JPH07123296B2 - Video printer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a video printer.

[Outline of Invention]

The present invention supplies a video signal to an A / D conversion circuit to convert it into a digital video signal, supplies a screen unit of the digital video signal to a memory for writing, and reads a line signal of the digital video signal from the memory. Are sequentially written in the buffer memory, line signals of the digital video signals read from the buffer memory are sequentially supplied to the line head, and the image is printed by the line head on the recording medium vertically moved by the motor. In the video printer, the horizontal and vertical address signals from the horizontal and vertical address counters provided in the control circuit are supplied to the memory, and the horizontal and vertical address counters of the horizontal and vertical address counters are supplied based on the horizontal and vertical sync signals separated from the video signals. By controlling the counting start timing respectively, the printing range of the line head on the recording medium can be controlled. By setting the start positions in the horizontal and vertical directions respectively, and controlling the count value of each of the different clock signals counted by the horizontal and vertical address counters, the counting end timing of the horizontal and vertical address counters is controlled respectively, The horizontal and vertical end positions of the printing range are set, the motor speed is switched, and the vertical length distortion of the printing range due to the control of the end timing of the horizontal address counter is corrected. By interlocking the switching of the start timing, the end timing and the rotation speed of the motor, the printing range of the image printed on the recording medium by the line head can be changed and the end timing of the horizontal address counter is controlled. It was made possible to correct the vertical length distortion of the printing range due to Than it is.

[Conventional technology]

Conventionally, a video signal is supplied to an A / D conversion circuit to be converted into a digital video signal, the digital video signal is supplied to a memory and written, and based on the digital video signal read from this memory, a head is used. There has been proposed a video printer that prints an image on a recording medium.

[Problems to be solved by the invention]

By the way, as an image to be printed on a recording medium by using such a video printer, there is a received television image, an image picked up by a television camera, or a reproduced image by these VTRs.

In this case, when the video signal portion except the synchronizing signal portion of the received television signal is directly supplied to this video printer and the image is printed on the recording medium, the portion outside the effective screen is printed with a black frame, and The width of the black frame may differ depending on the reception channel. Since such a black frame is unsightly, it is desirable that it is not printed.

In addition, when the image signal from the television camera is supplied to the video printer and the image is printed on the recording medium,
Since there may be valid information on the periphery of the image to be printed, in the case of such an image, it is desirable that the periphery is surely printed.

In view of such a point, the present invention proposes a video printer capable of varying the printing range of an image printed on a recording medium.

[Means for solving problems]

According to the present invention, a video signal is supplied to an A / D conversion circuit (5) to be converted into a digital video signal, and a screen unit portion of the digital video signal is supplied to a memory (7) to be written to the memory (7). The line signals of the digital video signals read out from the buffer memory (9) are sequentially written, and the line signals of the digital video signals read from the buffer memory (9) are sequentially supplied to the line head (16), which is driven by the motor (32). In a video printer in which an image is printed by the line head (16) on a recording medium RP that is transported in the vertical direction, horizontal and vertical address counters are provided, and horizontal and vertical addresses from the horizontal and vertical address counters are provided. A memory control circuit (8) for supplying a signal to the memory (7) and a horizontal and vertical sync signal based on the horizontal and vertical sync signals separated from the video signal. Start timing control means (19, 20) for respectively setting the horizontal and vertical start positions of the printing range of the line head (16) with respect to the recording medium RP by controlling the counting start timing of the address counter respectively, and horizontal and vertical The end timing for setting the horizontal and vertical end positions of the printing range by controlling the count end timing of the horizontal and vertical address counters respectively by controlling the count value of each different clock signal counted by the address counter. Control means (21,22)
And a rotation speed switching means (31) for switching the rotation speed of the motor (32) to correct the vertical length distortion of the printing range by the end timing control means (21, 22), and the start timing control means ( 19, 20), end timing control means (21, 22), and rotation speed switching means (31) are interlocked with each other, and switching means (24 to 30) are provided.

[Action]

According to the present invention, the start timing control means (19, 20) sets the horizontal and vertical start positions of the printing range, respectively, and the end timing control means (21, 22) sets the horizontal and vertical positions of the printing range. The end position in the vertical direction is set and the end timing control means (21, 2) is provided by the rotation speed switching means (31) for switching the rotation speed of the motor (32) for vertically moving the recording medium RP.
By controlling the counting end timing of the horizontal address counter in 2), the vertical length distortion of the printing range is corrected. Further, the start timing control means (19, 20), the end timing control means (21, 22) and the rotation speed switching means (31) are interlocked and switched by the switching means (24 to 30).

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIG. (1) is an input terminal to which a composite video signal from a TV tuner, a VTR or the like is supplied. The composite video signal supplied to the input terminal (1) is supplied to the variable gain amplifier circuit (2), and the contrast of the composite video signal is adjusted by adjusting the gain. When the composite video signal from the amplifier circuit (2) is a color video signal, the chromaticity signal is a trap circuit (3).
And the luminance signal alone is supplied to the clamp circuit (4). The clamp circuit (4) can change the brightness (brightness) of the video signal (brightness signal) by changing the clamp level. The composite video signal from the amplifier circuit (2) is supplied to the sync separation circuit (17), which separates the horizontal and vertical sync signals. And this sync separation circuit (17)
Is supplied to the clamp pulse generating circuit (18), and the clamp pulse obtained from the clamp pulse generating circuit (18) is supplied to the clamp circuit (4) to perform, for example, pedestal clamping.

The video signal from the clamp circuit (4) is supplied to the A / D conversion circuit (5), and only the video signal portion excluding the sync signal is, for example, a 5-bit digital video signal (32 gray scales). Video signal). This A / D conversion circuit (5)
Is supplied with the clock signal from the clock oscillator (6). The parallel 5-bit digital video signal obtained from the A / D conversion circuit (5) is supplied to the frame memory (7) and is printed by turning on the switch (23) connected to the memory control circuit (8). Written when there is a copy command. Writing and reading of this frame memory (7) are controlled by a memory control circuit (8). This memory control circuit (8) includes a sync separation circuit (1
The sync signal from 7) is supplied. The memory control circuit (8) includes horizontal and vertical address counters.

The horizontal address counter counts the clock signal from the clock oscillator (22), and the horizontal address signal obtained from this is supplied to the frame memory (7). The vertical address counter counts the horizontal sync signal from the sync separation circuit (17), and the vertical address signal obtained from this is supplied to the frame memory (7).

The digital video signals (digital still image signals) read out from the frame memory (7) in the same order as when they were written have a storage capacity of 1H (H is horizontal synchronization) of the digital video signals (640 × It is supplied to and written in a 5-bit buffer memory (9). This memory (9) is also controlled by the memory control circuit (8).

The digital video signal read from the memory (9) is supplied to the pulse width modulation (PWM) circuit (10) and modulated. This pulse width modulation circuit (10) is a digital comparator (11) to which the digital video signal from the memory (9) is supplied.
And a gray scale counter (12) which gives, for example, 31 gray scale reference level signals. This pulse width modulation circuit (10) is also controlled by the memory control circuit (8).

Then, the 32-gradation pulse width modulated video signal obtained from the pulse width modulation circuit (10) is supplied to the 640-stage shift register (13). A shift pulse is supplied to the shift register (13) from the memory control circuit (8). The 640 parallel outputs from the shift register (13) are supplied to the latch circuit (14). This latch circuit (1
A latch pulse is supplied to 4) from the memory control circuit (9). The 640 outputs from the latch circuit (14) are supplied to the thermal head (16) having 640 heating elements arranged in a line through the drive circuit (15), and each heating element (resistive heating element). The energization time for is controlled according to the pulse width. Then, a roll-shaped or sheet-shaped thermosensitive recording paper RP (see FIG. 2) is opposed to the head (16), and the recording paper is moved in a direction orthogonal to the arrangement direction of the heating elements of the head (16). So, on this recording paper,
Up to 640 according to the video signal supplied to the input terminal (1)
An image (still image) consisting of × 525 dots is printed.

In this case, a still image in which the direction orthogonal to the transfer direction is the horizontal direction and the transfer direction is the vertical direction is printed on the recording paper. If the frame memory (7) is read in the vertical direction instead of the horizontal direction,
A still image is printed on the recording paper in which the moving direction is horizontal and the direction orthogonal to the moving direction is vertical.

Then, a horizontal start pulse generation circuit (19) for controlling the counting start timing of the horizontal address counter of the memory control circuit (8) and a vertical start pulse generation circuit (20) for controlling the counting start timing of the vertical address counter.
And a vertical end pulse generation circuit (21) for controlling the counting end timing of the vertical address counter, and the synchronization signals (horizontal synchronization signal and vertical synchronization signal) from the synchronization separation circuit (17) are supplied to them. That is, the horizontal synchronizing signal from the common-purpose separation circuit 17 is the horizontal start pulse generating circuit (19)
The vertical sync signal from the sync separation circuit 17 is supplied to the vertical start pulse generation circuit (20) and the vertical end pulse generation circuit (21).

In (24) to (28), the range (here, rectangle) of the image printed on the recording paper RP is wide as shown by Pf in FIG. 2 (in this case,
640 × 525 dots) or as narrow as shown by Pn (in this case, for example, 616 × 505 dots), a changeover switch which is provided with a movable contact a, a wide side contact f, and a narrow side contact n. The movable contacts a are interlocked and switched to fixed contacts f and n having the same sign.

The horizontal start pulse generation circuit (19) obtains a start pulse generated immediately after the horizontal blanking period of the video signal supplied to the input terminal (1) and a start pulse delayed by a predetermined time from the horizontal blanking period. It is supplied to the fixed contacts f and n of the changeover switch (24), and the output of the movable contact a thereof is supplied to the horizontal address counter of the memory control circuit (8) to control the counting start timing.

The vertical start pulse generation circuit (20) obtains a start pulse generated immediately after the vertical blanking period of the video signal supplied to the input terminal (1) and a start pulse generated after a predetermined time delay from that, respectively. It is supplied to the fixed contacts f and n of the changeover switch (25) and the output of the movable contact a thereof is supplied to the vertical address counter of the memory control circuit (8) to control the timing for starting the counting.

In the vertical end pulse generation circuit (21), input terminal (1)
The start pulse generated immediately before the vertical blanking period of the video signal supplied to the terminal and the end pulse generated a predetermined time earlier than that are obtained, and the changeover switch (2
It is supplied to the fixed contacts f and n in 6), and the output of the movable contact a is supplied to the vertical address counter of the memory control circuit (8) to control the timing of the end of counting.

The clock oscillator (22) delays the counting end timing of the horizontal address counter of the memory control circuit (8),
Depending on whether the speed is increased, two high and low frequency clock signals Fn and Ff are generated and supplied to the fixed contacts f and n of the changeover switch (27), and the clock signal from the movable contact a is supplied to the memory control circuit. It is supplied to the horizontal address counter of (8) and counted.

Reference numeral (32) is a platen motor, and the platen is rotated by the motor (32) to transfer the recording paper RP shown in FIG. 2 as described above. (31) is a drive circuit for driving the motor (32), which generates two drive signals for rotating the motor (32) at two different rotation speeds,
Each of them is supplied to the fixed contacts f and n of the changeover switch (28) to correct the distortion of the vertical length of the image due to the difference in the clock frequency of the clock oscillator (22).

(29) is a switch control circuit for controlling the switching of each of the above-mentioned changeover switches (24) to (28), and each movable contact a thereof is fixed in accordance with ON / OFF of an ON / OFF switch (30) connected thereto. The contacts are switched to f and n.

According to such a video printer of the present invention, it is possible to change the printing range of the image printed on the recording medium. Therefore, when printing the received television image, when the printing range is narrow as shown by Pn in FIG. The print range may be widened as shown in Pf of FIG.

Although the printing range is variable in two steps in the above-described embodiment, it may be in multiple steps of three steps or more.

In this embodiment, the monochrome image is printed on the recording paper, but the color image may be printed.

Further, in this embodiment, the case where the thermal head is used as the head (16) has been described, but other heads such as an inkjet head, a laser head, an electrostatic head may be used.

〔The invention's effect〕

According to the present invention described above, the timing of starting and ending the counting of the horizontal and vertical address counters of the memory control circuit that supplies the horizontal and vertical address signals to the memory that writes the digital video signal in screen units and reads in line units. Since the control is performed in conjunction with each other, the printing range of the image printed on the recording medium by the line head can be changed. Further, according to the present invention, the number of rotations of the motor for vertically moving the recording medium is switched in association with the control of the timing of ending the counting of the horizontal address counter. It is possible to correct the distortion of the vertical length of the printing range due to the control of the.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram thereof. (5) is an A / D conversion circuit, (6) is a clock oscillator,
(7) is a frame memory, (8) is a memory control circuit,
(16) is a head, (19) is a horizontal start pulse generating circuit, (20) is a vertical start pulse generating circuit, (21) is a vertical end pulse generating circuit, and (24) to (28) are changeover switches.

Claims (1)

[Claims] 1. A line of a digital video signal read from the memory by supplying a video signal to an A / D conversion circuit to convert it into a digital video signal, supplying a screen unit of the digital video signal to a memory for writing. The signals are sequentially written in the buffer memory, the line signals of the digital video signals read from the buffer memory are sequentially supplied to the line head, and the image is printed by the line head on the recording medium vertically moved by the motor. In the above video printer, a horizontal and vertical address counter is provided, a memory control circuit for supplying the horizontal and vertical address signals from the horizontal and vertical address counter to the memory, and a horizontal and vertical synchronizing signal separated from the video signal. Based on the above, by controlling the counting start timing of the horizontal and vertical address counters respectively, By the start timing control means for setting the horizontal and vertical start positions of the printing range on the recording medium by the line head respectively, and the control of the count value of each separate clock signal counted by the horizontal and vertical address counters, respectively. End timing control means for controlling the counting end timings of the horizontal and vertical address counters respectively to set the horizontal and vertical end positions of the printing range, and the end timing control by switching the rotation speed of the motor. The rotation speed switching means for correcting the vertical length distortion of the printing range by the means, and the switching means for switching the start timing control means, the end timing control means and the rotation speed switching means in interlocking manner. Video printer characterized by.