a plurality of bit capacities are used as one transfer unit, the data of one transfer unit can be transferred without transferring all the data of the one transfer unit. If you transfer all the data,
The same effect can be obtained. As a result, the data transfer rate is significantly improved.

Further, according to the present invention, the maximum value of one line is detected in advance, and the number of times the signal is sent to the heating resistor is set by this maximum value. It can be stopped early.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic structure of a thermal printer 11 which is an embodiment of the present invention, and FIG. 2 is a sectional view showing the structure around the thermal head 1 of the thermal printer 11. 11 …… Thermal printer, 13 …… A / D conversion circuit, 14 ……
Control circuit, 16 ... Line memory, 17 ... Maximum value detection circuit, 18 ... Latch circuit, 19 ... Comparison circuit, 21 ... Buffer, D1-DN ... Video data

Claims (1)

[Claims] 1. A thermal printer which energizes and heats a heating resistor according to a video signal to be recorded, and records a plurality of sets of data having a plurality of bit capacities in a thermal printer, and transfers the data to the heating resistor as one line data. In the data transfer device, the line memory 16 that stores the input 1-line data
A maximum value detection circuit 17 for sequentially comparing input data and holding a larger data value in the latch circuit, and a buffer 21. Output from 1
And a control circuit 14 for converting the line data into voltage application data, storing the data in the buffer, and transferring the data stored in the buffer to the heating resistor by the number of times of maximum value data held in the latch circuit. A data transfer device characterized by the above.